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Sawaguchi, Takuma; Takai, Shizuka; Sasagawa, Tsuyoshi; Uchikoshi, Emiko*; Shima, Yosuke*; Takeda, Seiji
MRS Advances (Internet), 8(6), p.243 - 249, 2023/06
In the intermediate depth disposal of relatively high-level radioactive waste, a method to confirm whether the borehole for monitoring is properly sealed should be developed in advance. In this study, groundwater flow analyses were performed for the hydrogeological structures with backfilled boreholes, assuming sedimentary rock area, to understand what backfill design conditions could prevent significant water pathways in the borehole, and to identify the confirmation points of borehole sealing. The results indicated the conditions to prevent water pathways in the borehole and BDZ (Borehole Disturbed Zone), such as designing the permeability of bentonite material less than or equal to that of the host rock, and grouting BDZ.
Nishihara, Kenji; Makino, Hitoshi; Koo, Shigeru*
no journal, ,
In the ImPACT project, transmutation technology of long-lived fission products (LLFPs) is being developed in addition to minor actinides (MAs) transmutation studied in other programs. If MAs, LLFPs, and heat-generating fission products (FPs), which are Sr-90 and Cs-137, are removed from high-level waste (HLW), drastic benefit is anticipated on the disposal of HLW. In the present study, we tried to estimate two impacts through transport analysis of radionuclide: (1) disposal of the waste after transmutation in the deep underground repository designed for the conventional HLW, and (2) disposal of the waste after transmutation in the intermediate depth disposal designed for the low level radioactive wastes such as hull and end-pieces of the spent fuel assembly. As the result, the reduction of public dose in analysis (1) was observed, and the dose was enough small in analysis (2).
