Review of Pressurized Water Reactor Pressurizer Heater Operating
Experience (with Emphasis on Potential for Pressurizer Heater
Sheath Degradation)
by
Daniel B. Denis
An Engineering Project Submitted to the Graduate
Faculty of Rensselaer Polytechnic Institute
in Partial Fulfillment of the
Requirements for the Degree of
Master of Engineering
Major Subject: Engineering Science
Approved:
Ernesto Gutierrez-Miravete, Project Adviser
Rensselaer Polytechnic Institute
Hartford, CT
December, 2014
i
Table of Contents
List of Tables ..................................................................................................................................... 3
List of Figures .................................................................................................................................... 4
Acronyms ........................................................................................................................................... 5
Keywords ........................................................................................................................................... 6
Acknowledgements ............................................................................................................................ 7
Abstract.............................................................................................................................................. 8
1.0
2.0
Pressurizer Heater Introduction ................................................................................................. 1
1.1
Pressurizer Heater Operation ........................................................................................... 1
1.2
Pressurizer Heater Design ................................................................................................ 2
Stress Corrosion Cracking ......................................................................................................... 4
2.1
3.0
Reactor Coolant System Chemistry .................................................................................. 4
Pressurizer Heater Degradation ................................................................................................ 6
3.1
Sheath Degradation .......................................................................................................... 6
3.2
Sizewell B Incident............................................................................................................ 6
3.3
Industry Response ............................................................................................................ 7
4.0
Combustion Engineering Alloy 600 Pressurizer Heater Sleeves ................................................ 9
5.0
Pressurizer Heater Operating Experience ............................................................................... 14
5.1
Pressurizer Heater Operating Experience (1970-1985)................................................... 14
5.2
Pressurizer Heater Operating Experience (1986-1990)................................................... 20
5.3
Pressurizer Heater Operating Experience (1991-1995)................................................... 35
5.4
Pressurizer Heater Operating Experience (1996-2000)................................................... 43
5.5
Pressurizer Heater Operating Experience (2000-2005)................................................... 46
5.6
Pressurizer Heater Operating Experience (2006-2010)................................................... 52
5.7
Pressurizer Heater Operating Experience (2011-2014)................................................... 55
6.0
Summary and Conclusion ....................................................................................................... 58
7.0
References .............................................................................................................................. 59
ii
List of Tables
Table 1: Primary Chemistry Limits for RCS [4] ...................................................................................... 5
Table 2: Plants with Alloy 600 Pressurizer Sleeves and Year of Pressurizer Replacement ................... 9
iii
List of Figures
Figure 1: Schematic of Westinghouse Pressurizer [8] ........................................................................... 1
Figure 2: Typical Heater Cross-section [2] ......................................................................................... 2
Figure 3: Cartridge Heater (Note that pressurizer heaters typically use Type 316 stainless steel
sheaths) [2] ............................................................................................................................................ 2
Figure 4: Pressurizer with Inserted Heaters [2]...................................................................................... 3
Figure 5: Gordon Curve of Incidents of SCC of Austenitic Stainless Steel in High Temperature Water
by Oxygen and Chloride Concentration .................................................................................................. 5
Figure 6: Leak Site at Sizewell B [8] ...................................................................................................... 7
Figure 7: Failed Heater Elements from Sizewell B [8]............................................................................ 7
Figure 8: Axial Cracks in a Plant Heater [8] ........................................................................................... 8
Figure 9: Nickel-base Alloys in Combustion Engineering Pressurizers [3] .............................................. 9
iv
Acronyms
DMW
EPRI
IGSCC
MgO
Mg(OH)2
ppb
ppm
PWR
RCS
SCC
TGSCC
Dissimilar Metal Weld
Electric Power Research Institute
Intergranular Stress Corrosion Cracking
Magnesium Oxide
Magnesium Hydroxide
parts per billion
parts per million
Pressurized Water Reactor
Reactor Coolant System
Stress Corrosion Cracking
Transgranular Stress Corrosion Cracking
v
Keywords
Heater
Heater Well Inserts
Pressurizer
Pressurizer Heater
Pzr
Reactor Coolant System
Sheaths
Sleeves
Stress Corrosion Cracking
vi
Acknowledgements
I would like to thank Westinghouse Electric Company, Bob Lisowyj, Frank Gift, Dave Taylor, and
Damian Testa for their support. Westinghouse has contributed with its emphasis of my education and
on pressurizer heater events and future developments. Bob has provided frequent career advice and
has provided review of this document and other pressurizer heater projects in their entirety. Frank has
provided support for the RPI Master’s Program and has focused on the path of my technical and career
development. Dave and Damian (as the cognizant pressurizer heater engineer and manager,
respectively) have assisted with the gathering of pressurizer heater references and have reviewed
various pressurizer heater documentation.
I would like to thank Len, Lainey, and Jeffrey Denis for their unwavering support and for their
relentless insistence that this project work should be completed.
Finally, thanks are due to Ernesto Gutierrez-Miravete, for his unwavering support over the
school semesters and for his review and comments on this Master’s Project.
vii
Abstract
Pressurizer heaters have been utilized in Pressurized Water Reactors since original installation
to ensure that the primary reactor coolant system stay in liquid form without boiling. Because of the
function and relatively harsh environment of the heaters, they are highly redundant. Pressurizer
heaters have functioned throughout the plant lifetimes, but the Sizewell B pressurizer heater incident
brought additional attention to the potential for primary pressure boundary leakage.
There is much documented operating experience related to pressurizer heaters, but because
many past events did not result in immediate primary coolant leakage, effects of sheath failures were
not necessarily evaluated. This assessment evaluated prior pressurizer heater operating history to
determine if any previous events had the potential for sheath damage that could eventually lead to
heater degradation.
viii
1.0
1.1
Pressurizer Heater Introduction
Pressurizer Heater Operation
Pressurized water reactors (PWRs) maintain the coolant in liquid form, without boiling to create
a two phase system. Because of the temperature of the coolant (up to 650°F), it must be maintained at
a high pressure (2250 psia). Pressurizers are vessel components used at PWRs that function to
maintain the single phase by managing a steam bubble with the feedback of pressurizer heaters to add
heat to the system or spray valves to cool the system and reduce pressure.
The immersion heaters used to provide heat to the pressurizer contain electrical heating
elements, surrounded by an insulation material of magnesium oxide (MgO) and then protected from the
primary coolant by a stainless steel sheath. These heaters are inserted into the bottom shell of the
pressurizer through heater well inserts (HWIs) or sleeves.
Austenitic materials are limited by the ASME Boiler & Pressure Vessel Code to a temperature of
800°F to limit the possibility of time-dependent degradation such as creep [1]. However, because of
the nature of the immersion heaters to heat the pressurizer, the Code of Federal Regulations [7] has an
exception to allow operation of pressurizer heaters to allow the component to reach temperatures not
exceeding 900°F. The pressurizer heaters become one of the highest temperature components in the
reactor coolant system (RCS), with the exception of nuclear fuel and fuel cladding.
Figure 1: Schematic of Westinghouse Pressurizer [8]
1
1.2
Pressurizer Heater Design
The pressurizer heater sheaths are frequently made of stainless steel (typically Type 316) that
is swaged down around the heater elements (resistance heaters). Because of the cold work induced
by the swaging process, tensile residual stress exists at the outer diameter of the sheath material. A
magnesium oxide is used because of its dielectric properties and ability to be backed inside the sheath
material.
Figure 2: Typical Heater Cross-section [2]
Figure 2 and Figure 3 show the cross-sectional arrangement for heaters produced for
pressurizer heaters. Figure 4 shows the insertion of the heaters in the bottom of the pressurizer for
operation.
Figure 3: Cartridge Heater (Note that pressurizer heaters typically use Type 316 stainless steel sheaths)
[2]
2
Figure 4: Pressurizer with Inserted Heaters [2]
3
2.0
Stress Corrosion Cracking
Stress corrosion cracking (SCC) is a material degradation mechanism potentially associated
with austenitic stainless steels. Components in PWRs can be susceptible to SCC when three
conditions are met:
1. Susceptible material or material condition
2. Aggressive environment
3. Tensile operating stress
Elimination of any of these conditions will preclude the occurrence of SCC. Austenitic stainless steel is
susceptible to both intergranular stress corrosion cracking (IGSCC) and transgranular stress corrosion
cracking (TGSCC) under the appropriate conditions.
Austenitic stainless steel has a nominal (weight) composition of 18 chromium and 8 nickel. The
chromium provides corrosion protection and the nickel stabilizes the austenite.
IGSCC generally
occurs in austenitic stainless steels that have undergone sensitization by experiencing the temperature
range of 800°F-1,500°F [6].
During sensitization, the chromium that is present in the material
precipitates out of solution at grain boundaries as chromium carbides, which locally depletes the
chromium from the zone adjacent to the grain boundaries. This process reduces the resistance to
corrosion in an area around the boundary, allowing initiation of a crack that will propagate between the
grains and along the grain boundaries in IGSCC. Low carbon grades (e.g., 304L, 316L, etc, with limits
on carbon content of 0.035%) can often preclude sensitization, as less carbon is available to form the
chromium carbides along the grain boundary.
IGSCC can also occur with materials that are subject to cold work. The cold work increases the
strength of the material but also increases the susceptibility of the material to SCC. Stagnant flow
locations, where oxygen and chlorides can accumulate, can provide an area of increased susceptibility
for TGSCC to initiate and propagate across the grain boundaries.
(Note: For the purposes of this report, primary water stress corrosion cracking (PWSCC) is
considered to be associated with iron-nickel base alloys such as Alloy 600 and its associated weld
metals Alloy 82 and Alloy 182.)
2.1
Reactor Coolant System Chemistry
The bulk chemistry conditions for the primary reactor coolant system are defined by guidelines
provided by EPRI [1]. The limits are set for reactivity control, pH balance, and to limit the deleterious
effects from foreign contaminants for corrosion, neutron moderation, departure from nucleate boiling,
and worker dose rate control. The main contributors to SCC are dissolved oxygen and chlorides that
can accumulate in stagnant low-flow areas of the system, as shown by Figure 5.
4
Figure 5: Gordon Curve of Incidents of SCC of Austenitic Stainless Steel in High Temperature Water by
Oxygen and Chloride Concentration
The limits are imposed to reduce potential corrosion, degradation, and material interaction,
while maintaining appropriate limits for fuel moderation, criticality management, and fuel reliability.
Table 1: Primary Chemistry Limits for RCS [4]
Control Parameter
Chloride, ppb
Flouride, ppb
Sulfate, ppb
Lithium, ppm
Hydrogen, cc
(STP)/kg H2O
Dissolved Oxygen,
ppb
Action Level 1
Plant-specific
Plant-specific
Plant-specific
Plant-specific
<25
>50
>5
5
Action Level 2
>150
>150
>150
N/A
<15
Action Level 3
>1,500
>1,500
>1,500
N/A
<5>
>100
>1000
3.0
3.1
Pressurizer Heater Degradation
Sheath Degradation
Because of the cold working process, accumulated residual stress, the high temperature of the
heater, and the environment of primary water in the pressurizer, stainless steel pressurizer heater
sheaths are potentially susceptible to SCC, which can initiate and propagate in the stainless steel
material. The construction of the heater makes this degradation especially problematic, as water
ingress through the sheath can wet the MgO insulation. MgO is hygroscopic, absorbing water to
change from MgO to magnesium hydroxide (Mg(OH)2), accompanied by a volume change that can
exacerbate sheath cracks and rupture the sleeve of the heater.
Accompanying the water ingress, the electrical system of the heater will generally cease to
function, shutting down the heater and reducing the overall plant pressurizer heater margin. There
may be some amount of incubation time between crack initiation and eventual rupture. Material failures
can eventually lead to pressure boundary leakage, as a path is established between the primary
coolant in the pressurizer and the outer low alloy steel shell of the pressurizer.
An additional issue with ruptured and swollen heaters is that removal is non-trivial. The
expanded heaters exceed the prior dimensional tolerances, and the Mg(OH)2 insulation is difficult to
drill out of the heater. Electrical issues in heaters are a common occurrence and are not necessarily
indicative of any material concerns outside of the heating element.
3.2
Sizewell B Incident
On March 16, 2010 the Sizewell B high radiation alarms were triggered in the containment
building. The reactor coolant system was leaking at a rate of 4.5 L/min, which triggered the high
radiation alarms. The leak was from one of the seventy-eight pressurizer heater wells. The leak was
marginally agove the Technical Specifications limit that required under safety protocol to shut down the
reactor, which was safely shutdown March 17, 2010. An axial crack (approximately 13mm) was located
on the heater well insert of a pressurizer heater [14].
The Sizewell B pressurizer has two horizontal support plates for the heaters. Between 2000
and 2010, a total of ten heaters became non-functional. Although the electrical non-functionality was
observed, a potential root cause could have been sheath degradation. The failure mechanism for
sheath degradation was reported as stress corrosion cracking in the stainless steel sheath material. As
the crack propagated, the heater sheath was breached, allowing water to make contact with the
magnesium oxide (MgO) insulation of the heater, which undergoes a reaction to transform to
magnesium hydroxide (MgOH2). Figure 6 shows the leak site, and Figure 7 shows the degraded
heaters with insulation emerging from the sheath.
6
Figure 6: Leak Site at Sizewell B [8]
Three heaters were found with significant mechanical damage in addition to the heater
associated with the leak. These heaters (and thirteen heaters that were electrically non-functional)
were removed from the pressurizer. The electrically non-functional heaters had ceased function over
thirteen previous years, beginning in 1997. The heater of concern was electrically non-functional and
then suffered sheath failure within an eighteen month cycle. Seventeen total heaters were removed.
Figure 7: Failed Heater Elements from Sizewell B [8]
3.3
Industry Response
Currently, the industry recommends that non-functional heaters be removed from service at the
“next convenient opportunity”, which is considered to be the next refueling outage. There is currently
7
no technique to definitively demonstrate that a non-functional heater has only been damaged
electrically. Many plants respond different to the occurrence of a non-functional heater, and there is
currently no standard plan in the industry for addressing such issues. Figure 8 shows an axial crack
in a heater from an operating plant.
Figure 8: Axial Cracks in a Plant Heater [8]
8
4.0
Combustion Engineering Alloy 600 Pressurizer Heater Sleeves
Original fabrication of many pressurizers for the Combustion Engineering domestic fleet used
Alloy 600 nickel-base material for pressurizer heater sheaths. As a general best practice to replace
pressure boundary Alloy 600, many pressurizers were replaced. For the units that also had Alloy 600
sheath material heaters, new heaters with stainless steel sheath material were introduced. Table 2 lists
the CE designed plants with the status of their pressurizer replacement.
Figure 9: Nickel-base Alloys in Combustion Engineering Pressurizers [3]
Table 2: Plants with Alloy 600 Pressurizer Sleeves and Year of Pressurizer Replacement
Plant
Fort Calhoun Station
Maine Yankee*
Calvert Cliffs Unit 1
Calvert Cliffs Unit 2
St. Lucie Unit 1
St. Lucie Unit 2
Millstone Unit 2
San Onofre Unit 1*
San Onofre Unit 2*
San Onofre Unit 3*
*Unit currently decommissioned or without plan for restart
9
Replaced
Yes
No
No
No
Yes
Yes
No
No
No
No
In the year 1988 at Palo Verde Unit 1,
Sheath Degradation Assessment:
At time of release of CE NPSD 555 (Task 585) of the Combustion Engineering Owners Group, a
survey was conducted to obtain information regarding pressurizer heater operating experience. Of low
watt density pressurizer heaters with Inconel Alloy 600 sheaths made by one manufacturer
(Manufacturer A), the plants Palisades, Fort Calhoun, St. Lucie Unit 1, and Millstone Unit 2 returned
survey results. Of the 432 heater population of these plants, six heaters were reported to be electrically
non-functional. (No sheath assessment has been specifically performed as these Alloy 600 heaters
were subsequently replaced. The electrical non-functionality may have been indicative of sheath
degradation.)
Ninety-six Alloy 600 sheath heaters were constructed by one manufacturer (Manufacturer B)and
supplied to Arkansas Nuclear One Unit 2. Twenty-three of these heaters were non-functional when
energized in Air. Two additional non-functional heaters were since reported. (No sheath assessment
has been specifically performed as these Alloy 600 heaters were subsequently replaced. The electrical
non-functionality may have been indicative of sheath degradation.)
Twenty-nine Alloy 600 sheath heaters that were constructed by one manufacturer (Manufacturer
C) were delivered as replacements for Arkansas Nuclear One Unit 2 to replace twenty-three nonfunctional heaters that were replaced in 1982 (ans two replacement heaters were electrically nonfunctional in 1985). In April of 1987 a leaking heater sleeve was verified at the X1 position. The X1
and T4 heaters have ruptured sheaths and heater AA1 was electrically non-functional. Locations X1
and T4 were subsequently plugged. The remaining twenty-one heaters from Manufacturer C were
removed and replaced with six spare heaters and fifteen sleeve plugs.
From May 1985 until February 1990, no issues with high watt density pressurizer heaters with
alloy 600 sheaths were reported.
High watt density pressurizer heaters with Type 316 stainless steel sheaths. No issues from
December 1987 through February 1990 were reported for Palo Verde Unit 3. Non-functional heaters
were reported for Waterford Unit 3 (9 heaters) and St. Lucie Unit 2 (1 heater). San Onofre Unit 3 and
Palo Verde Unit 2 both experienced pressurizer heater sheath degradation.
San Onofree Unit 3 reported heater issues (two with “ruptured sheaths”, two with “cracked
sheaths”, and two with “internal problems”.
In February 1997 at Tricastin Unit 1,
Sheath Degradation Assessment:
At Chooz B2
In the year 2000 at Civaux 1,
Sheath Degradation Assessment:
In November 2002 at Paluel 3,
Sheath Degradation Assessment:
10
On November 4, 2003 at Three Mile Island Unit 1, the pressurizer lower bundle was identified
as leaking due to PWSCC of Alloy 600 material and its associated weld metals Alloy 82 and Alloy 182.
The lower bundle was replaced during T1R15 [12].
Sheath Degradation Assessment: As this plant is of B&W design, this assessment is not applicable.
11
From December 2004 through February 2005, four replacement heaters (replacement “A” for
this discussion) at Palo Verde in the proportional heater banks failed. On May 23, 2005, Palo Verde
replaced nine heaters with new heaters (replacement “B” for this discussion). During the next heatup,
five replacement “A” heaters in the backup heater banks failed. All remaining replacement “A” heaters
were replaced with replacement “B” heaters [11] [12].
Sheath Degradation Assessment: Although electrically non-functional, there was an apparent failure
point that was traced to manufacture that could have been connected with the potential for a sheath
breach. The higher resulting temperature from the manufacturing issue would have been a negatively
contributor to SCC. All heaters were replaced, so no potentially compromised heaters are in the primary
system.
During the spring 2005 outage, Waterford Unit 3 replaced twenty-nine heaters with replacement
heaters, two replaced heaters had partial ejection of epoxy, six experienced failure due to grounding,
and several experienced martial melting of the seal at the bottom of the receptacles. Twenty-three
heaters were replaced with different heaters while the remaining six heaters were electrically
disconnected [11] [12].
Sheath Degradation Assessment: Although electrically non-functional, there was an apparent failure
point that was traced to manufacture that could have been connected with the potential for a sheath
breach. The higher resulting temperature from the manufacturing issue would have been a negatively
contributor to SCC. Because the heaters are still in the RCS, a sheath breach with coolant penetrating
to the insulation could potentially create an issue with heater swelling.
In April 2006 at Braidwood Unit 1, a boric acid leak was traced to the upper socket weld of the
#52 pressurizer heater coupling.
Sheath Degradation Assessment:
As was previously discussed, the Sizewell B incident on March 16, 2010 resulted in external
leakage that caused a forced shutdown of the unit.
Sheath Degradation Assessment: Significant sheath degradation was observed a led to pressure
boundary leakage.
On March 19, 2010 at Surry Unit 2, pressurizer heater group “A” did not energize when
demanded both automatically and manually using the heater breaker control switch.
Sheath Degradation Assessment: The operating experience report does not clearly indicate that the
heaters were subsequently energized. Electrical non-functionality in the heater may be indicative of
degradation of the heater sheath. Potential sheath degradation may be evident.
On March 29, 2010 at Robinson Unit 2, the on/off indication for pressurizer heater backup group
“B” was non-functional. The control power fuses for the feeder breaker 52/6B were replaced.
Sheath Degradation Assessment: Although electrical issues can be indicative of sheath degradation,
the successful subsequent operation of the heaters indicates that sheath degradation is unlikely.
On April 5, 2010, at Millstone Unit 2, the pressurizer heaters would not reset until the
“Pressurizer Heater Selector Switch” was placed to “channel Y”.
Sheath Degradation Assessment: Although electrical issues can be indicative of sheath degradation,
the successful subsequent operation of the heaters indicates that sheath degradation is unlikely.
On May 9th, 2010 at Fort Calhoun Station, non-functional heaters were identified. Heater
number 26 was determined to have a sheath crack and other heaters were determined to not have
sheath cracking.
Sheath Degradation Assessment: The non-functional heater was determined to have a sheath
breach, while other non-functional heaters did not (at time of removal) have sheath breaches. Non-
12
functional heaters have potential susceptibility for sheath degradation.
On May 27, 2010 at St. Lucie Unit 1, six non-functional pressurizer heaters were identified that
were the result of deterioration of epoxy potting within the connection assembly.
Sheath Degradation Assessment: Although the apparent root cause was the epoxy on the
connection assembly, electrical non-functionality in the heater itself may be indicative of degradation of
the heater sheath. Potential sheath degradation may be evident.
On June 6th, 2010 at Oconee Unit 2 (B&W), a main breaker was tripped for teh Unit 2 Bank 2
Group D heaters.
Sheath Degradation Assessment: Assessment of B&W heaters is not within the scope of the current
evaluation.
On June 22, 2010 at Catawba Unit 2, a blackout bus resulted in a loss of power to a Technical
Specification required train of pressurizer heaters.
Sheath Degradation Assesssment: The blackout bus is not associated with the heater itself and
therefore sheath degradation is unlikely.
On July 22, 2010 at Palisades, a pressurizer heater breaker was found tripped during
containment entry.
Sheath Degradation Assessment: The breaker trip is separate from the heater itself and therefore
sheath degradation is unlikely.
On August 24, 2010 at Catawba Unit 2, experienced a pressurizer spray flow actuation.
Sheath Degradation Assessment: Because the spray actuation is not associated with the pressurizer
heaters, sheath degradation is unlikely.
On August 4th, 2010 at Robinson Unit 2, Pressurizer Heater B4 tripped.
Sheath Degradation Assessment: It is assumed that the backup heater was subsequently restarted
(and is functional) and because of the normal operation of the heater group, degradation of the sheath
is unlikely. Permanent electrical non-functionality is associated with potential for sheath degradation,
and these heaters could be monitored for future electrical issues that may be indicative of sheath
degradation.
At North Anna Unit 1 on October 13, 2010, Pressurizer Heater Group #5 tripped.
Sheath Degradation Assessment: It is assumed that the heater group was subsequently restarted
and because of the normal operation of the heater group, degradation of the sheath is unlikely.
Permanent electrical non-functionality is associated with potential for sheath degradation, and these
heaters could be monitored for future electrical issues that may be indicative of sheath degradation.
At Three Mile Island Unit 1 on August 22, 2012, an unisolable leak in the upper pressurizer
heater bundle diaphragm plate was found. The root cause was determined to be PWSCC of the Alloy
600 material used in construction. The bundle was replaced and further Alloy 600 is planned to be
replaced [13]. A similar leak was noted in the lower bundle in 2003.
Sheath Degradation Assessment: As this plant is of B&W design, this assessment is not applicable.
13
5.0
Pressurizer Heater Operating Experience
Because the Sizewell B incident was extremely severe relative to the leak rate and the unplanned
outage duration, 2010 re-emphasized the importance of maintaining the integrity of the pressurizer
heater sheath. There are many issues in operating experience that have been documented relative to
the pressurizer heater, but the emphasis on sheath degradation was not at the same level when many
of these instances occurred.
This project reviews nuclear industry operating experience from a variety of sources to determine
the potential for latent sheath degradation in incidents that have occurred during plant operation during
over 45 years of plant operation.
5.1
Pressurizer Heater Operating Experience (1970-1985)
On October 22, 1974, at Prairie Island Unit 1, the pressurizer heater supply breaker would not
close. The breaker was repaired and put into service. [ICES Report #343]
Sheath Degradation Assessment: Because the breaker is separate from the heater, sheath
degradation is unlikely.
On October 15, 1975, at San Onofre Unit 1, an SCR failed for current phase B of pressurizer
heater group “A”. The SCR was subsequently replaced. [ICES Report #1158]
Sheath Degradation Assessment: Because the SCR is separate from the heater, sheath degradation
is unlikely.
On April 15, 1979, at Connecticut Yankee Unit 1, an indicator light for the auto-shutoff for the
pressurizer heater failed. The light source was replaced. [ICES Report #4867]
Sheath Degradation Assessment: Because the light source is separate from the heater, sheath
degradation is unlikely.
On September 11, 1981, at Connecticut Yankee Unit 1, pressurizer group “E” would not energize
at plant startup. A dirty contact on a breaker prevented operation. The contacts were subsequently
cleaned with contact spray. [ICES Report #7746]
Sheath Degradation Assessment: Because the breaker contacts are separate from the heater,
sheath degradation is unlikely.
On February, 22, 1982, at Kewaunee Unit 1, a low megger reading (insulation resistance) was
found on Group 1D during preventative maintenance. The connections were “dirty” and were therefore
cleaned and tightened. No information about a subsequent reading was given. [ICES Report #8467]
Sheath Degradation Assessment: Low insulation resistance has been thought to be associated with
a short between the sheath and the heater elements, potentially from water ingress due to sheath
degradation. Because no subsequent reading was given in the report, it is assumed that the low
megger reading might be an indication of potential sheath degradation.
On September 21, 1982, at David-Besse Unit 1, breaker BE106 opened causing MCCE12A to deenergized. Readings and test current showed that a heater in the bank was open. The breaker was
repaired. [ICES Report #9592]
14
Sheath Degradation Assessment: Because the breaker is separate from the heater, sheath
degradation is unlikely.
On March 26, 1983, at Farley Unit 2, the pressurizer heater group breaker did not auto close,
resulting in a high pressurizer level deviation. The operator attempted to close the breaker remotely
and with local hand switches without success. The micro switch was adjusted and the breaker tested
satisfactory and was returned to service.
Sheath Degradation Assessment: Because the switch and breaker are separate from the heater,
sheath degradation is unlikely.
On August 18, 1983, at Three Mile Island Unit 1, for the pressurizer “A” group, a failed light lit on
the controller for group 3. Heater number 23 of group 3 was found to have its threaded connection
melted and separated from the bundle. The remained of group 3 was returned to service at the time of
failure. In the 1990 outage all connectors for heaters were eliminated and replaced with a silver
soldered connect between the cable and heater element and the potted in a ceramic material. [ICES
Report #12137]
Sheath Degradation Assessment: As this plant is of B&W design, this assessment is not applicable.
On September 29, 1983, at Zion Unit 1, pressurizer heater backup group “C” breaker 137-3B
would not trip on signal. The defective amptector on breaker 137-3B was replaced. [ICES Report
#12585]
Sheath Degradation Assessment: Because the amptector is separate from the heater, sheath
degradation is unlikely.
On November 11, 1983, at Beaver Valley Unit 1, the pressurizer heater group A” bell alarm was
working intermittently. Because the bell assembly was dirty, the bell was cleaned and lubed. [ICES
Report #12957]
Sheath Degradation Assessment: Because the bell assembly is separate from the heater, sheath
degradation is unlikely.
On January 24, 1984, at North Anna Unit 2, the air flow switch on the pressurizer heater controller
failed, preventing control heater bank 3 from energizing. The loose wire was retightened and tested.
Heaters then energized and operated in a satisfactory manner, returned to service. [ICES Report
#14281]
Sheath Degradation Assessment: Because the air flow switch is separate from the heater, sheath
degradation is unlikely.
On February 11, 1984, at San Onofre Unit 2, the pressurizer heater circuit breaker would not
close or reset. The cause was a failed pressurizer heater element, with a repair scheduled for a future
outage. Electronic characterization and diagnostic testing found an open element with an unknown
cause. [ICES Report #14707]
Sheath Degradation Assessment: The failed heater element due to an unknown cause would
demonstrate a potential for sheath degradation that could have allowed for water ingress that
subsequently caused failure of the heater element. Also, because the heater was not immediately
replaced, there could be potential for a degraded sheath to remain installed. An installed degraded
heater could leak to issues with pressure boundary leakage.
On April 18, 1984, at St. Lucie Unit 1, the pressurizer backup heater circuit breaker would not
15
open or close due to sticking or binding of the trip unit. The breaker was replaced. [ICES Report
#16345]
Sheath Degradation Assessment: Because the circuit breaker is separate from the heater, sheath
degradation is unlikely.
On May 24, 1984, at Connecticut Yankee Unit 1, the group “A” pressurizer heater circuit breaker
would not control as required. Dirt on the X-relay caused binding movement which failed to operate the
close coil. The X-relay was replaced and the breaker cleaned. The generic problem with the breaker
design was identified at a later date. [ICES Report #17255]
Sheath Degradation Assessment: Because the circuit breaker and X-relay separate from the heater,
sheath degradation is unlikely.
On June 5, 1984, at Summer Unit 1, the pressurizer heater power panel back-up group 2 tripped
after installation. The breaker was replaced and operated satisfactorily. [ICES Report #17522]
Sheath Degradation Assessment: Because the power panel is separate from the heater, sheath
degradation is unlikely.
On July 7, 1984, Kewaunee Unit 1, the feeder breaker for a pressurizer heater kept tripping. The
fuse was subsequently replaced. [ICES Report #18367]
Sheath Degradation Assessment: Because the fuses are separate from the heater, sheath
degradation is unlikely.
On August 3, 1984, at North Anna Unit 1, pressurizer heater fuses were blown, due to high
temperature and resistance fatigue. The fuses were replaced and tested for operability and made
ready for service. [ICES Report #18972]
Sheath Degradation Assessment: Because the fuses are separate from the heater, sheath
degradation is unlikely.
On August 3, 1984, at North Anna Unit 2, an electrical connector failed due to a high temperature
and resistance fatigue. The connector was replaced and tested for operability and was ready for
service. [ICES Report #18974]
Sheath Degradation Assessment: It is unclear from the report where specifically the connector was
in relation to the heater. Although this incident does not seem to be associated with sheath
degradation, a localized elevated temperature for a heater (relative to nearby heaters) would be a
cause for concern in screening for susceptibility to SCC, as higher temperatures are at greater risk for
SCC relative to lower temperatures.
On August 14, 1984, at Surry Unit 2, the circuit breaker for pressurizer heater AB tripped and
would only reset for short duration. Fatigue of the breaker was determined to cause the failure. The
breaker was subsequently replaced. [ICES Report #19204]
Sheath Degradation Assessment: The breaker is separate from the heater, so sheath degradation is
unlikely.
On August 23, 1984, at North Anna Unit 2, a pressurizer heater electrical connector failed, due to
high temperature and resistance fatigue. A new connector was installed and tested for operability. The
circuit was tested and made ready for service. [ICES Report #19434]
Sheath Degradation Assessment: It is unclear from the report where specifically the connector was
16
in relation to the heater. Although this incident does not seem to be associated with sheath
degradation, a localized elevated temperature for a heater (relative to nearby heaters) would be a
cause for concern in screening for susceptibility to SCC, as higher temperatures are at greater risk for
SCC relative to lower temperatures.
On September 5, 1984, at St. Lucie Unit 2, a pressurizer heater breaker BRK-40304 tripped and
would not reset. The trip unit was found to be defective and replaced. The breaker was installed,
tested, and returned to service. [ICES Report #19746]
Sheath Degradation Assessment: The breaker is separate from the heater, so sheath degradation is
unlikely.
On September 16, 1984, at Farley Unit 2, a pressurizer heater breaker closing spring would not
charge. A charging motor model was shorted and was subsequently replaced to return the breaker to
service. [ICES Report #20000]
Sheath Degradation Assessment: The breaker is separate from the heater, so sheath degradation is
unlikely.
On September 21, 1984, at Connecticut Yankee Unit 1, the pressurizer heater control would not
calibrate. The resistors within the converter were replaced. [ICES Report #20112]
Sheath Degradation Assessment: The converter is separate from the heater, so sheath degradation
is unlikely.
On November 13, 1984, at St. Lucie Unit 2, a pressurizer heater breaker BRK-40304 would not
close and was mechanically bound. The closing mechanism was out of adjustment, was subsequently
adjusted, tested, and found to operate satisfactorily. [ICES Report #21603]
Sheath Degradation Assessment: The circuit breaker is separate from the heater, so sheath
degradation is unlikely.
On December 7, 1984, at Arkansas Nuclear One (ANO) Unit 2, a blown fuse and silicon controlled
rectifier (SCR) were found to be defective, possibly worn. The fuse, SCR, and diode were replaced.
[ICES Report #22349]
Sheath Degradation Assessment: Because the fuse, SCR, and diode are separate from the heater,
no sheath degradation is expected.
On March 1, 1985, at Arkansas Nuclear One (ANO) Unit 1, proportional heater T1 was nonfunctional due to a failed heater element. The defective element was drawing excessive current, which
blew fuses in the heater control circuitry. The root cause was “normal, expected wear”. The element
was replaced. [ICES Report #24929]
Sheath Degradation Assessment: As this plant is of B&W design, this assessment is not applicable.
On March 5, 1985, at Farley Unit 2, a pressurizer heater group would not energize due to a supply
breaker not properly closing. An open conductor was found and replaced to return the breaker to
service. [ICES Report #25031]
Sheath Degradation Assessment: The circuit breaker is separate from the heater, so sheath
degradation is unlikely.
On April 6, 1985, at Arkansas Nuclear One (ANO) Unit 1, pressurizer heater T1 became nonfunctional due to heater element number six in bank #28 and element eleven in bank #30. The plant is
17
of a B&W design. The root cause determined that the heater failure was due to “normal, expected
wear”. [ICES Report #26058]
Sheath Degradation Assessment: As this plant is of B&W design, this assessment is not applicable.
On April 25, 1985, at Waterford Unit 3, a heater was accidentally removed from service when a
loaded breaker was accidentally removed from maintenance, lowering the capacity of a pressurizer
heater bank from 150 kW to 100 kW, violating technical specifications. Work authorizations were made
to correct the issue. [ICES Report #277286]
Sheath Degradation Assessment: The circuit breaker is separate from the heater, so sheath
degradation is unlikely.
On June 20, 1985, at San Onofre Unit 1, defects were found in the pressurizer heater group “C”
backup breaker during preventive maintenance. Latch adjustement and lubrication were made to clear
up the issue. Over-torqueing of bolts by the vendor was an issue for the breaker. [ICES Report
#28593]
Sheath Degradation Assessment: The circuit breaker is separate from the heater, so sheath
degradation is unlikely.
On June 26, 1985, at San Onofre Unit 3, some bus bars were overheating, causing failure. Clips
were replaced and lugs tightened (crimped). In addition some lugs and stabs were replaced to bring
the item to proper service. [ICES Report #28785]
Sheath Degradation Assessment: The circuit breaker is separate from the heater, so sheath
degradation is unlikely.
On June 26, 1985, at San Onofre Unit 2, a low-power system for pressurizer heaters failed.
Some lugs and stabs were replaced to correct the issue and return to satisfactory operation. [ICES
Report #28796]
Sheath Degradation Assessment: The circuit breaker is separate from the heater, so sheath
degradation is unlikely.
On July 8, 1985, at Beaver Valley Unit 1, pressurizer heater back up group B supply breaker was
found out of specifications during maintenance. The power sensor (defective due to wear) was
replaced with a rebuilt sensor. [ICES Report #29146]
Sheath Degradation Assessment: The circuit breaker is separate from the heater, so sheath
degradation is unlikely.
On August 16, 1985, at St. Lucie Unit 2, circuit breaker 40302 would not close as indicated in the
control room. A defective overload device was replaced, tested, and found to be satisfactory. [ICES
Report #30418]
Sheath Degradation Assessment: The circuit breaker is separate from the heater, so sheath
degradation is unlikely.
On September 11, 1985, at McGuire Unit 1, pressurizer heater group 1B was inoperable while
diesel generator 1A was inoperable. McGuire has four banks of heaters (A, B, C, and D). A breaker for
group 1B was tripped, rendering the bank inoperable and placed the Unit in Action Statement C of the
technical specifications (3.8.1.1). The diesel generator was returned to operable to remedy the
situation. No further mention of the heaters was made in the report, with the assumption that they were
later brought back to service from the breaker trip. [ICES Report #278472]
18
Sheath Degradation Assessment: The circuit breaker and the diesel generator are separate from the
heater, so sheath degradation is unlikely.
On September 25, 1985, at Indian Point Unit 3, a circuit breaker from heater backup group
number 31 was unable to be closed from the control room. Maintenance personnel adjusted the
breaker for proper operation. [ICES Report #31710, #31619]
Sheath Degradation Assessment: The circuit breaker is separate from the heater, so sheath
degradation is unlikely.
On October 15, 1985, at San Onofre Unit 1, pressurizer heater group “A” control breaker tripped
and would not reset. A piece of the latching mechanism had broken off. Service was returned to the
bank by use of a spare breaker. The breaker was later repaired with replacement parts. [ICES Report
#32404]
Sheath Degradation Assessment: The circuit breaker is separate from the heater, so sheath
degradation is unlikely.
On October 29, 1985, at Byron Unit 1, a pressurizer heater breaker stab and conductors
overheated (Breaker 1RY03ED-B3) due to an improperly undersized stab. The breaker continued to
operate. The existing breakers were replace with a proper model to address the issue. [ICES Report
#32962, #32960]
Sheath Degradation Assessment: The circuit breaker is separate from the heater, so sheath
degradation is unlikely.
On November 6th, 1985, at Summer Unit 1, during routine preventive maintenance on the
pressurizer heater backup circuit breaker, after replacement of a broken cotter pin, the breaker would
not operate. This was during an outage. The charging motor brushes were replaced, the breaker was
cycled, and tested satisfactorily. [ICES Report #33301]
Sheath Degradation Assessment: The circuit breaker is separate from the heater, so sheath
degradation is unlikely.
On November 14, 1985 at Beaver Valley Unit 1, a circuit breaker to the pressurizer backup heater
(Group E ACB) was not functioning properly. The handle on the breaker was replaced and the closing
assembly was adjusted until proper operation was attained. [ICES Report #33592]
Sheath Degradation Assessment: The circuit breaker is separate from the heater, so sheath
degradation is unlikely.
19
5.2
Pressurizer Heater Operating Experience (1986-1990)
On January 23, 1986, at McGuire Unit 1, pressurizer heater control panel 1A was suspected of
having a blown fuse because of a low current flow. The blown fuse was found and replaced. [ICES
Report #36096]
Sheath Degradation Assessment: The breaker is separate from the heater, so sheath degradation is
unlikely.
On January 26, 1986, at McGuire Unit 1, a pressurizer heater bank alarmed the control room of
a loss of the #1 heater bank in Group A because the Y-Phase fuse to the heater was blown and a loose
wire connection existed for the heater group. The fuse was replaced and the loose connection was
tightened. [ICES Report #36182]
Sheath Degradation Assessment: The fuse and loose wire connection are separate from the heater,
so sheath degradation is unlikely.
On January 28, 1986, at Palo Verde Unit 1, a fire watch could not make the rounds to rooms
appropriately for various reasons. The areas affected included the unit pressurizer heater transformer
room and the Unit 2 pressurizer heater transformer room. [ICES Report #279650]
Sheath Degradation Assessment: The transformer rooms are separate from the heater, so sheath
degradation is unlikely.
On January 28, 1986, at Sequoyah Unit 1 (and Sequoyah Unit 2), a fire watch was unable to
complete his route because of various reasons. The areas included the unit 1 pressurizer heater
transformer room and the unit 2 pressurizer heater transformer room. [ICES Report #279652]
Sheath Degradation Assessment: The transformer rooms are separate from the heater, so sheath
degradation is unlikely.
On February 18, 1986, at Kewaunee Unit 1, a broken tab was found on the circuit breaker
switch for pressurizer heater group 1C because of an end to life due to age. The circuit breaker was
replaced. [ICES Report #36954]
Sheath Degradation Assessment: The breaker is separate from the heater, so sheath degradation is
unlikely.
On March 3, 1986, at D.C Cook Unit 2, the safety pins in the fire door 316 protecting the
pressurizer heater transformer room were in place with no personnel in the area, making the fire door
inoperable. The issue was corrected in procedures. [ICES Report #279934]
Sheath Degradation Assessment: The pressurizer heater transformer fire door is separate from the
heater, so sheath degradation is unlikely.
On April 7, 1986, at Surry Unit 1, the pressurizer heater circuit breaker 1B12 had tripped. After
resetting it continued to trip because of a short in the breaker. The breaker was replaced. [ICES Report
#38994]
Sheath Degradation Assessment: The breaker is separate from the heater, so sheath degradation is
unlikely.
On April 7, 1986, at Arkansas Nuclear One Unit 2, a 480 V breaker supplying power for
pressurizer heater bank #6 was removed from service and was found to be inoperable due to a broken
right phase contact assembly. The two secondary disconnects, operator mechanism, base and contact
20
molding, and contact assembly were replaced. The breaker tested satisfactorily and was returned to
service. [ICES Report #38967]
Sheath Degradation Assessment: The breaker is separate from the heater, so sheath degradation is
unlikely.
On April 10, 1986, at Byron Unit 1, during pressurizer heater surveillance, the variable heaters
failed to register any current flow because the pressure control card in the variable heater circuit went
bad. Therefore, the failed card was replaced and the bad card was shelved for repair. [ICES Report
#39118]
Sheath Degradation Assessment: The pressure control card is separate from the heater, so sheath
degradation is unlikely.
On May 6, 1986, at Farley Unit 2, the group “A” pressurizer heater breaker would not close
because the breaker trip shaft was out of adjustment. The trip shaft was adjusted, verified for proper
operation, and returned to service. [ICES Report #40118]
Sheath Degradation Assessment: The breaker is separate from the heater, so sheath degradation is
unlikely.
On May 22, 1986, at San Onofre Unit 1, maintenance was requested to investigate the cause of
pressurizer heater group “A” control breaker tripping free. The breaker would trip free on automatic
closure, but would close on manual signal. Amptector mounting bolts were too long, impeding the
latching mechanism. Previous modifications may have contributed to issues. The amptector mounting
bolts were replaced with new bolts, the breaker was tested and returned to service. [ICES Report
40721]
Sheath Degradation Assessment: The amptector mounting bolts are separate from the heater, so
sheath degradation is unlikely.
On June 2, 1986, at Arkansas Nuclear One Unit 1, the control room received a pressurizer
heater ground fault alarm for proportional heater bank II, group #14. The heater bank short was
possibly caused by heat and moisture, but the root cause is uncertain. The grounded heater was
removed from service (disconnected). [ICES Report #41089]
Sheath Degradation Assessment: As this plant is of B&W design, this assessment is not applicable.
On June 7, 1986, at St. Lucie Unit 1, a routine observation indicated that pressurizer heater #2
on the 1B bank was not working. Circuit breaker 40302 was tripped and would not reset due to
mechanical binding of the linkage. Adjustment and realignment of the breaker linkage was made. The
breaker was tested and operated satisfactorily. [ICES Report #41306]
Sheath Degradation Assessment: The breaker is separate from the heater, so sheath degradation is
unlikely.
On June 16, 1986, at Callaway Unit 1, while measuring and recording the phase currents of
pressurizer heater banks number 5, number 6, and number 27, phase “B” of the feeder breaker gave
no reading. The breaker was found to be open on the “B” phase. A new breaker was installed, and
heater megger readings were acceptable. [ICES Report #41522]
Sheath Degradation Assessment: The breaker is separate from the heater, so sheath degradation is
unlikely.
On June 26, 1986, at San Onofre Unit 2, infrared inspection of the pressurizer heater
21
distribution panel was performed to investigate possible overheating of the bus bars. The investigation
found bad connections on bucket to bus bars, causing “extreme” overheating. The clips were replaced
and the lugs were tightened (crimped). Some lugs and stabs were replaced, verification of power to the
panel was performed and the item was satisfactorily returned to service. [ICES Report #42075]
Sheath Degradation Assessment: The distribution panel is separate from the heater, so sheath
degradation is unlikely.
On August 12, 1986, at McGuire Unit 2, the plant tripped when an individual accidentally
“bumped” the main supply breaker. Included in the incident was pressurizer heater group B tripped.
The circuit was reset and a protective cover was put in place to avoid the a similar incident in the future.
[ICES Report #281319]
Sheath Degradation Assessment: The main supply breaker is separate from the heater, so sheath
degradation is unlikely.
On August 13, 1986, at San Onofre Unit 1, the pressurizer heater group “C” backup breaker
would not close on signal from control room because the investigation found a piece of broken arc
chute was jammed between the control relay contacts, keeping the relay from closing. The arc chute
piece was removed and a new piece was installed, tested, and returned to service. [ICES Report #
43724
Sheath Degradation Assessment: The breaker is separate from the heater, so sheath degradation is
unlikely.
On September 25, 1986, at St. Lucie Unit 2, the control panel for pressurizer heater bank circuit
breaker 40303 would trip a few minutes after energizing because a relay was defective due to fatigue.
A new relay was installed, and the breaker was tested and returned to service. [ICES Report #45208]
Sheath Degradation Assessment: The breaker is separate from the heater, so sheath degradation is
unlikely.
On October 1, 1986, at Arkansas Nuclear One Unit 2, there was no power to the 1 pressurizer
heater bank because the circuit breaker was cycling (but there was no output from the controller) due to
the silicon controlled rectifier being out of calibration, and three fuses were blown. The fuses were
replaced and the SCR was calibrated. [ICES Report #45404]
Sheath Degradation Assessment: The breaker is separate from the heater, so sheath degradation is
unlikely.
On November 6, 1986, at San Onofre Unit 1, the pressurizer heater group “A” control breaker
was unable to be closed electrically after the breaker was reracked due to a broken latching
mechanism. The latching lever was replaced, the breaker was tested and returned to service. [ICES
Report #46681]
Sheath Degradation Assessment: The breaker is separate from the heater, so sheath degradation is
unlikely.
On November 6, 1986, at Sequoyah Unit 2, pressurizer heater circuit breaker (off 2A-A
shutdown board) would not open from main control room handswitch when the breaker was closed
because possibly the relay coil burned up due to normal wear. The relay was replaced, the fuses and
fuses holders were cleaned, and the breaker was returned to service. [ICES Report #46683]
Sheath Degradation Assessment: The breaker is separate from the heater, so sheath degradation is
unlikely.
22
On November 16, 1986, at San Onofre Unit 1, the breaker for pressurizer heater group “A”
could not be opened because the auxiliary switch linkage had come loose preventing the breaker from
opening. The linkage was reset and the breaker was returned to service. [ICES Report #46975]
Sheath Degradation Assessment: The breaker is separate from the heater, so sheath degradation is
unlikely.
On November 17, 1986, at Sequoyah Unit 1, pressurizer heater backup group 1B-B was
operating erratically because the main toggle pin for mechanical mechanism pivoting broke due to
frequent operation of the breaker. The main toggle pin was replaced and the breaker was returned to
service. [ICES Report #47012]
Sheath Degradation Assessment: The toggle pin is separate from the heater, so sheath degradation
is unlikely.
On November 21, 1986, at Racho Seco Unit 1, pressurizer heaters in the bundle were damaged
because the pressurizer level monitoring system was incorrectly reading the water level in the
pressurizer, which caused the heaters to energize inappropriately. [ICES Report #282106]
Sheath Degradation Assessment: As this plant is of B&W design, this assessment is not applicable
On November 29, 1986, at Sequoyah Unit 2, pressurizer heater 2A would not open, after
closing, until manually tripped because the mechanical pivot arm that actuated the auxiliary contacts
was loose. The pivot arm was tightened to actuate the auxiliary contacts. [ICES Report #47482]
Sheath Degradation Assessment: The pivot arm is separate from the heater, so sheath degradation
is unlikely.
On November 29, 1986, at Arkansas Nuclear One Unit 1, pressurizer heater number 3 in the
lower heater bundle had termination problems. The element had a loose terminal and a broken
ceramic insulator. The damaged termination could not be repaired. The heater element was
disconnected. [ICES Record #47487]
Sheath Degradation Assessment: As this plant is of B&W design, this assessment is not applicable
On December 8, 1986, at San Onofre Unit 1, there were breaker trips on pressurizer heater
group “A” control because the “first toggle leve” had a broken piece. The broken piece was replaced
and the breaker was adjusted, tested, and returned to service. [ICES Report #47783]
Sheath Degradation Assessment: The toggle lever is separate from the heater, so sheath
degradation is unlikely.
On January 15, 1987, at Three Mile Island Unit 1, an open circuit was found on element 34 of
group 5 heaters. The connector on element number 34 in the middle of the bundle was faulty. It was
potentially due to high temperature but not confirmed because all connectors experience the same
temperature. During the 1990 refueling outage, all heater connectors were removed and replaced with
a silver soldered connection between the cable and the heater element that was then potted in a
ceramic material. [ICES Report #48967]
Sheath Degradation Assessment: As this plant is of B&W design, this assessment is not applicable.
On January 21, 1987, at Farley Unit 2, the breaker for pressurizer heater group “A” (breaker
“EA-11”) would not automatically charge when racked in. The auxiliary contact and the motor cut off
switch were dirty because of expected wear and aging. The contacts and cut off switch were cleaned
23
and proper breaker operation was verified. [ICES Report #49177]
Sheath Degradation Assessment: The auxiliary contact and motor cut off switch were separate from
the heater, so sheath degradation is unlikely.
On February 1, 1987, at Arkansas Nuclear One Unit 2, the pressurizer heater controllers would
not synchronize because a rectifier on the “B” phase of the 1 controller was shorted, so the rectifier was
replaced and the controllers were synchronized. [ICES Report #49546]
Sheath Degradation Assessment: The rectifier is separate from the heater, so sheath degradation is
unlikely.
On February 9, 1987, at Sequoyah Unit 2, the 2C pressurizer heater breaker failed the physical
inspection portion of surveillance because the trip coil had burned up due to normal wear. The trip coil
was replaced and all circuits in the breaker were checked for shorts or grounds. The limit switch was
cleaned and the breaker was returned to service. [ICES Report #49781]
Sheath Degradation Assessment: The trip coil and the limit switch are separate from the heater, so
sheath degradation is unlikely.
On February 15, 1987, at McGuire Unit 1, pressurizer heater bank “B” failed its quarterly
capacity test. Three fuses were found to be blown in the group “B” circuits. The fuses were replaced
and the heaters passed the capacity test. [ICES Report #49978]
Sheath Degradation Assessment: The fuses are separate from the heater, so sheath degradation is
unlikely.
On March 31, 1987, at McGuire Unit 1, pressurizer heater bank “B” went out of service when
rainwater got into the breaker panel and blew fuses. The panel was dried and the fuses were replaced.
[ICES Report #51654]
Sheath Degradation Assessment: The breaker panel and fuses are separate from the heater, so
sheath degradation is unlikely.
On April 15, 1987, at San Onofre Unit 3, the pressurizer heater backup bank feeder breaker
tripped. The breaker was replaced with an appropriately rated breaker and returned to service. [ICES
Report #52243]
Sheath Degradation Assessment: The breaker is separate from the heater, so sheath degradation is
unlikely.
On April 18, 1987, at Sequoyah Unit 2, the pressurizer heater control group 2D breaker arcing
contact was cracked due to normal wear. The contact was replaced and the contact bolts were
torqued. The breaker was closed three times to ensure proper seating. [ICES Report #52347]
Sheath Degradation Assessment: The breaker is separate from the heater, so sheath degradation is
unlikely.
On April 19, 1987, at Sequoyah Unit 2, the pressurizer heater control group 2D closing time was
too fast. The bridge pivot pressure was out of adjustment, so the pressure was adjusted to obtain
acceptable opening and closing times, and the item was returned to service. [ICES Report #52360]
Sheath Degradation Assessment: The breaker is separate from the heater, so sheath degradation is
unlikely.
24
On April 20, 1987, at Sequoyah Unit 1, the breaker for pressurizer heater control group 1D was
closing too fast, due to normal wear. The opening and closing time was adjusted to meet surveillance
criteria, and the item was returned to service. [ICES Report #52382]
Sheath Degradation Assessment: The breaker is separate from the heater, so sheath degradation is
unlikely.
On April 22, 1987, at Arkansas Nuclear One Unit 2, a degraded sheath was confirmed leading
to a leak rate of 60 drops per minute. Stress corrosion cracking of the heater sheath was determined,
allowing water to react with magnesium oxide insulation which expanded on hydration and ruptured the
“X1” and “T4” heater sleeves. The “X1” heater was damaged severely enough to produce an external
leak through the welded sleeve fitting. The “X1” and “T4” heaters were removed and plugs were
installed (RAC 2-87-050) [ICES Report #52488]
Sheath Degradation Assessment: This issue was determined to have been caused from degradation
of a heater sheath.
On May 31, 1987, at Diablo Canyon Unit 1, pressurizer heater group 1-3 circuit breakers 5 and
5R and 1 and 1R were found tripped open. The failure was attributed to an open heater. The circuit
breakers were left open and the failed (non-functional) heater will be determined during the next unit
shutdown, or heater maintenance. [ICES Report #54038]
Sheath Degradation Assessment: This heater may have become non-functional due to sheath
degradation, as no root cause was determined. The future plan for mitigating any issue has only vague
details with regard to specific resolution.
On June 23, 1987, at Vogtle Unit 1 pressurizer heater bank “D” did not automatically energize
when pressure dropped to the low pressurizer pressure setpoint. An operational check of bank “D” was
performed by repeatedly automatically energizing the bank. During subsequent trips the bank properly
energized. The reactor tripped from a main turbine trip from a main generator trip. [ICES Report
#283756]
Sheath Degradation Assessment: The main turbine and main generator are separate from the
heater, so sheath degradation is unlikely.
On July 6, 1987, at Arkansas Nuclear One Unit 2, a primary reactor coolant system pressure
boundary leak was discovered at the pressurizer heater weld. The leakage was approximately three
drops per minute and was documented on RAC 2-87-095. There was a personnel error in the welding
process that led to a lack of fusion between the weld filler material and the base metal. Five heaters
were cut out and plugs were removed and replaced by new plugs per a plant design change package.
[ICES Report #55367]
Sheath Degradation Assessment: The weld in question was not specifically mentioned. Leakage
can be associated with sheath degradation, so the removal of the heaters mitigates the potential issue
associated with heater insulation swelling and causing primary leakage.
On July 8, 1987, at Diablo Canyon Unit 2, pressurizer heater group 24 was found to have a
ground. The failure was attributed to loose pigtail connections on the charging motor and a ground
sensor relay. The motor and relay were replaced, and the breaker was returned to service. [ICES
Report #55435]
Sheath Degradation Assessment: The motor and relay are separate from the heater, so sheath
degradation is unlikely.
25
On August 19, 1987, at San Onofre Unit 3, the pressurizer heater backup heater circuit breaker
tripped. The breaker and the lugs were damaged beyond repair and caused by previous maintenance.
The breaker was replaced with a new one. The bus leads to the breaker were repaired and returned to
service. [ICES Report #56789]
Sheath Degradation Assessment: The breaker and lugs are separate from the heater, so sheath
degradation is unlikely.
On September 20, 1987, at North Anna Unit 1, a pressurizer heater was found grounded. The
cause of failure was unknown and “normal aging” was suspected. The heater was repaired and
successfully returned to service. [ICES Report #57963]
Sheath Degradation Assessment: The specifics were not provided in the report about how the
heater was repaired and whether it was replaced or modified. A non-functional heater may convey the
potential for a degraded heater sheath. Although repair removed from the heater may not be
associated with sheath degradation, the specifics for this incident were not clearly delineated.
On October 9, 1987, at Byron Unit 1, the 10 amp supply fuse blew when the control switch for
the pressurizer heater backup group “B” contactor control was closed. The contactor coils were found
burned so that the breaker would not work. All of the coils and blown fuses were replaced. The circuit
tested satisfactory. [ICES Report #58642]
Sheath Degradation Assessment: The breaker is separate from the heater, so sheath degradation is
unlikely.
On October 9, 1987, at St. Lucie Unit 1, the feeder breaker for pressurizer heater transformer
1A3 would not close when operated from the control room. The fuses were cleaned, and the breaker
was successfully tested and returned to service. [ICES Report #58670]
Sheath Degradation Assessment: The breaker is separate from the heater, so sheath degradation is
unlikely.
On November 5, 1987, at Indian Point Unit 3, the breaker for pressurizer heater number 33
would not remain in the closed position. A loose wire from the shunt trip coil was found. The loose wire
was reattached, retested, and put pressurizer heater group number 33 back in service.
Sheath Degradation Assessment: The breaker is separate from the heater, so sheath degradation is
unlikely.
On November 26, 1987, at St. Lucie Unit 2, long term trip screws were out of adjustment,
tripping the pressurizer heater circuit breakers at a thermal temperature of 40 degrees. The overloads
were changed out and the air gap on the long term trip paddle was adjusted. [ICES Report #60490]
Sheath Degradation Assessment: The trip screws are separate from the heater, so sheath
degradation is unlikely.
On December 17, 1987, at Palo Verde Unit 3, following a trip, a relay/contact (94/CNTR)
assembly did not operate properly which resulted in the Class 1E pressurizer heaters continuing to
remain energized below the low level trip setpoint. The relay/contact assembly was replaced and the
heaters were verified to be operating properly. [ICES Report #285167]
Sheath Degradation Assessment: Although initial sheath damage is unlikely, continued potential
operation at greater than design temperatures would be a contributor to increased susceptibility to
stress corrosion cracking and associated sheath degradation.
26
On December 17, 1987, at Palo Verde Unit 3, a pressurizer heater did not energize as required
due to a malfunction following a reactor trip. The report is incomplete. The root cause was associated
with a deviation in positioning of two control element assembly subgroups. [ICES Report #295171]
Sheath Degradation Assessment: Although the details are unclear, the control element assembly
subgroups and electronic controls for the heater are separate from the heater, so sheath degradation is
unlikely.
On December 22, 1987, at Sequoyah Unit 2, an abnormality indicated that pressurizer heater
backup group “2A-A” would not trip electrically. The spring that kicks the closing lever back was
adjusted and the arc chute assembly was replaced. The breaker was verified to be operating properly.
[ICES Report #61433]
Sheath Degradation Assessment: The breaker is separate from the heater, so sheath degradation is
unlikely.
On January 12, 1988, at Diablo Canyon Unit 2, the pressurizer heater group 4 circuit breaker
failed to close upon demand from the control room. The cause was unknown but the breaker bench
tested satisfactorily, the auxiliary contact stabs were cleaned and the breaker was returned to service.
[ICES Report #62134]
Sheath Degradation Assessment: The breaker is separate from the heater, so sheath degradation is
unlikely.
On January, 16, 1988, at North Anna Unit 1, the number 4 pressurizer heater breaker would not
close on demand from the control room. The close button on the breaker was sticking shut. The
contacts were cleaned and lubricated, and the breaker tested satisfactorily. [ICES Report #62283]
Sheath Degradation Assessment: The breaker is separate from the heater, so sheath degradation is
unlikely.
On January 21, 1988, at Davis-Besse Unit 1, pressurizer heater bank 2 would not energize from
the control room manually. Manual operation from the auxiliary shutdown panel was attempted but also
unsuccessful. A faulty relay in a circuit breaker was discovered. In addition, blown fuses were found
on the primary and secondary sides of the control transformer. The defective relay was replaced and
the circuit was tested, found operable, and returned to service. [ICES Report #62467]
On February 28, 1988, at Zion Unit 1, the pressurizer backup heater circuit breaker for bank “C”
heaters would not open with the control switch in the off position. The breaker would not open even
with attempts locally. Electricians cleaned, overhauled, and lubricated the backup heater’s circuit
breaker. [ICES Report #63928]
Sheath Degradation Assessment: The breaker is separate from the heater, so sheath degradation is
unlikely.
On March 7, 1988, at Trojan Unit 1, an operator noticed pressurizer heater breaker B-1029 was
tripped while performing rounds and again noticed it on March 9, 1988. The failure was due to the
breaking heating up as a result of high resistance, and tripping on thermal overload. Although the
cause of the high resistance was unknown, the breaker was replaced and returned to service. [ICES
Report #64253]
Sheath Degradation Assessment: The breaker is separate from the heater, so sheath degradation is
unlikely.
27
On March 11, 1988, at Davis-Besse Unit 1, pressurizer heater Bank #2 would not energize from
the control room. A fuse was blown on the primary side of the control transformer. The cause was
unknown, and the pressurizer heater system was scheduled to be further revamped during the refueling
outage. [ICES Report #64417]
Sheath Degradation Assessment: An unknown issue preventing the energizing of a heater may be
associated with sheath degradation that caused short circuits within the heater system. Some heaters
may have common circuitry that can cause multiple issues. The non-resolution of the root cause of the
non-functional heaters may point to the potential for a degraded sheath.
On March 12, 1988, at St. Lucie Unit 2, a circuit breaker to backup bank “B2” kep tripping. A
dirty connection was noted and subsequently cleaned with “Scotch Brite”. The breaker was
reassembled and returned to service. [ICES Report #64495]
Sheath Degradation Assessment: The breaker is separate from the heater, so sheath degradation is
unlikely.
On March 28, 1988, at St. Lucie Unit 1, Pressurizer Heater backup bank “B-6” would not close.
Hot spots were found on the breaker and line starter connections, and the contacts were dirty and
pitted. The contacts were cleaned and the breaker test satisfactorily. [ICES Report #65102]
Sheath Degradation Assessment: The breaker is separate from the heater, so sheath degradation is
unlikely.
On March 30, 1988, at Palo Verde Unit 1, [ICES Report #285884]
On April 22, 1988, at San Onofre Unit 2, the pressurizer heater circuit breaker was found that
the “C” phase had no current flow. The breaker had an open circuit in the “C” phase, so it was
replaced, tested, and returned to service. [ICES Report #66104]
Sheath Degradation Assessment: The breaker is separate from the heater, so sheath degradation is
unlikely.
On April 27, 1988, at St. Lucie Unit 1, pressurizer heater bank “B6” supply breaker would not
reset. The stab was disassembled, repaired, cleaned, reinstalled, test, and returned to service. [ICES
Report #66300]
Sheath Degradation Assessment: The breaker is separate from the heater, so sheath degradation is
unlikely.
On May 13, 1988, at Farley Unit 1, when closure of the supply breaker for pressurizer heater
backup group “B” was attempted, the breaker would not close. Failure was attributed to a previous
repair. The contacts were placed in the normal closed position, verified, and returned to service. [ICES
Report #66920]
Sheath Degradation Assessment: The breaker is separate from the heater, so sheath degradation is
unlikely.
On May 25, 1988, at South Texas Unit 1, [ICES Report #286272]
On July 1, 1988, at San Onofre Unit 3, the pressurizer heater controller feeder breaker had a
faulty secondary disconnect. The disconnected piece part was replaced and was returned to service.
28
[ICES Report #68505]
Sheath Degradation Assessment: The breaker is separate from the heater, so sheath degradation is
unlikely.
On July 8, 1988, at Trojan Unit 1, an operator found group “B” pressurizer heater breaker
tripped while performing rounds. The breaker would trip at 100% and 90% of its rated 100 ampere
limit, so the breaker was replaced and returned to service. [ICES Report #68712]
Sheath Degradation Assessment: The breaker is separate from the heater, so sheath degradation is
unlikely.
On July 15, 1988, at Oconee Unit 2, the vacuum supply breaker for pressurizer heater group
“2J” was found tripeed after heater bank #4 neither responded in automatic nor manual mode of
operation. The breaker was reset and tested. [ICES Report #68896]
Sheath Degradation Assessment: As this plant is of B&W design, this assessment is not applicable.
On July 18,1988, at St. Lucie Unit 1, during preventive maintenance inspection, pressurizer
heater breaker PP-130-CKT-4 would not reset. The cause of the failure was unknown, but a new
breaker was installed, tested, and returned to service. [ICES Report #68999]
Sheath Degradation Assessment: The breaker is separate from the heater, so sheath degradation is
unlikely.
On July 18, 1988, at Diablo Canyon Unit 2, in hot shutdown a pressurizer heater isolation circuit
breaker repeatedly cycled while the heater control switch was in the off position. The closing coil was
out of alignment and sticking, causing the mechanism to “bound up”. The breaker was replaced with a
spare that tested satisfactorily. [ICES Report #68984]
Sheath Degradation Assessment: The breaker is separate from the heater, so sheath degradation is
unlikely.
On July 24, 1988, at Diablo Canyon Unit 2, the breaker for pressurizer heater group number 4
was tripped on overcurrent during cold shutdown when placing the group in service. The main contacts
of the breaker were damaged and the breaker was therefore replaced. [ICES Report #69174]
Sheath Degradation Assessment: The breaker is separate from the heater, so sheath degradation is
unlikely.
On July 29, 1988, at Wolf Creek Unit 1, the control room received a “pressurizer high level
deviation heater on” alarm and a “pressurizer heater group lock-out” alarm. Portions of the control
system failed low, and therefore the NCB-1 card was replaced.
Sheath Degradation Assessment: The NCB-1 card is separate from the heater, so sheath
degradation is unlikely.
On September 9, 1988, at Browns Ferry Unit 3,
On September 25, 1988, at Oconee Unit 3, a computation module failed that controlled the
pressurizer heaters. Operators bypassed the interlock to allow operation of the heaters and the static
multiplier was removed from service. A “like” replacement module was modified per instrument
procedure and installed in the cabinet. The multiplier was tested for proper operation successfully.
[ICES Report #71357]
Sheath Degradation Assessment: The multiplier module is separate from the heater, so sheath
29
degradation is unlikely.
On October 14, 1988, at Beaver Valley Unit 1, the pressurizer heater backup group “E” power
supply circuit breaker tripped during the overcurrent test. The power sensor was defective, so it was
replaced with a new model that tested satisfactorily. [ICES Report #72087]
Sheath Degradation Assessment: The power sensor is separate from the heater, so sheath
degradation is unlikely.
On October 16, 1988, at San Onofre Unit 1, a breaker for pressurizer heater group “C” backup
heater circuit breaker was found that the left movable pole was binding. The breaker was
disassembled and the main contact assembly was replaced. The arc contact gap was adjusted and the
breaker was reassembled. The breaker was functionally tested and returned to service. [ICES Report
#72145]
Sheath Degradation Assessment: The circuit breaker is separate from the heater, so sheath
degradation is unlikely.
On October 17, 1988, at Crystal River Unit 3,
On October 20, 1988, at Three Mile Island, a blown fuse was found related to failed pressurizer
heater elements. Insulation installed in 1986 caused heat accelerated degradation of these connectors,
which then caused insulation between the conductors to fail, allowing a short. The blown fuses were
replaced and in 1990, all of the cable to heater connectors were replaced with a silver soldered
connection which was then potted in a ceramic material. The insulation for the bundle flange was also
permanently removed. [ICES Report #72321]
Sheath Degradation Assessment: As this plant is of B&W design, this assessment is not applicable.
On November 20, 1988, at Arkansas Nuclear One Unit 1, the pressurizer heater
automatic/manual transfer relay failed to integrate up when placed in the “automatic” start position
during a surveillance test. The root cause of the failure was insulation breakdown within the relay coil
from a worn out relay card that allowed overload. The defective relay was removed and replaced and
proper operation was performed. [ICES Report #73528]
Sheath Degradation Assessment: As this plant is of B&W design, this assessment is not applicable.
On November 22, 1988, at San Onofre Unit 2, the pressurizer hater circuit breaker was found
tripped. The breaker had shorted out and upon reset it tripped accompanied by a loud pop and arcing
that propagated through the enclosure door seal. The shorted light socket and burnt lugs were
replaced, and the breaker tested as satisfactory. [ICES Report #73603]
Sheath Degradation Assessment: The circuit breaker is separate from the heater, so sheath
degradation is unlikely.
On December 8, 1988, at Arkansas Nuclear One Unit 1, there was a ground on one of the
circuit breakers to a pressurizer heater group, and the breaker would not remain energized. The
grounded cable’s leads were lifted so that the other heaters in the group would be operational. [ICES
Report #74192]
Sheath Degradation Assessment: As this plant is of B&W design, this assessment is not applicable.
However, an unknown root cause may be associated with an issue with sheath integrity.
30
On January 19, 1989, at St. Lucie Unit 1, [ICES Report #75624]
On January 20, 1989, at Arkansas Nuclear One Unit 1, [ICES Report #75665]
On January 20, 1989, at Arkansas Nuclear One Unit 1, [ICES Report #75676]
On January 20, 1989, at Arkansas Nuclear One Unit 1, [ICES Report #75703]
On January 21, 1989, at Arkansas Nuclear One Unit 1, [ICES Report #75706]
On January 21, 1989, at Arkansas Nuclear One Unit 1, [ICES Report #75708]
On January 24, 1989, at Palisades Unit 1, [ICES Report #75831]
On January 27, 1989, at Waterford Unit 3, [ICES Report #75944]
On January 28, 1989, at Three Mile Island Unit 1, [ICES Report #75982]
On February 26, 1989, at Three Mile Island Unit 1, [ICES Report #77254]
On March 1, 1989, at Three Mile Island Unit 1, [ICES Report #77351]
On March 21, 1989, at Calvert Cliffs Unit 2, [ICES Report #78171]
On March 21, 1989, at Calvert Cliffs Unit 2, [ICES Report #78170]
On March 27, 1989, at Sequoyah Unit 1, [ICES Report #78448]
On April 12, 1989, at Farley Unit 2, [ICES Report #79112]
On April 23, 1989, at Farley Unit 1, [ICES Report #79565]
On April 26, 1989, at Three Mile Island Unit 1, [ICES Report #79746]
On May 2, 1989, at Three Mile Island Unit 1, [ICES Report #79967]
On May 5, 1989, at Calvert Cliffs Unit 2, [ICES Report #296397]
On May 5, 1989, at Calvert Cliffs Unit 2, [ICES Report #296281]
On May 5, 1989, at Calvert Cliffs Unit 2, [ICES Report #80132
On May 15, 1989, at Salem Unit 1, [ICES Report #80579]
On May 15, 1989, at Farley Unit 2, [ICES Report #80582]
31
On May 23, 1989, at St. Lucie Unit 2, [ICES Report #80908]
On May 28, 1989, at Summer Unit 1, [ICES Report #81075]
On May 30, 1989, at Indian Point Unit 2, [ICES Report #81157]
On June 9, 1989, at Three Mile Island Unit 1, [ICES Report #81579]
On June 20, 1989, at Calvert Cliffs Unit 1, [ICES Report #296435]
On June 22, 1989, at Seabrook Unit 1, [ICES Report #288846]
On July 9, 1989, at Three Mile Island Unit 1, [ICES Report #82714]
On July 10, 1989, at Harris Unit 1, [ICES Report #82782
On July 13, 1989, at Sequoyah Unit 2, [ICES Report #82869]
On July 19, 1989, at North Anna Unit 1, [ICES Report #83091]
On July 24, 1989, at Three Mile Island Unit 1, [ICES Report #83194]
On July 31, 1989, at St. Lucie Unit 2, [ICES Report #83455]
On August 2, 1989, at St. Lucie Unit 2, [ICES Report #83523]
On August 15, 1989, at Calvert Cliffs Unit 1, [ICES Report #296431]
On September 23, 1989, at Oconee Unit 1, [ICES Report #85354]
On September 26, 1989, at Calvert Cliffs Unit 1, [ICES Report #296493]
On September 26, 1989, at Callaway Unit 1, [ICES Report #85465]
On September 27, 1989, at Three Mile Island Unit 1, [ICES Report #85559]
On November 1, 1989, at San Onofre Unit 2, [ICES Report #87073]
On November 7, 1989, at Diablo Canyon Unit 1, [ICES Report #87284]
On November 27, 1989, at Kewaunee Unit 1, [ICES Report #88059]
On December 7, 1989, at San Onofre Unit 1, [ICES Report #88510]
On January 26, 1990, at Crystal River Unit 3, [ICES Report #90207]
On January 30, 1990, at Surry Unit 1, [ICES Report #90368]
32
On February 8, 1990, at Crystal River Unit 3, [ICES Report #90707]
On February 28, 1990, at St. Lucie Unit 1, [ICES Report #91407]
On February 28, 1990, at St. Lucie Unit 1, [ICES Report #91406]
On March 7, 1990, at Oconee Unit 3, [ICES Report #91690]
On March 7, 1990, at Oconee Unit 3, [ICES Report #91691]
On March 7, 1990, at Oconee Unit 3, [ICES Report #91692]
On March 19, 1990, at Cook Unit 1, [ICES Report #92213]
On March 21, 1990, at Wolf Creek Unit 1, [ICES Report #92346]
On April 11, 1990, at Surry Unit 1, [ICES Report #93280]
On April 22, 1990, at Diablo Canyon Unit 2, [ICES Report #93759]
On April 25, 1990, at St. Lucie Unit 2, [ICES Report #93933]
On May 18, 1990, at Millstone Unit 3, [ICES Report #94904]
On May 23, 1990, at Surry Unit 2, [ICES Report #95101]
On May 27, 1990, at Turkey Point Unit 3, [ICES Report #95239]
On June 8, 1990, at Palisades Unit 1, [ICES Report #95694]
On June 9, 1990, at Palisades Unit 1, [ICES Report #296872]
On June 9, 1990, at South Texas Unit 1, [ICES Report #95751]
On June 25, 1990, at Calvert Cliffs Unit 1, [ICES Report #96340]
On June 27, 1990, at Indian Point Unit 3, [ICES Report #96419]
On July 2, 1990, at South Texas Unit 1, [ICES Report #96637]
On July 3, 1990, at Fort Calhoun Unit 1, [ICES Report #96678]
On July 4, 1990, at Millstone Unit 3, [ICES Report #96693]
On July 16, 1990, at Harris Unit 1, [ICES Report #97108]
On August 6, 1990, at St. Lucie Unit 1, [ICES Report #97714]
33
On August 23, 1990, at Comanche Peak Unit 1, [ICES Report #98336]
On August 23, 1990, at North Anna Unit 2, [ICES Report #98352]
On September 7, 1990, at Sequoyah Unit 1, [ICES Report #98844]
On September 11, 1990, at Sequoyah Unit 2, [ICES Report #291070]
On September 27, 1990, at Sequoyah Unit 2, [ICES Report #291142]
On October 3, 1990, at Cook Unit 2, [ICES Report #99891]
On November 5, 1990, at Sequoyah Unit 2, [ICES Report #101365]
On November 6, 1990, at South Texas Unit 1, [ICES Report #101395]
On November 13, 1990, at Oconee Unit 3, [ICES Report #101713]
On December 2, 1990, at Diablo Canyon Unit 1, a 480 volt circuit breaker for pressurizer heater
group 1-3 would not rack in and it exhibited excessive resistance. The failure was caused by a rough
grounding shoe because the silver surface was off in several places and the copper showing through
was worn and rough. Lubrication was applied to the breaker which brought it back to operating status.
The grounding shoe will be replaced during the next refueling outage. [ICES Report #102400]
Sheath Degradation Assessment: The circuit breaker is separate from the heater, so sheath
degradation is unlikely.
On December 28, 1990, at Indian Point Unit 2, while performing pressurizer heater control
maintenance during normal power operation, the output controller fluctuated when the chassis was
disturbed slightly. The controller was replaced and returned to service. [ICES Report #103390]
Sheath Degradation Assessment: The output controller is separate from the heater, so sheath
degradation is unlikely.
34
5.3
Pressurizer Heater Operating Experience (1991-1995)
On January 12, 1991, at Cook Unit 1, [ICES Report #291621]
On February 17, 1991, at St. Lucie Unit 1, [ICES Report #105493]
On March 3, 1991, at Palisades Unit 1, [ICES Report #106012]
On March 19, 1991, at South Texas Unit 1, [ICES Report #106712]
On March 28, 1991, Westinghouse technical bulletin 91-04 was issued [ICES Report #107136]
On April 1, 1991, at Oconee Unit 3, [ICES Report #107273]
On April 1, 1991, at Oconee Unit 3, [ICES Report #107309]
On April 3, 1991, at Beaver Valley Unit 1, [ICES Report #107402]
On April 8, 1991, at Trojan 1, [ICES Report #107641]
On May 6, 1991, at North Anna Unit 2, [ICES Report #108931]
On May 11, 1991, at Farley Unit 1, [ICES Report #109159]
On May 16, 1991, at Oconee Unit 1, [ICES Report #109418]
On May 24, 1991, at Sequoyah Unit 1, [ICES Report #109746]
On May 31, 1991, at Ginna Unit 1, [ICES Report #109985]
On June 3, 1991, at Harris Unit 1, [ICES Report #110075]
On June 20, 1991, at Beaver Valley Unit 1, [ICES Report #110651]
On July 15, 1991, at Fort Calhoun Unit 1, [ICES Report #111474]
On July 23, 1991, at Surry Unit 1, [ICES Report #292345]
On July 24, 1991, at Connecticut Yankee Unit 1, [ICES Report #111723]
On August 10, 1991, at Diablo Canyon Unit 1, [ICES Report #292411]
On August 13, 1991, at Cook Unit 2, [ICES Report #112342]
On August 19, 1991, at Oconee Unit 3, [ICES Report #112540]
On September 5, 1991, at North Anna Unit 2, [ICES Report #292494]
35
On September 20, 1991, at Oconee Unit 1, [ICES Report #113629]
On October 6, 1991, at Catawba Unit 1, [ICES Report #114388]
On October 10, 1991, at Diablo Canyon Unit 2, [ICES Report #114546]
On October 27, 1991, at Palo Verde Unit 3, [ICES Report #115291]
On October 27, 1991, at Palo Verde Unit 1, [ICES Report #115290]
On November 17, 1991, at Cook Unit 2, [ICES Report #116236]
On November 19, 1991, at San Onofre Unit 1, [ICES Report #116343]
On December 8, 1992, at Crystal River Unit 3, [ICES Report #117083]
On December 18, 1991, at Surry Unit 2, [ICES Report #117491]
On December 26, 1991, St. Lucie Unit 1, [ICES Report #117719]
On January 1, 1992, at Waterford Unit 3, [ICES Report #117868]
On January 2, 1992, at Surry Unit 1, [ICES Report #117930]
On January 2, 1992, at Surry Unit 1, [ICES Report #117929]
On January 2, 1992, at Surry Unit 1, [ICES Report #117938]
On January 3, 1992, at Surry Unit 1, [ICES Report #117983]
On January 9, 1992, at Palo Verde Unit 2, [ICES Report #118242]
On January 17, 1992, at Indian Point Unit 3, [ICES Report #118522]
On January 22, 1992, at South Texas Unit 2, [ICES Report #118738]
On January 24, 1992, at Trojan 1, [ICES Report #118882]
On February 14, 1992, at Ginna Unit 1, [ICES Report #119694]
On February 18, 1992, at Ginna Unit 1, [ICES Report #119837]
On March 3, 1992, at San Onofre Unit 3, [ICES Report #120582]
On March 5, 1992, at North Anna Unit 1, [ICES Report #120677]
On March 9, 1992, at McGuire Unit 2, [ICES Report #120888]
36
On March 12, 1992, at Commanche Peak Unit 1, [ICES Report #121024]
On March 25, 1992, at Waterford Unit 3, [ICES Report #121674]
On April 7, 1992, at Indian Point Unit 3, [ICES Report #122428]
On April 16, 1992, at Sequoyah Unit 2, [ICES Report #122987]
On May 13, 1992, at Ginna Unit 1, [ICES Report #124403]
On May 13, 1992, at St. Lucie Unit 2, [ICES Report #124420]
On May 15, 1992, at Farley Unit 2, [ICES Report #124529]
On May 26, 1992, at Farley Unit 2, [ICES Report #124912]
On May 26, 1992, at Farley Unit 2, [ICES Report #124971]
On May 31, 1992, at South Texas Unit 1, [ICES Report #125195]
On June 14, 1992, at San Onofre Unit 3, [ICES Report #125758]
On June 19, 1992, at Ginna Unit 1, [ICES Report #125950]
On June 21, 1992, at Three Mile Island Unit 1, [ICES Report #126009]
On July 2, 1992, at Sequoyah Unit 1, [ICES Report #126469]
On July 5, 1992, at Byron Unit 2, [ICES Report #126533]
On July 5, 1992, at Byron Unit 2, [ICES Report #126532]
On July 6, 1992, at Ginna Unit 1, [ICES Report #126573]
On July 22, 1992, at Calvert Cliffs Unit 1, [ICES Report #127160]
On August 3, 1992, at Calvert Cliffs Unit 2, [ICES Report #127558]
On September 13, 1992, at St. Lucie Unit 1, [ICES Report #128926]
On September 22, 1992, at Three Mile Island Unit 1, [ICES Report #129294]
On September 26, 1992, at Farley Unit 1, [ICES Report #129500]
On October 10, 1992, at Cook Unit 1, [ICES Report #130085]
On October 18, 1992, at Diablo Canyon Unit 1, [ICES Report #130443]
37
On October 21, 1992, at Sequoyah Unit 1, [ICES Report #130590]
On November 16, 1992, at Beaver Valley Unit 1, [ICES Report #131499]
On November 18, 1992, at Waterford Unit 3, [ICES Report #131564]
On November 25, 1992, at Indian Point Unit 3, [ICES Report #131781]
On December 1, 1992, at Zion Unit 2, [ICES Report #131960]
On December 3, 1992, at Arkansas Nuclear One Unit 1, [ICES Report #132029]
On December 13, 1992, at Farley Unit 1, [ICES Report #132318]
On December 22, 1992, at San Onofre Unit 2, [ICES Report #132611]
On December 30, 1992, at Crystal River Unit 3, [ICES Report #132741]
On January 19, 1993, at Ginna Unit 1, [ICES Report #133304]
On January 26, 1993, at Byron Unit 2, [ICES Report #133485]
On January 28, 1993, at Salem Unit 2, [ICES Report #133569]
On February 2, 1993, at Cook Unit 2, [ICES Report #133732]
On February 4, 1993, at Palo Verde Unit 3, [ICES Report #133795]
On February 4, 1993, at Palo Verde Unit 3, [ICES Report #133794]
On February 4, 1993, at Palo Verde Unit 3, [ICES Report #133796]
On February 9, 1993, at Surry Unit 1, [ICES Report #133924]
On February 11, 1993, at Turkey Point Unit 3, [ICES Report #133997]
On February 15, 1993, at Palo Verde Unit 3, [ICES Report #134070]
On February 17, 1993, at Palo Verde Unit 3, [ICES Report #134120]
On February 25, 1993, at Catawba Unit 1, [ICES Report #134340]
38
On February 27, 1993, at Byron Unit 1, [ICES Report #134362]
On February 28, 1993, at Byron Unit 1, [ICES Report #134382]
On March 2, 1993, at St. Lucie Unit 2, [ICES Report #134430]
On March 3, 1993, at St. Lucie Unit 2, [ICES Report #134474]
On April 23, 1993, at Ginna Unit 1, [ICES Report #136228]
On April 30, 1993, at Summer Unit 1, [ICES Report #136446]
On May 13, 1993, at Arkansas Nuclear One Unit 2, [ICES Report #136811]
On June 17, 1993, at McGuire Unit 2, [ICES Report #137639]
On June 26, 1993, at Comanche Peak Unit 1, [ICES Report #137827]
On July 3, 1993, at Sequoyah Unit 2, [ICES Report #137975]
On July 15, 1993, at Crystal River Unit 3, [ICES Report #138209]
On August 7, 1993, at Braidwood Unit 2, [ICES Report #138713]
On August 13, 1993, at Indian Point Unit 2, [ICES Report #138869]
On August 26, 1993, at Crystal River Unit 3, [ICES Report #139156]
On September 12, 1993, at Byron Unit 1, [ICES Report #139557]
On September 16, 1993, at Palisades Unit 1, [ICES Report #139685]
On September 20, 1993, at Connecticut Yankee Unit 1, [ICES Report #139770]
On September 23, 1993, at Peach Bottom Unit 2, [ICES Report #139863]
On September 25, 1993, at Farley Unit 2, [ICES Report #139939]
On October 5, 1993, at Diablo Canyon Unit 1, [ICES Report #140240]
On October 7, 1993, at Harris Unit 1, [ICES Report #140343]
On October 7, 1993, at Three Mile Island Unit 1, [ICES Report #140351]
On October 9, 1993, at Palisades Unit 1, [ICES Report #140391]
On October 13, 1993, at Crystal River Unit 3, [ICES Report #140523]
39
On October 13, 1993, at South Texas Unit 1, [ICES Report #140549]
On October 23, 1993, at Braidwood Unit 1, [ICES Report #140850]
On October 31, 1993, at Oconee Unit 1, [ICES Report #141074]
On December 6, 1993, at Crystal River Unit 3, [ICES Report #142034]
On December 8, 1993, at Palo Verde Unit 1, [ICES Report #142079]
On December 17, 1993, at St. Lucie Unit 1, [ICES Report #142259]
On December 27, 1993, at San Onofre Unit 3, [ICES Report #142462]
On January 4, 1994, at Palo Verde Unit 1, [ICES Report #142595]
On January 13, 1994, at South Texas Unit 1, [ICES Report #142836]
On January 24, 1994, at Calvert Cliffs Unit 2, [ICES Report #143115]
On February 4, 1994, at Millstone Unit 2, [ICES Report #143366]
On February 13, 1994, at South Texas Unit 2, [ICES Report #143548]
On February 24, 1994, at Calvert Cliffs Unit 1, [ICES Report #143785]
On February 28, 1994, at Oconee Unit 3, [ICES Report #143880]
On March 3, 1994, at Crystal River Unit 3, [ICES Report #143950]
On March 12, 1994, at Summer Unit 1, [ICES Report #144178]
On March 15, 1994, at Oconee Unit 3, [ICES Report #144247]
On March 16, 1994, at St. Lucie Unit 2, [ICES Report #144265]
On March 17, 1994, at Oconee Unit 3, [ICES Report #144290]
On March 21, 1994, at Calvert Cliffs Unit 1, [ICES Report #144384]
On March 30, 1994, at Braidwood Unit 1, [ICES Report #144632]
On April 20, 1994, at Calvert Cliffs Unit 1, [ICES Report #145209]
On May 31, 1994, at Davis-Besse Unit 1, [ICES Report #146182]
On June 16, 1994, at Diablo Canyon Unit 1, [ICES Report #146526]
40
On June 21, 1994, at Oconee Unit 1, [ICES Report #146630]
On July 6, 1994, at Calvert Cliffs Unit 1, [ICES Report #146877]
On August 5, 1994, at Diablo Canyon Unit 1, [ICES Report #147460]
On September 22, 1994, at Wolf Creek Unit 1, [ICES Report #148347]
On September 30, 1994, at Wolf Creek Unit 1, [ICES Report #148536]
On October 7, 1994, at Three Mile Island Unit 1, [ICES Report #148721]
On October 8, 1994, at Comanche Peak Unit 2, [ICES Report #148752]
On October 18, 1994, at Salem Unit 2, [ICES Report #149005]
On December 18, 1994, at St. Lucie Unit 2, [ICES Report #150199]
On February 7, 1995, at Davis-Besse Unit 1, [ICES Report #151103]
On February 14, 1995, at Calvert Cliffs Unit 1, [ICES Report #151274]
On March 7, 1995, at Callaway Unit 1, [ICES Report #151732]
On March 10, 1995, at Summer Unit 1, [ICES Report #151824]
On March 27, 1995, at North Anna Unit 1, [ICES Report #152180]
On April 8, 1995, at Fort Calhoun Unit 1, [ICES Report #152501]
On May 3, 1995, at Robinson Unit 2, [ICES Report #153052]
On May 8, 1995, at Indian Point Unit 3, [ICES Report #153136]
On June 8, 1995, at Ginna Unit 1, [ICES Report #153662]
On June 13, 1995, at Calvert Cliffs Unit 1, [ICES Report #153741]
On July 22, 1995, at San Onofre Unit 3, [ICES Report #154360]
On August 6, 1995, at Palisades Unit 1, [ICES Report #154579]
On August 8, 1995, at St. Lucie Unit 1, [ICES Report #154616]
On August 25, 1995, at St. Lucie Unit 1, [ICES Report #154873]
On August 8, 1995, at Oconee Unit 1, [ICES Report #154965]
41
On September 12, 1995, at Indian Point Unit 2, [ICES Report #155216]
On September 13, 1995, at Cook Unit 1, [ICES Report #155220]
On September 29, 1995, at Maine Yankee Unit 1, [ICES Report #155563]
On October 11, 1995, at Three Mile Island Unit 1, [ICES Report #155842]
On November 2, 1995, at Crystal River Unit 3, [ICES Report #156325]
On November 2, 1995, at Calvert Cliffs Unit 2, [ICES Report #156342]
On November 2, 1995, at South Texas Unit 2, [ICES Report #156344]
On November 8, 1995, at Fort Calhoun Unit 1, [ICES Report #156448]
On December 12, 1995, at Arkansas Nuclear One Unit 2, [ICES Report #157094]
42
5.4
Pressurizer Heater Operating Experience (1996-2000)
On January 9, 1996, at Braidwood Unit 2, [ICES Report #157503]
On February 7, 1996, at Kewaunee Unit 1, [ICES Report #157971]
On February 14, 1996, an NRC Information Notice was issue, [ICES Report #185100]
On May 1, 1996, at Diablo Canyon Unit 2, [ICES Report #159615]
On June 10, 1996, at Millstone Unit 3, [ICES Report #160251]
On July 27, 1996, at Salem Unit 2, [ICES Report #160784]
On July 31, 1996, at Prairie Island Unit 1, [ICES Report #160823]
On September 12, 1996, at Salem Unit 1, [ICES Report #161342]
On October 15, 1996, at Farley Unit 1, [ICES Report #161850]
On October 18, 1996, at Maine Yankee Unit 1, [ICES Report #161904]
On October 24, 1996, at Diablo Canyon Unit 2, [ICES Report #162004]
On November 15, 1996, at Palisades Unit 1, [ICES Report #162336]
On January 31, 1997, at Harris Unit 1, [ICES Report #163413]
On February 6, 1997, at Seabrook Unit 1, [ICES Report #163546]
On February 19, 1997, at Surry Unit 1, [ICES Report #163824]
On March 16, 1997, at Farley Unit 1, [ICES Report #164326]
On March 18, 1997, at Davis-Besse Unit 1, [ICES Report #164355]
On March 18, 1997, at Ginna Unit 1, [ICES Report #164373]
On March 23, 1997, at Sequoyah Unit 1, [ICES Report #164499]
On March 24, 1997, at Diablo Canyon Unit 1, [ICES Report #164519]
On April 8, 1997, at Waterford Unit 3, [ICES Report #164841]
On April 28, 1997, at Watts Bar Unit 1, [ICES Report #165246]
On May 3, 1997, at Oconee Unit 3, [ICES Report #165346]
43
On May 23, 1997, at Byron Unit 1, [ICES Report #165800]
On July 12, 1997 at Braidwood Unit 1, [ICES Report #166802]
On July 20, 1997, at Oconee Unit 2, [ICES Report #166952]
On July 27, 1997, at Byron Unit 1, [ICES Report #167097]
On September 3, 1997, at Byron Unit 1, [ICES Report #167780]
On December 18, 1997, at Indian Point Unit 3, [ICES Report #170021]
On December 18, 1997, at Indian Point Unit 3, [ICES Report #170027]
On March 3, 1998, at Ginna Unit 1, [ICES Report #171452[
On April 7, 1998, at North Anna Unit 2, [ICES Report #172226]
On April 14, 1998, at Calvert Cliffs Unit 1, [ICES Report #172389]
On April 17, 1998, at Calvert Cliffs Unit 1, [ICES Report #172440]
On May 5, 1998, at Catawba Unit 1, [ICES Report #172877]
On May 8, 1998, at Harris Unit 1, [ICES Report #172937]
On May 14, 1998, at Catawba Unit 1, [ICES Report #173060]
On May 14, 1998, at Palo Verde Unit 1, [ICES Report #173067]
On June 17, 1998, at Oconee Unit 1, [ICES Report #173783]
On July 6, 1998, at Catawba Unit 1, [ICES Report #174129]
On July 25, 1998, at Calvert Cliffs Unit 2, [ICES Report #174468]
On July 25, 1998, at Calvert Cliffs Unit 2, [ICES Report #174476]
On August 5, 1998, at Oconee Unit 3, [ICES Report #174638]
On September 1, 1998, at Davis-Besse Unit 1, [ICES Report #175062]
On September 8, 1998, at Summer Unit 1, [ICES Report #175229]
On December 15, 1998, at Oconee Unit 3, [ICES Report #177092]
On January 3, 1999, at Comanche Peak Unit 2, [ICES Report #177377]
44
On January 15, 1999, at Robinson Unit 2, [ICES Report #177424]
On January 18, 1999, at South Texas Unit 1, [ICES Report #177691]
On January 23, 1999, at Prairie Island Unit 1, [ICES Report #177791]
On January 24, 1999, at Oconee Unit 2, [ICES Report #177810]
On January 25, 1999, at North Anna Unit 2, [ICES Report #177832]
On February 16, 1999, at Summer Unit 1, [ICES Report #178208]
On March 16, 1999, at South Texas Unit 2, [ICES Report #178761]
On March 18, 1999, at Diablo Canyon Unit 2, [ICES Report #178821]
On April 28, 1999, at McGuire Unit 2, [ICES Report #179690]
On May 10, 1999, at Millstone Unit 3, [ICES Report #179930]
On May 11, 1999, at Summer Unit 1, [ICES Report #179965]
On May 12, 1999, at Oconee Unit 1, [ICES Report #179971]
On May 26, 1999, at Catawba Unit 1, [ICES Report #180248]
On June 4, 1999, at St. Lucie Unit 2, [ICES Report #180395]
On July 6, 1999, at South Texas Unit 1, [ICES Report #180901]
On October 20, 1999, at Oconee Unit 3, [ICES Report #182776]
On November 22, 1999, at San Onofre Unit 2, [ICES Report #183419]
45
5.5
Pressurizer Heater Operating Experience (2000-2005)
On January 13, 2000, at Vogtle Unit 2, [ICES Report #184191
On January 19, 2000, at Seabrook Unit 1
, [ICES Report #184293
On January 29, 2000, at North Anna Unit 2, [ICES Report #184466
On April 1, 2000, at South Texas Unit 2, [ICES Report #185570
On April 8, 2000, at Palo Verde Unit 3, [ICES Report #185734
On May 1, 2000, at Crystal River Unit 3, [ICES Report #186132
On May 15, 2000, at ANO Unit 2, [ICES Report #186407
On June 23, 2000, at Wolf Creek Unit 1, [ICES Report #187000
On July 22, 2000, at Calvert Cliffs Unit 2, [ICES Report #187413
On July 30, 2000, at ANO Unit 2, [ICES Report #187536
On July 30, 2000, at ANO Unit 2
, [ICES Report #187535
On August 28, 2000, at Crystal River Unit 3
, [ICES Report #188009
On September 10, 2000, at Calvert Cliffs Unit 1, [ICES Report #188233
On September 30, 2000, at North Anna Unit 2, [ICES Report #188651
On October 4, 2000, at Palo Verde Unit 2, [ICES Report #188723
On October 4, 2000, at Palo Verde Unit 2
, [ICES Report #188724
On October 17, 2000, at North Anna Unit 2, [ICES Report #188997
On October 17, 2000, at North Anna Unit 2
, [ICES Report #188990
On October 17, 2000, at Waterford Unit 3
, [ICES Report #188992
On October 19, 2000, at South Texas Unit 2, [ICES Report #189032
On October 22, 2000, at Fort Calhoun Unit 1
, [ICES Report #189090
On November 11, 2000, at Calvert Cliffs Unit 1, [ICES Report #189504
On December 15, 2000, at South Texas Unit 1
, [ICES Report #189998
On December 16, 2000, at Catawba Unit 1, [ICES Report #190008
On January 4, 2001, at ANO Unit 1, [ICES Report #190236
On January 13, 2001, at Oconee Unit 1, [ICES Report #190377
On February 13, 2001, at Farley Unit 1
, [ICES Report #190816
On February 17, 2001, at Oconee Unit 3
, [ICES Report #190876
On February 20, 2001, at Robinson Unit 2
, [ICES Report #190913
On March 23, 2001, at Millstone Unit 2, [ICES Report #191440
On March 24, 2001, at ANO Unit 1
, [ICES Report #191450
On March 27, 2001, at Fort Calhoun Unit 1, [ICES Report #191510
On April 28, 2001, at Oconee Unit 2
, [ICES Report #192063
On May 6, 2001, at Byron Unit 1, [ICES Report #192218
46
On May 7, 2001, at Oconee Unit 3, [ICES Report #192239
On June 6, 2001, at Oconee Unit 2, [ICES Report #192726
On July 4, 2001, at Oconee Unit 1, [ICES Report #193155
On July 31, 2001, at Callaway Unit 1, [ICES Report #193539
On September 30, 2001, at Palo Verde Unit 3, [ICES Report #194426
On October 11, 2001, at Catawba Unit 2, [ICES Report #194633
On October 12, 2001, at Three Mile Island Unit 1
, [ICES Report #194645
On November 12, 2001, at Oconee Unit 3, [ICES Report #195167
On November 12, 2001, at Oconee Unit 3
, [ICES Report #195164
On December 15, 2001, at Vogtle Unit 1, [ICES Report #195657
On December 31, 2001, at Salem Unit 2
, [ICES Report #195854
On January 16, 2002, at Summer Unit 1
, [ICES Report #196079
On February 19, 2002, at Millstone Unit 2, [ICES Report #196618
On February 19, 2002, at Millstone Unit 2
, [ICES Report #196610
On March 7, 2002, at Oconee Unit 1, [ICES Report #196907
On March 7, 2002, at Oconee Unit 3, [ICES Report #196909
On March 7, 2002, at Oconee Unit 2, [ICES Report #196908
On March 7, 2002, at Oconee Unit 1
, [ICES Report #196899
On April 1, 2002, at Oconee Unit 1
, [ICES Report #197338
On April 10, 2002, at Braidwood Unit 1, [ICES Report #197525
On April 15, 2002, at ANO Unit 2, [ICES Report #197614
On April 30, 2002, at ANO Unit 2, [ICES Report #197902
On April 30, 2002, at ANO Unit 2
, [ICES Report #197886
On May 5, 2002, at Sequoyah Unit 2
, [ICES Report #197991
On May 27, 2002, at Summer Unit 1, [ICES Report #198385
On May 28, 2002, at Summer Unit 1, [ICES Report #198405
On June 25, 2002, at INPO
, [ICES Report #198842
On August 27, 2002, at Kewaunee Unit 1, [ICES Report #199827
On September 19, 2002, at Point Beach Unit 1
On October 7, 2002, at ANO Unit 1
, [ICES Report #200174
, [ICES Report #200491
On October 15, 2002, at Oconee Unit 2
, [ICES Report #200683
On October 31, 2002, at Crystal River Unit 3
, [ICES Report #201001
On January 6, 2003, at Palo Verde Unit 3, [ICES Report #202001
On January 11, 2003, at Indian Point Unit 3, [ICES Report #202082
On March 1, 2003, at South Texas Unit 1, [ICES Report #202987
On March 1, 2003, at South Texas Unit 1, [ICES Report #202988
47
On March 4, 2003, at South Texas Unit 2, [ICES Report #203047
On March 29, 2003, at Palo Verde Unit 3, [ICES Report #203609
On March 29, 2003, at Palo Verde Unit 3, [ICES Report #203610
On March 29, 2003, at Palo Verde Unit 3
, [ICES Report #203600
On April 8, 2003, at Kewaunee Unit 1, [ICES Report #203828
On April 15, 2003, at INPO
, [ICES Report #203966
On July 15, 2003, at Kewaunee Unit 1, [ICES Report #205408
On August 7, 2003, at Kewaunee Unit 1, [ICES Report #205707
On August 11, 2003, at Calvert Cliffs Unit 2, [ICES Report #205742
On August 27, 2003, at ANO Unit 2
, [ICES Report #206018
On September 2, 2003, at Catawba Unit 1, [ICES Report #206130
On September 3, 2003, at Cook Unit 1, [ICES Report #206147
On October 2, 2003, at Palo Verde Unit 3, [ICES Report #206680
On October 5, 2003, at Catawba Unit 1, [ICES Report #206724
On October 11, 2003, at Millstone Unit 2, [ICES Report #206835
On October 15, 2003, at Palo Verde Unit 2, [ICES Report #206900
On October 15, 2003, at Palo Verde Unit 2
, [ICES Report #206889
On October 21, 2003, at South Texas Unit 1, [ICES Report #207013
On October 24, 2003, at Waterford Unit 3
, [ICES Report #207068
On October 26, 2003, at Waterford Unit 3, [ICES Report #207098
On November 2, 2003, at Millstone Unit 2
, [ICES Report #207197
On November 4, 2003, at Three Mile Island Unit 1
, [ICES Report #207234
On November 7, 2003, at Catawba Unit 1, [ICES Report #207291
On November 26, 2003, at Cook Unit 1, [ICES Report #207565
On January 23, 2004, at Calvert Cliffs Unit 2
, [ICES Report #208333
On January 23, 2004, at Calvert Cliffs Unit 2
, [ICES Report #208333
On February 4, 2004, at Kewaunee Unit 1, [ICES Report #208659
On February 4, 2004, at Kewaunee Unit 1, [ICES Report #208659
On February 10, 2004, at Calvert Cliffs Unit 1, [ICES Report #208749
On February 10, 2004, at Calvert Cliffs Unit 1, [ICES Report #208749
On February 29, 2004, at Palo Verde Unit 3, [ICES Report #209045
On February 29, 2004, at Palo Verde Unit 3
, [ICES Report #209042
On February 29, 2004, at Palo Verde Unit 3, [ICES Report #209045
On February 29, 2004, at Palo Verde Unit 3
, [ICES Report #209042
On March 8, 2004, at Oconee Unit 2, [ICES Report #209186
On March 8, 2004, at Oconee Unit 2, [ICES Report #209186
48
On April 7, 2004, at Diablo Canyon Unit 1
, [ICES Report #209708
On April 7, 2004, at Diablo Canyon Unit 1
, [ICES Report #209708
On April 24, 2004, at ANO Unit 1
, [ICES Report #210000
On April 24, 2004, at ANO Unit 1
, [ICES Report #210000
On May 8, 2004, at Robinson Unit 2
, [ICES Report #210260
On May 8, 2004, at Robinson Unit 2
, [ICES Report #210260
On May 11, 2004, at Braidwood Unit 2, [ICES Report #210293
On May 11, 2004, at Braidwood Unit 2, [ICES Report #210293
On May 21, 2004, at Salem Unit 2, [ICES Report #210443
On May 21, 2004, at Salem Unit 2, [ICES Report #210443
On August 25, 2004, at Palo Verde Unit 2, [ICES Report #211809
On August 25, 2004, at Palo Verde Unit 2, [ICES Report #211809
On September 25, 2004, at Braidwood Unit 2, [ICES Report #212252
On September 25, 2004, at Braidwood Unit 2
, [ICES Report #212232
On September 25, 2004, at Braidwood Unit 2, [ICES Report #212252
On September 25, 2004, at Braidwood Unit 2
, [ICES Report #212232
On September 29, 2004, at ANO Unit 2
, [ICES Report #212304
On September 29, 2004, at ANO Unit 2
, [ICES Report #212304
On September 30, 2004, at ANO Unit 2, [ICES Report #212335
On September 30, 2004, at ANO Unit 2, [ICES Report #212335
On October 4, 2004, at St. Lucie Unit 2, [ICES Report #212404
On October 4, 2004, at St. Lucie Unit 2, [ICES Report #212404
On October 17, 2004, at San Onofre Unit 3
, [ICES Report #212622
On October 17, 2004, at San Onofre Unit 3
, [ICES Report #212622
On November 19, 2004, at San Onofre Unit 2
, [ICES Report #213113
On November 19, 2004, at San Onofre Unit 2
, [ICES Report #213113
On November 20, 2004, at North Anna Unit 2, [ICES Report #213135
On November 20, 2004, at North Anna Unit 2, [ICES Report #213135
On December 13, 2004, at Summer Unit 1, [ICES Report #213462
On December 13, 2004, at Summer Unit 1, [ICES Report #213462
On December 29, 2004, at North Anna Unit 2, [ICES Report #213650
On December 29, 2004, at North Anna Unit 2
, [ICES Report #213647
On December 29, 2004, at North Anna Unit 2, [ICES Report #213650
On December 29, 2004, at North Anna Unit 2
, [ICES Report #213647
On January 11, 2005, at Vogtle Unit 1, [ICES Report #213825
On January 11, 2005, at Summer Unit 1
, [ICES Report #213819
49
On January 11, 2005, at Vogtle Unit 1, [ICES Report #213825
On January 11, 2005, at Summer Unit 1
, [ICES Report #213819
On February 16, 2005, at Palo Verde Unit 3, [ICES Report #214396
On February 16, 2005, at Palo Verde Unit 3, [ICES Report #214396
On February 17, 2005, at Palisades Unit 1, [ICES Report #214421
On February 17, 2005, at Palisades Unit 1
, [ICES Report #217935
On February 17, 2005, at Palisades Unit 1, [ICES Report #214421
On February 17, 2005, at Palisades Unit 1
, [ICES Report #217935
On March 3, 2005, at Crystal River Unit 3, [ICES Report #214665
On March 3, 2005, at Crystal River Unit 3, [ICES Report #214665
On March 9, 2005, at ANO Unit 2
, [ICES Report #214781
On March 9, 2005, at ANO Unit 2
, [ICES Report #214781
On March 12, 2005, at ANO Unit 2, [ICES Report #214843
On March 12, 2005, at ANO Unit 2, [ICES Report #214843
On March 16, 2005, at ANO Unit 2, [ICES Report #214924
On March 16, 2005, at ANO Unit 2, [ICES Report #214924
On March 28, 2005, at Palo Verde Unit 2, [ICES Report #215123
On March 28, 2005, at Palo Verde Unit 2, [ICES Report #215123
On April 10, 2005, at Millstone Unit 2
, [ICES Report #215391
On April 10, 2005, at Millstone Unit 2
, [ICES Report #215391
On April 19, 2005, at Waterford Unit 3
, [ICES Report #215602
On April 19, 2005, at Waterford Unit 3
, [ICES Report #215602
On April 23, 2005, at Palo Verde Unit 2, [ICES Report #215663
On April 23, 2005, at Palo Verde Unit 2, [ICES Report #215663
On May 26, 2005, at Waterford Unit 3
, [ICES Report #216255
On May 26, 2005, at Waterford Unit 3
, [ICES Report #216255
On August 19, 2005, at Palo Verde Unit 1, [ICES Report #217430
On August 19, 2005, at Palo Verde Unit 1, [ICES Report #217430
On August 25, 2005, at Summer Unit 1
, [ICES Report #217513
On August 25, 2005, at Summer Unit 1
, [ICES Report #217513
On December 3, 2005, at San Onofre Unit 2, [ICES Report #218909
On December 3, 2005, at San Onofre Unit 2
, [ICES Report #218908
On December 3, 2005, at San Onofre Unit 2, [ICES Report #218909
On December 3, 2005, at San Onofre Unit 2
On December 7, 2005, at Prairie Island Unit 1
On December 7, 2005, at San Onofre Unit 2
50
, [ICES Report #218908
, [ICES Report #218957
, [ICES Report #218959
On December 7, 2005, at Prairie Island Unit 1
On December 7, 2005, at San Onofre Unit 2
, [ICES Report #218957
, [ICES Report #218959
On December 12, 2005, at Calvert Cliffs Unit 2, [ICES Report #219037
On December 12, 2005, at Calvert Cliffs Unit 2, [ICES Report #219037
On December 15, 2005, at Ginna Unit 1, [ICES Report #219076
On December 15, 2005, at Ginna Unit 1, [ICES Report #219076
51
5.6
Pressurizer Heater Operating Experience (2006-2010)
On January 12, 2006, at Byron Unit 2, [ICES Report #219381
On January 12, 2006, at Byron Unit 2, [ICES Report #219382
On January 12, 2006, at Byron Unit 2, [ICES Report #219381
On January 12, 2006, at Byron Unit 2, [ICES Report #219382
On February 13, 2006, at INPO
, [ICES Report #219837
On February 13, 2006, at INPO
, [ICES Report #219837
On March 18, 2006, at Palo Verde Unit 1, [ICES Report #220347
On March 18, 2006, at Palo Verde Unit 1, [ICES Report #220347
On March 22, 2006, at Palo Verde Unit 1
, [ICES Report #220408
On March 22, 2006, at Palo Verde Unit 1
, [ICES Report #220408
On March 25, 2006, at Crystal River Unit 3, [ICES Report #220468
On March 25, 2006, at Crystal River Unit 3, [ICES Report #220468
On March 29, 2006, at Kewaunee Unit 1, [ICES Report #220533
On March 29, 2006, at San Onofre Unit 3
, [ICES Report #220528
On March 29, 2006, at Kewaunee Unit 1, [ICES Report #220533
On March 29, 2006, at San Onofre Unit 3
, [ICES Report #220528
On April 4, 2006, at San Onofre Unit 3
, [ICES Report #220623
On April 4, 2006, at San Onofre Unit 3
, [ICES Report #220623
On April 6, 2006, at ANO Unit 2
, [ICES Report #220652
On April 6, 2006, at ANO Unit 2
, [ICES Report #220652
On April 19, 2006, at Braidwood Unit 1
, [ICES Report #220860
On April 19, 2006, at Braidwood Unit 1
, [ICES Report #220860
On April 25, 2006, at Braidwood Unit 1
, [ICES Report #220951
On April 25, 2006, at Braidwood Unit 1
, [ICES Report #220951
On May 21, 2006, at Catawba Unit 1, [ICES Report #221383
On May 21, 2006, at Catawba Unit 1, [ICES Report #221383
On May 30, 2006, at Diablo Canyon Unit 1, [ICES Report #221509
On May 30, 2006, at Diablo Canyon Unit 1, [ICES Report #221509
On June 10, 2006, at ANO Unit 1, [ICES Report #221669
On June 10, 2006, at ANO Unit 1, [ICES Report #221669
On June 13, 2006, at Ginna Unit 1, [ICES Report #221708
On June 13, 2006, at Ginna Unit 1, [ICES Report #221708
On June 15, 2006, at INPO
, [ICES Report #221735
On June 15, 2006, at INPO
, [ICES Report #221735
52
On June 25, 2006, at Catawba Unit 1
, [ICES Report #221896
On June 25, 2006, at Catawba Unit 1
, [ICES Report #221896
On July 17, 2006, at INPO
, [ICES Report #227617
On July 17, 2006, at INPO
, [ICES Report #227617
On August 29, 2006, at McGuire Unit 2
, [ICES Report #222666
On August 29, 2006, at McGuire Unit 2
, [ICES Report #222666
On September 18, 2006, at Palo Verde Unit 1, [ICES Report #222906
On September 18, 2006, at Palo Verde Unit 1
, [ICES Report #222893
On September 18, 2006, at Palo Verde Unit 1, [ICES Report #222906
On September 18, 2006, at Palo Verde Unit 1
, [ICES Report #222893
On September 25, 2006, at Fort Calhoun Unit 1
, [ICES Report #222985
On September 25, 2006, at Fort Calhoun Unit 1
, [ICES Report #222985
On September 27, 2006, at San Onofre Unit 3
, [ICES Report #223028
On September 27, 2006, at San Onofre Unit 3
, [ICES Report #223028
On September 28, 2006, at North Anna Unit 1
, [ICES Report #223041
On September 28, 2006, at North Anna Unit 1
, [ICES Report #223041
On October 6, 2006, at Palo Verde Unit 1
, [ICES Report #223162
On October 6, 2006, at Palo Verde Unit 1
, [ICES Report #223162
On October 7, 2006, at Palo Verde Unit 2
, [ICES Report #223179
On October 7, 2006, at Palo Verde Unit 2
, [ICES Report #223179
On October 16, 2006, at Byron Unit 1, [ICES Report #223346
On October 16, 2006, at Byron Unit 1, [ICES Report #223346
On October 17, 2006, at San Onofre Unit 3
, [ICES Report #223375
On October 17, 2006, at San Onofre Unit 3
, [ICES Report #223375
On October 18, 2006, at Braidwood Unit 2, [ICES Report #223384
On October 18, 2006, at Braidwood Unit 2, [ICES Report #223384
On October 26, 2006, at San Onofre Unit 3
, [ICES Report #223545
On October 26, 2006, at San Onofre Unit 3
, [ICES Report #223545
On November 15, 2006, at Summer Unit 1, [ICES Report #223870
On November 15, 2006, at Summer Unit 1, [ICES Report #223870
On November 26, 2006, at Fort Calhoun Unit 1
, [ICES Report #224038
On November 26, 2006, at Fort Calhoun Unit 1
, [ICES Report #224038
On March 3, 2010, at Catawba Unit 1
, [ICES Report #241885
On March 19, 2010, at Surry Unit 2, [ICES Report #242157
On March 29, 2010, at Robinson Unit 2, [ICES Report #242342
On April 5, 2010, at Millstone Unit 2, [ICES Report #242494
53
On April 25, 2010, at South Texas Unit 2
, [ICES Report #242905
On May 2, 2010, at Braidwood Unit 1, [ICES Report #243046
On May 9, 2010, at Fort Calhoun Unit 1, [ICES Report #293138
On May 27, 2010, at St. Lucie Unit 1
, [ICES Report #243477
On June 1, 2010, at Oconee Unit 2, [ICES Report #243553
On June 19, 2010, at Catawba Unit 2
, [ICES Report #243856
On July 22, 2010, at Palisades Unit 1
, [ICES Report #244301
On August 4, 2010, at Robinson Unit 2
, [ICES Report #244478
On August 15, 2010, at ANO Unit 2
, [ICES Report #244650
On August 24, 2010, at Catawba Unit 2, [ICES Report #244808
On October 13, 2010, at Diablo Canyon Unit 1, [ICES Report #245653
On October 30, 2010, at North Anna Unit 1, [ICES Report #245964
On November 5, 2010, at Seabrook Unit 1, [ICES Report #246080
On November 29, 2010, at Oconee Unit 3, [ICES Report #246470
54
5.7
Pressurizer Heater Operating Experience (2011-2014)
On January 4, 2011, at Millstone Unit 2, [ICES Report #246919
On January 4, 2011, at Millstone Unit 2
, [ICES Report #246910
On January 15, 2011, at Oconee Unit 1, [ICES Report #247095
On February 14, 2011, at Calvert Cliffs
, [ICES Report #247539
On February 17, 2011, at Calvert Cliffs Unit 2, [ICES Report #247617
On March 18, 2011, at Byron Unit 1
, [ICES Report #248124
On April 6, 2011, at St. Lucie Unit 2, [ICES Report #248461
On April 13, 2011, at St. Lucie Unit 2, [ICES Report #248594
On April 28, 2011, at Braidwood Unit 2
, [ICES Report #248879
On May 25, 2011, at St. Lucie Unit 2, [ICES Report #249343
On June 1, 2011, at Oconee Unit 1, [ICES Report #249454
On June 6, 2011, at Point Beach Unit 2, [ICES Report #249516
On June 7, 2011, at Oconee Unit 1, [ICES Report #249553
On June 7, 2011, at Fort Calhoun Unit 1
, [ICES Report #249543
On June 13, 2011, at St. Lucie Unit 2
, [ICES Report #249634
On June 24, 2011, at Oconee Unit 1, [ICES Report #249808
On June 24, 2011, at Oconee Unit 1
, [ICES Report #249806
On June 30, 2011, at Kewaunee Unit 1
, [ICES Report #249893
On July 8, 2011, at Oconee, [ICES Report #250009
On July 28, 2011, at INPO, [ICES Report #250253
On August 6, 2011, at Palo Verde Unit 1, [ICES Report #250375
On August 11, 2011, at Oconee Unit 1
, [ICES Report #250439
On September 21, 2011, at Peach Bottom Unit 3
, [ICES Report #250992
On September 26, 2011, at Robinson Unit 2, [ICES Report #251077
On September 27, 2011, at Summer Unit 1, [ICES Report #251095
On October 7, 2011, at Watts Bar Unit 1, [ICES Report #251255
On October 20, 2011, at Robinson Unit 2, [ICES Report #251451
On October 29, 2011, at Fort Calhoun Unit 1
On October 30, 2011, at Salem Unit 1
, [ICES Report #251606
, [ICES Report #304974
On October 30, 2011, at San Onofre Unit 1, [ICES Report #251616
On December 14, 2011, at Watts Bar Unit 2, [ICES Report #252214
On February 28, 2012, at Calvert Cliffs Unit 1, [ICES Report #253163
On March 18, 2012, at Wolf Creek Unit 1, [ICES Report #300806
On March 24, 2012, at North Anna Unit 1
, [ICES Report #253505
55
On April 14, 2012, at Oconee Unit 3, [ICES Report #253770
On April 16, 2012, at Harris Unit 1, [ICES Report #300719
On May 23, 2012, at Fort Calhoun Unit 1
, [ICES Report #254068
On June 20, 2012, at Robinson Unit 2, [ICES Report #300320
On June 28, 2012, at Oconee Unit 3, [ICES Report #293478
On July 21, 2012, at Calvert Cliffs Unit 1
, [ICES Report #300389
On July 24, 2012, at Millstone Unit 2
, [ICES Report #310658
On August 16, 2012, at Sequoyah Unit 2
, [ICES Report #300469
On August 16, 2012, at Calvert Cliffs Unit 2
, [ICES Report #306982
On August 22, 2012, at Three Mile Island Unit 1
, [ICES Report #300487
On August 22, 2012, at Three Mile Island Unit 1
, [ICES Report #300485
On September 6, 2012, at McGuire, [ICES Report #301164
On September 12, 2012, at Prairie Island
, [ICES Report #308833
On September 12, 2012, at Prairie Island
, [ICES Report #301729
On September 16, 2012, at ANO Unit 2, [ICES Report #301034
On September 20, 2012, at Three Mile Island Unit 1
, [ICES Report #300713
On September 29, 2012, at McGuire Unit 2, [ICES Report #301415
On October 4, 2012, at ANO Unit 2
, [ICES Report #301320
On October 17, 2012, at Catawba Unit 1
, [ICES Report #301793
On October 31, 2012, at Browns Ferry
, [ICES Report #301333
On November 5, 2012, at Ginna Unit 1
, [ICES Report #302172
On December 3, 2012, at McGuire Unit 2
, [ICES Report #304915
On December 14, 2012, at Palo Verde Unit 2, [ICES Report #302721
On December 14, 2012, at Palo Verde Unit 1
, [ICES Report #302412
On December 14, 2012, at Palo Verde Unit 3, [ICES Report #302722
On January 17, 2013, at McGuire Unit 1, [ICES Report #304760
On January 29, 2013, at Palo Verde Unit 1, [ICES Report #302729
On January 29, 2013, at Palo Verde Unit 3, [ICES Report #302732
On January 29, 2013, at Palo Verde Unit 1, [ICES Report #302733
On January 29, 2013, at Palo Verde Unit 3, [ICES Report #302735
On January 29, 2013, at Palo Verde Unit 2, [ICES Report #302731
On January 29, 2013, at Palo Verde Unit 2, [ICES Report #302734
On February 11, 2013, at Watts Bar Unit 1
, [ICES Report #305420
On February 26, 2013, at Watts Bar Unit 1, [ICES Report #305487
On February 27, 2013, at Braidwood Unit 2
, [ICES Report #305473
On March 4, 2013, at Oconee, [ICES Report #305332
56
On March 17, 2013, at Monticello Unit 1
, [ICES Report #305471
On April 1, 2013, at Farley Unit 2
, [ICES Report #306090
On April 8, 2013, at Oconee
, [ICES Report #305393
On May 6, 2013, at South Texas Unit 1
On May 14, 2013, at Vogtle Unit 1
, [ICES Report #306077
, [ICES Report #306695
On June 12, 2013, at Fort Calhoun Unit 1
, [ICES Report #309054
On August 10, 2013, at Wolf Creek Unit 1
, [ICES Report #307590
On September 30, 2013, at Fort Calhoun Unit 1
On November 18, 2013, at Harris Unit 1
, [ICES Report #308352
, [ICES Report #308581
On November 29, 2013, at Oconee Unit 1
, [ICES Report #309067
On December 6, 2013, at Sequoyah Unit 2
, [ICES Report #309237
On December 11, 2013, at Wolf Creek Unit 1
, [ICES Report #310957
On December 16, 2013, at South Texas Unit 2
, [ICES Report #309109
On January 2, 2014, at Three Mile Island Unit 1
On January 18, 2014, at Harris Unit 1
, [ICES Report #309732
, [ICES Report #309283
On January 30, 2014, at Millstone Unit 2
, [ICES Report #309971
On February 12, 2014, at Catawba Unit 1
, [ICES Report #310891
On February 25, 2014, at Sequoyah Unit 2
, [ICES Report #310326
On February 26, 2014, at Millstone Unit 2
, [ICES Report #310166
On March 3, 2014, at Millstone Unit 2
, [ICES Report #310253
On March 17, 2014, at Turkey Point Unit 3
, [ICES Report #310917
On March 22, 2014, at South Texas Unit 1
, [ICES Report #311620
On April 24, 2014, at McGuire Unit 2
, [ICES Report #313021
On May 1, 2014, at South Texas Unit 1
, [ICES Report #312999
On July 25, 2014, at Fort Calhoun Unit 1
, [ICES Report #312884
On September 19, 2014, at Prairie Island
, [ICES Report #313027
57
6.0
Summary and Conclusion
Evident in the operating history for pressurizer heaters are instances of events with heater
sheath degradation that are potential contributors to pressure boundary leakage. The event reports do
not contain all of the information associated with the utility’s disposition and mitigation of potential events,
nor does it extrapolate the consequences of various response options available to the plants.
Most of the issues associated with the pressurizer heaters relate to electrical issues within the
control, power, and monitoring systems, without relation to the material degradation of the heater
sheaths. These electrical issues are manageable and can frequently be remedied with replacement of
electrical equipment, unlike sheath degradation that requires advanced refueling outage preparation and
execution to repair or replace components.
Although a small fraction of the operating experience, sheath degradation is one of the more
highly consequential failures that can occur to the pressurizer heaters. The heating functionality of each
individual heater is highly redundant, with backup banks and excess heating margin available should a
heater become non-functional or unresponsive to control. For sheath degradation, one breach can force
a plant to shutdown for extended periods of time, a tremendous economic impact to the operating utility
and a negative response from the public perception of plant reliability and safety. The review shows that
the issue present at Sizewell B is a potential concern for the currently operating PWR fleet in the United
States, and lessons learned from the degradation at Sizewell should be used in maintaining the integrity
of pressurizer heaters.
The industry has been addressing these issues for both currently operating, and newly under
construction plants, to improve the pressurizer heater design to ensure reliable use for continuing
operation. Utilities should continue to review operating experience as it emerges to track current industry
issues and prepare for organizational and operational vulnerabilities.
It is the responsibility for all proponents and opponents of nuclear power to be aware of the
issues affecting operation, reliability, and safety, to continue to improve the utilization of the technology.
The power generation industry will continue to encounter issues in the future, and engineers must
address these issues to promote public safety and welfare.
58
7.0
References
1. ASME Boiler & Pressure Vessel Code, Section III, Division 1 – Subsection NB, Class 1
Components, “Rules for Construction of Nuclear Facility Components,” 2013 Edition.
2. Watlow Catalog <http://www.watlow.com/downloads/en/catalogs/heaters.pdf>
3. IAEA Nuclear Energy Series, No. NP-T-3.2, “Heavy Component Replacement in Nuclear Power
Plants: Experience and Guidelines,” October 2008.
4. Pressurized Water Reactor Primary Water Chemistry Guidelines: Volume 1, Revision 6. EPRI,
Palo Alto, CA: 2007. 1014986.
5. Materials Reliability Program: PWR Internals Material Aging Degradation Mechanism
Screening and Threshold Values (MRP-175). EPRI, Palo Alto, CA: 2005. 1012081.
6. United States Nuclear Regulatory Agency Regulatory Guide, Regulatory Guide 1.44, Rev. 1,
“Control of the Processing and Use of Stainless Steel,” March 2011.
7. Code of Federal Regulations, 10 CFR 50.55(a), “Codes and Standards”, 77 FR 3074, January
23, 2012.
8. Westinghouse Report, WCAP-17801, Rev. 0, “Feasibility Assessment for Characterizing Nonfunctional Pressurizer Heaters,” February 10, 2014.
9. Materials Reliability Program: Stress Corrosion Cracking of Stainless Steel Components in
Primary Water Circuit Environments of Pressurized Water Reactors (MRP-236). EPRI, Palo
Alto, CA: 2007 1015540.
10. Combustion Engineering Owners Group Document, CE NPSD-555 CEOG Task 585,
“Pressurizer Heater Performance in C-E Plants,” February 1990.
11. United States Nuclear Regulatory Commission Information Notice, IN 2006-04, “Design
Deficiency in Pressurizer Heaters for Pressurized-water Reactors,” Februrary 13, 2006.
12. Framatome ANP Report, ADAMs Accession Number ML052140277, “10 CFR Part 21
Notification of Existence of a Defect,” July 28, 2005.
13. Exelon Report, TMI-12-154 (ADAMs Accession Number ML12298A035), “Licensee Event
Report (LER) No. 2012-003-00 “Pressurizer Heater Bundle Leak””, October 22, 2012.
14. INPO Level 3 Event Report 12-10, “Primary Coolant Leak Caused by Swelling and Mechanical
Failure of Pressurizer Heaters” January 31, 2012. Referenced by [13].
15. Database on Industry Events
16. Pwrsm <http://www.nrc.gov/reactors/pwrs.html> Accessed October 4, 2014.
17. P27
59