Full-scale demonstration of sealing technique in geological disposal

Toida, Masaru*; Shiogama, Yukihiro*; Masumoto, Kazuhiko*; Suyama, Yasuhiro*; Abe, Yasunori*; Furuichi, Mitsuaki*

For the geological disposal of high level radioactive wastes, after placement of the wastes, it is necessary to close off (to be called sealing hereafter) the udergroud potential passages (disposal pits, disposal tunnels, main and connectimg tunnels and access tunnels) with an effective combination of engineered barriers such as buffers, backfilling materials, plugs alld grout. It is necessary to ensure the long-term durability to isolate disposed wastes in the system. The results of the research works this year are as follows; (1)It could be estimated in the tunnel sealing experiments at URL site that seepage, swelling pressure and tracer concentration in the plug were changed with increase of pressure. (2)The transport properties around the plug could be evaluated based on a comparison between the results of tracer test and numerical analysis.