Catawba Nuclear Station
Industry Perspective – HDPE Applications and Economic Benefits
Steve Lefler - Principal Engineer Duke Energy
Catawba Nuclear Station
Industry Perspective on HDPE Applications and Economic Benefits
•
Located 19 miles southwest of Charlotte, NC on shores of Lake Wylie
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Two Units 1160 MW each (net) Westinghouse PWR
•
Main condenser cooling provided by forced draft cooling towers
•
Once through service water systems use Lake Wylie for cooling
•
Commercial operation in 1985 (Unit 1) and 1986 (Unit 2)
•
Catawba is jointly owned by:
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North Carolina Electric Membership Corporation
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North Carolina Municipal Power Agency Number One
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Piedmont Municipal Power Agency
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Duke Energy
Catawba Nuclear Station
Industry Perspective on HDPE Applications and Economic Benefits
• Site Background
• Low Pressure Service Water System secondary cooling
and cooling tower makeup. (Designed to ASME B31.1
Code or Civil Building Codes)
• Nuclear Service Water System cooling to nuclear safety
related components that now includes 4000 feet of
HDPE. (Designed to ASME Section III ND Code)
• Both systems combined total approximately 45,00050,000 feet of piping
Catawba Nuclear Station
Industry Perspective on HDPE Applications and Economic Benefits
• Site Background
• Low Pressure Service Water System secondary cooling
and cooling tower makeup. (Designed to ASME B31.1
Code or Civil Building Codes)
• Nuclear Service Water System cooling to nuclear safety
related components. (Designed to ASME Section III ND
Code)
• Both systems combined total approximately 45,00050,000 feet of piping
Catawba Nuclear Station
Industry Perspective on HDPE Applications and Economic Benefits
• Operating Issues with original carbon steel piping
• Fouling and Occlusion
• General Corrosion
• Through wall pin hole leaks
• Selective Weld Zone Attack
Catawba Nuclear Station
Industry Perspective on HDPE Applications and Economic Benefits
Fouling of carbon steel piping
Catawba Nuclear Station
Industry Perspective on HDPE Applications and Economic Benefits
Fouling of carbon steel piping
Catawba Nuclear Station
Industry Perspective on HDPE Applications and Economic Benefits
HDPE piping -generator hydrogen coolers
Catawba Nuclear Station
Industry Perspective on HDPE Applications and Economic Benefits
comparison of carbon steel and HDPE generator hydrogen cooler pipe
Catawba Nuclear Station
Industry Perspective on HDPE Applications and Economic Benefits
• Reliability improved with use of HDPE
• Before replacement with HDPE:
– Flow control valves fully open to the containment ventilation
chillers
– Chiller condenser pressures near 150 psig trip set point
• After replacement with HDPE and two operating cycles:
– Flow control valves 50% open
– Chiller condenser pressure around 125 psig
Catawba Nuclear Station
Industry Perspective on HDPE Applications and Economic
Benefits
ASME Class 3 HDPE
• Unit 1 realized a 20-25% flow margin
improvement due to HDPE.
• Unit 2 has data indicates that improvement
will be on the order of 15%. The Unit 2
improvement is less than Unit 1
improvement because of the smaller amount
of buried piping on Unit 2.
Catawba Nuclear Station
Industry Perspective on HDPE Applications and Economic Benefits
Selective weld attack of carbon steel piping
Catawba Nuclear Station
Industry Perspective on HDPE Applications and Economic Benefits
Selective weld attack of carbon steel piping
Catawba Nuclear Station
Industry Perspective on HDPE Applications and Economic Benefits
External corrosion of buried carbon steel piping
Catawba Nuclear Station
Industry Perspective on HDPE Applications and Economic Benefits
Installation of 32 inch HDPE piping
Catawba Nuclear Station
Industry Perspective on HDPE Applications and Economic Benefits
Installation of 32 inch HDPE piping
Catawba Nuclear Station
Industry Perspective on HDPE Applications and Economic Benefits
HDPE Piping
Catawba Nuclear Station
Industry Perspective on HDPE Applications and Economic
Benefits
HDPE piping
Catawba Nuclear Station
Industry Perspective on HDPE Applications and Economic Benefits
• Success with use of HDPE for non safety system service
water system led to decision to pursue use of HDPE for
safety related nuclear service water system
• EDF Sizewell B Nuclear Station installed HDPE in ASME
Section III Class 3 system and now has several miles of
HDPE installed in nuclear safety related cooling water
piping in the United Kingdom.
Catawba Nuclear Station
Industry Perspective on HDPE Applications and Economic Benefits
•Summary of Catawba Relief Request
•Limited to replacement of buried ASME Section III Class 3 service
water piping for the four emergency diesel generators for Units 1
and 2
• HDPE design and installation requirements based on draft of Code
Case N-755 Rev. 0
• Limited to HDPE Pipe, Mitered Elbows and Flange Adapters
•
Limited to Butt fused joints and flanged joints
Catawba Nuclear Station
Industry Perspective on HDPE Applications and Economic Benefits
Timeline – Catawba HDPE Use
•1995 – HDPE used in non safety service water system
• June 2005 – Meeting with NRC to discuss HDPE for ASME Class 3
•October 2006 – Relief request submitted to the NRC
•March 2007 – ASME Code Case N-755 issued
•May 2009 – NRC issued Catawba safety evaluation
•June 2009 – Began installation of ASME Class 3 HDPE piping
•October 2010 – Unit 2 ASME Class 3 HDPE, buried service water
piping to the emergency diesel generators completed and in
service
•June 2011 – Unit 1 ASME Class 3 HDPE, buried service water
piping to the emergency diesel generators completed and in
service
Catawba Nuclear Station
Industry Perspective on HDPE Applications and Economic
•Summary of Catawba HDPE for nuclear safety related
cooling water piping
•
•
•
•
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4,000 feet of 12 inch HDPE pipe, SDR 11 (1.159 in. wall
thickness)
HDPE 4710 Material (ASTM D3350 cell classification 445574C)
Replaced 10 inch sch 40 carbon steel piping abandoned in place
Transitions from HDPE to steel were made in underground vaults
Impact tensile testing performed to demonstrate joint integrity
Catawba Nuclear Station
Industry Perspective on HDPE Applications and Economic Benefits
•Safety Evaluation for Catawba
•Supplemental Requirements to Code Case N-755 imposed by the NRC
safety evaluation issued for the Catawba relief request.
•
•
•
•
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HDPE flaw depth allowance of 0.041 inches
Reporting of ongoing industry HDPE test program results
Periodic tensile impact testing of field joints
Provision for access to inside of pipe
Remote visual inspection of fused joints from inside pipe
Catawba Nuclear Station
Industry Perspective on HDPE Applications and Economic Benefits
Installation of 12 inch ASME Cl. 3 HDPE piping
Catawba Nuclear Station
Industry Perspective on HDPE Applications and Economic Benefits
Installation of 12 inch ASME Class 3 HDPE piping
Catawba Nuclear Station
Industry Perspective on HDPE Applications and Economic Benefits
Access to inside of HDPE piping provided by tee with blind flange
Catawba Nuclear Station
Industry Perspective on HDPE Applications and Economic Benefits
Fusing 12 inch ASME Class 3 HDPE piping
Catawba Nuclear Station
Industry Perspective on HDPE Applications and Economic Benefits
Fusing joint for ASME Class 3 HDPE
Catawba Nuclear Station
Industry Perspective on HDPE Applications and Economic Benefits
Catawba Nuclear Station
Industry Perspective on HDPE Applications and Economic Benefits
Installation of 12 inch ASME Cl. 3 HDPE piping
Catawba Nuclear Station
Industry Perspective on HDPE Applications and Economic Benefits
Evaluation for Gouge Depth in HDPE Piping
Catawba Nuclear Station
Industry Perspective on HDPE Applications and Economic Benefits
Evaluation for Gouge Depth in HDPE Piping
Typical scratches in HDPE
Sample
NPS
DR
Depth
%
1
24
9
0.022 in
0.8
2
24
9
0.140 in
6.3
3
8
17
0.029 in
5.5
4
8
11
0.029 in
3.7
5
30
21
0.049 in
2.7
6
30
21
0.032 in
2.3
7
12
11
0.039 in
3.3
8
12
11
0.071 in
6.1
9
10
11
0.047 in
4.9
10
20
11
0.002 in
0.001
Sample 5
Catawba Nuclear Station
Industry Perspective on HDPE Applications and Economic
Benefits
Catawba NRC Safety Evaluation Requirements
Periodic Tensile Impact Testing
• Impact tensile testing performed on daily and random samples of
fused joints.
• Impact tensile test first fusion joint of each work shift for each fusing
machine (daily joint).
• Impact tensile test one random fusion joint chosen during a four
work shift period.
• At least 10 percent of field joints from each machine required to be
tested during a production shift.
• Fused joints involving fittings were excluded from random testing.
Catawba Nuclear Station
Industry Perspective on HDPE Applications and Economic Benefits
ASTM F 2634, Standard Test Method for Testing PE Butt Fusion Joints
Catawba Nuclear Station
Industry Perspective on HDPE Applications and Economic
Benefits
Catawba NRC Safety Evaluation Requirements
Periodic Tensile Impact Testing
U
N
I
T
Joints
Daily
Joints
Random
Joints
Joints
Total
% of
Joints
Tested
1
107
66
16
189
43%
2
63
40
8
111
43%
1&2
170
106
24
300
43%
Catawba Nuclear Station
Industry Perspective on HDPE Applications and Economic
Benefits
Catawba NRC Safety Evaluation Requirements
Periodic Tensile Impact Testing
•No failures of tensile impact tests provided high level of
confidence in installed fused joints
•A minimum of 20% of the joints were tested each work shift
compared to the minimum of 10% required by the safety
evaluation
•Random testing performed on 13% of the Unit 1 joints
•Random testing performed on 11% of the Unit 2 joints
Catawba Nuclear Station
Industry Perspective on HDPE Applications and Economic
Benefits
Estimated Project Cost
August 2006
Item
6% Moly
HDPE
Total Project
$ (millions)
32.6
20.9
Material Cost
$ (millions)
13.8
2.9
Labor Cost
$ (millions)
18.5
17.6
Catawba Nuclear Station
Industry Perspective on HDPE Applications and Economic
Benefits
Relative Material Costs
Catawba Nuclear Station
Industry Perspective on HDPE Applications and Economic
Benefits
Comparison of 6% Moly and HDPE Materials
Item
6 % Moly
HDPE
Carbon Stl
Pipe
$750
$61.70
$33.30
90o Elbow
$8070
$600
$558.31
Tee
$8507
NA
-
Flange
$4336
-
-
Joints
10 hours
30 minutes
10 hours
Catawba Nuclear Station
Industry Perspective on HDPE Applications and Economic
Benefits
Much of the potential cost savings was not realized.
Project costs that were not accurately estimated or considered:
•Cost for testing of HDPE joints
•Qualification of fusing process
•Excavation
•Backfilling
•Transition vaults for flanged joints
•Costs associated with schedule delays and changes
Catawba Nuclear Station
Industry Perspective on HDPE Applications and Economic
Benefits
Target Areas to Support Future HDPE for nuclear safety related
cooling water service
•Regulator approval of ASME Code Case for use of HDPE
•Non Destructive Testing for Joints and Acceptance Standard
•Resistance to slow crack growth at higher temperatures
•Fusion joint process qualification
• Complete development of code requirements for above ground
use of HDPE and regulator approval.
• Develop approval for use of electrofusion joints
• Approval of additional fittings (tees, reducers, branch fittings)
Catawba Nuclear Station
Industry Perspective on HDPE Applications and Economic
Benefits
Summary
HDPE used in service water piping at
Catawba has proven to be effective
and cost efficient for solving fouling
and corrosion problems.
Questions?