Jefferson Lab
Technical Basis Document for
Radioactivity Limits in Liquids as a
Result of Activation or Contamination
Jlab Tech Note
JLAB-TN-06-01
Keith Welch, Erik Abkemeier, Bob May
January 20, 2006
Thomas Jefferson National Accelerator Facility
12000 Jefferson Avenue
Newport News, VA 23606
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Technical Basis Document for Radioactivity Limits in Liquids as a Result of
Activation or Contamination
Table of Contents
I.
Introduction
1. Scope
2. Background
II.
A Review of Regulatory and Jefferson Lab Specific Limits and Guidelines
1. EPA Regulations
2. NRC Regulations
3. DOE Regulations
4. Jefferson Lab Requirements
A. Action Level Development
B. Bases fro Action limits for Liquids
III.
Action Levels for Water
A. ENVIRONMENTAL PROTECTION
1.
2.
3.
4.
Groundwater Discharge
Other Releases to the Surface
System Limits and Controls
Releases to Sumps
A. Accelerator Ring Sumps
B. End Station Floor Sump
5. Posting
6. Discharge to Sanitary Sewer
B. OCCUPATIONAL EXPOSURE CONTROL
1. Surface Contamination
2. Airborne Radioactivity
IV.
Action Levels for Non-Aqueous Liquids and Media
1. Ion-exchange Resins
2. Oils
V.
Analytical Requirements
VI.
References
VII.
Appendices
Appendix A. Summary of Action Levels and Actions
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Technical Basis Document for Radioactivity Limits in Liquids as a Result of
Activation or Contamination
I. Introduction
1. Scope
This document addresses the control of radioactivity in water, water-borne media
and other liquids in order to (a) control dose to exposed workers, (b) prevent the
spread of contamination, and (c) minimize the potential for exceeding statutory or
permit limits on environmental releases in the event of a spill or leak from an
affected system. This document also describes the conditions and allowable
methods for release of these liquids from radiological control. Action levels will
be established requiring certain controls or mitigating actions, depending on the
type and location of the system.
These issues have been raised recently due to increased levels of activity being
found in a low conductivity cooling water (LCW) system. In response to this
discovery, a review of the applicable limits and standards was conducted, and it
became apparent that many of the specific conditions related to radioactivity in
liquids have not been specifically addressed in Jlab radiological control
requirements or procedures. This document attempts to fill some of the gaps we
have found with respect to specific controls for activated liquids at the lab. The
bulk of the information focuses on LCW systems, but we also address other
common or potential situations involving controls on potentially radioactive
liquid.
2. Background
Historically, activity levels in LCW systems have been so low that controls for
handling and disposition of the water have not been required. The activity
concentration in (non-beam dump) LCW has never exceeded the EPA drinking
water limit. Detectable levels of some radionuclides have been found, as
expected, in filter and resin media used to maintain water purity. This material is
either (conservatively) disposed of as Low Level Radioactive Waste (LLRW) or,
in the case of resin, released for regeneration if below previously established
action limits (These action limits will also be reviewed in this document).
Tritium (H-3) is a primary nuclide of concern, in that it is easily producible in
water, has a relatively long half-life of 12.3 years, and has a tendency to disperse
rapidly throughout fluids and surfaces. Be-7 is also easily produced in water via
spallation of oxygen, but has a relatively short half-life of 53.7 days. Some other
nuclides are produced which have longer half-lives than Be-7 (eg. Mn-54, Co-58,
Co-60), but their production rates are considerably lower. All these nuclides
(except H-3) have been detected in LCW resins, but not in the cooling water
itself.
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Technical Basis Document for Radioactivity Limits in Liquids as a Result of
Activation or Contamination
Recently, LCW samples were obtained from components in Hall C that had
measurable levels of H-3 and Be-7. These samples were taken during the removal
of HKS (E01-011) experimental equipment (magnets in the chicane region of the
beamline). (Note: beam loss in this region was unusually high with this
experiment, due to an unprecedented beam line configuration involving a “split
beam” setup, including steering of the beam downstream of the target. This
resulted in considerable beam loss into the downstream magnets and their
associated cooling water jackets.) Analysis of the local cooling water samples
yielded a tritium concentration of 1.92E-6 uCi/ml and Be-7 activity on the order
of 3E-5 uCi/ml. Samples were also taken of the LCW system at the main system
headers in both Hall A and Hall C, and in building 92 at the main system ionexchange sidestream loop. Be-7 was detected at the Hall C header (comparable to
the concentration at the magnets). No activity above MDA for any nuclide was
detected in the water at building 92 (end station LCW supply system).
The existence of detectable Be-7 in the system is somewhat surprising, given
assumptions about removal efficiency by the ion-exchange system. This indicates
that Be-7 may remain suspended in the system longer than previously assumed
due to flow/distribution irregularities or chemical form of the beryllium. The
presence of detectable H-3 locally at the magnets with no detectable activity
elsewhere also supports the idea that the Halls (or other segments of LCW
systems) or individual components may act to restrict cooling water flow such
that activity may build up locally to levels of concern for contamination control
purposes. Only one of the samples taken exceeded the Derived Concentration
Guide (DCG) values for drinking water systems in DOE 5400.5. But we regard
the implications as potentially significant, particularly in light of long-term 12
GeV operations and the rather conservative permit limits.
II. A Review of Regulatory and Jefferson Lab Specific Limits and Guidelines
1. EPA Regulations
EPA drinking water standards as delineated in 40 CFR 141.66 specify a limit of
20,000 pCi/l (2E-5 uCi/ml) of tritium concentration in drinking water, as well as a
combined limit of 4 mrem/year total dose equivalent from all beta-gamma
emitting radionuclides (in the absence of any other nuclides, this implies a limit of
40,000 pCi/l or 4E-5 uCi/ml for Be-7).
2. NRC Regulations
NRC regulations (10 CFR 20.1301) establish a primary dose limit of 100 mrem/y
to any individual in the public (uranium fuel cycle operations are further restricted
by 40 CFR 190 such that there is “reasonable assurance” that no member of the
public will receive a total dose of 25 mrem/yr from such operations).
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Technical Basis Document for Radioactivity Limits in Liquids as a Result of
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Accordingly, 20.1302 allows release of liquid effluents in concentrations of 1E-3
uCi/ml (1E6 pCi/l) tritium to the boundary of an unrestricted area (values are
listed in Appendix B, Table 2 of the rule). This concentration corresponds to a
dose of 50 mrem/yr from continuous exposure based on annual oral ingestion for
standard reference man. Part 20 allows for possible adjustments to the effluent
concentration values based on chemical/physical characteristics of the effluent.
Of course, EPA drinking water standards would still apply to a water source to
which an effluent stream containing 1E-3 uCi/ml of tritium is directed. Therefore
the NRC rule does not imply a dose limit of 50 mrem from drinking water.
Effluent concentration values are a starting point containing conservative
assumptions, with implicit expectations of dose pathway analyses.
3. DOE Regulations
DOE O 5400.5 Chg.2 of 1/7/93 also begins with a primary dose limit of 100
mrem/y to members of the public. The Order uses a similar approach to
controlling effluents as 10 CFR 20, listing Derived Concentration Guide (DCG)
values which are based on the same dose-to-concentration relationship as Part 20
(and those referenced in EPA standards). For instance, the DCG value for tritium
is 2E-3 uCi/ml (2E6 pCi/l), which corresponds to a dose of 100 mrem/y under the
same exposure conditions as are used in Part 20. Order 5400.5 explicitly states
that the DCG values “are not release limits, but rather are screening values for
considering BAT (Best Available Technology) for these [liquid] discharges and
for making dose estimates.”
Rulemaking for environmental regulation by DOE is contained in 10 CFR 834,
which has been stalled in a draft version for many years. Primary dose limits in
the draft mirror the 5400.5 limits. Action levels contained in the draft rule would
require (except for H-3) best available technology (BAT) treatment of liquid
discharges (not sewage) to limit the radioactivity concentration when the average
annual concentration in the discharge exceeds the DCG, or could result in a TEDE
greater than 10 mrem/y to members of the public (and, of course, drinking water
supplies must meet EPA requirements). Action levels in both the draft rule and
5400.5 for sanitary sewer release require the use of BAT treatment above five
times the DCG.
4. Jefferson Lab Requirements
No specific water concentration limits exist in the Jefferson Lab EH&S RadCon
Supplement. The Jlab Work-Smart Standards (WSS) contain references to our
primary permits under the Virginia Pollutant Discharge Elimination System
(VPDES) and the Hampton Roads Sanitation District (HRSD). No other
radiological effluent discharge references are contained in the WSS (the DOE
standards are referenced, but not with respect to liquid effluents). VPDES permit
#VA0089320 addresses groundwater quality, both in-situ (well monitoring) and
related to discharges of groundwater to the surface (end station dewatering).
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Technical Basis Document for Radioactivity Limits in Liquids as a Result of
Activation or Contamination
The de-facto limit for the surface discharges is the EPA drinking water standard
(at the point of dewatering sump discharge). Other discharges to surface waters
are technically not addressed by this permit. Monitoring for permit compliance is
conducted at the dewatering sump. However, additional monitoring of the surface
discharge channels is conducted, and any degradation of this effluent at any
location would be cause for concern and action. HRSD permit #0117 addresses
discharges to the sanitary sewer. The primary limit is 5 Ci of H-3 and 1 Ci of all
other gamma emitting nuclides. In addition, a monthly average H-3 concentration
limit of 0.1 uCi/ml applies to these discharges, not to exceed 10 mCi/day.
A. Action Level Development
Given the impact of a non-compliance event involving exceedance of a
permit limit, it is reasonable and prudent to establish internal action limits
for controlling liquids contained in cooling systems or other potentially
activated/contaminated liquid-handling systems.
In 1997, JLab established action levels for aqueous demineralizer resins of
one tenth of the concentration in 10 CFR 20 Appendix B, Table 2, Column
2, in order to allow release of resin bottles for reprocessing. Below this
limit, the resin is to be considered non-radioactive. However, no specific
guidance was developed for the designation or control of resin media
which exceeds the release limit. The limit is applicable to resin only.
Internal procedures establish action levels for sewer disposal of End
Station Floor Drain sump water and for addressing contamination in soil.
The RCG has also made some progress on developing a method for
analyzing potentially activated/contaminated lubricating oils to support
establishment of release criteria for oils.
B. Bases for Action Limits for Liquids
Controls on liquids and liquid systems are based on a number of factors
such as; the location of the system, the type of liquid, statutory limits on
environmental release, contamination of surfaces and materials and the
potential for dose from introducing the material into a given environment.
Action limits are associated as closely as possible with existing permits
where applicable. Wherever feasible, the DOE 5400.5 DCGs are used
(with basic dose pathway evaluations) to derive action limits for liquids
not addressed by a permit. The action limits contain considerable
conservatism, such that we believe it is reasonable to consider liquids that
fall below the activity action limits as non-radioactive (where the limit is
used to determine the need for radiological control). In some cases,
materials above the action level may also be released from radiological
control, where analysis shows potential exposures to be below regulatory
concern and the Radcon Manager approves such release.
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Technical Basis Document for Radioactivity Limits in Liquids as a Result of
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III. Action Levels for Water
A. ENVIRONMENTAL PROTECTION
This section deals primarily with limits and controls targeted at preventing environmental
impacts or doses to the public.
1. Groundwater Discharge
The VPDES permit limits radioactivity concentration in groundwater discharged
to the surface to the EPA drinking water standard. Quarterly grab samples are
taken for permit compliance purposes. Radcon tracks the activity of the
dewatering sump discharge on an ongoing basis.
Action Level An action level consistent with the limit for C-ring wells (<MDA,
where MDA is specified as 1000 pCi/l for H-3) will be applied to this continuing
monitoring.
The permit specifies MDA values for four nuclides and gross beta. Adopting
these values for action levels with regard to the dewatering sump is analogous to
their use in the C-ring monitoring well system as a means to ensure that no
degradation of offsite surface waters occurs.
Action Triggered Should the action level be exceeded, immediate corrective
action is warranted, and would include:
(1) an investigation into the possible sources of the radioactivity, and
(2) follow-up sampling of the sump at increased frequency; and potentially:
(3) curtailment of accelerator operations,
(4) discussions with the Virginia Department of Environmental Quality regarding
temporary variance to the permit limits, or
(5) diversion of the discharge flow to sanitary sewer (which would require
consultation with HRSD).
It should be noted that MDA for H-3 analysis at Jlab is routinely about a factor of
two better (lower) than the permit-required MDA. Any detectable activity in a
location for which MDA is the action level will trigger action, including
anomalous sample results that indicate activity but do not meet the statistical
requirements for MDA.
2. Other Releases to the Surface
Although the VPDES permit does not specifically address surface discharges
other than from groundwater, it is reasonable to follow a similar approach for all
surface water regardless of the source. That approach is applied as follows.
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Technical Basis Document for Radioactivity Limits in Liquids as a Result of
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Discharge Limit Primary onsite limit for all surface discharges: Under normal
conditions of operation, no liquids with activity greater than the EPA drinking
water standard* shall be intentionally discharged to the surface without the
express written permission of the Radcon Manager.
Action Level For the system of surface water discharge (stormwater) channels
around the site, an action level equal to the C-ring wells (<MDA) will be used.
Action Triggered Should this action level be exceeded at the site surface water
outflow points (location of routine sampling), immediate remedial action is
warranted, and would include:
(1) investigation to determine the source of the activity,
(2) follow-up sampling in additional water channels leading to points of site
outflow, and if necessary
(3) isolation of the sluice gates at the site outflow.
3. System Limits and Controls
Controls on activity levels in various liquid systems will be implemented to
minimize the potential for environmentally significant discharge events. The
threat to surface water quality exists mainly from two broad categories of
discharge: (1) discrete spills of small quantities of significantly contaminated
water, and (2) large volume or long term leaks or spills from mildly or minimally
radioactive systems. Large releases of highly radioactive water (i.e. >> 10 times
the drinking water limit) directly to the environment are not considered credible
events due to enhanced integrity and containment design employed in the affected
systems.
It is unlikely that small spills of water (even if highly contaminated) could present
a condition that would jeopardize the quality of the surface water leaving the site.
High activity water (or other liquids) will be primarily controlled based on
limiting conditions such as potential surface contamination or uptake by workers.
However, controls on handling such water must also ensure that environmental
hazards are minimized. The specific criteria for establishing these controls are
described elsewhere in this document.
*Reference to the EPA drinking water limit refers to the stated limit of 2E4 pCi/l for tritium, and the
implied concentration limit (based on dose) of four percent of the DCG for other single nuclides. For
mixtures, the sum of the fractions of the concentration of each nuclide to four percent of its DCG must be
less than 1.
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Technical Basis Document for Radioactivity Limits in Liquids as a Result of
Activation or Contamination
The most likely scenario for environmental releases is the loss of water from a
large volume system such as a low conductivity cooling water (LCW) system.
Action levels addressing this condition will be conservatively applied to all
systems or storage tanks meeting the following criteria:
-
System or storage tank capacity greater than 100 gallons, and;
System piping or tanks located outside, or in buildings which, in the event of a
system rupture, have no features designed to contain a spill (eg. cofferdams)
Action Level An action limit equivalent to the EPA drinking water standard is
applied to these cases, such that any such system or storage tank exceeding the
limit is scheduled for remediation at the earliest possible time. Normally, this
would be in conjunction with scheduled accelerator maintenance periods.
Action Triggered
(a) Remediation for an LCW system will entail purging the system (to sanitary
sewer) and refilling with clean water (this process requires about three days).
(b) Portable or fixed storage tanks exceeding the action limit will be moved,
drained or equipped with secondary containment provisions if the concentration
can not reasonably be reduced.
Maintaining these systems to levels below the drinking water limit minimizes the
probability of causing detectable radioactivity in surface water, even in the case of
a complete loss of the system contents due to a catastrophic rupture. A
hypothetical example is given below.
If we assume the loss of the entire contents of a typical LCW system onto the
surface, the spill volume is assumed to be 5000 gallons (personal communication
w/Bill Rust of Facilities Management). If the H-3 concentration in the water was
at 20,000 pCi/l, the total activity would be:
(2E4 pCi/l) (3.785 l/gal) (5000 gal) = 3.8E8 pCi (380 uCi) in 1.9E4 liters.
We estimate that the site has approximately 3 linear kilometers of surface
drainage channels. For this estimate, a channel is assumed to have a semi-circular
cross section with a radius of about 180 cm. The storm channels typically contain
a volume of standing water which varies with weather conditions. We will
assume a baseline condition where the ditches contain 20 cm of water. The initial
volume of water in the surface channel is:
[R2 cos-1{d/R} – d(R2-d2)1/2 ] [3E5 cm] = 6.6E8 cm3 = 6.6E5 liters
Where:
d = 160 cm
R = 180 cm
Another 1.9E4 liters is added by the spill, giving a total of 6.79E5 liters.
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Technical Basis Document for Radioactivity Limits in Liquids as a Result of
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The average concentration caused by the spill would be:
3.8E8 pCi/6.79E5 liters = 560 pCi/l
Although the local concentration near a spill area would be higher than the
average value, it is extremely unlikely that the entire contents of an LCW system
could be lost to the environment. Also, only a portion of the water lost during
such an event would go directly to the stormwater ditch. Much of the activity
would be distributed over a large area of the ground, limiting the movement of the
activity into the surface channels. And of course, activation of the LCW to a
concentration approaching the drinking water standard is highly improbable. In
any event, the mitigating actions described above would be invoked in order to
minimize impact on the environment.
4. Releases to Sumps
LCW systems of concern (as well as other, smaller volume liquid systems) all
have the potential to impact accelerator enclosure sumps in the event of rupture or
leakage.
The action levels imposed on LCW systems with regard to environmental releases
should also protect the various pathways that exist via sump discharge.
A. Accelerator Ring Sumps
Accelerator ring floor sumps are pumped to the surface where the contents
are either captured in holding tanks, or in some cases, released directly to
the storm ditch. Due to the pathway established through these sumps, this
represents another potential route for LCW impact on surface waters.
Action Level In the event the action level is reached for LCW supplying
the accelerator ring (EPA drinking water limit), one of the following
related mitigating actions will be taken.
Action Triggered
(1) all sumps affected by the condition will be configured to pump to
holding tanks (which are subsequently emptied to sewer disposal), or
(2) any affected sump not so configured will be disabled such that
automatic discharge cannot occur, with administrative tag-out. The
controls will remain in place until the radioactivity in the LCW system in
question has been reduced below the action level.
B. End Station Floor Sump
The end station floor sump (ESS) is discharged to sanitary sewer, and its
contents are regulated under the HRSD permit. Activity concentration in
the ESS often exceeds the drinking water standard. An LCW discharge
into the end stations therefore has comparatively low impact on the sump.
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Technical Basis Document for Radioactivity Limits in Liquids as a Result of
Activation or Contamination
The primary impact of a catastrophic rupture of the end station LCW
system on the sump would be a potential to cause overflow into one or
more of the end stations, potentially contaminating the floor, and possibly
impacting the end station dewatering sump. The capacity of the ESS is
approximately 6000 gallons, so it is possible that draining the entire end
station LCW system into the sump could occur without overflowing the
sump (however, due to make-up system response, the potential exists for
the LCW system to continue to supply water in excess of the static system
volume). This would cause a high level sump alarm, as well as many
other equipment failures and alarms that make it unlikely for such an event
to persist unabated.
If the LCW system was contaminated at a concentration of ten times the
drinking water standard, and its entire contents were lost to the ESS, the
total activity in the sump would be less than half the daily discharge limit.
No additional action levels are established for the ESS due to the
potential for impact by the LCW system. Specific action levels for the
end station sump are discussed below.
5. Posting
Buildings which house LCW systems that have the potential to become
measurably radioactive, or to build up radioactivity in filter/resin media should be
posted appropriately to notify personnel of the condition. Although water in the
range of the drinking water limit is not considered “radioactive material”,
disposition of filter/resin media and conduct of maintenance that could potentially
result in a significant loss of water to the environment should be coordinated with
Radiation Control staff.
6. Discharge to Sanitary Sewer
Liquids being disposed of by means of the sanitary sewage system are regulated
under the HRSD permit. The annual limit on H-3 discharge of 5 Ci is effectively
mitigated by a daily limit of 10 mCi (10 mCi per day, for 365 days yields 3.65
Ci). Therefore, the daily discharge limit is the primary “working” limit to which
we are held.
Action Level A previous incident, in which this limit was exceeded, was the
catalyst for a set of action levels now contained in HPP-ENV-003(1). The action
levels apply specifically to the ESS. These action levels are considered
appropriate for purposes of ensuring the permit limits are not exceeded based on
sump activity.
Action Triggered See Appendix A .or HPP-ENV-003
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Technical Basis Document for Radioactivity Limits in Liquids as a Result of
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The high power dump water disposal system (“TMDU”) also discharges to the
sewer. The total activity discharged through the TMDU and the ESS must be
below the HRSD permit limits. The higher activity water disposed of through the
TMDU drives the controls on discharges to HRSD. At this time, TMDU and ESS
discharges are initiated manually, following sampling and analysis of the
contents. An informal working goal of no more than 7.5 mCi has been adopted to
determine TMDU discharge volumes. The goal was chosen to allow for ESS
discharges to occur if necessary on the same days as TMDU discharges.
Discharge Limit Consistent with this, and looking forward to resumed
implementation of automated discharges, a primary action limit for TMDU
discharges is set at 8 mCi in any one day. No intentional TMDU discharge
(manual or automatic) above this level shall be made.
Action Triggered If automated discharge processes are in place, and it is
determined that this level has been or will likely be exceeded, the automated
process will be halted until the Radcon manager is satisfied that the condition has
been adequately addressed.
Discharge Limit Given that ESS and TMDU systems operate independently from
each other, the following conditions also apply.
(1) Automated operation of the TMDU will not be initiated unless the H-3
concentration in the dump water (both halls combined) is less than 0.1 uCi/ml.
(2) If TMDU is in automatic operation, system discharge parameters will be
selected such that the maximum expected daily discharge activity is no more
than 7 mCi.
(3) If TMDU and ESS are in automatic operation, system discharge parameters
for the ESS will be set such that the maximum expected daily discharge
activity of the ESS is less than 2 mCi. All action levels in HPP-ENV-003
must also be met.
Given these conditions, the maximum anticipated daily activity that could be
discharged under fully automatic operation of both systems is less than 90% of
the HRSD limit. The activity of the gamma emitting nuclides in the water must
meet the same criteria scaled to the applicable limits.
B. OCCUPATIONAL EXPOSURE CONTROL
This section addresses action levels which apply primarily to workplace contamination
limits and doses to workers due to spills or leaks from contaminated systems. We will
derive triggers at which liquids and liquid systems are to be considered radioactive for
occupational exposure purposes.
None of the action levels or controls described in this section are intended to replace or
reduce the need for surveys and practices to assess and control radioactivity in the
workplace, particularly with respect to release of potentially contaminated items or areas.
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Technical Basis Document for Radioactivity Limits in Liquids as a Result of
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These levels and controls supplement procedures and practices used to control
radioactive materials, and provide consistent standards for handling potentially
radioactive liquids.
1. Surface Contamination
The most direct and limiting condition in which aqueous radioactivity can impact
a work area is a spill or leak of the water, causing surface contamination above
the limits. The primary limits for surface contamination are contained in 10 CFR
835. For H-3, the limit for removable contamination is 10,000 dpm/100 cm2. All
other beta-gamma emitters applicable to Jefferson Lab are limited to 1000
dpm/100 cm2. However, for Be-7 in Controlled Areas, Jefferson Lab has a
specific limit of 30,000 dpm/100 cm2 (2).
We will conservatively estimate a concentration level such that if the water in
question were spilled, it would not create a surface contamination level above the
limit. Experimentation shows that 1 ml water covers approximately 3.14 cm2
surface area in a controlled pouring situation (the area is limited due to surface
tension, suggesting a conservative estimate compared to larger volume spills).
If we assume that the total quantity of radioactivity in the water is instantaneously
deposited on the surface, we can estimate the water concentration necessary to
create an area contaminated above the limits:
For H-3:
pCi/L = (10,000 dpm/100 cm2) (0.45 pCi/1 dpm) (1000 ml/1 L) (3.14 cm2/1 ml)
Yielding 141,000 pCi/L
Rounding this value down to 1E5 pCi/L (1E-4 uCi/ml) provides even more
conservatism, allowing for the potential for buildup of activity from slow leaks or
multiple spills, and ties conveniently with an action limit in HPP-ENV-003.
Action Level We will consider water (or any liquid) containing tritium activity
greater than 1E-4 uCi/ml, and any system or container in which it is housed to be
radioactive.
Action Triggered Specific actions required above this level include:
(1) such systems and containers will be housed indoors,
(2) these systems and containers (except for small quantities for samples, etc.)
must have secondary containment systems in place capable of preventing any
credible breach or spill from the system from entering the environment (surface or
groundwater) or unmonitored sewage discharge point,
(3) posting of rooms or buildings housing such systems as radioactive material
areas,
(4) conspicuous marking of piping/system components such that workers are
made aware of the particular systems or containers containing the water, and
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Technical Basis Document for Radioactivity Limits in Liquids as a Result of
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(5) a requirement for the use of PPE when work occurs which might expose
workers directly to the water or internal surfaces of the systems (type and extent
of PPE to be determined based on job and system-specific conditions).
For Be-7 and other beta-gamma emitters:
Using the same unit analysis methodology as above for tritium yields a limit of
423,000 pCi/l for Be-7 if the parameter of concern is exceeding a 30,000 dpm/100
cm2 surface contamination limit.
Action Level Again, to provide conservative control, and in keeping with the
approach for H-3, a value of 200,000 pCi/l, or 2E-4 uCi/ml (five times the implied
drinking water limit for Be-7 alone) is established as the action level for Be-7.
Likewise, the action level for other beta-gamma emitters produced at JLab is set
at five times the implied drinking water limit for the individual nuclide, or
equivalently, one fifth of the DCG value in 5400.5.
The action level for mixtures is unity for the sum of the ratios of the concentration
of each nuclide to its corresponding action level (nuclides with activity below the
implied drinking water limit for those nuclides need not be considered in the sum
of the ratios calculation).
Action Triggered The specific actions listed above for H-3 shall apply to all
nuclides and mixtures.
Notes pertinent to section 1.
(1) Systems containing more than 4000 gallons of water may require posting as
radioactive material even when the activity concentration is below the action
level, in order to meet the requirements of 10 CFR 835. This is not likely to occur
however, given the relatively low concentration normally present in larger
systems.
(2) Liquids not exceeding the action limit do not meet the definition of radioactive
material for purposes of transportation regulations, as long as the quantities
transported are less than approximately 350 gallons.
(3) Although systems containing water with activity below the action level
normally need not be controlled as radioactive material, the controls in section A
apply if the activity exceeds the thresholds in that section.
2. Airborne Radioactivity
Some potential exists with contaminated systems (especially H-3) for the
exposure of personnel to airborne radioactivity or the spread of contamination
through evaporation of the contents of open containers or systems operating at
high temperatures. Since tritium is by far the most mobile of such contaminants,
we will conservatively estimate the H-3 concentration necessary to produce a
concern.
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Technical Basis Document for Radioactivity Limits in Liquids as a Result of
Activation or Contamination
We will assume a saturation vapor density of 17.3 g/m3 at standard conditions and
that one gram of water is equivalent to 1 ml. We also conservatively assume that
in a closed space containing contaminated water, we achieve 100% relative
humidity by saturation of the air with the contaminated water. The DAC for H-3
is 2E-5 uCi/cc. The required activity concentration in the water to achieve 1 DAC
of airborne activity is:
uCi/ml = (1E6 cc/17.3 ml) (2E-5 uCi/cc) = 1.16 uCi/ml
This far exceeds the typical activity of the most contaminated systems at Jlab,
however to ensure the potential for any uptake is minimized, the following action
level is established.
Action Level H-3 activity concentration above 0.1 uCi/ml.
Action Triggered When the H-3 activity exceeds the action level,
(1) the air or gas headspace in the container or system is considered radioactive,
and shall not be purged to the atmosphere except through a system designed to
retain the H-3 activity (i.e. a “bubbler”), and
(2) Such tanks and systems shall, to the extent practical, be kept tightly sealed (i.e.
not subject to evaporation), or
(3) If it is not practical to keep such a system sealed, periodic surveys and samples
will be taken to ensure the radioactivity does not adversely affect the surrounding
area. For instance, samples of air-conditioning condensate and smears of surfaces
will be taken and analyzed for tritium.
IV. Action Levels for Non-Aqueous Liquids and Media
1. Ion-exchange Resins
The current Jlab limit established for release of resin containing Be-7 (generally,
the most predominant nuclide of concern in LCW resins) is 6E-5 uCi/ml. This
value was chosen by taking 10% of the NRC Table 2, Column 2 limit for effluent
discharge. The same ratio is used to establish release for other applicable
nuclides. Here we re-evaluate the limits for inclusion into this document.
In developing the rationale for release of resin for reprocessing, we take into
account the fact that the resin media is not intended for, and will not be in any
appreciable quantity, consumed, as is the assumption for the release of aqueous
effluents. However, during reprocessing, spent resin is regenerated by flushing
with large amounts of aqueous compounds. According to an industry source(3),
about 100 gallons of water is required for reprocessing each cubic foot of resin.
Typical resin columns at JLab contain 1.4 ft3 of resin, requiring 140 gallons of
water for regeneration.
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Technical Basis Document for Radioactivity Limits in Liquids as a Result of
Activation or Contamination
Using an extremely conservative approach, in which we assume the water used
for resin regeneration becomes, without dilution or filtration, a primary source of
drinking water, we can calculate the activity in the resin that corresponds to the
limit for that water. We will also assume the following.
- All the activity in the resin is removed and uniformly entrained in the flush
water
- Be-7 is the only nuclide in the resin, and is the only nuclide of concern for
purposes of meeting the drinking water standard (i.e. 4 mrem/y limit)
- No appreciable difference in wet and dry resin volume
So, the activity in the resin corresponding to this scenario is:
uCi/ml in resin = (1E-3 uCi/ml) (0.04) (140 gal) (3785 ml/gal) = 5.35E-4 uCi/ml
1.4 cu ft (2.83E4 ml/cu ft)
Therefore the current limit is approximately a factor of ten restrictive beyond
what is indicated by this highly conservative estimate.
We also consider the possibility of surface contamination caused by a resin spill.
The degree to which a volume of wet resin might cover a surface is somewhat
more variable than for a spill of water. The physical attributes of resin also make
for unusual characteristics regarding the transferability of the material. In
general, contact (such as stepping onto a surface) with a mass of resin, even in a
thick layer, results in the transferal of only a small portion of the resin to the
object. We will assume that the amount of resin transferred in this fashion is
conservatively modeled by a thin, essentially single layer of resin beads.
We determined by experiment that a thin layer of wet resin beads covering an area
of 100 cm2 would have a mass of about 5g. For this estimate, we will assume wet
resin has a density of about 1 g/cc, or 1 g/ml.
For a spill of resin in a Controlled Area, where Be-7 is the nuclide of concern, the
activity in the resin necessary to cause contamination of 30,000 dpm/100 cm2 is
then:
uCi/ml = (30,000 dpm/100 cm2) (4.5E-7 uCi/1 dpm) (100 cm2/5 ml) = 2.7E-3 uCi/ml
However, since the intention here is to release the resin to unrestricted areas for
regeneration, using the more restrictive non-Controlled Area contamination limit
of 1000 dpm/100 cm2, we arrive at a concentration in the resin of 9E-5 uCi/ml.
Action Level It appears that the current limit is appropriate for the control of resin
to be released for this purpose, however, for purposes of using consistent bases
for the limits, the existing limit for Be-7 will be adjusted slightly to 5E-5 uCi/ml,
or 1/20th the 5400.5 DCG. Other nuclides will be limited similarly. Limits for
mixtures are derived by the sum of the ratios method described in part III.
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Technical Basis Document for Radioactivity Limits in Liquids as a Result of
Activation or Contamination
Action Triggered Resin exceeding the action levels above will not be released for
regeneration. However, at levels up to ten times the action limit it may be
released for landfill disposal with the concurrence of the Radcon manager. Resin
found to be above the action level may be held for decay of the short-lived
nuclides for subsequent regeneration. If so, it should be re-sampled prior to
release for processing.
2. Oils
From time to time, lubricating oils and other non-aqueous liquid wastes are
generated in accelerator enclosures and systems, where there is some potential for
activation or contamination of the material. These liquids may present difficulties
in analysis for nuclide content, particularly H-3, due to interferences in the liquid
scintillation counting process.
The information in this section is presented under the assumption that the method
used for radio-assay of the material has been demonstrated to be reliable, meets
appropriate quality assurance standards and has been authorized by the Radcon
manager.
Since oils and coolants are not consumed, and are not disposed of through
discharge to surface or ground water, effluent limits and guides are only roughly
applicable in determining an appropriate action level for control. A thorough
examination of every possible exposure scenario for these materials is beyond the
scope of this document. However, it is reasonable, given the small quantities of
these materials handled at Jlab, to develop a release strategy that protects the
public and the environment.
Contact with residual films and coatings in containers or with materials used to
absorb and clean up spills is assumed to be the primary exposure pathway for
radioactivity in oils and coolants. The biological behavior of organically bound
tritium (OBT) is the subject of current study within DOE and elsewhere.
However, current guidelines(4) suggest that dose conversion factors for these
materials are on the order of 2-3 times greater than for HTO. In addition, DOE
has produced air concentration values (ACV) for controlling uptakes of OBT. For
insoluble OBT in stable aerosols (such as oil vapors), the ACV is about a factor of
13 more restrictive than the DAC for HTO. Since surface contamination limits
are derived in part for purposes of limiting uptakes, our approach will limit
radioactivity in oily films and residues to a fraction of the contemporary release
limits for surface contamination.
We wish to address conditions that may occur in the course of disposing of waste
oil. This may include incidental contact with oily surfaces or materials used to
clean up spills. It takes very little oil to form a residual oily film on a surface.
One ml of oil can easily cover 100 cm2 or more of surface area. However, the
further we assume the material is spread, the less conservative our limit becomes.
Using the same approach as in earlier sections of this document, we calculate the
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Technical Basis Document for Radioactivity Limits in Liquids as a Result of
Activation or Contamination
activity concentration necessary to result in contamination on a given surface
area. Again, through experiment, we determined that on order of 5 ml of oil will
thoroughly cover an area about the size of the palm of the hand (approximately
100 cm2), and that more than this is not readily retained on the surface.
We apply a factor of 20 to the usual surface contamination limit for H-3, and our
result is:
uCi/ml = (500 dpm/100cm2) (4.5E-7 uCi/dpm) (100 cm2/5 ml) = 4.5E-5 uCi/ml
Action Level Due to the extreme conservatism in this calculation, we round the
value to 5E-5 uCi/ml. This is 1/40th the 5400.5 DCG for H-3.
For other nuclides of concern, we apply a factor of ten to the surface
contamination release limit of 1000 dpm/100 cm2, yielding:
uCi/ml = (100 dpm/100cm2) (4.5E-7 uCi/dpm) (100 cm2/5 ml) = 9E-6 uCi/ml
For the typical nuclides of concern, this value is more than a factor of ten less
than the DCG. We can therefore consistently apply the same action level used for
resins.
Action Level For Be-7 and other beta-gamma emitting nuclides, the action level is
set at 1/20th the 5400.5 DCG.
Mixtures are assessed using the sum of the fractions method.
Action Triggered If any nuclide exceeds this action level in a waste oil, oil-based
product, glycol-based coolant or solvent, the material will not be free released.
This restrictive action level is intended to provide a hold point to allow for further
analysis. Factors to be considered include the chemical characteristics of the
material and intended use or disposition. Further evaluation may lead to a
decision to release the material. The RCM shall approve any such release above
the action level.
V. Analytical Requirements
Samples used to determine if a material can be released as non-radioactive shall be
analyzed such that the MDA for each nuclide of concern is at least a factor of five less
than the applicable action level specified in this document (except where the action limit
is defined as MDA, in which case the value for the MDA is specified).
Samples analyzed at Jefferson Lab shall be analyzed using equipment and methods which
are evaluated by participation in the Mixed Analyte Performance Evaluation Program,
conducted by the DOE Radiological and Environmental Sciences Laboratory. Other
laboratories used to conduct sample analysis applicable to the activities in this standard
shall participate in a similar quality assessment program.
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Technical Basis Document for Radioactivity Limits in Liquids as a Result of
Activation or Contamination
VI. References
1. HPP-ENV-003: HRSD Monitoring for Experimental Hall Floor Drain Sump Pit
2. DOE Exemption from Surface Contamination Limits for Be-7 (10 CFR 835,
Appendix D, dated June 8, 1998.
3. Ion-Exchange Primer
A guide to understanding the basic principles of ion exchange...
Francis J. DeSilva and
Michael C. Gottlieb
ResinTech, Inc.
Cherry Hill, New Jersey
4. Radiological Control Technical Position RCTP 2001 – 02
Department of Energy
Office of Worker Protection Policy and Programs
VII. Appendices
Appendix A. Summary of Action Levels and Actions
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Technical Basis Document for Radioactivity Limits in Liquids as a Result of Activation or Contamination
Appendix A
Summary of Action Levels and Actions
Parameter
Groundwater discharge to surface (dewatering sump)
Action Level
> MDA in sump
> EPA primary drinking water standard
Other discharges to surface
> MDA at surface water outfall
LCW and other systems or storage tanks
Discharges to sewer from ESS
Discharge to sewer from TMDU
Any liquid system
> EPA primary drinking water standard
Increase by X 10 > MDA
>1E-4 uCi/ml
>5E-4 uCi/ml
>2 mCi/day
>0.1 uCi/ml
>7 mCi/day
>8 mCi/day
H-3 > 1E-4 uCi/ml
Other nuclides > 1/5 DOE 5400.5 DCG
H-3 > 0.1 uCi/ml
> 1/20 DOE 5400.5 DCG
Ion Exchange Resins
Oils, oil-based solvents, glycols, etc.
> 1/10 DOE 5400.5 DCG
H-3 > 5E-5 uCi/ml
Other nuclides > 1/20 DOE 5400.5 DCG
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Action or Restriction
Investigation
Follow-up sampling
Halt accelerator operations
Permit variance
Dispose via HRSD
No discharge to surface w/o RCM
Investigation
Follow-up sampling
Isolate sluice gates
Post areas for Radcon contact
Purge and refill system
Drain, move or contain tanks
*For accelerator ring LCW
(a) Configure all sumps to tanks, or
(b) Disable sumps discharging to surface
Notify RCM
Notify RCM
No automatic ESS pumping
No automatic Ops set > A.L. when TMDU is
in automatic Ops
No automatic Operation of TMDU
No automatic Ops set > A.L.
No discharge > A.L. w/o RCM approval
System considered radioactive
Secondary containment
Posting of areas and components
PPE
Controlled venting only
Monitoring required if open to atmosphere
No regeneration
Landfill disposal with RCM concurrence
Disposal as LLRW only
No free release