Characterization and storage of radioactive zeolite waste

Yamagishi, Isao ; Nagaishi, Ryuji ; Kato, Chiaki   ; Morita, Keisuke ; Terada, Atsuhiko  ; Kamiji, Yu; Hino, Ryutaro; Sato, Hiroyuki; Nishihara, Kenji  ; Tsubata, Yasuhiro   ; Tashiro, Shinsuke ; Saito, Ryuichi; Sato, Tomonori  ; Nakano, Junichi; Ji, W.*; Fukushima, Hisashi*; Sato, Seichi*; Denton, M.*

For safe storage of zeolite wastes generated by treatment of radioactive saline water at the Fukushima Daiichi Nuclear Power Station, properties of the Herschelite adsorbent were studied and its adsorption vessel was evaluated for hydrogen production and corrosion. Hydrogen production depends on its water level and dissolved species because hydrogen is oxidized by radicals in water. It is possible to evaluate hydrogen production rate in Herschelite submerged in seawater or pure water by taking into account of the depth effect of the water. The reference vessel of decay heat 504 W with or without residual pure water was evaluated for the hydrogen concentration by thermal hydraulic analysis using obtained fundamental properties. Maximum hydrogen concentration was below the lower explosive limit (4 %). The steady-state corrosion potential of a stainless steel 316L increased with absorbed dose rate but its increase was repressed by the presence of Herschelite. At 750 Gy/h and 60C which were values evaluated at the bottom of the vessel of 504 W, the localized corrosion of SUS316L contacted with Herschelite would not immediately occur under 20,000 ppm of Cl concentration.