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USEPA radioactive waste disposal standards: Issued and under development
NUCLEAR AND CHEMICAL WASTE MANAGEMENT, Vol. 8, pp, 3-12, 1988 Printed in the USA. All rights reserved.
0191-815X/88 $3.00 + .OO Copyright 0 1988 Pergamon Press plc
USEPA RADIOACTIVE WASTE DISPOSAL STANDARDS: ISSUED AND UNDER DEVELOPMENT
W. F. Holcomb, * R. L. Clark, R. S. Dyer, and F. L. Galpin U.S.Environmental Protection Agency, Of$cc of Radiation Programs, Washington, DC 20460
ABSTRACT.
The USEPA has issued and is developing generally applicable environmental standards for the disposal of radioactive wastes. Standards have been issued for the disposal of spent nuclear fuel, high-level and transuranic wastes, and for uranium mill tailings. Standards are being developed for the land disposal of low-level radioactive wastes and for wastes considered “Below Regulatory Concern.” Regulations for ocean disposal of low-level radioactive wastes are also under consideration.
INTRODUCTION
Control Act (5), each of which may be applicable under certain circumstances. Another reason is the feasibility of implementation. This is related to the form of the standard or (e.g., working levels for radon daughters roentgens for gamma-ray exposure), the time span over which the potential hazard is to be evaluated (e.g., annually or thousands of years), how compliance is demonstrated, and the presence of nonradioactive, hazardous materials in the waste. A cost-effectiveness analysis is usually done as a basis for the standards and takes the form of comparing the cost of various control methods, the potential radiation exposure reduction, the residual exposure that remains, and any other benefits and costs. In the final analysis, the proposed level of a standard is a judgment which is based in part on this cost-effective analysis. This is a very simplified description of our standards-setting processs. Another factor which is considered is the compatibility with other EPA standards and policies. With the exception of standards for ocean disposal of low-level radioactive waste and standards which might be promulgated for naturally occurring and accelerator-produced radioactivity, EPA does not implement or enforce its radioactive waste disposal standards. Enforcement falls to the Nuclear Regulatory Commission (NRC), the Department of Energy (DOE), or the States through agreement with the NRC. Also, the process must “consist of establishing generally applicable environmental standards for the protection of the general environment,” which means requirements may not be site-
The United States Environmental Protection Agency (EPA) has a responsibility to develop standards and
guides to minimize adverse impacts on public health and the environment from radiation. A major part of this effort, over the past few years, has been directed at radioactive waste disposal activities. Within EPA, the Office of Radiation Programs is responsible for activities related to radiation protection. EPA APPROACH One question often arises in regard to EPA’s approach to setting waste disposal standards: Why not have just one radiation exposure standard to cover all activities? The suggestion is that some universal levels of acceptable exposure could be established that would apply to all waste disposal operations. There are several reasons why we consider this impracticable as well as inappropriate. First, several legislative authorities include radiation protection; some give EPA leeway in setting standards, some do not. The most often used legal authorities to set radiation standards are the Atomic Energy Act (AEA) as amended (1) and the Reorganization Plan No. 3 (2). In addition, EPA has radiation protection authorities under the Marine Protection, Research and Sanctuaries Act (3), the Resource Conservation and Recovery Act (4) and the Toxic Substances RECEIVED20 MAY 1987; ACCEPTED12 JANUARY1988. *Corresponding Author
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specific (2). Therefore, EPA’s AEA standards usually take the form of numerical performance requirements, indicating the level of control to be achieved, and are typically expressed in terms of dose, environmental concentrations or release limits. ENVIRONMENTAL STANDARDS FOR URANIUM AND THORIUM MILL TAILINGS Uranium mill tailings consist mainly of nonradioactive materials but also contain essentially all of the thorium and radium present in the ore. The largest source of radiation exposure is the short-lived radioactive decay products of radon-222, itself a decay product of radium-226. Radon can build up to high levels indoors when tailings are placed around buildings or when buildings are located close to tailings piles. Other problems with tailings include gamma radiation and a water contamination potential from radioactive and the nonradioactive, hazardous constituents in the tailings. In 1978, Congress passed the Uranium Mill Tailings Radiation Control Act (6) to deal with these problems. Two programs were established under this Act. First, for the inactive sites, DOE is required to identify and list such sites and then to reclaim tailings piles and cleanup of off-site properties under standards provided by EPA. Second, for licensed sites, NRC and its Agreement States are required to control tailings as a licensed material, again under standards provided by EPA. Risk Analysis The analyses by EPA (7,8) indicate a lung cancer risk of about 1 in 100 (lifetime) for people living near a tailings pile and as high as 4 in 100 (lifetime) for people living in houses where tailings have been placed around the foundation. Groundwater contamination was found at several sites. External radiation levels could be high for some situations. Finally, the long half-life of the radionuclides are a matter of concern. Based on these analyses, EPA identified objectives for standards for uranium mill tailings disposal. The primary objective of standards for control of hazards from tailings is isolation and stabilization to prevent the tailings from misuse by man and dispersal by natural forces (floods, wind, rain, etc) and through air pathways. The secondary objective is to optimize control of radon emissions from tailings piles. Methods that are likely to be used to isolate and stabilize piles are assumed to control external radiation and provide for long-term control. The primary objective of standards to protect groundwater is prevention of seepage of hazardous constituents from tailings into groundwat-
W. F. HOLCOMB ET AL.
er. The secondary objective is to assure that any contamination of groundwater does not exceed levels that are protective of public health and the environment and to take corrective actions as needed to achieve such levels. Inactive Sites The 1983 EPA standards for inactive sites, 40 CFR 192 (9), require that, for disposal of tailings, control measures shall be designed to: 1. Be effective for up to one thousand years, if reasonably achievable, and, in any case, for at least two hundred years. 2. Provide reasonable assurance that releases of radon-222 from residual radioactive material, to the atmosphere, will not exceed an average release rate of 20 pCi/m2s (0.74 Bq/m2/s) or alternatively, will not increase the annual average concentration of radon-222 in air at or above any location outside the disposal site by more than 0.5 pCi/L (0.019, BqIL). The standards for remedial actions, as a result of residual radioactive materials, require cleanup so as to provide reasonable assurance that: 1. The concentration
of radium-226 in land, averaged over any area of 100 square meters, shall not exceed the background level by more than 5 pCi/g (0.19 Bq/g), averaged over the first 15 centimeters (cm) of soil below the surface, and 15 pCi/g (0.56 Bq/g), averaged over 15-cm thick layers of soil more than 15 cm below the surface. 2. In any occupied or habitable building the objective of remedial action shall be, and reasonable effort shall be made to achieve, an annual average (or equivalent) radon decay product concentration (including background) not to exceed 0.02 working levels (WL). In any case, the radon decay product concentration (including background) shall not exceed 0.03 WL. In addition, the level of gamma radiation shall not exceed the background level by more than 20 pR/‘hr (5.2 nCikg/hr) per hour.
Active Sites The 1983 EPA standards for licensed sites cover both operational and closure phases (10). Operational phase standards require that: 1. Surface impoundments (except for any existing portion) must have a liner that is designed, constructed, and installed to prevent any migration of wastes out of the impoundment to the adjacent subsurface soil or groundwater or surface water
RADIOACTIVE
WASTE DISPOSAL STANDARDS
at any time during the active life of the impoundment. Or alternatively, no liner is required if the regulatory agency finds, based on a demonstration by the owner or operator, that alternate design and operating practices, together with location characteristics, will prevent the migration of any hazardous constituents into groundwater or surface water at any future time. 2. A monitoring system will be operated and, if hazardous constituents are found in the uppermost aquifer at the edge of the tailings impoundment, groundwater protection standards will be established at background levels for such constituents, except for those constituents for which drinking water standards are available, then the standards are established at those levels. A corrective action program will be conducted, if the groundwater protection standard is being exceeded in the uppermost aquifer at the edge of the tailings. This program must be continued until the groundwater protection standards are achieved. Alternate concentration limits may be applied for, instead of taking corrective actions. The limits of 40 CFR 190, “Environmental Radiation Protection Standards for Nuclear Power Operations,” are met (11). These standards, promulgated in 1977, limit the radiation dose to any individual to 25 millirem (0.25 mSv) per year to the whole body and any organ except for 75 mrem (0.75 mSv) to the thyroid. Part 190 excludes radon-222 and its short-lived decay products. 5. The 40 CFR Part 440 Subpart C standards under the Clean Water Act are met. These standards prohibit discharges to surface waters, except at locations where annual average precipitation exceeds average annual evaporation. 6. The 40 CFR Part 61 Subpart W national emission standard for radon-222 emissions from tailings (as a result of requirements under the Clean Air Act) requires that any new tailings impoundments be no more than 40 acres in area or that, for dewatered tailings, no more than 10 acres of tailings are uncovered at any time. Covered tailings must meet the after-closure requirements discussed below. If impoundments are used, no more than two can be in operation at any one site and at any one time. The use of tailings impoundments, existing in 1986, must be terminated by the end of 1992, however, extensions are available under certain conditions. After closure of a tailings impoundment, measures shall be designed to:
control
1. Be effective for up to one thousand years, to the
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extent reasonably achievable, and, in any case, for at least two hundred years. 2. Provide reasonable assurance that releases of radon-222 from residual radioactive material, to the atmosphere, will not exceed an average release rate of 20 pCi/m2/s (0.74 Bqim’is) per square meter per second. However, the above two requirements shall not apply to any portion of a licensed and/or disposal site which contains a concentration of radium-226 in land, averaged over an area of 100 square meters, which as a result of tailings, does not exceed the background level by more than: (a) S pCi/g (0.19 Bq/g), averaged over the first I.5 cm below the surface; and (b) 15 pCi/g (0.56 Bq/g), averaged over 15-cm thick layers more than 15 cm below the surface. Thorium Tailings Standards for disposal of licensed thorium mill tailings are provided by adding “and thorium” every place “uranium” appears in the licensed uranium mill tailings standards, “and radon-220” every appears, and “radium-228” place “radon-222” appears. Also added every place “radium-226” were standards to limit the radiation dose to any individual to 25 mrem (0.25 mSv) per year to the whole body and any organ except for 75 mrem (0.75 mSv) to the thyroid. Thus, standards for licensed thorium mill tailings disposal are the same as standards for licensed uranium mill tailings disposal. It is noted that for thorium tailings there are no national emission standards under the Clean Air Act or effluent limitation guidelines under the Clean Water Act. Court Actions The uranium mill tailings standards were contested by the uranium industry, environmental groups, states, and by individuals. The major challenges included: (a) asking the Administrator to make a finding regarding the acceptability of the risk from mill tailings, (b) questioning whether the risk from mill tailings, after the disposal standards were met, was unacceptably high, (c) suggesting that the states had sole authority for establishing groundwater standards, and (d) asking that quantitative groundwater standards for inactive tailings be required. The court dismissed all challenges except one. It set aside the groundwater provisions of the inactive standards and remanded them to EPA “. . . to treat these toxic chemicals that pose a groundwater risk as it did in the active mill site regulations.” The agency has proposed groundwater standards for inactive sites to replace those set aside by the court (12).
W. F. HOLCOMB
6 TABLE
ET AL.
1
Release Limits for Containment Requirements (15). Release Limit (curies)
Radionuclide Americium-241 or -243 Carbon- 14 Cesium-135 or -137 Iodine- 129 Neptunium-237 Plutonium-238, -239, -240, or -242 Radium-226 Strontium-90 Technetium-99 Thorium-230 or -232 Tin-126 Uranium-233, -234, -235, -236, or -238 Any other alpha-emitting radionuclide with a half-life greater than 20 years. Any other radionuclide with a half-life greater than 20 years that does not emit alpha particles.
100
100 1000 100 100 100 100 1000 10000 10 1000 100 1000
Notes: (1) Cumulative releases to the accessible environment for 10000 years after disposal. (2) Release limit is per 1000 MTHM or other unit of waste as defined in Appendix A of 40 CRF Part 191.
ENVIRONMENTAL STANDARDS FOR THE MANAGEMENT AND DISPOSAL OF SPENT NUCLEAR FUEL, HIGH-LEVEL AND TRANSURANIC RADIOACTIVE WASTES
to members of the public resulting from the management and storage of spent fuel, HLW or TRU wastes carried out during activities at facilities licensed by the NRC, and from the same type of activities and facilities managed by the DOE at waste disposal facility sites. At NRC-licensed facilities, the limits are the same as those in 40 CFR 190 (1 l), that is, 25 mrem (0.25 mSv) to the whole body, 75 mrem (0.75 mSv) to the thyroid, and 25 mrem (0.25 mSv) to any other critical organ. For DOE non-NRC-licensed facilities, the limits are 25 mrem (0.25 mSv) to the whole body and 75 mrem (0.75 mSv) to any critical organ.
In the Nuclear Waste Policy Act (13), Congress explicitly stated the responsibility of the EPA to establish generally applicable environmental standards for the disposal of spent nuclear fuel and highlevel radioactive wastes. In 1985, EPA promulgated Standards for the 40 CFR 191, “Environmental Management and Disposal of Spent Nuclear Fuel, High-Level and Transuranic Radioactive Wastes” (14,15). The standards are arranged in two parts, Subpart A and Subpart B. Subpart A applies to the management and storage of spent nuclear fuel, high-level radioactive wastes (HLW), or transuranic (TRU) radioactive wastes. Management is defined as any activity, operation, or process (except transportation) conducted to prepare spent fuel, HLW or TRU wastes for storage or disposal, or the activities associated with placing such wastes in a disposal system. Subpart B sets release limits for disposal systems which provide permanent isolation of spent fuel, HLW or TRU wastes from the accessible environment with no intent of recovery; this Subpart takes effect when the system is sealed.
Disposal Standards Subpart B contains containment (quantitative), assurance (qualitative), individual protection, and groundwater protection requirements. The containment requirements set numerical limits on the projected release of specific radionuclides to the accessible environment over the 10,000 year period following closure of the repository. The limits are based on an overall societal objective of no more than 1,000 excess cancer deaths over 10,000 years from 100,000 metric tons of spent fuel. This level of risk is comparable to the risks that future generations would face from the amount of uranium ore needed to make the fuel had it never been mined.
Management and Storage Standards Subpart A establishes annual radiation dose limits
Containment Requirements The containment requirements
were set for two
RADIOACTIVE
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WASTE DISPOSAL STANDARDS
categories of releases in terms of their probability of occurring. A reasonable expectation of conformance with the requirement is to be based on a performance assessment which incorporates an overall probability distribution of the cumulative releases. Specifically, the cumulative probability of releases to the environment, exceeding the specific radionuclide release limits in Table 1, must be less than one chance in ten. The second category limits releases, caused by events which cumulatively have greater than one chance in a thousand of exceeding ten times the specific radionuclide release limits in Table 1. No limits were set for releases, caused by very unlikely events, which cumulatively have less than one chance in a thousand of occurring. Individual Protection Requirements The individual protection requirements limit the annual exposure from the disposal system to a member of the public in the accessible environment, for the first 1,000 years after disposal, to 25 mrem (0.25 mSv) to the whole body or 75 mrem (0.75 mSv) to any critical organ. Groundwater Protection Requirements The groundwater protection requirements apply only to groundwater supplies serving thousands of people, and limit the water withdrawn from these special sources to concentrations similar to those established for the output of community water systems, as set forth by EPA’s National Interim Primary Drinking Water Regulations, 40 CFR 141 (16). Assurance Requirements The assurance requirements, applicable to DOE facilities, are good-sense principles crafted to provide an extra margin of assurance that the containment requirements will be met despite the large uncertainties that confront the prediction of disposalsystem performance over 10,000 years. The NRC is finalizing conforming amendments to provide consistent, assurance requirements for facilities they license (,17). The essence of the six assurance requirements is: 1. Disposal systems shall not depend on active institutional controls for more than 100 years after disposal (i.e., closure). 2. Long-term disposal system performance should be monitored for a reasonable time to detect substantial and detrimental deviations from expected performance. 3. Disposal systems shall be marked and their locations recorded in appropriate government records. 4. Disposal systems shall be designed with several
different types of barriers, both natural and engineered. 5. Sites should not be located where scarce or easily accessible resources are located. 6. Wastes shall be recoverable for a reasonable time after disposal. Legal Action Concerning 40 CFR Part 191 In March 1986, several environmental groups, led by the Natural Resources Defense Council, and the States of Maine, Minnesota, Texas, and Vermont filed petitions for review in several Federal courts around the country; these petitions were consolidated in the U.S. Court of Appeals for the First Circuit. The court rendered its decision in July 1987. That decision vacated and remanded the entirety of 40 CFR Part 191 even though only the two sections dealing with groundwater, 191.15 (Individual Protection Requirements) and 191.16 (Ground Water Protection Requirements), were found defective. In August 1987, the Justice Department, on behalf of EPA, filed a motion requesting reinstatement of those portions of the standards which were upheld. In September 1987, the Court consented to reinstate Subpart A but continued the remand of Subpart B. Briefly, the court concluded that: Disposal of HLW in mined, geologic repositories might be underground injection and that EPA failed to consider the Safe Drinking Water Act’s (SDWA) Part C requirements on underground injection by potentially allowing endangerment of groundwater by exceeding EPA’s own drinking water standards. Therefore, EPA must reconcile Sections 191.15 and 191.16 with the SDWA or adequately explain the divergence. EPA must supply an adequate explanation for selecting the 1,000 year design criterion in 19 1.15 and 191.16. Section 191.16, the Ground Water Protection Requirements, was promulgated without proper notice and comment and must be reproposed for public comment. Currently, an approximate two year effort is envisioned to comply with the terms of the remand. ENVIRONMENTAL STANDARDS FOR THE MANAGEMENT AND LAND DISPOSAL OF LOW-LEVEL RADIOACTIVE WASTES In 1983, the EPA published an Advanced Notice of Proposed Rulemaking (ANPRM) (18) to indicate its intention to develop generally applicable, environmental standards for the land disposal of LLW using AEA and Reorganization Plan No. 3 authorities.
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It is EPA’s intention that the LLW standards, when they are published, will protect public health and the environment, taking into account the possible control methods that are available, their effects on reducing risks, and their costs. The LLW standards would cover disposal of all AEA materials not controlled by other EPA standards. An important point is that they would cover all LLW disposal facilities owned and operated by the Federal Government, as well as commercial LLW disposal facilities, whereas current NRC regulations apply only to facilities licensed by the Agreement States or NRC itself. This is significant, because the Federal Government generates and disposes of more than 40% of all LLW nationwide. A uniform standard for all LLW disposal is both a desirable and an achievable goal. Publication of a proposed LLW standard is planned in 1988, and a final standard a year later. The early standards development plans indicated the intent to cover only AEA wastes. Comments in response to the ANPRM and at public outreach meetings, especially from state representatives, strongly recommended that the standard should also cover certain wastes from use of natural and accelerator-produced radioactive materials (NARM). It was determined to be sufficiently worthwhile, and the plan was subsequently modified. The Toxic Substances Control Act (TSCA) (5) is being considered for the necessary authority to regulate NARM. Section 6 of this act provides that if the administrator determines that an unreasonable risk exists, he may promulgate regulations on the disposal to mitigate such risks. The EPA LLW Standard is intended to cover disposal of all AEA materials not covered by other EPA standards. This standard will have several important and closely related areas of focus: 1. LLW predisposal operations, storage and management. This would include limits on radiation exposure to individuals during processing, management, and storage of LLW. 2. Definition of radiation exposures related to radioactive waste disposal that are sufficiently small, that they either do not need to be regulated regarding their radiation hazard or the wastes can be disposed of with minimal controls (i.e., a level “below regulatory concern”). 3. Radiation exposure limits to individuals after the disposal site is closed (i.e., after it stops receiving waste). 4. Groundwater protection for both pre- and postdisposal phases. 5. High-concentration, relatively low-volume NARM wastes in the same standards promulgation. This will be in a separate segment of the Code of Fed-
W. F. HOLCOMB ET AL.
era1 Regulations because it uses TSCA authority rather than the AEA (5). 6. Other areas will include guidance on implementation and qualitative assurance requirements. Individual Operations
Radiution Exposure urld Management
Limits
Daring
This area would limit annual individual exposures from all environmental pathways to members of the public from nonuranium-fuel-cycle facilities which process, manage, or store LLW. Waste generators are now opting for volume reduction, waste processing, and packaging, not only to meet NRC’s 10 CFR 61 requirements (19), but as methods to reduce disposal costs and to stay within reduced out-of-state volume limits imposed by host states for existing LLW disposal facilities under the Low-Level Radioactive Waste Policy Act Amendments of 1985 (20). Confronted with growing trends to create a large number of diverse facilities for treating and processing LLW, plus the potential for facilities that would be dedicated to the storage of LLW for periods beyond our previous experience, the agency deems it prudent to include limits on these potential exposures in our standards. This would also make the EPA LLW standards parallel and consistent in structure with the 25 mrem (0.25 mSv) per year standards EPA promulgated for the Uranium Fuel Cycle, 40 CFR Part 190 (11) and High-Level Radioactive Waste, 40 CFR Part 191(15). Individual Disposal
Radiation
Exposure
Limits
fbr Post-
The standard will establish limits on exposure through all pathways to members of the public from the land disposal of LLW. It would apply to any LLW disposal facility using any land disposal method any place in the United States. A persuasive reason would be needed to significantly depart from the 25 mrem (0.25 mSv) per year chosen by the NRC. EPA’s technical analysis has not revealed any such reason so far. Groundwater
Protection
The protection of the nation’s groundwaters is of major importance in EPA and such a consideration is particularly appropriate in waste disposal standards. The agency’s Groundwater Protection Strategy calls for the protection of groundwater commensurate with its value and use (21). The approach to groundwater protection from radioactivity will be developed in this context. Class 1 groundwaters require the highest levels of protection and represents those that serve as irreplaceable sources of drinking water for large populations (i.e., 2,500 people or more). It is appropriate to give these groundwaters the highest level of
RADIOACTIVE
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WASTE DISPOSAL STANDARDS
protection and, therefore nondegradation criteria are being considered. The draft EPA groundwater classification system generally defines a Class II groundwater as any that is not Class I and is potable (i.e., contains less than 10,000 ppm (10 g/L) dissolved solids). This may be too broad a category for regulatory purposes. As a second level for regulation, a subset of Class II groundwaters> which represents the more productive aquifers that are presently, or could in the future, serve as community water supplies, is being considered. One thought is to assure that no community has to remove radionuclides from their drinking water because of releases from a LLW facility. In such an instance, the EPA Interim Primary Drinking Water Regulations (16) could be the recommended limit. Any actual consumption or use of other groundwaters would, of course, have to be considered in determining compliance with the individual radiation exposure limits.
The considerations for the regulation of these specific NARM wastes are to: I. Assure the same protection from disposal of discrete nondiffuse, low volume, high-activity NARM wastes as for similar Atomic Energy Act wastes. 2. Provide for a manifest system that will track the NARM waste from generator to disposal. 3. Provide criteria for state assumption of federal NARM authority. To define which NARM wastes should be subject to the Low-Level Waste Standard, a specific activity of 1 to 2 nCi (37-74 Bq) per gram is being considered as a lower limit for applicability of the standard’s requirements (22). Qualitrdtivc Requirements Another area of coverage in the standards is the matter of qualitative requirements and guidance intended to make clear the context and assumptions within which we expect the standards to be implemented. These requirements would address areas not appropriate for quantitative requirements and compensate for the uncertainties that necessarily accompany plans to isolate radioactive wastes from the environment for a long time. They would include considerations concerning: active institutional controls (such as guarding and maintenance), passive institutional measures (such as permanent markers), monitoring during disposal and postdisposal phases, and location away from areas con-
taining materials sources.
not widely available
from other
“Below Regulutory Concern” Criteria Criteria are being developed for identifying wastes as “Below Regulatory Concern” (BRC) which could be disposed of as a nonradioactive waste. However, if it has Resource Conservation and Recovery Act (RCRA) hazardous characteristics, it would have to be disposed of in compliance with RCRA regulations. The EPA would not be involved in identifying or selecting specific LLW types which qualify as BRC wastes; the NRC, states, and DOE would implement the use of these criteria. If the BRC criteria are implemented, as currently envisioned, most wastes identified as BRC wastes, and not having RCRA hazardous characteristics, would be disposed of as trash in a municipal sanitary disposal facility or be incinerated and subsequently so disposed. The risk analyses show that with careful selection and segregation of waste, the population, individual and on-site risks can be quite low. LL W Technical Analysis Mrthoclology The analysis has centered on estimating the risk resulting from LLW disposal as it has been conducted, and as it might be conducted with the standards in place. To provide a mechanism for such risk assessments, a series of dynamic models for near-surface disposal was developed (23). The analysis encompassed the following disposal options: 1. Conventional shallow-land burial as practiced today by DOE. 2. Improved shallow-land burial as required under NRC’s Licensing Requirements for Land Disposal of Radioactive Waste, 10 CFR Part 61(19). 3. Intermediate-depth disposal (deeper than 10 meters). 4. Deep geological disposal in a mined cavity (more than 100 meters deep). 5. Hydrofracturing. 6. Deep-well injection. 7. Engineered mound (similar to the method used by the French). 8. Modular concrete canisters placed in a trench. In developing the scenarios for modelling these disposal methods, three hydrogeologic and climatic settings were used. We believe these settings cover the expected range of values for parameters affecting radionuclide retention and site performance any place in the United States. The pathways involving the highest levels of exposure from the disposal site to man are those via water.
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The recommended LLW standards will include an analysis of the relationship between the reduction of risk through the application of available technology and the cost of accomplishing that reduction. Two types of risks are estimated; the health effects received by the general population during the 10,000 years following disposal, and an annual dose to the critical population group (individuals) over 1,000 years. Below Regulatory Concern Rationale There is some degree of radioactivity in all matter. This includes the buildings we live in, ordinary municipal garbage, and the human body itself. The understanding that all things are radioactive leads to the conclusion that when wastes contain sufficiently small concentrations of radioactivity, there is no reason why it cannot be disposed of as normal trash. After a certain level of health protection has been achieved, the effort and expense of further regulation overshadows the gain in increased risk reduction. However, this is not to say that there is no remaining risk or that any form of waste disposal is risk free. EPA recognizes that this remaining risk should be estimated and carefully managed to insure that it does not become unreasonable. The term “Below Regulatory Concern” (BRC) has been chosen to describe the agency’s intentions and to demonstrate that a careful analysis was made before proposing a level below which disposal, in a LLW facility, is no longer warranted. It should be emphasized that, in carrying out this analysis, protection of the public and the environment are always the agency’s most important considerations. In setting a BRC level, the idea is that reducing releases to absolute zero is an impracticable objective. The enactment of the Low-Level Radioactive Waste Policy Amendments Act of 1985 (20) endorsed the BRC concept, thus the question no longer remains of whether or not there should be a category of material “below regulatory concern,” but “how” it should be defined, and the appropriate standards and procedures developed. We are convinced that it is an appropriate goal, and that it can be accomplished if pursued in a reasonable and prudent manner. BRC Analysis Methodology Several waste sources producing very little radioactivity were analyzed. These were expected to produce low radiation doses and have large volumes which would provide cost savings when compared to regulated disposal. The waste sources in the analysis represent wastes coming from fuel cycle facilities as well as industrial, medical and educational facilities. To evaluate the range of cumulative health im-
W. F. HOLCOMB ET AL.
pacts from several candidate BRC waste streams, scenarios with various combinations of candidate BRC waste streams were developed for the risk assessments. The scenarios include a variety of disposal alternatives (e.g., municipal sanitary landfills, dumps, on-site landfills, with optional incineration in rural, suburban and urban demographic settings). Health effects were estimated for the general population and risks attributed to annual exposures for both the on-site worker and off-site critical population groups (individuals) for 10,000 years. BRC Approach The evaluated BRC exposure criteria ranged from 0.1 to 15 mrem (0.001 to 0.15 mSv) per year to the individual. For a 1 to 4 mrem (0.01 to 0.04 mSv) per year criterion, the following advantages result: Would reduce volume of regulated waste by about 35%. ?? Could save up to $540 million over 20 years. ?? Exposures from many of the disposal scenarios were under 4 mrem (0.04 mSv) per year, thus providing a maximum, estimated lifetime risk for the critical individual of 1.1 x 10w4. ??
OCEAN DISPOSAL CRITERIA
REGULATIONS
AND
Existing Regulations The Marine Protection, Research, and Sanctuaries Act (MPRSA) of 1972, as amended, (3) gives EPA the specific authority to issue permits for ocean disposal of radioactive waste and to designate disposal sites for this purpose. In 1977, a final revision of the 1973 ocean dumping regulations was published which specified that high-level radioactive wastes and radiological warfare agents are prohibited from ocean disposal, and that other radioactive materials must be contained to prevent direct dispersion or dilution in ocean waters (24). Furthermore, the materials should radiodecay to environmentally innocuous materials or levels within the life expectancy of the containers or their inert matrix. In 1983, amendments to the MPRSA (25) required that: (a) for a 2-year period after enactment, EPA could issue only research permits relative to LLW disposal; (b) after the 2-year restriction, all applicants must prepare and submit to EPA a sitespecific Radioactive Material Disposal Impact Assessment; and (c) if EPA determines that a permit should be issued to the applicant, the recommendation must be transmitted to both Houses of Congress and approved by a joint resolution within 90 days of receipt. No permits have been issued to date.
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RADIOACTIVE WASTE DISPOSAL STANDARDS
International Activities In 1974, the United States became a Contracting Party to the Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter, also known as the London Dumping Convention (LDC), which provides for international control over ocean disposal of all wastes including wastes containing radioactive materials (26). In 1978, the Contracting Parties adopted the Intemational Atomic Energy Agency’s (IAEA) definition for high-level radioactive wastes which are prohibited from disposal into the ocean, and the IAEA recommendations for special-care permits for radioactive wastes not considered high-level (27). The EPA is participating in IAEA programs to: (a) define an upper-bound dose; (b) make comparisons with land-based alternatives; (c) assess effects of low-levels of radioactivity on populations of marine organisms; and (d) define de minimis (below significant) levels of radioactivity for purposes of ocean disposal. The EPA is also closely following the activities of the LDC, specifically those studies addressing the 1985 nonbinding resolution calling for countries not to use ocean disposal for LLW until completion of an international review of the scientific, technical, legal, social, and economic aspects of such disposal. Current Domestic Activities Presently, EPA is planning to revise the 1977 MPRSA regulations and criteria in 1988 to: (a) accommodate recent court decisions including consideration of availability, capacity and impacts of land-based alternatives; (b) incorporate statutory amendments made subsequent to the 1977 regulations, such as the requirements for a Radioactive Material Disposal Impact Assessment for ocean disposal of LLW; (c) include the quantitative definition of high-level radioactive waste originally developed for the LDC by the IAEA (27), and recently amended (28) and recognized by LDC signatories at the Tenth Consultative Meeting in 1986 (29); and (d) revise existing criteria in view of continued field experience and refinement of testing procedures and site designation protocols. Revisions to the ocean disposal regulations and criteria of the MPRSA are consistent with an EPA priority for tiscal year 1987, to promulgate regulations that encourage alternatives to land disposal (30). The EPA has gained valuable information from past U.S. ocean disposal practices, and surveys it has conducted at formerly used Atlantic and Pa&c disposal sites (31, 32, 33), that will contribute to developing: (a) waste package performance criteria; (b) site-designation criteria specific to the intemational recommendation that disposal of LLW must be at depths greater than 4,000 meters; (c) sediment
monitoring criteria to characterize the retentive or adsorptive properties of the sediment; and (d) biological monitoring criteria designed to characterize deep sea benthic organisms.
REFERENCES 1. U.S. Congress,
Atomic Energy Act of 1954, as Amended. 42 U.S.C. 2011, Washington, DC. 2. The President. Reorganization Plan No. 3 of 1970. Ehdcrul Register 35(194): 15623-15626 (1970). 3. U.S. Congress, The Marine Protection, Research, and Sanctuaries Act of 1972, as amended. Public Law 92-532, Washington, DC (1972). U.S. Congress, Resource Conservation and Recovery Act. Public Law 94-580 (1976). U.S. Congress, Toxic Substances Control Act. Public Law 94-469, (1976). U.S. Congress, Uranium Mill Tailings Radiation Control Act of lY78. Public Law 95-604, Washington, DC (1978). U.S. Environmental Protection Agency, FEIS for remedial action standards for inactive uranium processing sites (40 CFR 192). EPA 52014-82-013-I and -2, Washington, DC, (1982). 8. U.S. Environmental Protection Agency, FEIS for standards for the control of byproduct materials from uranium ore processing (40 CFR 192). EPA 52011-83-008-l and -2, Washington, DC (1983). 9. U.S. Environmental Protection Agency, 40 CFR 192, Standards for remedial actions at inactive uranium processing sites, final rule. Federal Regisfer 48(3): 590-604 (1983). 10. U.S. Environmental Protection Agency, 40 CFR 192, Environmental standards for uranium and thorium mill tailings at licensed commerical processing sites, final rule. Federcrl Register 48( 1%): 45926-45947 (1983). 11. U.S. Environmental Protection Agency, 40 CFR 190, Environmental radiation protection standards for nuclear power operations. Federul Rvgisrer 42(9): 2858-2861 (1977). 12. U.S. Environmental Protection Agency, 40 CFR 192, Standards for remedial actions at inactive uranium processing sites, proposed rule. Federul Registcjr 52( 185): 36000-36008 (1987). 13. U.S. Congress, Nuclear Waste Policy Act of 1982. Public Law 97-425 Washington, DC (1983). 14. U.S. Environmental Protection Agency, High-level and transuranic radioactive wastes, background information document for final rule. EPA 52011-85-023, Washington, DC (1985). 15. U.S. Environmental Protection Agency, 40 CFR 191, Environmental standards for the management and disposal of spent nuclear fuel, high-level and transuranic radioactive wastes, final rule. Federal Register 50(182): 38066-38089 (1985). 16. U.S. Environmental
Protection Anencv. 40 CFR 141. Interim primary drinking water regulations, promulgation of regulations on radionuclides. Fc~drral Register 41(133): 28402-28405 (1976).
17. U.S. Nuclear Regulatory Commission, 10 CFR 60, Disposal of high-level radioactive wastes in geologic repositories; conforming amendments, proposed rule. Federal Register 51(118): 22288-22301 (1986). 18. U.S. Environmental Protection Agency, Environmental radiation protection standards for low-ievel radioactive waste disposal, advance notice of proposed rulemaking. Fedem/
Register
48(170): 39563 (1983).
12
W. F. HOLCOMB ET AL.
19. U.S. Nuclear Regulatory Commission, 10 CFR Parts 2, 19, 20,21,30,40,51,61,70,73, 170, Licensing requirements for land disposal of radioactive waste. Federal Rcgisrer 47(248) 57446-57482 (1982). 20. U.S. Congress, Low-Level
21.
22.
23.
24.
Radioactive Waste Policy Amendments Act of 1985. Public Law 99-240, Washington, DC (1986). U.S. Environmental Protection Agency, Ground-water protection strategy. Office of Ground-Water Protection, Washington, DC (1984). Bandrowski, M. S. and Gruhlke, J. M. Inclusion of NARM in the EPA LLW Standard. Proceedings of 8th Annual Department of Energy Low-Level Radioactive Waste Management Forum, Volume VII, CONF-860990, EG&G Idaho, Idaho Falls, ID (1987). Bandrowski, M. S., Hung, C. Y., Meyer, G. L., and Rogers, V. C. Summary of EPA’s risk assessment results from the analysis of alternative methods of low-level waste disposal. Proceedings of the Symposium on Waste Management ‘87, Volume 3 Low-Level Waste, University of Arizona, Tucson, AZ (1987). U.S. Environmental Protection Agency, 40 CFR 220-229, Ocean dumping, final revision of regulations and criteria.
Federal Register 42(7): 2462-2490 (1977). 25. U.S. Congress, The Surface Transportation
Assistance Act of 1982. Public Law 97-424, Washington, DC (1983). 26. International Atomic Energy Agency, Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter. INFCIRCRO5, Vienna, Austria (1978).
27. International Atomic Energy Agency, Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter; The Definition Required by Annex I, paragraph 6 to the Convention, and Recommendations Required by Annex II, Section D. INFCIRCi205 Addendum 1, Revision I, Vienna, Austria (1978). 28. International Atomic Energy Agency, Definition and Recommendations for the Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter, 1972. Safety Series No. 78, Vienna. Austria (1986). 29. International Maritime Organization, Report of the Tenth Consultative Meeting of Contracting Parties to the Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter. LDC 10115, London, England (1986). 30. U.S. Environmental Protection Agency, Agency operating guidance, FY 1987. Office of the Administrator, Washington, DC (1986). 31. Holcomb, W. F. A history of ocean disposal of packaged low-level radioactive waste. Nuclrar Sqfet!: 23(2): 183-197 (1982). 32. Dyer, R. S. Environmental surveys of two deepsea radioactive waste disposal sites using submersibles. In: Mnnrrgement of Radioactive Wastes from the Nuclear Fuel Cycle, Vol. II. International Atomic Energy Agency, Vienna, Austria (1976). 33. Pryor, M. Vigilance in the deep sea environment. EPA Journul ll(8): 28-30 (1985).
0191-815X/88 $3.00 + .OO Copyright 0 1988 Pergamon Press plc
USEPA RADIOACTIVE WASTE DISPOSAL STANDARDS: ISSUED AND UNDER DEVELOPMENT
W. F. Holcomb, * R. L. Clark, R. S. Dyer, and F. L. Galpin U.S.Environmental Protection Agency, Of$cc of Radiation Programs, Washington, DC 20460
ABSTRACT.
The USEPA has issued and is developing generally applicable environmental standards for the disposal of radioactive wastes. Standards have been issued for the disposal of spent nuclear fuel, high-level and transuranic wastes, and for uranium mill tailings. Standards are being developed for the land disposal of low-level radioactive wastes and for wastes considered “Below Regulatory Concern.” Regulations for ocean disposal of low-level radioactive wastes are also under consideration.
INTRODUCTION
Control Act (5), each of which may be applicable under certain circumstances. Another reason is the feasibility of implementation. This is related to the form of the standard or (e.g., working levels for radon daughters roentgens for gamma-ray exposure), the time span over which the potential hazard is to be evaluated (e.g., annually or thousands of years), how compliance is demonstrated, and the presence of nonradioactive, hazardous materials in the waste. A cost-effectiveness analysis is usually done as a basis for the standards and takes the form of comparing the cost of various control methods, the potential radiation exposure reduction, the residual exposure that remains, and any other benefits and costs. In the final analysis, the proposed level of a standard is a judgment which is based in part on this cost-effective analysis. This is a very simplified description of our standards-setting processs. Another factor which is considered is the compatibility with other EPA standards and policies. With the exception of standards for ocean disposal of low-level radioactive waste and standards which might be promulgated for naturally occurring and accelerator-produced radioactivity, EPA does not implement or enforce its radioactive waste disposal standards. Enforcement falls to the Nuclear Regulatory Commission (NRC), the Department of Energy (DOE), or the States through agreement with the NRC. Also, the process must “consist of establishing generally applicable environmental standards for the protection of the general environment,” which means requirements may not be site-
The United States Environmental Protection Agency (EPA) has a responsibility to develop standards and
guides to minimize adverse impacts on public health and the environment from radiation. A major part of this effort, over the past few years, has been directed at radioactive waste disposal activities. Within EPA, the Office of Radiation Programs is responsible for activities related to radiation protection. EPA APPROACH One question often arises in regard to EPA’s approach to setting waste disposal standards: Why not have just one radiation exposure standard to cover all activities? The suggestion is that some universal levels of acceptable exposure could be established that would apply to all waste disposal operations. There are several reasons why we consider this impracticable as well as inappropriate. First, several legislative authorities include radiation protection; some give EPA leeway in setting standards, some do not. The most often used legal authorities to set radiation standards are the Atomic Energy Act (AEA) as amended (1) and the Reorganization Plan No. 3 (2). In addition, EPA has radiation protection authorities under the Marine Protection, Research and Sanctuaries Act (3), the Resource Conservation and Recovery Act (4) and the Toxic Substances RECEIVED20 MAY 1987; ACCEPTED12 JANUARY1988. *Corresponding Author
3
4
specific (2). Therefore, EPA’s AEA standards usually take the form of numerical performance requirements, indicating the level of control to be achieved, and are typically expressed in terms of dose, environmental concentrations or release limits. ENVIRONMENTAL STANDARDS FOR URANIUM AND THORIUM MILL TAILINGS Uranium mill tailings consist mainly of nonradioactive materials but also contain essentially all of the thorium and radium present in the ore. The largest source of radiation exposure is the short-lived radioactive decay products of radon-222, itself a decay product of radium-226. Radon can build up to high levels indoors when tailings are placed around buildings or when buildings are located close to tailings piles. Other problems with tailings include gamma radiation and a water contamination potential from radioactive and the nonradioactive, hazardous constituents in the tailings. In 1978, Congress passed the Uranium Mill Tailings Radiation Control Act (6) to deal with these problems. Two programs were established under this Act. First, for the inactive sites, DOE is required to identify and list such sites and then to reclaim tailings piles and cleanup of off-site properties under standards provided by EPA. Second, for licensed sites, NRC and its Agreement States are required to control tailings as a licensed material, again under standards provided by EPA. Risk Analysis The analyses by EPA (7,8) indicate a lung cancer risk of about 1 in 100 (lifetime) for people living near a tailings pile and as high as 4 in 100 (lifetime) for people living in houses where tailings have been placed around the foundation. Groundwater contamination was found at several sites. External radiation levels could be high for some situations. Finally, the long half-life of the radionuclides are a matter of concern. Based on these analyses, EPA identified objectives for standards for uranium mill tailings disposal. The primary objective of standards for control of hazards from tailings is isolation and stabilization to prevent the tailings from misuse by man and dispersal by natural forces (floods, wind, rain, etc) and through air pathways. The secondary objective is to optimize control of radon emissions from tailings piles. Methods that are likely to be used to isolate and stabilize piles are assumed to control external radiation and provide for long-term control. The primary objective of standards to protect groundwater is prevention of seepage of hazardous constituents from tailings into groundwat-
W. F. HOLCOMB ET AL.
er. The secondary objective is to assure that any contamination of groundwater does not exceed levels that are protective of public health and the environment and to take corrective actions as needed to achieve such levels. Inactive Sites The 1983 EPA standards for inactive sites, 40 CFR 192 (9), require that, for disposal of tailings, control measures shall be designed to: 1. Be effective for up to one thousand years, if reasonably achievable, and, in any case, for at least two hundred years. 2. Provide reasonable assurance that releases of radon-222 from residual radioactive material, to the atmosphere, will not exceed an average release rate of 20 pCi/m2s (0.74 Bq/m2/s) or alternatively, will not increase the annual average concentration of radon-222 in air at or above any location outside the disposal site by more than 0.5 pCi/L (0.019, BqIL). The standards for remedial actions, as a result of residual radioactive materials, require cleanup so as to provide reasonable assurance that: 1. The concentration
of radium-226 in land, averaged over any area of 100 square meters, shall not exceed the background level by more than 5 pCi/g (0.19 Bq/g), averaged over the first 15 centimeters (cm) of soil below the surface, and 15 pCi/g (0.56 Bq/g), averaged over 15-cm thick layers of soil more than 15 cm below the surface. 2. In any occupied or habitable building the objective of remedial action shall be, and reasonable effort shall be made to achieve, an annual average (or equivalent) radon decay product concentration (including background) not to exceed 0.02 working levels (WL). In any case, the radon decay product concentration (including background) shall not exceed 0.03 WL. In addition, the level of gamma radiation shall not exceed the background level by more than 20 pR/‘hr (5.2 nCikg/hr) per hour.
Active Sites The 1983 EPA standards for licensed sites cover both operational and closure phases (10). Operational phase standards require that: 1. Surface impoundments (except for any existing portion) must have a liner that is designed, constructed, and installed to prevent any migration of wastes out of the impoundment to the adjacent subsurface soil or groundwater or surface water
RADIOACTIVE
WASTE DISPOSAL STANDARDS
at any time during the active life of the impoundment. Or alternatively, no liner is required if the regulatory agency finds, based on a demonstration by the owner or operator, that alternate design and operating practices, together with location characteristics, will prevent the migration of any hazardous constituents into groundwater or surface water at any future time. 2. A monitoring system will be operated and, if hazardous constituents are found in the uppermost aquifer at the edge of the tailings impoundment, groundwater protection standards will be established at background levels for such constituents, except for those constituents for which drinking water standards are available, then the standards are established at those levels. A corrective action program will be conducted, if the groundwater protection standard is being exceeded in the uppermost aquifer at the edge of the tailings. This program must be continued until the groundwater protection standards are achieved. Alternate concentration limits may be applied for, instead of taking corrective actions. The limits of 40 CFR 190, “Environmental Radiation Protection Standards for Nuclear Power Operations,” are met (11). These standards, promulgated in 1977, limit the radiation dose to any individual to 25 millirem (0.25 mSv) per year to the whole body and any organ except for 75 mrem (0.75 mSv) to the thyroid. Part 190 excludes radon-222 and its short-lived decay products. 5. The 40 CFR Part 440 Subpart C standards under the Clean Water Act are met. These standards prohibit discharges to surface waters, except at locations where annual average precipitation exceeds average annual evaporation. 6. The 40 CFR Part 61 Subpart W national emission standard for radon-222 emissions from tailings (as a result of requirements under the Clean Air Act) requires that any new tailings impoundments be no more than 40 acres in area or that, for dewatered tailings, no more than 10 acres of tailings are uncovered at any time. Covered tailings must meet the after-closure requirements discussed below. If impoundments are used, no more than two can be in operation at any one site and at any one time. The use of tailings impoundments, existing in 1986, must be terminated by the end of 1992, however, extensions are available under certain conditions. After closure of a tailings impoundment, measures shall be designed to:
control
1. Be effective for up to one thousand years, to the
5
extent reasonably achievable, and, in any case, for at least two hundred years. 2. Provide reasonable assurance that releases of radon-222 from residual radioactive material, to the atmosphere, will not exceed an average release rate of 20 pCi/m2/s (0.74 Bqim’is) per square meter per second. However, the above two requirements shall not apply to any portion of a licensed and/or disposal site which contains a concentration of radium-226 in land, averaged over an area of 100 square meters, which as a result of tailings, does not exceed the background level by more than: (a) S pCi/g (0.19 Bq/g), averaged over the first I.5 cm below the surface; and (b) 15 pCi/g (0.56 Bq/g), averaged over 15-cm thick layers more than 15 cm below the surface. Thorium Tailings Standards for disposal of licensed thorium mill tailings are provided by adding “and thorium” every place “uranium” appears in the licensed uranium mill tailings standards, “and radon-220” every appears, and “radium-228” place “radon-222” appears. Also added every place “radium-226” were standards to limit the radiation dose to any individual to 25 mrem (0.25 mSv) per year to the whole body and any organ except for 75 mrem (0.75 mSv) to the thyroid. Thus, standards for licensed thorium mill tailings disposal are the same as standards for licensed uranium mill tailings disposal. It is noted that for thorium tailings there are no national emission standards under the Clean Air Act or effluent limitation guidelines under the Clean Water Act. Court Actions The uranium mill tailings standards were contested by the uranium industry, environmental groups, states, and by individuals. The major challenges included: (a) asking the Administrator to make a finding regarding the acceptability of the risk from mill tailings, (b) questioning whether the risk from mill tailings, after the disposal standards were met, was unacceptably high, (c) suggesting that the states had sole authority for establishing groundwater standards, and (d) asking that quantitative groundwater standards for inactive tailings be required. The court dismissed all challenges except one. It set aside the groundwater provisions of the inactive standards and remanded them to EPA “. . . to treat these toxic chemicals that pose a groundwater risk as it did in the active mill site regulations.” The agency has proposed groundwater standards for inactive sites to replace those set aside by the court (12).
W. F. HOLCOMB
6 TABLE
ET AL.
1
Release Limits for Containment Requirements (15). Release Limit (curies)
Radionuclide Americium-241 or -243 Carbon- 14 Cesium-135 or -137 Iodine- 129 Neptunium-237 Plutonium-238, -239, -240, or -242 Radium-226 Strontium-90 Technetium-99 Thorium-230 or -232 Tin-126 Uranium-233, -234, -235, -236, or -238 Any other alpha-emitting radionuclide with a half-life greater than 20 years. Any other radionuclide with a half-life greater than 20 years that does not emit alpha particles.
100
100 1000 100 100 100 100 1000 10000 10 1000 100 1000
Notes: (1) Cumulative releases to the accessible environment for 10000 years after disposal. (2) Release limit is per 1000 MTHM or other unit of waste as defined in Appendix A of 40 CRF Part 191.
ENVIRONMENTAL STANDARDS FOR THE MANAGEMENT AND DISPOSAL OF SPENT NUCLEAR FUEL, HIGH-LEVEL AND TRANSURANIC RADIOACTIVE WASTES
to members of the public resulting from the management and storage of spent fuel, HLW or TRU wastes carried out during activities at facilities licensed by the NRC, and from the same type of activities and facilities managed by the DOE at waste disposal facility sites. At NRC-licensed facilities, the limits are the same as those in 40 CFR 190 (1 l), that is, 25 mrem (0.25 mSv) to the whole body, 75 mrem (0.75 mSv) to the thyroid, and 25 mrem (0.25 mSv) to any other critical organ. For DOE non-NRC-licensed facilities, the limits are 25 mrem (0.25 mSv) to the whole body and 75 mrem (0.75 mSv) to any critical organ.
In the Nuclear Waste Policy Act (13), Congress explicitly stated the responsibility of the EPA to establish generally applicable environmental standards for the disposal of spent nuclear fuel and highlevel radioactive wastes. In 1985, EPA promulgated Standards for the 40 CFR 191, “Environmental Management and Disposal of Spent Nuclear Fuel, High-Level and Transuranic Radioactive Wastes” (14,15). The standards are arranged in two parts, Subpart A and Subpart B. Subpart A applies to the management and storage of spent nuclear fuel, high-level radioactive wastes (HLW), or transuranic (TRU) radioactive wastes. Management is defined as any activity, operation, or process (except transportation) conducted to prepare spent fuel, HLW or TRU wastes for storage or disposal, or the activities associated with placing such wastes in a disposal system. Subpart B sets release limits for disposal systems which provide permanent isolation of spent fuel, HLW or TRU wastes from the accessible environment with no intent of recovery; this Subpart takes effect when the system is sealed.
Disposal Standards Subpart B contains containment (quantitative), assurance (qualitative), individual protection, and groundwater protection requirements. The containment requirements set numerical limits on the projected release of specific radionuclides to the accessible environment over the 10,000 year period following closure of the repository. The limits are based on an overall societal objective of no more than 1,000 excess cancer deaths over 10,000 years from 100,000 metric tons of spent fuel. This level of risk is comparable to the risks that future generations would face from the amount of uranium ore needed to make the fuel had it never been mined.
Management and Storage Standards Subpart A establishes annual radiation dose limits
Containment Requirements The containment requirements
were set for two
RADIOACTIVE
7
WASTE DISPOSAL STANDARDS
categories of releases in terms of their probability of occurring. A reasonable expectation of conformance with the requirement is to be based on a performance assessment which incorporates an overall probability distribution of the cumulative releases. Specifically, the cumulative probability of releases to the environment, exceeding the specific radionuclide release limits in Table 1, must be less than one chance in ten. The second category limits releases, caused by events which cumulatively have greater than one chance in a thousand of exceeding ten times the specific radionuclide release limits in Table 1. No limits were set for releases, caused by very unlikely events, which cumulatively have less than one chance in a thousand of occurring. Individual Protection Requirements The individual protection requirements limit the annual exposure from the disposal system to a member of the public in the accessible environment, for the first 1,000 years after disposal, to 25 mrem (0.25 mSv) to the whole body or 75 mrem (0.75 mSv) to any critical organ. Groundwater Protection Requirements The groundwater protection requirements apply only to groundwater supplies serving thousands of people, and limit the water withdrawn from these special sources to concentrations similar to those established for the output of community water systems, as set forth by EPA’s National Interim Primary Drinking Water Regulations, 40 CFR 141 (16). Assurance Requirements The assurance requirements, applicable to DOE facilities, are good-sense principles crafted to provide an extra margin of assurance that the containment requirements will be met despite the large uncertainties that confront the prediction of disposalsystem performance over 10,000 years. The NRC is finalizing conforming amendments to provide consistent, assurance requirements for facilities they license (,17). The essence of the six assurance requirements is: 1. Disposal systems shall not depend on active institutional controls for more than 100 years after disposal (i.e., closure). 2. Long-term disposal system performance should be monitored for a reasonable time to detect substantial and detrimental deviations from expected performance. 3. Disposal systems shall be marked and their locations recorded in appropriate government records. 4. Disposal systems shall be designed with several
different types of barriers, both natural and engineered. 5. Sites should not be located where scarce or easily accessible resources are located. 6. Wastes shall be recoverable for a reasonable time after disposal. Legal Action Concerning 40 CFR Part 191 In March 1986, several environmental groups, led by the Natural Resources Defense Council, and the States of Maine, Minnesota, Texas, and Vermont filed petitions for review in several Federal courts around the country; these petitions were consolidated in the U.S. Court of Appeals for the First Circuit. The court rendered its decision in July 1987. That decision vacated and remanded the entirety of 40 CFR Part 191 even though only the two sections dealing with groundwater, 191.15 (Individual Protection Requirements) and 191.16 (Ground Water Protection Requirements), were found defective. In August 1987, the Justice Department, on behalf of EPA, filed a motion requesting reinstatement of those portions of the standards which were upheld. In September 1987, the Court consented to reinstate Subpart A but continued the remand of Subpart B. Briefly, the court concluded that: Disposal of HLW in mined, geologic repositories might be underground injection and that EPA failed to consider the Safe Drinking Water Act’s (SDWA) Part C requirements on underground injection by potentially allowing endangerment of groundwater by exceeding EPA’s own drinking water standards. Therefore, EPA must reconcile Sections 191.15 and 191.16 with the SDWA or adequately explain the divergence. EPA must supply an adequate explanation for selecting the 1,000 year design criterion in 19 1.15 and 191.16. Section 191.16, the Ground Water Protection Requirements, was promulgated without proper notice and comment and must be reproposed for public comment. Currently, an approximate two year effort is envisioned to comply with the terms of the remand. ENVIRONMENTAL STANDARDS FOR THE MANAGEMENT AND LAND DISPOSAL OF LOW-LEVEL RADIOACTIVE WASTES In 1983, the EPA published an Advanced Notice of Proposed Rulemaking (ANPRM) (18) to indicate its intention to develop generally applicable, environmental standards for the land disposal of LLW using AEA and Reorganization Plan No. 3 authorities.
8
It is EPA’s intention that the LLW standards, when they are published, will protect public health and the environment, taking into account the possible control methods that are available, their effects on reducing risks, and their costs. The LLW standards would cover disposal of all AEA materials not controlled by other EPA standards. An important point is that they would cover all LLW disposal facilities owned and operated by the Federal Government, as well as commercial LLW disposal facilities, whereas current NRC regulations apply only to facilities licensed by the Agreement States or NRC itself. This is significant, because the Federal Government generates and disposes of more than 40% of all LLW nationwide. A uniform standard for all LLW disposal is both a desirable and an achievable goal. Publication of a proposed LLW standard is planned in 1988, and a final standard a year later. The early standards development plans indicated the intent to cover only AEA wastes. Comments in response to the ANPRM and at public outreach meetings, especially from state representatives, strongly recommended that the standard should also cover certain wastes from use of natural and accelerator-produced radioactive materials (NARM). It was determined to be sufficiently worthwhile, and the plan was subsequently modified. The Toxic Substances Control Act (TSCA) (5) is being considered for the necessary authority to regulate NARM. Section 6 of this act provides that if the administrator determines that an unreasonable risk exists, he may promulgate regulations on the disposal to mitigate such risks. The EPA LLW Standard is intended to cover disposal of all AEA materials not covered by other EPA standards. This standard will have several important and closely related areas of focus: 1. LLW predisposal operations, storage and management. This would include limits on radiation exposure to individuals during processing, management, and storage of LLW. 2. Definition of radiation exposures related to radioactive waste disposal that are sufficiently small, that they either do not need to be regulated regarding their radiation hazard or the wastes can be disposed of with minimal controls (i.e., a level “below regulatory concern”). 3. Radiation exposure limits to individuals after the disposal site is closed (i.e., after it stops receiving waste). 4. Groundwater protection for both pre- and postdisposal phases. 5. High-concentration, relatively low-volume NARM wastes in the same standards promulgation. This will be in a separate segment of the Code of Fed-
W. F. HOLCOMB ET AL.
era1 Regulations because it uses TSCA authority rather than the AEA (5). 6. Other areas will include guidance on implementation and qualitative assurance requirements. Individual Operations
Radiution Exposure urld Management
Limits
Daring
This area would limit annual individual exposures from all environmental pathways to members of the public from nonuranium-fuel-cycle facilities which process, manage, or store LLW. Waste generators are now opting for volume reduction, waste processing, and packaging, not only to meet NRC’s 10 CFR 61 requirements (19), but as methods to reduce disposal costs and to stay within reduced out-of-state volume limits imposed by host states for existing LLW disposal facilities under the Low-Level Radioactive Waste Policy Act Amendments of 1985 (20). Confronted with growing trends to create a large number of diverse facilities for treating and processing LLW, plus the potential for facilities that would be dedicated to the storage of LLW for periods beyond our previous experience, the agency deems it prudent to include limits on these potential exposures in our standards. This would also make the EPA LLW standards parallel and consistent in structure with the 25 mrem (0.25 mSv) per year standards EPA promulgated for the Uranium Fuel Cycle, 40 CFR Part 190 (11) and High-Level Radioactive Waste, 40 CFR Part 191(15). Individual Disposal
Radiation
Exposure
Limits
fbr Post-
The standard will establish limits on exposure through all pathways to members of the public from the land disposal of LLW. It would apply to any LLW disposal facility using any land disposal method any place in the United States. A persuasive reason would be needed to significantly depart from the 25 mrem (0.25 mSv) per year chosen by the NRC. EPA’s technical analysis has not revealed any such reason so far. Groundwater
Protection
The protection of the nation’s groundwaters is of major importance in EPA and such a consideration is particularly appropriate in waste disposal standards. The agency’s Groundwater Protection Strategy calls for the protection of groundwater commensurate with its value and use (21). The approach to groundwater protection from radioactivity will be developed in this context. Class 1 groundwaters require the highest levels of protection and represents those that serve as irreplaceable sources of drinking water for large populations (i.e., 2,500 people or more). It is appropriate to give these groundwaters the highest level of
RADIOACTIVE
9
WASTE DISPOSAL STANDARDS
protection and, therefore nondegradation criteria are being considered. The draft EPA groundwater classification system generally defines a Class II groundwater as any that is not Class I and is potable (i.e., contains less than 10,000 ppm (10 g/L) dissolved solids). This may be too broad a category for regulatory purposes. As a second level for regulation, a subset of Class II groundwaters> which represents the more productive aquifers that are presently, or could in the future, serve as community water supplies, is being considered. One thought is to assure that no community has to remove radionuclides from their drinking water because of releases from a LLW facility. In such an instance, the EPA Interim Primary Drinking Water Regulations (16) could be the recommended limit. Any actual consumption or use of other groundwaters would, of course, have to be considered in determining compliance with the individual radiation exposure limits.
The considerations for the regulation of these specific NARM wastes are to: I. Assure the same protection from disposal of discrete nondiffuse, low volume, high-activity NARM wastes as for similar Atomic Energy Act wastes. 2. Provide for a manifest system that will track the NARM waste from generator to disposal. 3. Provide criteria for state assumption of federal NARM authority. To define which NARM wastes should be subject to the Low-Level Waste Standard, a specific activity of 1 to 2 nCi (37-74 Bq) per gram is being considered as a lower limit for applicability of the standard’s requirements (22). Qualitrdtivc Requirements Another area of coverage in the standards is the matter of qualitative requirements and guidance intended to make clear the context and assumptions within which we expect the standards to be implemented. These requirements would address areas not appropriate for quantitative requirements and compensate for the uncertainties that necessarily accompany plans to isolate radioactive wastes from the environment for a long time. They would include considerations concerning: active institutional controls (such as guarding and maintenance), passive institutional measures (such as permanent markers), monitoring during disposal and postdisposal phases, and location away from areas con-
taining materials sources.
not widely available
from other
“Below Regulutory Concern” Criteria Criteria are being developed for identifying wastes as “Below Regulatory Concern” (BRC) which could be disposed of as a nonradioactive waste. However, if it has Resource Conservation and Recovery Act (RCRA) hazardous characteristics, it would have to be disposed of in compliance with RCRA regulations. The EPA would not be involved in identifying or selecting specific LLW types which qualify as BRC wastes; the NRC, states, and DOE would implement the use of these criteria. If the BRC criteria are implemented, as currently envisioned, most wastes identified as BRC wastes, and not having RCRA hazardous characteristics, would be disposed of as trash in a municipal sanitary disposal facility or be incinerated and subsequently so disposed. The risk analyses show that with careful selection and segregation of waste, the population, individual and on-site risks can be quite low. LL W Technical Analysis Mrthoclology The analysis has centered on estimating the risk resulting from LLW disposal as it has been conducted, and as it might be conducted with the standards in place. To provide a mechanism for such risk assessments, a series of dynamic models for near-surface disposal was developed (23). The analysis encompassed the following disposal options: 1. Conventional shallow-land burial as practiced today by DOE. 2. Improved shallow-land burial as required under NRC’s Licensing Requirements for Land Disposal of Radioactive Waste, 10 CFR Part 61(19). 3. Intermediate-depth disposal (deeper than 10 meters). 4. Deep geological disposal in a mined cavity (more than 100 meters deep). 5. Hydrofracturing. 6. Deep-well injection. 7. Engineered mound (similar to the method used by the French). 8. Modular concrete canisters placed in a trench. In developing the scenarios for modelling these disposal methods, three hydrogeologic and climatic settings were used. We believe these settings cover the expected range of values for parameters affecting radionuclide retention and site performance any place in the United States. The pathways involving the highest levels of exposure from the disposal site to man are those via water.
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The recommended LLW standards will include an analysis of the relationship between the reduction of risk through the application of available technology and the cost of accomplishing that reduction. Two types of risks are estimated; the health effects received by the general population during the 10,000 years following disposal, and an annual dose to the critical population group (individuals) over 1,000 years. Below Regulatory Concern Rationale There is some degree of radioactivity in all matter. This includes the buildings we live in, ordinary municipal garbage, and the human body itself. The understanding that all things are radioactive leads to the conclusion that when wastes contain sufficiently small concentrations of radioactivity, there is no reason why it cannot be disposed of as normal trash. After a certain level of health protection has been achieved, the effort and expense of further regulation overshadows the gain in increased risk reduction. However, this is not to say that there is no remaining risk or that any form of waste disposal is risk free. EPA recognizes that this remaining risk should be estimated and carefully managed to insure that it does not become unreasonable. The term “Below Regulatory Concern” (BRC) has been chosen to describe the agency’s intentions and to demonstrate that a careful analysis was made before proposing a level below which disposal, in a LLW facility, is no longer warranted. It should be emphasized that, in carrying out this analysis, protection of the public and the environment are always the agency’s most important considerations. In setting a BRC level, the idea is that reducing releases to absolute zero is an impracticable objective. The enactment of the Low-Level Radioactive Waste Policy Amendments Act of 1985 (20) endorsed the BRC concept, thus the question no longer remains of whether or not there should be a category of material “below regulatory concern,” but “how” it should be defined, and the appropriate standards and procedures developed. We are convinced that it is an appropriate goal, and that it can be accomplished if pursued in a reasonable and prudent manner. BRC Analysis Methodology Several waste sources producing very little radioactivity were analyzed. These were expected to produce low radiation doses and have large volumes which would provide cost savings when compared to regulated disposal. The waste sources in the analysis represent wastes coming from fuel cycle facilities as well as industrial, medical and educational facilities. To evaluate the range of cumulative health im-
W. F. HOLCOMB ET AL.
pacts from several candidate BRC waste streams, scenarios with various combinations of candidate BRC waste streams were developed for the risk assessments. The scenarios include a variety of disposal alternatives (e.g., municipal sanitary landfills, dumps, on-site landfills, with optional incineration in rural, suburban and urban demographic settings). Health effects were estimated for the general population and risks attributed to annual exposures for both the on-site worker and off-site critical population groups (individuals) for 10,000 years. BRC Approach The evaluated BRC exposure criteria ranged from 0.1 to 15 mrem (0.001 to 0.15 mSv) per year to the individual. For a 1 to 4 mrem (0.01 to 0.04 mSv) per year criterion, the following advantages result: Would reduce volume of regulated waste by about 35%. ?? Could save up to $540 million over 20 years. ?? Exposures from many of the disposal scenarios were under 4 mrem (0.04 mSv) per year, thus providing a maximum, estimated lifetime risk for the critical individual of 1.1 x 10w4. ??
OCEAN DISPOSAL CRITERIA
REGULATIONS
AND
Existing Regulations The Marine Protection, Research, and Sanctuaries Act (MPRSA) of 1972, as amended, (3) gives EPA the specific authority to issue permits for ocean disposal of radioactive waste and to designate disposal sites for this purpose. In 1977, a final revision of the 1973 ocean dumping regulations was published which specified that high-level radioactive wastes and radiological warfare agents are prohibited from ocean disposal, and that other radioactive materials must be contained to prevent direct dispersion or dilution in ocean waters (24). Furthermore, the materials should radiodecay to environmentally innocuous materials or levels within the life expectancy of the containers or their inert matrix. In 1983, amendments to the MPRSA (25) required that: (a) for a 2-year period after enactment, EPA could issue only research permits relative to LLW disposal; (b) after the 2-year restriction, all applicants must prepare and submit to EPA a sitespecific Radioactive Material Disposal Impact Assessment; and (c) if EPA determines that a permit should be issued to the applicant, the recommendation must be transmitted to both Houses of Congress and approved by a joint resolution within 90 days of receipt. No permits have been issued to date.
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RADIOACTIVE WASTE DISPOSAL STANDARDS
International Activities In 1974, the United States became a Contracting Party to the Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter, also known as the London Dumping Convention (LDC), which provides for international control over ocean disposal of all wastes including wastes containing radioactive materials (26). In 1978, the Contracting Parties adopted the Intemational Atomic Energy Agency’s (IAEA) definition for high-level radioactive wastes which are prohibited from disposal into the ocean, and the IAEA recommendations for special-care permits for radioactive wastes not considered high-level (27). The EPA is participating in IAEA programs to: (a) define an upper-bound dose; (b) make comparisons with land-based alternatives; (c) assess effects of low-levels of radioactivity on populations of marine organisms; and (d) define de minimis (below significant) levels of radioactivity for purposes of ocean disposal. The EPA is also closely following the activities of the LDC, specifically those studies addressing the 1985 nonbinding resolution calling for countries not to use ocean disposal for LLW until completion of an international review of the scientific, technical, legal, social, and economic aspects of such disposal. Current Domestic Activities Presently, EPA is planning to revise the 1977 MPRSA regulations and criteria in 1988 to: (a) accommodate recent court decisions including consideration of availability, capacity and impacts of land-based alternatives; (b) incorporate statutory amendments made subsequent to the 1977 regulations, such as the requirements for a Radioactive Material Disposal Impact Assessment for ocean disposal of LLW; (c) include the quantitative definition of high-level radioactive waste originally developed for the LDC by the IAEA (27), and recently amended (28) and recognized by LDC signatories at the Tenth Consultative Meeting in 1986 (29); and (d) revise existing criteria in view of continued field experience and refinement of testing procedures and site designation protocols. Revisions to the ocean disposal regulations and criteria of the MPRSA are consistent with an EPA priority for tiscal year 1987, to promulgate regulations that encourage alternatives to land disposal (30). The EPA has gained valuable information from past U.S. ocean disposal practices, and surveys it has conducted at formerly used Atlantic and Pa&c disposal sites (31, 32, 33), that will contribute to developing: (a) waste package performance criteria; (b) site-designation criteria specific to the intemational recommendation that disposal of LLW must be at depths greater than 4,000 meters; (c) sediment
monitoring criteria to characterize the retentive or adsorptive properties of the sediment; and (d) biological monitoring criteria designed to characterize deep sea benthic organisms.
REFERENCES 1. U.S. Congress,
Atomic Energy Act of 1954, as Amended. 42 U.S.C. 2011, Washington, DC. 2. The President. Reorganization Plan No. 3 of 1970. Ehdcrul Register 35(194): 15623-15626 (1970). 3. U.S. Congress, The Marine Protection, Research, and Sanctuaries Act of 1972, as amended. Public Law 92-532, Washington, DC (1972). U.S. Congress, Resource Conservation and Recovery Act. Public Law 94-580 (1976). U.S. Congress, Toxic Substances Control Act. Public Law 94-469, (1976). U.S. Congress, Uranium Mill Tailings Radiation Control Act of lY78. Public Law 95-604, Washington, DC (1978). U.S. Environmental Protection Agency, FEIS for remedial action standards for inactive uranium processing sites (40 CFR 192). EPA 52014-82-013-I and -2, Washington, DC, (1982). 8. U.S. Environmental Protection Agency, FEIS for standards for the control of byproduct materials from uranium ore processing (40 CFR 192). EPA 52011-83-008-l and -2, Washington, DC (1983). 9. U.S. Environmental Protection Agency, 40 CFR 192, Standards for remedial actions at inactive uranium processing sites, final rule. Federal Regisfer 48(3): 590-604 (1983). 10. U.S. Environmental Protection Agency, 40 CFR 192, Environmental standards for uranium and thorium mill tailings at licensed commerical processing sites, final rule. Federcrl Register 48( 1%): 45926-45947 (1983). 11. U.S. Environmental Protection Agency, 40 CFR 190, Environmental radiation protection standards for nuclear power operations. Federul Rvgisrer 42(9): 2858-2861 (1977). 12. U.S. Environmental Protection Agency, 40 CFR 192, Standards for remedial actions at inactive uranium processing sites, proposed rule. Federul Registcjr 52( 185): 36000-36008 (1987). 13. U.S. Congress, Nuclear Waste Policy Act of 1982. Public Law 97-425 Washington, DC (1983). 14. U.S. Environmental Protection Agency, High-level and transuranic radioactive wastes, background information document for final rule. EPA 52011-85-023, Washington, DC (1985). 15. U.S. Environmental Protection Agency, 40 CFR 191, Environmental standards for the management and disposal of spent nuclear fuel, high-level and transuranic radioactive wastes, final rule. Federal Register 50(182): 38066-38089 (1985). 16. U.S. Environmental
Protection Anencv. 40 CFR 141. Interim primary drinking water regulations, promulgation of regulations on radionuclides. Fc~drral Register 41(133): 28402-28405 (1976).
17. U.S. Nuclear Regulatory Commission, 10 CFR 60, Disposal of high-level radioactive wastes in geologic repositories; conforming amendments, proposed rule. Federal Register 51(118): 22288-22301 (1986). 18. U.S. Environmental Protection Agency, Environmental radiation protection standards for low-ievel radioactive waste disposal, advance notice of proposed rulemaking. Fedem/
Register
48(170): 39563 (1983).
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19. U.S. Nuclear Regulatory Commission, 10 CFR Parts 2, 19, 20,21,30,40,51,61,70,73, 170, Licensing requirements for land disposal of radioactive waste. Federal Rcgisrer 47(248) 57446-57482 (1982). 20. U.S. Congress, Low-Level
21.
22.
23.
24.
Radioactive Waste Policy Amendments Act of 1985. Public Law 99-240, Washington, DC (1986). U.S. Environmental Protection Agency, Ground-water protection strategy. Office of Ground-Water Protection, Washington, DC (1984). Bandrowski, M. S. and Gruhlke, J. M. Inclusion of NARM in the EPA LLW Standard. Proceedings of 8th Annual Department of Energy Low-Level Radioactive Waste Management Forum, Volume VII, CONF-860990, EG&G Idaho, Idaho Falls, ID (1987). Bandrowski, M. S., Hung, C. Y., Meyer, G. L., and Rogers, V. C. Summary of EPA’s risk assessment results from the analysis of alternative methods of low-level waste disposal. Proceedings of the Symposium on Waste Management ‘87, Volume 3 Low-Level Waste, University of Arizona, Tucson, AZ (1987). U.S. Environmental Protection Agency, 40 CFR 220-229, Ocean dumping, final revision of regulations and criteria.
Federal Register 42(7): 2462-2490 (1977). 25. U.S. Congress, The Surface Transportation
Assistance Act of 1982. Public Law 97-424, Washington, DC (1983). 26. International Atomic Energy Agency, Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter. INFCIRCRO5, Vienna, Austria (1978).
27. International Atomic Energy Agency, Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter; The Definition Required by Annex I, paragraph 6 to the Convention, and Recommendations Required by Annex II, Section D. INFCIRCi205 Addendum 1, Revision I, Vienna, Austria (1978). 28. International Atomic Energy Agency, Definition and Recommendations for the Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter, 1972. Safety Series No. 78, Vienna. Austria (1986). 29. International Maritime Organization, Report of the Tenth Consultative Meeting of Contracting Parties to the Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter. LDC 10115, London, England (1986). 30. U.S. Environmental Protection Agency, Agency operating guidance, FY 1987. Office of the Administrator, Washington, DC (1986). 31. Holcomb, W. F. A history of ocean disposal of packaged low-level radioactive waste. Nuclrar Sqfet!: 23(2): 183-197 (1982). 32. Dyer, R. S. Environmental surveys of two deepsea radioactive waste disposal sites using submersibles. In: Mnnrrgement of Radioactive Wastes from the Nuclear Fuel Cycle, Vol. II. International Atomic Energy Agency, Vienna, Austria (1976). 33. Pryor, M. Vigilance in the deep sea environment. EPA Journul ll(8): 28-30 (1985).