An Overview of the Workshop Agenda
The workshop will focus on the generic issues of geological repositories for disposition of HLW, with illustrations from the experiences of national programs. The objective of the workshop is to provide new insights for the future directions of the geological disposal option. Such insights and other new information will be presented in a National Academies' report to be issued in spring, 2000. To encourage creative thinking, the workshop will emphasize informed and focused discussions by all participants during special sessions that will be described in the next pages of this workshop overview. Only four plenary papers will be presented.
Plenary speakers will include Frank Parker, Distinguished Professor of Water Resources Engineering at Vanderbilt University, and chairman of the National Research Council's Board on Radioactive Waste Management at the time that it produced the Council's 1990 Rethinking High-Level Radioactive Waste Disposal report (NRC, 1990). Dr. Parker will speak on geological repository development in the United States since Rethinking. Charles McCombie, Consultant and former Scientific and Technical Director, Swiss Cooperative for Radioactive Waste Disposal (NAGRA), will speak on international development of the geological disposition option during the past 10 years. Paul Slovic, President, Decision Research, and Professor of Psychology at the University of Oregon, will speak on public perceptions, trust, stigma, and the problems of achieving public acceptance of geological disposition. These plenary talks will be followed by invited comments from leaders and former leaders of national programs in the United States, France, and Sweden, and a distinguished sociologist from the United Kingdom. In the final session of the workshop, Francis Tombs, member of the U.K. House of Lords and chairman of the U.K. House of Lords enquiry into the management of nuclear wastes, will summarize how insights from the workshop can benefit national programs.
While there will be some opportunity for questions and answers with the plenary speakers and discussants, the main opportunity for participation by workshop attendees will be in the discussion sessions, which are described below.
Arrangements and Topics for Discussion Sessions
In planning the workshop, considering the range and amount of information to be covered and logistical realities, he workshop steering committee agreed upon seven topical discussion sessions. These seven sessions will be held concurrently so that the expected 200 participants can be divided into discussion groups of about 30. In their essential content, the seven sessions will be repeated three times, thus, workshop attendees can participate in three of the seven.
Attendees will have the opportunity at the beginning of the workshop to sign up for the sessions of their choice, and the organizers will try to accommodate their preferences. While the specific content presented in each of the repeated sessions may vary, the topic area will remain the same. The presenters and discussion leaders in each session will assume that those present have not attended a previous meeting of the same session. Attendees are strongly encouraged to share their views and provide their critical commentary on the material presented. More than half of each session will be devoted to discussion, after the planned presentations are made.
Key Issues for the Workshop.
In initiating the workshop, the National Academies' Board on Radioactive Waste Management suggested that three broad topical areas be examined: technical development of the geological disposition option, its scientific and policy challenges, and strategies for implementation. Key issues associated with each area, and to be included in the workshop discussions, were later identified by the workshop steering committee. Workshop attendees are encouraged to consider how they can contribute new ideas and approaches to the following issues:
Technical Development of the Geological Disposition Option—The scientific basis for the geological disposition option, how that option is being implemented on a worldwide basis, and the potential technical suitability and institutional maturity of the geological option.
- What are the key roles of the engineered and geological barriers?
- How site dependent are these?
- Robustness—What does it mean? How can we achieve it?
- What are the open technical areas in understanding engineered and geological barriers?
- Which of these can be cleared up by more R&D? Which are “intractable”?
- Modeling—Can we validate (including use of analogs)? Are “demonstration” experiments technically useful or do they contribute only to public confidence building?
- (How) can we use performance assessment to guide work on site characterization and on engineered barrier system design?
Scientific and Policy Challenges for Disposition of Highly Radioactive Waste Through Geological Isolation—Understanding natural processes and environmental change; predicting long-term repository performance; predicting long-term human behavior; limits to technical knowability.
- How should the scientific community describe to itself and to publics what is, or can be, known (climate, geology, social systems) for very long periods? How much knowledge is enough? (That is, what criteria can be used to judge information needs?) How does this knowledge relate to the choice among disposition approaches?
- To what extent can proof or certitude be achieved? What are the limits to system safety assessment methodologies such as total system performance assessment (TSPA)?
- How do we address the human concerns over irreversibility? What is the attractiveness of storage, retrievability, and monitoring? How do we deal with the possibility that a better alternative than geological disposal might be “just around the corner”?
- Are there benefits to a stepwise repository development program and what must be demonstrated at each step (technically and to policy makers)?
- How do we best address human intrusion (probabilities, information transfer, mitigating actions, etc.)?
- What type of analyses can best help us tackle the “irreducible uncertainties” (probabilistic, bounding)?
- Is commitment of enormous resources, especially rare metals, in geological disposal really justified?
Strategies for Implementing the Geological Disposition Option—Separating the technical and policy bases for licensing decisions; phased disposition options; long-term monitoring and surveillance; addressing public concerns about fairness in the decision process and long-term safety; other strategies to inform and involve publics; alternative disposition approaches.
- Should we store wastes rather than dispose of them “rapidly” (ethical, economic, public acceptance arguments)? How does the “storage vs. rapid disposal” issue relate to the question of how to proceed with siting and licensing of repositories?
- Do separations and transmutation provide real alternatives in the technical sense? In what time frame?
- The regulator's dilemma: how to deal with the conflict between the rigor and transparency required for regulatory processes and the intrinsic uncertainties in any performance assessment or in any real scientific predictions? What is reasonable confidence? Are there useful comparisons to regulation in other areas?
- What must the technical community provide to elected officials to best inform them about radioactive waste management alternatives? What do program managers need to know from publics?
- What is the value of simple transparent safety arguments versus opaque TSPA results?
- What are the critical factors that lead to success (such as the U.S. WIPP, Swedish success with low and intermediate level nuclear waste repositories and transport facilities, progress in Finland)? What are the lessons to be learned from these?
- What is the role of international cooperation (consensus building, international safety standards, proposals for international repositories)?
Description of the Discussion Sessions
The key issues will be approached from various perspectives in one or more of the workshop's seven discussion sessions. The seven discussion sessions that form the core of the workshop are listed as follows:
- Role of total system performance assessment in establishing the acceptability of geologic repositories: An interface between technology and policy;
- Timing and staging repository development: Maintaining technical and social balance in stepwise development from concept through implementation;
- The regulator's dilemma: Decision making in the presence of uncertainty;
- Public acceptance in the context of social distrust;
- Lessons learned from national programs: Tracing routes to success or setback;
- Is geological disposal required?; and
- Making progress through international cooperation.
Each session is described in the remainder of this paper.
Session 1: Role of Total System Performance Assessment in Establishing the Acceptability of Geologic Repositories: An Interface between Technology and Policy
Deep geologic disposal of nuclear waste relies on several key concepts. The waste, which may be harmful to humans for tens of thousands of years up to a million years, may be isolated with a number of barriers, each playing a specific role, for a specific time, in order to prevent premature dispersion of the waste in the environment. However, if or when a release from a repository occurs, the potential for harm to humans must be shown to be acceptably low, that is, within established regulatory parameters. The measure of the harm to humans is to be estimated by the doses that could be received in the future, based on today's understanding of pathways and effects of doses. When the release is not certain to occur, the risk (probability of occurrence and consequence) is usually considered rather than an assumed dose.
The acceptability of the geologic disposal option is to be established, for the technical community, the licensing community, the political community, and publics, by an analysis that would try to predict the future of the repository and the waste in three different but complementary ways:
How will the barrier system behave under the most likely conditions? These likely conditions need to be selected and justified based on present understanding of the natural system. The thrust of the prediction is on the “normal” evolution of a complex interacting system of a natural medium in which vast amounts of heat and of exogenous elements have been introduced. The basic physical and chemical laws that apply to the barrier system must be identified, the system modeled, the modeling validated, and the relevant parameters to be used for representing the behavior over thousands of years estimated from short-duration experiments. This clearly introduces uncertainties, which need to be identified and bounded.
What external events can alter the “normal” evolution of the repository? These can be the global evolution of the Earth (e.g., climate changes, sea level variations, or recurrent faulting) or events which are of a more random nature, like the fall of a meteorite or volcanic intrusion. Any of these events may be assessed a probability of occurring once in any given year. In general, those events with a probability of less than 10-8 per year are ignored. The impact of these events on the repository (immediate release or degraded barrier system) needs to be evaluated to estimate the resulting potential harm to humans.
What inadvertent human action occurring in the future, can alter the performance of the repository or lead to the direct release of radionuclides in the environment? These events may be considered with a probability of occurrence, and may depend on the properties of the site, such as the incentive for reconnaissance or exploitation of natural resources. Taking into account human intrusion is fundamental, but represents a special category of events, since the intrusion scenarios must be specified, and cannot be predicted based on scientific arguments.
Very long-term repository barrier behavior can never be predicted with certainty. TSPA is being used to estimate the repository behavior and give the uncertainty in that estimate. A repository concept must be evaluated as a whole, with each barrier assigned a series of assumed behaviors and properties, and of uncertainties. Only the result of the TSPA makes sense, there is no “general” role for any given barrier. Barriers depend not only on the site (e.g., rock properties at the repository level, dilution properties in the accessible environment) but also on the concept (e.g., Is one given barrier sufficient to outlive the thermal phase of the waste? Is the backfill in place to protect the canister, or to retard the leak of the radionuclides? Is the solubility limit of the waste form a barrier?). Furthermore, regulations may also require that the role of a given barrier be limited in time (e.g., that no credit be given to any engineered barrier after 10,000 or 100,000 years).
The session will be organized around the following presentations and discussions:
- Examples of a successful TSPA that led to licensing of the WIPP in the United States and of unsuccessful TSPAs. What went right and what went wrong?
- What should be the role of regulators during development of a TSPA?
- Is the TSPA credible to the public, or how can it be made more credible?
Issues to be addressed will include those in the following categories:
Technical. Is there a general consensus on the TSPA approach outlined above? Is there an alternative? Is there a limit of knowledge, which will prevent any confidence in describing possible situations in 10,000; 100,000; or 1 million years? Can we bound this limit of knowledge by estimating uncertainties? Is there a danger of building over-confidence on phenomena that are poorly known by trying to estimate ranges of uncertainties?
Regulatory Aspects Influencing the Technical Issues. Regulatory policy is by necessity involved in the safety performance analysis, by specifying time limits for the safety assessment, by specifying the type of potential receptors in the future (e.g., the assumed distance to the nearest well downstream from the repository), and the type of evaluation measure (e.g., deterministic peak dose, expected dose for a ensemble of probability-weighted scenarios or samples in the probabilistic parameter space, different dose limits for different scenarios, risk limit). How do the technical uncertainties affect the policy decisions of the regulators?
Regulatory Treatment of Human Intrusion Scenarios. Since these scenarios must be specified, is there a general international consensus on what these scenarios are? How to treat them? Which importance to give them relative to the performance of the system for all other scenarios? Is it adequate to merge all scenarios by giving a probability to the human intrusion scenarios (e.g., the probability of a new well to be drilled in the future based on the present observed drilling rate in the area), or should they be considered separately?
Social/Political. Is TSPA an appropriate approach for informing publics and public officials of the long-term performance of a repository? Will the discussion, on the contrary, be forced into assessing the role of individual barriers, and will the technical community be asked to “guarantee” the integrity of each individual barrier over a given lifetime? What is the importance given by publics to the human intrusion scenarios? Can TSPA be conducted in a way that addresses the concerns of various publics?
Session 2: Timing and Staging Repository Development: Maintaining Technical and Social Balance in Stepwise Development from Concept through Implementation
The many different national approaches to implementing geological disposal demonstrate that there is no unique or “best” approach. What has become clear, however, is that the development of a facility for disposition of high-level radioactive waste requires decades for completion. Compared to most industrial projects this development period is extremely long.
During this long process, the project implementers (the responsible waste management organization), the regulators, political officials and publics must establish a working relationship, a “partnership.” Without reaching consensus among the partners, progress will be unlikely. Experience shows that decisions made by only one or two partners (e.g., industry and government) and not including publics, are not likely to succeed. Thus the timing and staging of events in the course of repository development will depend on a balance of technical and social factors. Progress will involve the balancing of options and views regarding:
- political and legal matters,
- scientific and technical issues,
- public acceptance of sites and procedures,
- the interest of the nuclear industry, and
- needs to disposition waste from national defense activities.
A fundamental issue to be addressed is the question of retrievability or reversibility. Whether or not it should be possible to retrieve the waste may be considered in a wide perspective and is related to the views on technological advances, irreducible uncertainties, scientific understanding in general, and nuclear waste as a presumptive resource. This issue includes ethical and economic aspects regarding the appropriateness of the underground option.
Legal permissions and other legal aspects are important. The organizational structures, legal framework and regulatory review process are expected to provide a well-defined, logical and “credible” decision-making path. It is also expected that the basic principles of radiological protection against potential exposures are elaborated and that the roles for the implementers, regulators, and publics are clearly defined. These help to establish confidence in the regulatory procedures by which the facility would be either licensed or rejected.
The site selection process will involve many factors. Public acceptance will be of very special relevance. The balance among economic interests (industry and government), public and political acceptance, technical investigations and development, and estimation of environmental and social impacts will be decisive for a successful siting process.
The geoscientific database is an essential part of the siting background material. Different kinds of analyses (constructability, performance, and safety) follow different investigation phases. One has to consider that different levels of knowledge will be reached in each successive investigation phase. To be able to indicate whether a geoscientific parameter is a suitable evaluation factor, or to be
able to specify criteria, knowledge is needed concerning what precision can be expected in the parameter estimation after a given investigation stage. The precision in measuring essential parameters varies greatly from feasibility studies to site investigations and to detailed underground surveys.
In this context the question and role of underground research laboratories (URLs) arises. There might be a clear advantage in developing a URL into a final disposal or storage site. Usually the objectives of the URLs are only to verify physical and chemical processes in a general site specific scale or demonstrate essential activities in situ. In either instance, the URL offers an opportunity for involving publics and addressing their concerns.
The construction of a final repository or a storage site is largely a technical issue that can be divided up into different stages. Are there advantages in an experimental pre-disposal storage phase for say 10% of the fuel? Should evaluation of the constructability aspects precede the safety and performance evaluation or vice versa in the final investigation strategy?
The session will be organized around presentations and discussion of the experiences of selected countries in seeking to combine technical development and social concerns into a stepwise strategy for implementing geological disposal.
The following issues will be addressed in the context of timing and staging events that will best lead to establishment of a geological repository:
- What are the key decision points in repository development and what must be known at each, taking into account both the knowledge that will be available and the consequences of decisions at each stage of development?
- How can science and politics be merged in site selection?
- How can decisions about repository development be properly framed in terms of the realistically available alternatives?
- To what extent should technical issues (safety, performance, and construction) be integrated with the public acceptance issues? At what stages of development should this integration occur?
- How can publics best be involved in different stages of the decision process?
- To what extent does progress in reducing the uncertainties about geologic disposal depend on development and evaluation of specific designs tailored to specific sites?
- What are the pros and cons of underground research laboratories? Should they be used for research and demonstration only, or as the first step in site development?
- Should the disposition concept be evaluated through limited waste emplacements?
- For how long should maintenance, safeguarding, and monitoring of the facility be continued?
- For how long should the possibility to retrieve the waste be maintained?
Session 3: The Regulator's Dilemma: Decision Making in the Presence of Uncertainty
It is broadly accepted that attempts to project the performance of a deep-geological repository can never be very accurate over the multi-thousand-year time periods that are usually considered important. Even using the most advanced techniques for modeling repository behavior out to multi-thousand-year times, and in the hands of very skilled analysts, there will inevitably be major uncertainties in the numerical dose-commitment projections of such models. These uncertainties will always be large in part because the distant future cannot be predicted, but also because the amount of detail required of the models, in order to make such projections, is much greater than is usually obtainable at a given site. Most actual geological sites tend to be heterogeneous at small scales (scales of several meters or less), yet the projections of performance often depend on such details, which are typically unknowable or may be estimated only in a statistical sense. Also, even the engineering aspects of the repository, such as the long-term behavior of metallic canisters or of concrete tunnel-support structures, are difficult to model for time scales of thousands of years or more, time scales that are well beyond actual experience. Publics may be skeptical of the performance projections over many millennia of geological repositories, for the same reasons that underlie the technical difficulties with modeling.
The national authority that is charged with issuing a license or other legal permission for a repository (referred to as the “regulator” in this discussion) is put into a very difficult position by the realities mentioned above. The first job of the regulator is to establish a standard that will be the basis for granting or denying a license to the repository. Both the form of the standard, and the level of safety that the repository must meet or exceed, are difficult to establish in any event, but that difficulty is greatly magnified by the problems mentioned above: the problem that the technical projections are inevitably highly uncertain, and the problem that publics are often distrustful of the claims of technical experts. This requires the regulator to develop not only a standard of performance, but also a standard of proof that takes those unavoidable uncertainties into account.
How safe is safe enough? If the technical projections could be made with relatively high confidence, the answer to this question would be very different than must be the case when the projections have the technical uncertainties that they do have.
How much confidence must the regulator possess to issue a positive finding (a license to proceed)? Does the required level of confidence depend upon the step for which the license has been requested (construction, operating license, closure)? How should that level of confidence be embedded into legal language, and then used in a defensible regulatory decision?
The national regulatory agency will play a very important role in confronting and resolving the difficulties involved in making national decisions about repositories. But the main intrinsic positive resource that such an agency needs—the general trust of the public that it will “do the right thing”—may be lacking or lost unless the regulatory body can exercise all of its roles well.
These roles include at least the following, all of which must be juggled successfully:
- the standard-setting-rulemaking role vis-a-vis both the form of the standard and the issue of how safe is safe enough;
- the independent-technical-expert role in which the regulator must through its own expertise demonstrate its own competence on the technical matters under review;
- the application-review role in which a judgment must be made as to the adequacy of the license submittal; the listening-to-the-public role in which the public's (and the legislators') legitimate concerns must be dealt with; and finally,
- an adjudicatory role if and when its findings are challenged in court.
The regulator may also have a role in decision stages that are not required in the formal licensing procedure. For example, is there a responsibility to assure an appropriate balance between the confidence that a safe repository can be achieved and the commitment (in money or resources) required to take the next step in developing the repository?
The session will be organized for discussion of this “regulator's dilemma.” Its several aspects all deserve illumination from the many different perspectives represented by the several different sectors to which the regulator must be responsive. The objective is to air and discuss the different approaches that have been taken in different countries that have tried to confront this dilemma. Both success stories and failure stories need to be covered, with an emphasis on lessons learned.
Issues to be discussed include the following:
- Given unavoidable technical uncertainty, how should a regulator approach the issue “how safe is safe enough”?
- What level of confidence must a regulator have before granting a license application?
- How can a regulator's level of confidence be written into a legally defensible action?
- How should a regulator deal with the uncertainties of human intrusion?
- What measures should a regulator take to ensure fairness to stakeholders of all persuasions?
Session 4: Public Acceptance in the Context of Social Distrust
Most interested or concerned persons would probably agree that the public acceptance or rejection of the geological option is a central issue for radioactive waste management today. This issue of acceptance, however, is interpreted differently in various contexts. Implementers and decision makers may regard securing public acceptance as a necessary step, as a difficult obstacle, or as a worthy democratic imperative. Concerned citizens and residents may well seek, even demand, another role in waste management decisions than is implied by the notion of “coming to
accept” pre-arranged plans. Social scientists might observe that all of these views imply differing definitions of “acceptance,” or even of what is meant by “publics.” These views imply, as well, various ways of understanding, measuring, and working toward acceptance.
Experiences in the different countries suggests that some prior institutional conceptions and processes of decision making may need to change in order to move toward a situation deemed “acceptable” by major interests. At this time, it is useful to step back and consider why radioactive waste management programs seem to encounter such a high level of societal conflict, controversy, and opposition, and why efforts to move ahead with even redesigned programs may fail. In fact, a large body of studies provides a substantial base of knowledge about four factors at the roots of today's conflicts. These include the following:
Public perceptions of risk. According to extensive cross-national data, publics see the risks of nuclear power and radioactive wastes as very high and are greatly concerned about the dangers. The sources of these perceptions include qualitative aspects of the risks, perceived links with weapons of destruction, and memories of Chernobyl and Three Mile Island. There is also evidence that these perceptions are quite ingrained and unlikely to be changed by provision of risk information or proffered assurances from developers or authority figures.
High social distrust. A high level of social distrust of the managers and institutions charged with the waste management task is documented across a number of countries, including some that on other issues show high deference to authority. This distrust is both specific to the radioactive waste area, and also a more general phenomenon in society. Evidence exists that once lost, trust is often very difficult to regain. Patterns of media coverage may reinforce (or at least do nothing to diminish) attitudes of distrust. Management strategies under conditions of high distrust may well need to be different than when higher levels of social trust prevail.
Value and ethical issues. Mixed in with the risk and trust situations are some difficult value issues, including intragenerational equity, intragenerational (geographical) equity, procedural equity (fairness in process), and responsibilities to risk-bearers. Such values are becoming more paramount in society. There are increased expectations in many societies for consultation and public participation to meet the “fairness” criterion.
Legacy of past mistakes. For decades some radioactive waste management measures have been inadequate, mistake-prone, and often poorly implemented. Many lessons have been learned, and over the last decade institutions, processes, and strategies have been altered to adapt to societal requirements as they are better understood. Nevertheless, a legacy of past mistakes remains with publics. Ordinary people may wonder if national management programs can now overcome past deficiencies and deliver high-quality process and results. What will convince skeptical publics that there has been a radical break with the past and that new approaches and programs will now be handled much better? What
types of evidence are most likely to win confidence? This legacy factor encourages us to examine recent and future changes in institutions.
This session will be organized around the following series of questions for discussion:
- What are the core issues involved in public acceptance and distrust, and what do we know about them?
- How have these issues been addressed in various national programs? What approaches have been most satisfactory? Where have we gone wrong and why?
- How do we best move forward? What should our goals be in the area of “public acceptance”? What approaches or mid-course corrections offer the best chance of reaching those goals?
The sessions will open with framing papers to give data and insight on the four factors seen above to be at the root of today's conflict situations. The following topics will be addressed once from a research point of view and once in light of country cases. What do we know about public perceptions? Of what use can knowledge of perceptions be in radioactive waste management?
What patterns of trust and distrust are apparent across societies? Can trust be regained where it has been lost? How? How can program managers best proceed in a climate of distrust? Can trust be granted to institutions when the management task reaches very far into the long term? What institutions are best suited for such long-term tasks? What major value issues are involved in highlevel radioactive waste management? Are these unique to the field, or do they reflect issues facing all technologies in society? To what extent have they been successfully addressed in the various national programs? How might they be handled better in technical options and in sociopolitical processes?
What are the implications of the foregoing for types of technical approaches, institutional strategies, and processes for interacting with publics? Can comparisons from other fields of risk and technology be usefully made? What should the architects of radioactive waste management programs be aware of and aim for today?
Session 5: Lessons Learned from National Programs: Tracing Routes to Success or Setback
Countries seeking to implement the geological disposal option have gained much experience during the past decade. While the overall picture appears to be one of little progress and many setbacks, there have been notable successes. The purpose of the session is to solicit candid overviews on successes (and the contributing factors) together with setbacks (and what one should have done differently). The overviews should serve to initiate discussion on lessons learned on topics of common interest and on how transferable such experience is. Each of
the sessions on this topic will be introduced by three or four brief invited overviews from national programs.
A questionnaire has been prepared eliciting from speakers and other participants their opinions on lessons learned from national programs. Although different national programs will be described in each of the three meetings of this session, the questionnaire will ensure that the broad issues to be addressed will be consistent. A synthesis of responses to the questionnaire will be presented in the workshop summary and considered in the resulting National Academies' report.
Topics of concern to this session will also be addressed in other thematic sessions during the workshop. This session, however, is oriented toward comparing and contrasting specific experiences from individual national programs. Attendees should be prepared to discuss, analyze, and learn from the experiences of others. The session organizers will make clear in advance which case studies will be covered in each of the three meetings of this session.
This session will be organized around presentations of national experiences. The experiences of different national programs will be highlighted at each of the three different meetings of this session. Speakers will address themselves to answering a set of questions about their programs. Following the program presentations, the speakers will be invited to join a panel and help develop the discussion.
During the discussions, participants will be expected to give their personal views on what they believe to have driven programs along or tripped them up. We propose to distribute the questionnaire during each session; any of the participants can complete all or part of the form. This will address the same set of questions that speakers will cover in their talks. For programs that are well represented by participants, the output of the questionnaires may represent an interesting peer group consensus (or simply highlight uncertainties and differences!).
Issues addressed in this session will include the following:
- degree of public acceptance of geologic disposal (current status and trends);
- alternative site selection strategies (technical, volunteering, etc.);
- reference disposal concept (e.g., weight of engineered vs. geologic barriers);
- importance given to alternatives like separation and transmutation;
- impact of regulations;
- regulator-implementer relationships;
- influence of organizational structures on progress made;
- interacting with publics; and
- most effective arguments of opponents.
Questionnaire on National Experience
Session 6: Is Geological Disposal Required?
All countries with nuclear power programs face the problem of disposing of some form of high-level, long-lived radioactive waste. Some countries have chosen to reprocess the spent fuel, removing the plutonium (and uranium) for reuse as mixed oxide fuel. However, this cycle does not eliminate all the long-lived products.
For at least thirty years, the planning in most countries was to develop some form of geologic repository in which the waste could be isolated permanently. This was planned for both once-through cycles, in which the spent fuel was disposed of directly (suitably packaged), and for the waste from reprocessing, usually planned to be immobilized in glass or ceramic. No country has yet successfully developed such a repository, although the United States has started operation of a repository for transuranic waste.
Which problems is geological isolation intended to solve? For which is it a unique solution? Perhaps it is time to re-examine other options. The default option has been to leave the spent fuel in place at a reactor site or the waste at a reprocessing plant. This is an unintended form of monitored surface storage; surface storage is an alternative long advocated by some analysts. To understand some of the arguments for a repository, the “leave-in-place option” or storage in other controlled and maintained facilities with different levels of active safety functions will be examined in this session.
The committee that developed the 1995 NRC report Technical Bases for Yucca Mountain Standards wrote:
“We have not considered whether the development of a permanent repository should proceed at this time… . We were not asked and we did not attempt to address whether a repository is needed in the near future, nor did we compare the risks and benefits of proceeding with a repository now as opposed to those that might be realized by continued reliance on surface storage well into the next century.” (NRC, 1995, p. 21).
The Board on Radioactive Waste Management pointed out in Rethinking High-Level Radioactive Waste Disposal (NRC, 1990) that the process of geologic disposal involved decisions throughout the life of the project, and that those decisions should be made in the context of consideration of the alternatives:
“Judgments of whether enough is known to proceed with placement of waste in a repository will be needed throughout the life of the project. But these judgments should be based on a comparison of available alternatives, rather than a simplistic debate over whether, given current uncertainties, a repository site is ‘safe.’ Even while the detailed, long-term behavior of an underground repository is still being studied, it may be marginally safer to go ahead and store reactor waste there (in a way that permits retrieval if necessary), rather than leaving it at reactors.” (NRC, 1990, p. 5).
What is the time scale for the need for repositories? If plutonium with its very long half-life drives repository design and public concern, perhaps technology can be brought to bear. In particular, the NRC Committee on Separations and Transmutation reported:
“Some of the proposed solutions have focused on separating the hazardous long-lived radioactive radioactive components of the waste and transmuting them by neutron bombardment to form nuclides that would be either stable or radioactive with a much shorter half-life.” (NRC, 1996, p. 1).
It is timely to review this report from today's perspective, since most of the work cited was completed in 1993. One of the technologies that has progressed significantly since that time, at least in interest in many countries, is accelerator transmutation.
Historically, a range of alternative disposal technologies has been examined. These include subseabed emplacement, deep boreholes, island disposal, and space disposal. The international consensus has been that geologic repositories offer the most promising permanent disposal technology. Have there been any important developments in any of these technologies that would warrant reexamination of this consensus?
This session will be organized around presentations of possible alternative means of HLW disposition. Attendees should be prepared to discuss the alternatives, their viability, and how they might alter our present approach to geological disposal.
Issues to be addressed in this session are the following:
- Why is a repository required? Options, including spent fuel storage at reactors and transmutation.
- Might a repository become a mine for weapons material, or for expensive materials used in the engineered barriers?
- Advantages and disadvantages for international sites, including questions of institutional monitoring and controls, safeguards, and impacts on a country trying to develop its own site if an international site will become available.
- From an international perspective, are there any consistent requirements for an acceptable repository?
Session 7: Making Progress through International Cooperation
International cooperation toward implementing the geological option has two dimensions. Firstly, there are international organizations that are charged with maintaining responsible oversight of peaceful uses of nuclear technology.
Secondly, individual countries themselves participate in bi- or multi-lateral agreements in areas of nuclear technology.
During the past decade, there has been a growing interest in international cooperation for repository siting. Is this because there are superior sites available in non-nuclear power countries, or because a coalition of countries can convince (or make it worthwhile) for another country to host a repository, or for some other reason? One may ask “Why should we go through the difficult process to disposition our own waste if we can wait for others to do it for us?” Do the environmental, ethical, and economic aspects require, or justify, international solutions?
For an international site, some problems are harder to solve, some easier. Who provides institutional control and to what standards? How is funding determined? Should a major goal be to support the continuation or growth of nuclear power or should a requirement for participation be a timetable for shutting down nuclear power (e.g., Sweden, Germany). Do proliferation concerns exclude some international locations or arrangements? For how long can institutional controls be relied upon for an international site?
International organizations such as the IAEA and NEA have sponsored many projects in the area of geological disposal, both aimed at the technical community and at presenting consensus opinions to enhance public acceptance (NEA, 1991, 1995, 1999).
This session will be organized around presentations by representatives of international organizations and discussions of the role of international cooperation. Presentations are planned on the work of the IAEA and the NEA, with opportunities given to examine the value of specific past projects and to suggest future needs. The role of these organizations, and others such as the EU, in assisting countries with and without nuclear power programs will be discussed. International work on seabed disposal will be described and the technical merits and political problems debated. On the subject of international repositories, the intention is not only to present past and present proposals, but also to examine the technical, ethical, economic and political issues involved. Contributions to the debate will be solicited also from national programs that perceive the concept or the timing of international disposal schemes to be problematic.
Issues to be addressed in this session are the following:
- Exchange of information. Can this be used to avoid duplicating errors, to reduce expenditures, etc.? Has it been so used?
- Collaborative study projects. This includes international code comparisons, like Intraval, Decovalex, and Geoval.
- Collaborative experimental projects (e.g., analog studies, URL programs). Which are the biggest successes? In which areas could more be done?
- Value of international organizations. Do organizations such as the IAEA, NEA, and the EU provide a useful service to member countries? Is the answer the same for major nuclear countries and small nations?
- Coherent policies or regulations. Are they desirable? Feasible?
- Public communication and acceptance. Can collaboration in this field be as useful as in technical areas and what can be learned across national cultures?
- Exchanges of wastes. How much has taken place? What are equivalence principles?
- International repositories. Can they succeed? Which schemes are out there? What are the effects on national programs? What are safeguards benefits?
This discussion paper is intended as an introductory overview and preview for the attendees at the workshop. It is intended as a vehicle for beginning a dialogue among the workshop participants. Much has happened in the past decade regarding the development of geological HLW repositories, and it seems an excellent time for a revisiting and reformulation of the issues by the technical community as an input to the decision process for the national programs and for international cooperative efforts. The authors of this discussion paper look forward to interaction with the workshop participants. We hope that out of this dialogue will emerge a useful set of findings, conclusions, and recommendations for the subsequent National Academies' report that the Workshop Steering Committee is committed to produce.