AMERICAN NUCLEAR INSURERS. Potential for Unmonitored and Unplanned Off-Site Releases of Radioactive Material

Transcription

1 AMERICAN NUCLEAR INSURERS ANI NUCLEAR LIABILITY INSURANCE GUIDELINE Potential for Unmonitored and Unplanned Off-Site Releases of Radioactive Material March 2007 AMERICAN NUCLEAR INSURERS 95 GLASTONBURY BOULEVARD GLASTONBURY, CONNECTICUT, USA (860) Our inspections, and reports and other communications we issue, are for our insurance purposes only. We do not undertake to render any service to or on behalf of our Insureds or others or to determine or warrant the safety or healthfulness of any property or operation, or compliance with any law, rule, regulation or specification. We do not authorize anyone to rely on us for the safety of persons or property.

2 POTENTIAL FOR UNMONITORED AND UNPLANNED OFF-SITE RELEASES OF RADIOACTIVE MATERIAL Table of Contents Introduction..3 Background..3 Industry Actions and Initiatives...4 Guidelines 1.0 Fuel Pool Integrity Sumps Groundwater Intrusion Into Structures Storage Tanks Pipe Integrity Drinking Water Storm, Subsurface and Yard Drain Systems Settling Ponds (Settling / Catch / Stabilization) Sanitary Sewage On-site Landfills Groundwater Monitoring Program 14 Page 2 of 16

3 Potential for Unmonitored and Unplanned Off-Site Releases of Radioactive Material Introduction The purpose of this Guideline is to provide ANI Account Engineers with guidance for the conduct of comprehensive nuclear liability insurance assessments at ANI insured facilities to evaluate existence of or the potential for unmonitored and unplanned releases of radioactive materials off the site insurance boundary. The guidelines in this document are also intended to strengthen our insured s ability to demonstrate that reasonable actions have been taken to protect the general public and thereby provide for the defense of claims from members of the public alleging bodily injury or third party property damage caused by nuclear material emanating from the defined site. This document supplements other ANI Engineering Loss Control guidelines. Background Global risk management experience suggests that achieving compliance with applicable regulations does not always offer protection from future liabilities related to off-site damage to third parties. There is also growing public consciousness of environmental issues. In consideration of this, American Nuclear Insurers systematically examined a spectrum of conventional environmental and nuclear insurance programs, applications and insurance loss experience to profile environmental risk that could impact the ANI nuclear liability insurance policies. The results of that evaluation revealed that the nuclear industry environmental risk trends closely parallel those of other industries. Our evaluation has led us to believe that application of proactive contemporary risk management principles, that are not necessarily regulatory driven, could minimize insurance risk. Therefore the concept implicit in this document places emphasis on proactive risk minimization and quality decisions. Effluents to soil and groundwater are usually unplanned and the pathway of these releases may be unmonitored. Even when the pathway is monitored it would be difficult to identify a set of samples which would be representative of all possible release pathways and transport mechanisms. Historically many off-site sample locations are three tenths of a mile or more from the site and most are at a distance of several miles. At these distances, off-site groundwater contamination may be substantial before it would be detected by routine sampling of off-site monitoring points. As insurers, ANI looks at the nuclear insurance risk from a broad perspective consisting of several components and strategies all of which have the net effect of enhancing our insured s ability to demonstrate that reasonable actions have been taken to protect the general public and thereby provide for the defense of claims from members of the public alleging bodily injury or third party property damage caused by nuclear material emanating from the defined insurance site. Page 3 of 16

4 Industry Activities and Initiatives NEI - During 2006, the nuclear industry, under the auspices of the Nuclear Energy Institute, implemented a voluntary industry initiative requiring each utility operating a nuclear power plant to enhance the detection and management of inadvertent radiological releases in groundwater. Under the initiative, each utility developed an action plan which will provide for a comprehensive review of site conditions to assure timely detection and effective response to inadvertent releases of radiological material to the groundwater. The initiative also provides for improved communication to stakeholders in the event of a release. NRC - The NRC formed a Liquid Releases Lessons Learned Task Force in response to several incidents related to unplanned and unmonitored releases of radioactive liquids into the environment. The Task Force recently issued a comprehensive report that concluded that inadvertent releases of radioactive liquid to groundwater, containing primarily tritium, from commercial nuclear power plants had no significant impact on public health. The Task Force did issue however, 26 recommendations for the agency and nuclear plant operators. These included updating NRC regulations on monitoring radioactive releases to take into account state-of-the-art technology and practices. The task force also recommended that the industry voluntarily inform state and local agencies even in cases when releases are below the limit requiring NRC notification. INPO INPO conducts assessments of aspects of programs relating to control of radioactive materials, effluent releases, environmental monitoring, spent fuel pool integrity and subterranean piping integrity. EPRI There are several EPRI reports relating to groundwater monitoring, site characterization, and effluent releases. Most recently, EPRI formed a task force to develop a more comprehensive set of guidelines to address groundwater protection. ANSI/ANS ANSI/ANS 2.17 Evaluation of Subsurface Radionuclide Transport at Commercial Nuclear Power Facilities is currently under revision. This draft revision provides performance based standards for evaluating the transport of normal and abnormal subsurface radionuclide releases. Page 4 of 16

5 Guidelines 1.0 Fuel Pool Integrity 1.1 General A number of nuclear power plants have experienced leakage from their spent fuel pool. Visible flaws in their structure and hard to detect blockage of the leak-off collection systems have been experienced. Leakage of spent fuel pool water can also lead to structural degradation due to corrosion of steel reinforcing bars in the pool structure. The possibility of an undetected, unmonitored and unplanned release through an as-yet unidentified pathway exists, elevating nuclear liability risk from the plant. The NRC has issued Information Notice IN , Spent Fuel Pool Leakage to On-site Groundwater, which gives some background to the issue. Some spent fuel pools do not have a designed leak detection system. For these designs, alternative leak detection capability should be developed and implemented The integrity of the spent fuel pool should be evaluated with respect to NRC Information Notice , March 3, 2004, Spent Fuel Pool Leakage to Onsite Groundwater The results of the integrity review should be tracked and monitored for progress in the corrective action program Identified corrective actions should be assigned to a cognizant individual(s) along with priority, resource commitment and target dates for completion Corrective actions should be tracked and monitored for progress Details of spent fuel pool design and construction, type of liner, welds, access to sides and bottom, including elevations should be understood and documented Periodic surveillance of the accessible portions of exterior walls to inspect for through wall leakage from the spent fuel pool should be conducted Evidence of through-wall leakage should be formally reviewed and evaluated. The leakage should be stopped with corrective actions implemented. Any history of through wall (concrete) leaks should be documented. 1.2 Leak Detection / Collection System Spent Fuel Pools should incorporate a means to detect fuel pool liner leakage Details of the spent fuel pool s leak detection system should be documented. (Design, location, number of drain lines.) A formal routine surveillance program to monitor for leakage should be established. Page 5 of 16

6 2.0 Sumps Criteria should be established to determine the frequency of the surveillance The results of the surveillance should be reviewed by appropriate cognizant personnel (system engineer, operations, plant management) Leak-off from the Spent Fuel Pool leak collection system should be trended by leak rate (e.g., drips per minute, gallons per day, etc.). A decrease in leak rate may be indicative of blockage Leak-off collected from the Spent Fuel Pool leak-off collection system should be analyzed for the presence of iron and/or iron oxides to help determine if there is increased likelihood of structural reinforcing bar corrosion or other degradation associated with the Spent Fuel Pool liner and structure Any leakage should be collected and analyzed for boron (PWRs), calcium, tritium, gamma emitters or other contaminants, etc. to determine the origin and the age of the leak (old or new) The flow paths for the various lines from the Spent Fuel Pool leak-off collection system should be verified to be unobstructed such that free flow from all potential leak-off paths is ascertained. (boroscope, flushing) 1.3 Fuel Transfer Canal For PWRs, the fuel transfer canal connection (piping) between the spent fuel pool and the reactor building has been shown to leak water in the seismic (gap) area between the two buildings. The configuration typically includes the transfer tube (flanged inside containment with a large gate valve inside the spent fuel pool), bellows on one or both buildings and possibly a pipe which surrounds the outside of the transfer tube itself. Typically the transfer tube is left drained during plant operations and flooded during refueling. For some plants, the transfer canal is flooded during plant operation as well with the purpose of supplying emergency cooling water to the Reactor Coolant Pump seals Periodic surveillance should be performed to ensure integrity of the fuel transfer canal in the area between the containment and spent fuel pool buildings Surveillances should include criteria to determine frequency of inspection. The criteria should include consideration of material construction, degradation mechanisms, age, access, etc The results of any surveillances should be documented. Sumps located inside buildings and structures can have a direct pathway to the environment by way of construction methods used and by permeation through cracks and crevices and via Page 6 of 16

7 connecting piping systems. 2.1 Sumps containing radioactive liquids should be lined or coated with an impermeable coating. 2.2 Possible leak pathways to the groundwater should be evaluated and documented. 2.3 The integrity of sumps that contain radioactive material should be periodically verified by visual inspection or other means. 2.4 The integrity of subterranean piping or conduit systems connected to sumps should be periodically verified. (See Section 5.3.1) 3.0 Groundwater Intrusion into Structures Site hydrology can produce groundwater flow (which may be contaminated) from outside site structures into building sumps, lower plant elevations, etc. and result in the spread of contamination into areas not normally considered contaminated or managed as radiologically controlled areas. Under certain conditions, the water (which may be contaminated) can flow back out of the structure and subsequently back into the groundwater, contributing to contamination of groundwater. 3.1 Periodic surveillance should be performed to monitor (and control contamination to the extent practical) the potential for contaminated groundwater flow back into and out of buildings and structures. 3.2 Evaluations should be performed to determine significance and the potential for unmonitored releases back into the site groundwater. 3.3 The evaluations should be documented. 4.0 Storage Tanks (Above Grade and Below Grade) Tanks that contain radioactive materials where leakage could result in an unmonitored and unplanned release to the environment should be properly engineered and protected from degradation and periodically inspected or tested to verify integrity. Inspection frequency should consider tank contents, activity, construction material, design, age, proximate location to storm drains, groundwater, etc. 4.1 All tanks should be identified including, tank function and contents, design conditions, materials of construction, capacity, location, safety class, etc. 4.2 Tank exteriors should be periodically inspected for indications of corrosion, leaks, cracks, structural distortion and any other signs of deterioration. The inspection should include shell plates, roof plates, foundations, anchor bolts, insulation, condition of coatings, any previous repair work, condition of welds, vents, gauging devices, valves, ladders, pipe connections and ground connections. 4.3 Tank interiors should be periodically inspected for indications of corrosion, leaks, cracks, Page 7 of 16

8 structural distortion, and any other signs of deterioration. The inspection should include the tank bottom, shell plates, roof plates, pipe connections, condition of welds, condition of coatings, etc. A primary area of concern is the tank bottom. Depending on the tank contents and condition, draining, cleaning and repair may be required. Direct visual and non-destructive examination (NDE) is preferred. However, as a minimum, and if conditions allow, the inspection may be performed by underwater methods. 4.4 Indications of relevant cracking/pitting should be subjected to additional non-destructive testing (e.g. magnetic particle, dye penetrant, ultrasonic testing, etc.) to verify and quantify the extent of degradation. Indications of cracking or distortion should be formally evaluated as required by applicable codes and standards. 4.5 Tank internal diaphragms (if applicable) should be periodically inspected and/or replaced. The diaphragms are non-metallic and degrade over time. 4.6 Degradation should require repair and/or replacement. In addition, consideration should be given to installation of sentinel monitoring wells as discussed in Section 11 to monitor for potential leaks. 5.0 Pipe Integrity (Underground, Above Ground, Containing Radioactive Fluids and Gases, both on and off-site) As nuclear plants age, degradation of liquid and gaseous underground piping systems that contain or potentially contain radioactive materials may manifest in leakage to groundwater and surrounding environs. As a barrier to material degradation, buried underground piping systems are typically provided with protective exterior coatings and cathodic protection. Experience has shown that these two lines of defense (exterior coatings and cathodic protection) may not perform adequately and as a consequence leaks may develop over time. There are also situations in which there are no engineered barriers. To assure the integrity of buried piping and minimize the likelihood of leakage to the groundwater, integrity assessments of underground piping should be performed. 5.1 Each facility should have updated and accurate P&ID s, isometric drawings and/or other documentation which describes system design, location, configuration, and protection (e.g., coatings, cathodic protection) features. 5.2 Piping or equipment that contain radioactive materials where leakage could result in an unmonitored and unplanned release to the environment should be properly engineered and protected from degradation. 5.3 There should be a periodic inspection and testing program to verify system integrity of any piping that contain or could contain radioactive materials All piping systems that contain or could contain radioactive materials should be included. Inspection and testing methods may include: visual, UT, acoustic emission monitoring, hydrostatic or pressure drop testing, helium sniff, cameras/pipe crawlers, dye injection, etc. Engineering judgment should be used. Piping located in a sealed, engineered trench with leak detection capabilities may not need to be routinely inspected/tested, however these piping systems should be Page 8 of 16

9 included in the formal evaluation and documented appropriately. 5.4 In all cases, the inspection/testing program should include acceptance/repair criteria. 5.5 Above ground piping systems are preferred for new installations. 5.6 Above ground systems should be adequately monitored and protected. 5.7 A cathodic protection system (if installed) should be maintained The site s cathodic protection system should be formally assigned to a cognizant individual The location of electrical anodes should be documented Performance of rectifiers and electrical anodes should be periodically monitored. A 60 day frequency is suggested The rectifiers and electrical anodes that make up the system should be tested periodically to ensure the minimum pipe to soil potential(s) as established by site procedures. The National Association of Corrosion Engineers (NACE) recommends a minimum limit of -0.85VDC in the ground around the buried pipe The testing frequency should be based on generally accepted standards. 5.8 The results of all inspections and testing should be documented. 5.9 In the event of a pipe leak, the leak should be stopped and the consequences of the leak should be fully evaluated and documented The evaluation should include leak location, migration pathway identification and characterization of the plume, radionuclide contamination, effects on existing groundwater, potential for migration off-site, contamination of local aquifers and drinking water supplies as well as radiological dose assessment(s) The leak should be included in the plant s corrective action program and responsibility for corrective action should be assigned to a cognizant individual The piping should be repaired and/or replaced based on current industry standards The documentation should be retained based on the guidelines provided in ANI Bulletin 80-1A In the event of piping integrity degradation, the degradation should be fully evaluated and documented The degradation should be included in the plant s corrective action program and assigned to a cognizant individual. Page 9 of 16

10 6.0 Drinking Water An engineering and radiological assessment should be performed to justify continued use of the affected piping Monitoring wells should be placed proximate to high risk piping systems or components to provide for early detection indication of a leak. The monitoring wells should not be used as a substitute for integrity monitoring of known degraded piping. Well location should be based on site hydro-geological conditions. (See Section 11) An action plan should be developed which would include thresholds for piping repair and/or replacement. 6.1 Drinking water if drawn from sources in proximity to the site, should be monitored for gamma emitters and tritium. If the gamma isotopic or tritium analysis indicate contamination due to plant related radionuclides, the station should perform analyses for hard-to-detect radionuclides (e.g., Sr90, Fe55, Ni63, alpha emitters, etc.). The analyses should be based on the plant s source term, isotopic ratios, and transport characteristics. The results should be documented and retained based on the guidelines provided in ANI Bulletin 80-1A. 6.2 Contaminated drinking water should be documented. The documentation should be retained based on the guidelines provided in ANI Bulletin 80-1A. 6.3 Use of drinking water containing plant related radionuclides should be discouraged. 7.0 Storm, Subsurface and Yard Drains and Other Collection Systems (e.g., moats, dikes, etc.) Gaseous releases to the atmosphere may be washed out during rain, snow or weather inversions and may slightly contaminate the ground or collection system. Storm water discharge may become contaminated by the washout or by runoff when it contacts the ground. Additionally, some storm water or yard drain systems serve as a collection point and conduit for surface and subsurface groundwater which may be contaminated. Moats or dikes are often used as collection areas surrounding outdoor tanks. The purpose of monitoring the storm drains and other collection systems is to monitor for undetected leakage from plant systems or monitor for the migration of known leaks. 7.1 The storm water discharge path from the facility should be periodically monitored for gamma emitters and tritium. If the gamma isotopic or tritium analysis indicate contamination due to plant related radionuclides, the station should perform analyses for hard-to-detect radionuclides (e.g., Sr90, Fe55, Ni63, alpha emitters, etc.). The analyses should be based on the plant s source term, isotopic ratios, and transport characteristics. 7.2 Storm water discharges are typically controlled and permitted by a National Pollutant Discharge Elimination System (NPDES) permit. Where storm water systems have the potential to become contaminated or provide a conduit for contaminated groundwater, the outfall(s) should be considered for inclusion into the facility s Off-site Dose Page 10 of 16

11 Calculation Manual (ODCM). The ODCM should describe the discharge points, effluent release limits and sampling protocols. 7.3 If it is found that plant related radionuclide activity was released off-site, documentation of the release and radionuclide activity should be retained based on the guidelines provided in ANI Bulletin 80-1A. 7.4 Storm and subsurface drains containing radioactive materials should be modified (e.g., catch tank, flow totalizer, auto sampler) to allow for accurate flow rate measurement and representative sampling. 7.5 The integrity of the entire storm drain system should be periodically evaluated. The evaluation should consider inspection for debris, line breaks or any discontinuity that would contribute to an unplanned and unmonitored release of radioactive materials to the groundwater. 7.6 Water collected in moats, dikes or berms surrounding outdoor tanks, pumps or piping containing radioactive liquids, should be sampled for gamma emitters and tritium prior to disposition. If the sample indicates plant related radionuclides, an evaluation should be conducted to determine the source of the contaminants. Contaminated water should be directed to the radioactive waste processing system. 8.0 Settling Ponds (Settling / Catch / Stabilization) Some insured facilities have settling ponds (treatment ponds or water reservoirs) located onsite. Chemical treatment ponds may be used to hold up discharge of low level radioactive liquids, contaminated resin, or low concentrations of chemical wastes. There may also be areas for final retention of storm drainage water where the pond is enlarged to provide an increased surface area for evaporation of the water to the atmosphere. The use of settling ponds is normally not encouraged. Although the potential migration of radioactivity off-site from these ponds can be reduced by installing and maintaining engineered barriers, controlling the transport of radioactive liquids to these ponds or reservoirs and following specific environmental monitoring protocols, experience indicates that some ponds originally designed for complete retention have over the years allowed some migration to groundwater. 8.1 New or remediated ponds should be provided with a double liner with the capability for leak detection between the liners. 8.2 There should be procedures to approve the discharge of radioactive material to ponds and reservoirs. Review and approval could be by committee (e.g., environmental task force or engineering group) or by one individual (e.g., environmental manager). 8.3 Periodic radiological surveys should be performed to determine posting requirements and the presence of hot spots. 8.4 Testing should be performed periodically to verify pond (including lining) integrity. Additional methods such as hydraulic calculation, electromagnetic and resistivity survey Page 11 of 16

12 and seepage meters can be used for groundwater monitoring. Monitoring wells should be used as appropriate. 8.5 There should be periodic sampling and analysis of groundwater for radioactive contamination in the vicinity of the pond or reservoir The samples should be analyzed for principal gamma emitters and tritium. If the gamma isotopic or tritium analysis indicate contamination due to plant related radionuclides, the station should perform analyses for hard-to-detect radionuclides (e.g., Sr90, Fe55, Ni63, alpha emitters, etc.). The analyses should be based on the plant s source term, isotopic ratios, and transport characteristics. 8.6 If it is found that radionuclide activity was released off-site, documentation of the release and radionuclide activity should be retained based on the guidelines provided in ANI Bulletin 80-1A. 8.7 Soil and vegetation samples specifically designed to identify migration of contaminants from the ponds and reservoirs should be periodically collected and analyzed for gamma emitters. (It is suggested that gridding be performed since it serves to reference sample locations quite easily.) 8.8 A historical log of the reservoirs and ponds should be maintained documenting such items as: maintenance, inspections, repairs and operations. 8.9 Should the integrity of the reservoir or pond result in the potential for contamination of the groundwater or off-site release, remediation of the affected area should be implemented. 9.0 Sanitary Sewage 9.1 Inputs from areas that could contain radioactive materials should be identified. 9.2 A pathway analysis should be performed for all sewage effluents released from the site (e.g., clarified water from an on-site treatment facility, concentrated solids from an onsite treatment facility, raw sewage shipped to a Publicly Owned Treatment Works (POTW)). 9.3 Clarified water released to the environment should be analyzed for gamma emitters (gamma spectroscopy) and tritium. 9.4 Concentrated solids should be analyzed for gamma emitters (gamma spectroscopy). 9.5 Raw sewage released to a POTW should be analyzed for gamma emitters (gamma spectroscopy) and tritium. 9.6 If the gamma isotopic or tritium analysis indicate contamination due to plant related radionuclides, the station should perform analyses for hard-to-detect radionuclides (e.g., Sr90, Fe55, Ni63, alpha emitters, etc.). The analyses should be based on the plant s source term, isotopic ratios, and transport characteristics. Page 12 of 16

13 9.7. A 10CFR (Method for Obtaining Approval of Proposed Disposal Procedures) evaluation should be performed for sludge / concentrated wastes, containing plant related radionuclides, that are disposed of on-site or at an industrial landfill 10.0 On-Site Landfills Containing Radioactive Materials 10.1 On-site landfills that contain radioactive or potentially radioactive materials should be monitored for leakage The integrity of subterranean piping systems and components associated with the landfill should be verified New or remediated landfills containing radioactive materials should be designed and constructed with engineered barriers to minimize the potential for leaks An engineering analysis should be periodically performed to justify the use or continued use of landfills There should be procedures for approving and granting permission to send radioactive material to on-site landfills. Review and approval could be by committee (e.g., environmental task force or engineering group) or by one individual (e.g., environmental manager) Periodic radiological surveys should be performed to determine posting requirements and the presence of hot spots Testing should be performed periodically to verify landfill (including lining) integrity. Additional methods such as hydraulic calculation, electromagnetic and resistivity survey and seepage meters can be used for groundwater monitoring There should be periodic sampling and analysis of groundwater for radioactive contamination in the vicinity of the landfill The samples should be analyzed for principal gamma emitters and tritium. If the gamma isotopic or tritium analysis indicate contamination due to plant related radionuclides, the station should perform analyses for hard-to-detect radionuclides (e.g., Sr90, Fe55, Ni63, alpha emitters, etc.). The analyses should be based on the plant s source term, isotopic ratios, and transport characteristics If it is found that plant related radionuclide activity was released off-site, documentation of the release and radionuclide activity should be retained based on the guidelines provided in ANI Bulletin 80-1A Soil and vegetation samples specifically designed to identify migration of contaminants from on-site landfills should be periodically collected and analyzed for gamma emitters. (It is suggested that gridding be performed since it serves to reference sample locations quite easily.) Page 13 of 16

14 10.11 A historical log of the contents of the landfill should be maintained documenting such items as: maintenance, inspections, repairs, operations and radioactive material deposited Should the integrity of the landfill result in the potential for contamination of the groundwater or off-site release, a remedial action plant for the affected area should be implemented A 10CFR (Method for Obtaining Approval of Proposed Disposal Procedures) evaluation should be performed for soils containing plant related radionuclides, that are disposed of on insured property or an industrial landfill 11.0 Groundwater Monitoring Program Effluent releases to the soil and groundwater are usually unplanned. Since contaminant pathways to groundwater are not readily apparent, groundwater monitoring may be overlooked. Where the pathway is monitored, wells may not be representative of the general conditions of the environs. If on-site monitoring is not performed, the first indication of environmental contamination may in fact be radionuclide contamination of property off-site. Groundwater, as used in this document and consistent with the industry initiative means any subsurface water, whether in the unsaturated or vadose zone, or in the saturated zone of the earth. In hydrology the term groundwater has a very specific meaning. This is water located in the saturated zone of the earth s substrate. The Saturated zone is that portion of the earth substrate in which voids are filled with only water, generally this is water below the water table. The unsaturated or vadose zone is that portion of the earth substrate in which voids in the substrate are not completely filled with water. For purposes of this document, examples of water considered groundwater include: Any subsurface moisture or water, regardless of where it is located beneath the earth s surface. Any water located in wells, regardless of depth, type or whether or not it is potable. Water in storm drains, unless it has been demonstrated that the storm drains do not leak to the ground. Water in sumps that is released directly to the subsurface. The location of monitoring wells should be dependent on the hydrological conditions of the site. In the presence of fractured rock, for example, it may be impossible to monitor with certainty for underground migration of contaminants with vertically drilled wells, since a well would only detect contaminant migration through fractures that penetrate the well diameter. Similar problems occur in the vertical plane for aquifers in which horizontal groundwater flow is relatively unrestricted, but vertical flow is prevented by an aquiclude which is a confining layer of dense impermeable materials such as rock or clay. A further complication may arise in the presence of multiple levels of confined aquifers. In these cases, it is common to observe Page 14 of 16

15 that the flow in one level aquifer is in a different direction than the flow in another level aquifer. Groundwater contamination sampled at a single point only describes what the concentrations are at the measured location at a point in time. If the location sampled happens to be along the contaminant migration flow path downgradient of a specific system being monitored, then a sample will yield relevant data including the groundwater quality downgradient of that system. A Gaussian approximation allows the conclusion that the concentrations in all other directions are less. If the location at a point in time sampled does not happen to be along the flow path, or if the groundwater flow path is unknown, then the sample may not be representative of the true groundwater quality downgradient of the target system being monitored, only indicative of the single location sampled. If fundamental equilibrium groundwater parameters are known, including soil characteristics, flow direction and flow rates, then the migration of contaminants can be estimated with some assurance. Further, if these parameters are known and if a single sample for groundwater contamination has been measured, then an approximate concentration and the concentration gradient can be estimated. From these data the potential environmental risk presented can be evaluated and recommended corrective or remedial actions developed Current site hydro-geological characteristics should be validated with respect to fundamental groundwater parameters and expected natural flow patterns This should result in an understanding of predominant groundwater flow gradients based on current conditions and should include identification of potential pathways for groundwater migration from on-site locations to off-site locations through the groundwater. Existing hydrology studies from plant construction, historical environmental studies, license renewal reports, etc. may be considered but should not be a substitute for validation of current, site hydrogeological characteristics Groundwater monitoring should be an integral part of the environmental monitoring program Groundwater monitoring should routinely be conducted both on and off-site to identify the presence of groundwater contamination and to evaluate the rate and direction of migration of that contamination The design of a well monitoring system(s) should be determined by the local hydrogeological conditions and potential anthropogenic factors. Well monitoring components and depths should be selected accordingly Monitoring wells should be placed proximate to high risk systems, components or structures (e.g., piping, tanks, reservoirs and landfills) to provide early detection of a leak. The monitoring wells should not be used as a substitute for integrity monitoring, assessments or remediation of known degraded piping, tanks, reservoirs or landfills Risk characterization for installation of groundwater monitoring wells should consider the following: Page 15 of 16

16 Site Hydrogeologic Conditions Aquifer Location Prevalent Groundwater Flow Retention Pond and Landfill Locations Underground Piping Age, Materials, Integrity Assessments and Locations Above Ground Storage Tank Locations Areas of Known or Suspected Spills Lower Limit of Detection Drinking Water Supply Locations 11.7 The location of new monitoring wells should also consider known or suspected spills or other releases of contaminated water to the soil, or sources of contaminated water even in the absence of known or suspected spills. (e.g., spent fuel pools, etc.) 11.8 Groundwater monitoring should be sufficiently representative of the region being sampled such that the results obtained confidently provide a quantitative determination of the presence of radionuclides as described in below Where environmental samples have measured groundwater contaminants, several actions should be taken as a minimum: Thereafter, environmental samples should be routinely taken. Positive results should be verified and evaluated. Repeat samples may be required to confirm any positive results The samples should be analyzed for principal gamma emitters and tritium. If the gamma isotopic or tritium analysis indicate contamination due to plant related radionuclides, the station should perform analyses for hard-to-detect radionuclides (e.g., Sr90, Fe55, Ni63, alpha emitters, etc.). The analyses should be based on the plant s source term, isotopic ratios, and transport characteristics Positive results should be trended over time to determine whether the levels are time dependent and whether the trend observed is increasing, decreasing or constant Plume Characterization - The distribution of the contaminants should be estimated, including maximum concentrations and areas actually or potentially affected A careful determination should be made as to the need for further operational or remedial action The source of the leak should be identified and repaired Groundwater contamination events should be documented. The documentation should be retained based on the guidelines provided in ANI Bulletin 80-1A. Page 16 of 16