HLW Disposal Program in Japan
Japan's research and development program for HLW disposal started in 1976 (Fig. 24.1). The first progress report was released in 1992 by PNC (Power Reactor and Nuclear Fuel Development Corporation). PNC was reorganized as JNC (Japan Nuclear Fuel Cycle Development Institute) in 1998, then merged with JAERI (Japan Atomic Energy Research Institute) to be JAEA (Japan Atomic Energy Agency) in 2005).
In 1999, JNC released the second progress report, and more importantly, in 2000
the Specified Radioactive Waste Final Disposal Act (Final Disposal Act, hereinafter) was legislated.
The process for the legislation of the Final Disposal Act is shown in Fig. 24.2. As shown here, the Special Panel on Disposal of High-Level Radioactive Waste formed under the Japan Atomic Energy Commission (AEC) played an important
24 Issues of HLW Disposal in Japan 281
Fig. 24.1 Evolution of high-level radioactive waste (HLW) disposal in Japan (Modified from ANRE/METI and JAEA )
Fig. 24.2 Legislation of specific radioactive waste final disposal act (June 2000) (Private communication from NUMO on November 13, 2013)
282 K. Yamaji
Fig. 24.3 Organizations and roles in the HLW disposal program in Japan (CRIEPI Central Research Institute of Electric Power Industry, URL Underground Research Laboratory) (From NUMO )
role along with the second progress report of JNC to set the contents of the Final Disposal Act.
Under the act, geological disposal is chosen for HLW disposal, and NUMO (Nuclear Waste Management Organization of Japan) was established for implementing the final disposal of HLW.
Organizational structure and the roles of related organizations set by the Final Disposal Act are shown in Fig. 24.3. As shown here, METI (Ministry of Economy, Trade and Industry) decides a basic policy and supervises all related activities. Owners of nuclear power plants provide a waste fund, which is collected from the electricity tariff, and the fund management is done by RWMC (Radioactive Waste Management, Funding and Research Center), while implementation of HLW disposal including site selection is borne by NUMO.
According to the current final disposal plan (Fig. 24.1), site of the final HLW disposal is to be selected in the 2020s and the final disposal will start in the middle of 2030s.
The Final Disposal Act was amended in 2007 to include TRU (trans-uranium) waste as a second type of specified waste (first type is HLW canisters, vitrified waste) because TRU waste is also to be disposed by geological disposal technology. Although open solicitation for volunteer municipalities was employed for site selection, there has been no case except for a failed attempt by Toyo Town in Kochi Prefecture in 2007. Taking into account the failed attempt, METI added another scheme by the government to invite municipalities. The difficult situation, however, has continued, and after the Fukushima accident, the difficulties are increasing greatly.
Concept of Geological Disposal and Risk
Geological disposal is a globally common technology of HLW disposal for either vitrified HLW canisters or the spent nuclear fuel itself. Figure 24.4 shows the HLW disposal scheme employed in Japan, which incorporates the multi-barrier concept in the scheme. The first barrier is the vitrified HLW canister itself; the solubility of vitrified waste is very low and it is contained in a canister made of stainless steel. The second barrier is a thick package made of carbon steel, the third is a buffer made of bentonite and sand, and last, the multiply packaged waste is placed in stable host rock located deep underground.
Difficulty in securing the safety of HLW disposal comes from the requirement
that risks associated with HLW disposal must be maintained below an acceptable level for a very long period, beyond 10,000 years. Whatever technical measures are taken, risks would remain. This is basically the same problem as the case of safety measures for severe accidents of nuclear power plants. The safety issue of HLW disposal, however, is more difficult because of the very long time period in which human intervention for maintaining safety cannot be expected.