Safety assessment methodology focused on response characteristics of the disposal system and safety assessment for TRU w
- PDF / 464,097 Bytes
- 8 Pages / 432 x 648 pts Page_size
- 40 Downloads / 185 Views
Safety assessment methodology focused on response characteristics of the disposal system and safety assessment for TRU waste in Japan T. Ohi1, H. Ueda1, H. Hyodo1, T. Chiba2, T. Takase3 and H. Takamura4 Nuclear Waste Management Organization of Japan (NUMO), 1-23, Shiba 4-chome, Minato-ku, Tokyo, 108-0014 Japan 2 JGC Corporation, 2-3-1 Minatomirai, Nishi-ku, Yokohama-shi, Kanagawa, 220-6001 Japan 3 Mitsubishi Materials Corporation, 1-297 Kitabukuro-cho, Omiya-ku, Saitama-shi, Saitama, 3308508 Japan 4 Kajima Corporation, 6-5-30 Akasaka, Minato-ku, Tokyo, 107-8502 Japan
1
ABSTRACT In order to enhance the safety of geological disposal and the reliability of the safety assessment carried out for each stage of the geological disposal project, an assessment methodology focused on a sensitivity analysis and an evaluation of importance, which incorporates “system understanding” and “information feedback” into the existing assessment approach, has been developed in this study. In this paper, the assessment methodology and the assessment results as applied for the transuranic (TRU) waste disposal system in Japan will be described. In the sensitivity analysis, an approximate analytical solution was used in order to understand the response characteristics of the engineered barrier system (EBS). In the importance evaluation, important factors relating to the robustness of system safety were identified based on the response characteristics. Furthermore, important features, events, and processes (FEPs) related to such factors and high-impact scenarios were identified based on the information accumulated through “system understanding” and “information feedback”. Based on this approach, the robustness of the TRU waste disposal system was assessed and measures for improving the robustness were identified. INTRODUCTION In OECD/NEA [1], a safety assessment approach comprising the following factors was presented as a generic approach for assessing the long-term safety of geological disposal. Scenario development /Model development and application /Integrated assessment / Confidence building In past safety assessments [2, 3] of geological disposal in Japan, the above approach has been applied. Scenarios are developed for these assessments and the assessment models, analytical cases and data are selected according to the developed scenarios. A number of calculations based on the deterministic analysis method have also been carried out. In the assessment of the geological disposal of TRU waste, a variety of wastes and phenomena such as cementitious effects have been considered. Many uncertainties are contained in the assessment because the understanding of these phenomena has not always been sufficient. Therefore, in the integrated assessment of TRU waste, a sensitivity analysis [4] has been carried out in order to examine the impact of the large uncertainties contained in the assessment and to complement the deterministic analysis. The geological disposal project is based on a stepwise approach including site selection, construction, o
Data Loading...
