A Study on Multilateral Management Options for Spent Nuclear Fuels in Northeast Asia Using Multi-criteria Evaluation

Abstract

Civilian nuclear energy is still considered as a reasonable alternative to cope with the depletions of fossil fuels and the increase in greenhouse gas emissions. Many Asian countries have national plans to maintain or to increase their dependence on nuclear power despite the growing safety concern from Fukushima accident. Operations of nuclear power plant inevitably lead to the discharge of spent nuclear fuels (SNFs) which present serious challenges in safe disposal. So far only two different strategies are industrially used for managing spent fuels around world. Either the SNF is reprocessed to recover usable materials with some reduction of waste volume or it is directly disposed in a deep geological repository. Considering the risks of nuclear safety, security or nonproliferation relating to SNFs, SNF management is considered as national challenge in Northeast Asia where population densities are very high. Especially in the cases of Taiwan, Japan and ROK, it is difficult to employ two industrial strategies. The direct disposal option is not suitable for regions with high population density and/or with unstable geological conditions. Commercial reprocessing is restricted from both economy and safeguards aspects. With significant delay in finding solutions, The Republic of China (Taiwan) is forced to shut down nuclear power plants with the saturation of on-site storage. In the case of ROK, it is also headed towards similar course with the SNF saturation in 2024, and Japan has faced the same difficulty in managing SNFs. In this context, there has been several exploration for multilateral cooperation to the spent nuclear fuel management since the early time of peaceful use of nuclear energy. Now, multilateral approach suggested in 2000s has proven to be practical in case of the front end of fuel cycle as demonstrated by International Fuel Bank or International Uranium Enrichment Center while such effort for the backend cycle is yet to be developed. In past studies on SNF management options, some have examined unilateral and bilateral solutions to cope with the saturation problem with domestic perspective, whereas the other studies in broader perspectives have considered various solutions including multilateral options. In their evaluation, a set of criteria employed in earlier studies covered various factors as a whole, but without considering multilateral features in criteria. Therefore this thesis is designed to complement past studies with broadened criteria to evaluate to multilateral options for SNF management. The primary goal of this study is to set at examining and recommending feasible multilateral options for spent fuel applicable to the Northeast Asian region where high population density and low trust in Governments have created intense public concern. To achieve the goal of this study, the following research questions were determined:

1) What are the possible multilateral options for SNF management in Northeast Asia, and then how can these be evaluated? 2) Which multilateral option is preferred, and what criteria should be considered as significant? 3) What are the strategic plans for introducing multilateral options to Northeast Asia and the ROK?

Available options are examined by the process of elimination in order to reduce to a few choices suitable for Northeast Asian countries for multinational approach. To evaluate relative merits, a set of qualitative and quantitative criteria related to spent nuclear fuel management and its multilateralization have been derived., Finally the analytic hierarchy process (AHP) method has been employed as the best one for the multi-criteria decision making approach after reviewing available methods. The AHP method was applied using various evaluation criterion the SNF management or the innovative nuclear fuel cycle system. Moreover, it includes the multilateral characteristics based on the definition and basic principles of Multilateralism. Resultant seven top-tier criteria are selected to include the area of technology, nuclear safety, security and nonproliferation, environmental impact, economics, domestic acceptance, and multilateral acceptance. For more detailed assessment, a total of twenty second-tier criteria are defined as the in-depth evaluation basis. For acceptable options for SNF management in Northeast Asia, three multilateral options are selected as follows. First, a regional SNF repository established for disposing of SNFs in a joint repository facility which satisfies both geological conditions on the long-term safety and security requirements against human intrusion. This option is regarded as one of the most practical solutions since it does not modify original forms of SNF. It also can be featured as that candidate host countries can be not limited to nuclear power countries. Countries in the region regardless of own operating nuclear power plants can host the facility only if there are suitable sites. The second option is the concept of regional reprocessing and storage, which operates commercial reprocessing capacities and safeguards all sensitive nuclear materials within a joint facility. This approach utilizes the multilateral framework for a stable supply of commercial reprocessing services without spreading the sensitive technologies. Furthermore, enhanced security measures and safeguards can be expected by the joint control of sensitive materials produced by reprocessing. High Level Wastes generated at the facility will be bound to the country of origin or to a regional repository. The last, a multilateral partitioning and transmutation (P&T), is an approach based on future scaling-up of lab-proven innovative technologies that can reduce the final disposal burdens of SNF through P&T of high level wastes into intermediate and low level wastes. However, it needs significant amounts of time and money to promote from current stage of research and development (R&D) to commercialization thus a multilateral cooperation can be effective in its progress. Intermediate level waste/low level wastes will be bound to the country of origin considering that many countries already operate such repositories. Based on the selected criteria and possible multilateral options, this thesis establishes a comparative assessment model on suitable option(s) for multilateral SNF management. According to the results of expert survey for assessing practical and professional options of regional SNF repository preferred for SNF management in Northeast Asia. A regional SNF repository option receives the highest preference in most criteria. It is worthwhile to note that this option is similar with the ongoing proposal by Australian state government. The multilateral P&T is the next favorably evaluated option particularly on public acceptance, political support, ethical consideration and multilateral identity. The regional reprocessing and storage has relatively high acceptance only in the technology criteria. The main difference between these two recycling options is originated from the fact that the former, multilateral P&T, can eliminate the waste disposal burdens fundamentally. In addition it can also allow cooperation without discriminations in technical aspects because this option is based on innovative technologies requiring further R&D efforts. The most notable point is that the factors considered as important by the expert group are different from general perceptions. Feasibilities in technology and economics would be considered as important factors for deciding a national policy, R&D investment, or long-term plan but this study identifies the importance of other factors such as nuclear safety, security and nonproliferation, public acceptance and intention of hosting in the case of multilateral SNF management. Considering required time and features of multilateral SNF management, it indicates that public acceptance and siting as the requirement for long-term policy should be considered more important than technology and economics in current. If the multilateral management options for SNFs are to be introduced in Northeast Asian region, to manage SNFs, member countries must take proactive measures to enhance the level of regional nuclear safety, security and nonproliferation. In return, the multilateral cooperation on this matter can serve both as a confidence building measure easing the tensions in Northeast Asian region, and as a foundation for continuous collaborations among the regional countries. In case of ROK, if multilateral options are promoted in parallel with the domestic strategy for SNF management, the improvement of public acceptance can be achieved by providing alternatives to current national strategy to widen choices for national SNF management plan. Finally, it is emphasized that the multi-criteria evaluation model established in this thesis should be further verified to actively respond to the changes of policy environments on SNF management.