As the upper filler concrete material applied in the cavern type radioactive waste disposal facility is poured just over the radioactive waste packages stored in the facility where the environment may be in a high temperature because of the decay heat, it is concerned that the filling efficiency and the hardening character of the filler may be affected by the temperature. As the construction of upper filler material is done under radiation condition, there are some issues as follows; the filler must be constructed by unmanned remote operation, the filler needs to keep a certain thickness to guarantee the shielding capacity, and so on.
In this paper, we have designed the mix proportion of upper filler concrete through filling efficiency experiments simulating high-temperature environment, and have revealed the effect of the temperature on the hardening properties with high-temperature curing tests. Moreover, by doing a full-scale demonstration, we confirmed the feasibility of unmanned construction of upper filler concrete by pumping and movable bucket method.
