The glass solidified body reprocessed by the high level nuclear waste disposal in the process of nuclear fuel recycle was the final design condition to construct the underground disposal tunnel under the over 300m depth in Japan. The design methodology and construction technique of underground facilities had been discussed.
However, there has been 17,000 tons of spent nuclear fuel rods kept by the nuclear power plants at poresent. It is necessary to develop the research of the construction method of direct disposal of the spent nuclear fuel rod. In the direct waste disposal facilities, it is assumed to become tunnel section bigger because of workability of construction and operation and closing when consider with underground disposal facilities. Also, the dynamic influence of tunnel invert may be bigger when the waste transport and movement system operated because the weight of spent nuclear fuel rod is bigger than the glass solidified body.
Therefore, this study is performed about a dynamic stability of direct waste disposal facilities, during tunnel excavation, the influence of the ground specialty during excavation and the influence of the load from transport and movement system to tunnel invert. This study applied 2D and 3D numerical analysis.
The process of deep geological disposal of high-level nuclear radioactive waste reproducted by nuclear power plant is main disposal method in Japan. According to the report titled "The second progress report on research and development for the geological disposal of High Level Waste in Japan", a basic idea of geological disposal is called "multiple barrier system". In this system, waste liquid generated in the process of nuclear fuel recycle is fixed as the vitrification. The vitrified solid is covered with isolation material in the pit of disposal tunnel located deep underground. The geological disposal facility consists of vertical shafts, disposal tunnel and disposal pits. The design of this facility needs to consider the economic efficiency and the workability at each stage of operation on construction, operation and closure. In the design of a disposal tunnel where waste is transported and stored, there are three factors of design mechanical stability, workability of construction, operation, backfilling and economy. Then, the optimum sectional shape is proposed for the tunnel of the geological disposal facility.