Waste acceptance criteria for waste package destined for trench-type disposal facilities for waste generated from Research, Industrial and Medical Facilities; No harmful void

Nakata, Hisakazu ; Takao, Hajime*; Chijimatsu, Masakazu*; Noma, Yasutaka*; Amazawa, Hiroya; Sakai, Akihiro 

Japan Atomic Energy Agency plans to install disposal facilities for radioactive waste arising from research institutes. One relevant technical standard by the safety regulation is that the disposal facility shall be performance so as not to be left with harmful voids after backfilling with soil. Additionally no harmful void needs to exist in the waste packed in metal containers. The harmful void is supposed to result in the collapse of the disposal facility after structural materials of the container deteriorate and then become a state that can not retain the structure on its own. That leads to have an adverse impact on the facility such that the shape of cover soil deforms the way in which stagnant water is likely to occure. For which reason, a waste acceptance criteria relating to the quantity of voidage in a waste package needs to be defined quantitatively, which is preliminary less than 20% in a volum ratio based on this study.