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Nakata, Hisakazu; Takao, Hajime*; Chijimatsu, Masakazu*; Noma, Yasutaka*; Amazawa, Hiroya; Sakai, Akihiro
JAEA-Technology 2018-014, 43 Pages, 2019/03
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.
Yamazaki, Kazutoshi*; Takao, Hajime*; Kikuchi, Takahiro*; Kuriki, Yoshiro*; Kobayashi, Masato*; Kawakubo, Masahiro*; Shirase, Mitsuyasu*; Iwata, Yumiko*; Tochigi, Yoshikatsu*; Nakayama, Gen*; et al.
no journal, ,
Among factors affecting the corrosion behavior of carbon steel overpack, in order to consider materials (size) and realistic environmental factors which are difficult to reproduce in the laboratory scale test, engineering scale tests in the underground environment were carried out. A mock-up test of the same scale was also carried out on the ground with the aim of controlling and evaluating factors that govern the corrosion phenomenon. As a result of the test for about 3 years, there was no big difference between the average corrosion amount and the maximum corrosion amount of the simulated overpack base metal and the welded part. On the other hand, unlike the laboratory scale test, localization of corrosion due to the adhesion between the buffer material and the simulated overpack was also confirmed during the initial transient period.