ML20154N611
| ML20154N611 | |
| Person / Time | |
|---|---|
| Issue date: | 06/28/1978 |
| From: | Bishop W NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | |
| References | |
| TASK-TF, TASK-URFO NUDOCS 9810220037 | |
| Download: ML20154N611 (15) | |
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4 Testimony Before the Subcommittee on Fossil and Nuclear Energy Research, Development and Demonstration House Committee on Science and Technology Presented by Dr. William P. Bishop Assistant Director for Waste Management Division of Fuel Cycle and Material Safety USNRC June 28, 1978 E
9810220037 780628 NOMA pg ppR ORG y .
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Thank you for the opportunity to discuss the NRC's role in nucler "aste s management. As Mr. Meyers indicated, I will discuss our ongoing and planned research and how these studies support our main efforts in estab-lishing regulations and preparing for our licensing responsibilities.
First let me give some background on the fiscal development and status of our program. In 1975, NRC had no regulatory framework for nuclear waste management. About two man years total effort was expended to scope the NRC program and for licensing review of low-level waste burial grounds.
In mid 1975 a Waste Management Branch was established in the Division of Fuel Cycle and Material Safety in the Office of Nuclear Material Safety and Safeguards. Since that time we have assembled a highly qualified permanent technical staff. Our FY78 personnel ceiling is 37 and we have asked the Commission to consider an increase to 55 in FY79. Because of the importance placed by the NRC on the nuclear waste issue, the waste management staff has twice been reorganized and moved upward in the NRC heirarchy, and it is now at an Assistant Division Director level with two separate branches. In addition other parts of the NRC supply approximately 20 man years of expert supportive help dedicated to nuclear waste questions.
Our FY79 budget in NMSS for contractual support is $5.5 million with $3.2 million going to efforts in high-level waste management and $2.3 million i
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management program.
These contractual support funds go to support a variety of activities which are used in our establishment of regulations and standards or our preparation for licensing decisions. For the discussion today I have included some of the studies being used directly in our standards-setting or licensing actions (which are strictly speaking, " technical support").
These projects have some of the usual characteristics of research and add to that same body of knowledge generally considered to be research results.
The studies I shall briefly describe are all aimed at improving NRC capa-bilities fo licensing waste storage and disposal operations. Some of them are ai.ted at development of new analytical capabilities, but never at development of new technologies. Others are intended to supply key data for use in our analyses or to confirm the data supplied by others. For the bulk of the data we use in our day-to-day activities we rely on the DOE or the nuclear industry, but we do not take their facts at face value nor count on them for the data necessary for our advanced planning or preparation of regulations.
o o In the past, the NRC has generally relied on the national laboratories of the Department of Energy (00E) for quick responses to urgent needs for technical assistance. However, alternative sources for contractual support have had to be developed because the rapid expansion of the DOE's program in waste management has preempted the resources available in the labora-tories. In addition, because 00E is responsible for developing high-level waste repositories and will therefore be submitting waste repository applications for NRC licensing review, NRC needs sources of support inde-pendent of DOE's national laboratories. Accordingly, after issuing a request for proposals, the NRC selected 22 private firms to provide technical assistance in the evaluation of waste management options, development of system criteria, coordination of rapid studies of specific issues, and evaluation of specific waste management plans. Thus far, 11 competitive procurements have been processed and awarded.
I shall briefly describe a number of studies which are aimed at improving our information and understanding. Further, I shall note (even more briefly) areas we have identified as needing further research efforts.
For convenience I shall group my remarks in the areas of high-level waste (understanding a repository and what will go into it) and low-level waste (understanding shallow land burial and what is and should be so buried).
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High-Level Waste Program Research efforts in support of NRC's high-level waste program are currently directed towards enabling NRC to prepare regulations and criteria for disposal of high-level wastes, transuranic wastes, and spent fuel in deep
, geologic respositories. In so doing, we must calculate release pathways, assess risks and provide those tools which are required to evaluate a proposal submitted to us by DOE.
There are two major efforts under way, both being performed for us by DOE National Laboratories, designed to develop systems analyses and compile essential data for thoroughly understanding deep geologic repositories.
The efforts at Lawrence Livermore Laboratory (LLL) are generic studies of all repository systems from waste transportation to post sealing of the repository. This effort provides a major input to our standards develop-ment program. From the information developed by LLL we will derive and promulgate waste form performance criteria, repository site suitability criteria, repository design performance criteria, and repository operating and decommissioning (i.e., closure) criteria. The work at LLL involves the development of a complex systems analysis model and the use of that model to provide an understanding of how the many factors affecting the performance of a repository work together as a system, which of the factors are most important to the system's performance, and wh. ether there might be some critical limits on some of the parameters. That work is progressing
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well and we are beginning to understand some of the interactions of the system.
Efforts at Sandia Laboratories are also systems analyses but intended
. ultiimately for site-specific application. They are directed toward developing a systert model which can be used in evaluating a specific repository proposed by DOE against our standards. The title of the project is " Risk Methodology Development for Deep Geologic Isolation of Nuclear Waste and Spent Fuel." The specific research areas covered by this project are:
Waste release mechanisms (e.g., tectonic disturbance),
Migration of nuclides through geologic media, Nuclide transport through the environment, and Release pathways to man.
The LLL and Sandia systems models will be cross-checked with each other and with other models being developed both in the U.S. and in other countries. The U.S. gov unment is supporting at least five such studies.
From these systems studies and our own in-house analyses, we have identified a need for additional data gathering research, some of which includes confirmatory measurements. The measurements would provide actual NPC-
O O confirmed data for usa in the LLL and Sandia models. We are actively working on initiating requisite studies in such areas which can be listed under three general categories:
, 1. Geology and waste-rock interaction--which involve the interaction of soils, rock, and the available groundwater with the waste and its containers;
- 2. Waste migration via groundwater--which includes the modeling of various groundwater flow patterns and verification of these models;
- 3. Biological uptake--which, although relatively well understood for present situations, involves high uncertainty in modeling the long-term effects of radiation on man and his environment.
When it became clear that spent fuel must be considered a potential waste form, NRC redirected some of its research efforts. Specifically, the three areas of waste performance, repository design performance and repository site suitability have been reoriented from solidified high-level waste to spent fuel as the "high-level" waste.
Spent fuel differs from solidified high-level wastes from reprocessing in several potentially important ways:
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o The thermal output of spent fuel is considerably different from that of reprocessing high level waste after the first few hundred years.
o Spent' fuel contains all of the fission products (gases and solid) and plutonium formed in the reactor, as well as all of the residual uranium. Solidified high-level wastes from reprocessing contain no gaseous fission or activation products (predominantly krypton, tritium and carboa) and less than 1% of the plutonium and uranium present in the spent fuel dischargad from reactors.
o Spent fuel is predominantly irradiated uranium dioxide, and associated Zircaloy cladding. The chemical composition of solidified high-level raste is a function of the waste form. The waste will contain oxides of the fission products, actinides, and stable elements such as iron, chromium, and possibly silicon and boron.
All of these differences have implications in the performance of the overall repository system. Thus our research studies have been directed to investigate this particular waste form in a repository environment.
Finally, with regard to the high-level waste program, let me comment on
.;ome spuific factors which are not very well understood and for which I
further research could enhance confidence in our predictions of repository performance.
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(1) Radi>nuclide retardation factors _In-situ testing is needed of the retention capability of repository geologic materials. Experiments done to date have been conducted in the lab and the correlation of i those results to actual field data has not been studied.
, (2) Radionuclide solubility limits - Definition of both the in-situ water
- _ chemistry and the radionuclide and impurity species likely to exist in that environment is necessary to calculate the limits of radio-nuclide solubilities in groundwater.
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-(3) Fracture flow - The modeling of fracture flow is in its infancy.
{ If the option of waste disposal in crystalline rock is chosen this will be a major issue.
(4) Groundwater flow through low permeability rocks - The flow through rocks of low permeability will be dominated by diffusion and disper-sion if there is not extensive fracturing. The modeling of these processes has not been extensively studied.
(5) Thermal effects of the waste - The introduction of heat into the repository environment may caust: changes in some repository para-meters. Thermal effects may cause expansion of the rock and thus higher permeabilities. Elevated temperat'.ures may significantly G
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o o change the dissolution characteristics of the waste form. In salt, brine pockets may migrate toward the heat source and thus introduce water into an otherwise dry environment. These effects need further study to determine the extent and effect on the repository perform-
, ance.
Both the U.S. Geologic Survey (USGS) and the Office of Science and Technology Policy (OSTP) have recently released documents which describe areas in which knowledge is lacking, incomplete, or not fully proven.
These areas are not inconsistent with the areas I've noted above, but include many details which had not come out of our own studies at NRC.
Both of the documents (by their own admission) lack a perspective regarding which of the areas of uncertainty are really important to assessment of the performance of a repository. All could be potentially important in special circumstances. One of the very special features of any systems modelling effort such as I briefly described above is that it can provide aderstanding of which factors are of real significance.
Laking such understanding prudence dictates that all the areas identified by NRC, the USGS and OSTP be given some attention.
Low-Level Waste Program I
The Low-Level Waste (LLW) program currently includes a. number of research efforts primarily directed towards development of a data base to be used
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in formulating regulations, standards and criteria for shallow land burial of LLW. These studies include laboratory experiments and field investiga-tions at existing commercial burial sites to determine the processes and underlying principles controlling radionuclide migration through soil and
, to develop analytical models to predict site performance. Other research efforts are providing information needed to define requirements for record-keeping, operating, monitoring, decommissioning, long-term care and funding of shallow land burial sites.
Segregation of waste types within shallow land burial has been suggested as a method for improving burial site performance. This concept is based on indications that certain of the wastes currently disposed of by shallow land burial may not only possess higher chemical hazards than radiological hazards but also contain chemical or biological materials which can accelerate leaching and migration of radionuclides from the wastes. NRC has studies underway to characterize the physical and chemical properties of low-level wastes and to develop a method for determining relative chemical and radiological hazards in the wastes. Once the chemical constituents of the _
wastes are defined, further studies may be needed to evaluate the potential of these materials to accelerate radionuclide migration and the advantages to be gaired by waste segregation. -
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In recognition of the fact that shallow land burial is a dynamic system consisting of many interacting radionuclide release mechanisms, we are planning a comprehensive systematic analysis of all factors affecting shallow land burial. The resulting model will provide a tool for assessing
- relative risks from specific pathways and total risks from a site. In addition, the model will be used to define integrated criteria and standards which will minimize risk from shallow land burial.
Although much of NRC's ongoing low-level waste research concerns shallow land burial, an evaluation of alternative disposal methods for low-level wastes is being performed. Alternatives are being evaluated for technical, economic, environmental and institutienal merit. Identification of at least one and probably several acceptable alternatives is likely from this study. For each of these alternatives, short-term data development, modeling and other analyses may be necessary to formulate regulations, standards and criteria. For example, evaluation of impacts and develop-ment of siting criteria for ocean disposal of low-level wastes would require models for radionuclide migration mechanisms in marine environ-ments which are more sophisticated than currently exist.
i The LLW staff is developing licensing review methodologies, including both predictive models and review procedures, lo aid in licensing and review actions. Development and validation of these models will be one of the
o o products of the field studies being conducted at the existing burial sites.
One of the more important analytical tools being developed is a model for
- predicting waste disposal needs through the year 2000. The purpose of this project is to develop models for periodic independent projections of volumes, radioactivity and actinide mass for all nuclear wastes to be generated on a regional basis through the year 2000 and for estimating waste disposal costs. These will be utilized in decisions on the timing and location of proposed disposal sites and evaluations of environmental impacts.
Technical support programs to provide an adequate data base for policy decisions on decommissioning of reactors and fuel cycle facilities are in progress. One series of /0 studies is under way to define (1) character-istics of the plant and site; (2) aca ptable decontamination levels; (3) radiation exposure to the workers and the general public; (4) cost /
benefit ratios; and (5) additional research and development needs. The first two of these reports (PWR and reprocessing plant) are complete.
While we can already identify some R&D which would be useful in reducing decommissioning costs, basic technical capabilities exist. Problems which t
require serious study for the nuclear industry (as opp' osed to Federal facilities) are financial and institutional.
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i A program to develop a data base for regulating captured radioactive gases \
produced from the nuclear fuel cycle is planned though not yet underway.
Specific results from the study will include a comparison of costs and risks associated with alternate technologies for storing or disposing of radioactive gases, performance criteria for the physical form in which gases should be stored or disposed of; and general facility performance requirements (specifically the need for repository disposal techniques).
Conclusions
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I have become personally convinced over the past few years that our confidence regarding the disposal of nuclear waste can be substantially improved through research in a number of areas. This conviction has been reinforced by the recent papers from the USGS and OSTP. However, I have not been convinced that all of the additional knowledge identified is necessary to reach reasoned and fully supported decisions. The identification of that information which is essential can and will be done through the major systems / risk studies now underway at several locations. Furthermore, +Aa ,
structured decision procedures inherent in the licensing function of the NRC will narrow the focus toward on those issues which are really crucial in the decisions regarding any particular disposal proposal. No intuitive analysis or simple listing of information areas can provide such a ranking or such a focus.
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s The research needs I've discussed and those needs identified by others tend at present to be generic as opposed to site specific. However, it is clear that the complex geological, hydrological and engineered system which comprises a repository or a burial ground is very site and design
, ' specific. When you have seen one rock or soil or geologic setting you have not seen them all. Furthermore, the NRC decisions on licensing will necessarily be site and design specific. Two sites may perform similarly, but it will be the specific combination of diverse factors which add to similar performance; it will be very unlikely that more than a few of the important factors will be individually similar between two sites. Research of a generic nature is important to our planning of a waste management program. But it will need to be supplemented by site specific research in due course.
While NRC relies heavily on the research of others (notably DOE and the USGS) in the area of waste management, we have felt and continue to feel that we need some indept idently developed tools and some confirmatory data from our own efforts. Not only does this give us an independent check on information brought to us for our evaluation, but it provides us an essential understanding of how such information is derived and thus its quslity and the caveats which are required in understanding and interpreting it.
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