ML20154N675
| ML20154N675 | |
| Person / Time | |
|---|---|
| Issue date: | 08/06/1979 |
| From: | Dircks W NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | Kammerer C NRC OFFICE OF CONGRESSIONAL AFFAIRS (OCA) |
| References | |
| TASK-TF, TASK-URFO NUDOCS 9810220054 | |
| Download: ML20154N675 (6) | |
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UNIT'D STATES g t h NUCLEAR REGULATORY COT.*:.ilSSION
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WASHIN'., TON, D. C. 20055 Q ' -.,,j I g, i,0 G' 6 1979 MEF.GRAfiD'& FOR: Curiton Kammerer, Director Office of Congressional Affairs \\ THRU: Thomas Rehm ORIGINAC SIGNgg gy g. G. SMITH Assistant to the Executive Director for Operations 3 FROM: William J. Dir:cks, Qirector ~ V Office of Nuclear fiaterial Safety and Safeguards
SUBJECT:
II: SERT FOR THE RECCRD ON TESTIMONY BEFORE THE SUSCOMfilTT Oft ENERGY AND THE ENVIROt".ENT Enclesed for inclusion in the hearing on State Participation in Waste, -- Licensing are the Office of Nuclear flaterial Safety and Safeguards connents requested b) Representative Clausen. j ("') pgesa0 N 3 L' . William J. Dircks, Directof [ ~ Office of Nuclear Material Safety and Safeguards
Enclosure:
tr.SS Staff Coments e d e 991M 20054 790806 PDR ORG NOMA PDR 7... '.
((' ; *,'b, (][) (]) ENCLOSURE L INSERT FOR THE RECORD Udall' Committee Hearing on State Participation in the Waste Licensing Process Question: A description of the state of ?.he art of waste management technology i hich identifies the specific technological shortcomings, provides an estimate w of the amount of time necessary to resolve those problems, and defines the magnitude of the waste disposal problem. ' Answer: ( The High-Level Waste Problem Radioactive waste is the byproduct of the generation of electricity by nuclear reactors lor of the production of plutonium for weapons. Fuel assemblies must- .be removed periodically from nuclear reactors as fission products accumulate. These spent fuel asremblies contain large concentrations of fission products o l which decay.to innocuous levels in several hundred years, and of longer lived transuranic elements and their daughters ~which persist for hundreds of thousands of years. Spent fuel can be processed chemically to recover most of t'he plutonium and ~ unfissioned uranium for possible reuse. The residuum from this process is a highly radioactive byproduct usually referred to as "high-level waste." The . United States currently does not plar. to reprocess spent fuel; thus, the immediate problem of commercial radioactive waste is one of handling, storing, ,,_s - t _) .and ultimately disposing of spent fuel assemblies. s l Radioactive wastes from military activities are somewhat different. These wastes are mainly the residue.after plutonium has been extracted from l materials that have been irradiated in a reactor designed specifically to produce plutonium. Although military wastes contain many of the same fission products and transuranic elements as canmercial waste and occupy significant L volumes, their total radioactivity is lower per unit volume than that resulting ' from power reactors. At present, there is about the 'same total radioactivity in the waste' resulting from defense programs as that stored in spent-fuel assemblies from commercial reactors. 4 4 e i.
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- l The volume of commercial radioactive waste that will accumulate during the next few decades will depend upon'the growth of the nuclear power industry and on the form of the waste.
It has been estimated that by the year 2000, approximately 95,000 tons of spent fuel will be on hand if none has been reprocessed. If these spent fuel elements were to be reprocessed, the resulting3 solid high-level waste would occupy approximately 3,000 cubic meters (m ), and accompanying intermediate-level wastes contaminated by transuranic elements would occupy a volume one order of magnitude larger than the volume of high-level waste. Hioh-Level Waste Manaaement Technology High-level wastes are highly radioactive and biologically toxic and must be isolated from the biosphere. Isolation methods being investigated i o include disposal into space, transmutation of elements, rock melting, U disposal in very deep drill holes, disposal in seabed sediments, and disposal in mined repositories in d'eep continental geologic femations. The U.S. Department of Energy (DOE) is responsible for developing and implementing the technology for managing high-level radioactive waste and it is our understanding DOE tentatively views geologic repositories to offer the most viable near-term opportunity for the disposal of high-level l waste. Therefore, NRC is focusing its near term efferts on preparing to j l review an application for a geologic repository. The staff agrees with the findings of the Interagency Review Group (IRG) on Nuclear Waste Management that:* i "Present scientific and technological knowledge is adequate to identify potential repository sites for further investigation. No scientific or O technical reason is known that would prevent identifying a site that is U suitable for a repository provided that the systems view is utilized rigorously to evaluate the suitability of sites and designs, and in minimizing the influence of future human activities. A suitable site is one at which a repository would meet predetermined criteria and which would provide a high degree of assurance that radioactive waste can be success'ully isolated from the biosphere for periods of thousands of years. l For periods beyond a few thnusand years, our capability to assess the per-forTnance of the repository diminishes and the degree of assurance is therefore reduced. The feasibility of safely disposing of high-level waste in mined repositories can only be assessed on tha basis of specific investigations at and detenninations of suitability cf particular sites. Infonnation
- Report to the President by the Interagency Review Group on Nuclear Waste Management, March 1979, page 42.
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a p y, v o , obtained at each succe.ssive step of site selection and repository development will permit re-evaluat on of risks, uncertainties, and the ability of the site and repository to meet regulatory standards. Such re-evaluations would lead either to abondonment of the site or a decision to proceed to the next step. Reliance on conservative engineering practices and multiple independent barriers can reduce some risks and compensate for some uncertainties. However, even at the time of decommissioning some uncertainty about repository performance will still exist. Thus, in addition to technical evaluation, a societal judgment that considers the level of risk and the associated uncertainty will be necessary." The specific areas of scientific and technical uncertainty which our studies and our overall observation of high-1evel waste management activities indicate must be clarified with respect to the permanent disposal of waste, are as follows:* gO 1. The ability to analyze repository performance is limited by the large uncertainties which exist in site characterization. Uncertainty in the description of site characteristics arise from many sources, primarily the inherent limitations associated with the instrumentation used to acquire data, and the interpretation of site data into model pa rameters. Additionally, the investication of a site will most likely involve the use of intrusive or destructive testing methods (e.g., boreholes) which may introduce potential pathway for waste release. 2. The ability to analyze repository performance is also limited by the large uncertainties which are associated with the introduction or radiation and heat into a geologic system. These phonemena require significant addit ional study, particularly in the investigation of thermal effects a the mechanical properties of the rock (e.g., plasticity, stress and st-ain), and the thermal effects on the C, chemical interactions between the waste, groundwater and the rock (e.g., dissolution, retardation). 3. Uncertainty also exit 1 in the reliability of engineered barriers to perfom under repository conditions. Since the potential hazard from radioactive waste decreases significantly within the first five hundred years, engineered features such as waste form and specific repository design concepts can significantly contribute to confinement of the wastes during the most hazardous period.
- Additional infomation on the state of advanced waste manage.nent technologies is presented in the recently completed Department of Energy's Draft Environmental Impact Statement on the Management of Connercially Generated Waste, April 1979 (DOE /EIS-0046-D).
E.. :. (] p .~ v v. i T.o date, the designs of deep geoTogic repositories have placed major (if not total) reliance for containment of radionuclides on the surrounding geol ogy. Reliance on the waste form itself and its packaging to prevent radionuclide release over the long-term has not received intense emphasis. The waste form work that has been done has been devoted primarily to glass. Many feel that several geological settings should be characterized and " qualified" fore a commitment is made. The NRC waste management staff considers that an analogous argument applies to the waste fonn and packaging selection. The potential gains in assurance which could be made are, in our judgment, sufficiently large to warrant this approach. The long-term performance of the waste form, packaging, and its reactions with the host rock can be examined in the laboratory and can be ' extrapolated with some confidence through testing at aggravated ccnditiions. This approach (~~) has been used successfully in modern materials development work. A high degree of assurance of the performance of the waste form, packaging, host rock interface would also tend to offset the inevitable uncertainties in geologic performance. As a result, t'he NRC waste management staff believes that a much more aggressive waste form and packaging development and demonstration effort should be under-taken in order to provide a multi-barrier repository system. The completely encapsulated nuclear waste would be protected by its chemical form and packaging until most of its fission products had decayed. At that point, the geologic repository's radioactive content would not be much different than the original ore body. This would leave the geology as a fully redundant backup barrier. The NRC staff is working with DOE on this multi-barrier approach and our preliminary regulation work reflect this view. We are not able at this time to determine in an absolute sense the significance of these areas of uncertainty to the overall safety achievaole in permanent f) nuclear waste disposal programs. The evaluation of the absolute importance of each factor is site dependent, and cannot be meaningfully performed until we have a specific site to assess. Our studies have revealed, however, areas in which further study t necessary to improve our confidence in predictions of repository performance. These are: 1. assessment and testing of methods for processing waste into chemical i l and physical fonns which will provide optimum radiological safety for j handling; 2. development of improved methods for measuring and understanding the mechanisms, rates, probabilistics governing the migration of radio-nuclides to the biosphere due to hydrological processes, or other natural phenomena or by the activities of man in the distant f*uture; e O - 9
(3 p) %i Q. ' ' * ~ .- e . 3. development and test of probabilistic risk analysis models which will integrate and analyze the multidisciplinary data needed to provide predictive information for siting and licensing of high-level waste management facilities; 4. development of adequate understanding of the characteristics and effects of geochemical and hydrological processes which will be involved with waste and containers which are deposited in repositories; 5. assessments of the engineering designs and mining engineering practices that may likely be used in developing and operating repositories in geologic media; 6. confirmation of the short-term reliability and long-term durability of containers needed for handling and storing waste and spent fuel; and (~') 7. development of data to confirm understanding of the radiological pathways and potential impacts on man that could occur if radioactive products from '~' the wastes should be liberated into the biosphere in the future. All of these items are key areas requiring resolution before a repository can become operational. Since research can turn up new problems as well as resolve old ones, each of the above items should be pursued as quickly as possible. The most urgent are those which relate to site selection and to information required to evaluate the likely performance of'the site (items 2,3,and 4 above). This information is needed first so that an evaluation of the suitability of the site for a repository c:n be made to support a construction authorization. This is the point where a substantial commitment is made. Time Necessary to Resolve These Technological Problems g) The Interagency Review Group on Waste Management has expended considerable ( effort to review the technical problems associated with geologic disposal of radioactive wastes and has concluded that technical knowledge is sufficient to proceed with selecting sites for further investigations. These further investigations will lead either to abandonnent of the sites or further devel opment. The Department of Energy is responsible to resolve the uncertainties through their development program. While we cannot speak for the Department, we believe a vigorous, well managed, stepwise development program could reduce the uncertainties to levels which permit rational decisions over the next decade. e e}}