Prediction of the drying behavior of debris in Fukushima Daiichi Nuclear Power Station for dry storage

乾式保管に向けた福島第一原子力発電所のデブリの乾燥挙動の予測

仲吉 彬  ; 鈴木 誠矢 ; 岡村 信生 ; 渡部 雅之; 小泉 健治 

Nakayoshi, Akira; Suzuki, Seiya; Okamura, Nobuo; Watanabe, Masayuki; Koizumi, Kenji

Treatment policies for debris from Fukushima Daiichi Nuclear Power Station is not decided, however, any policies may include medium and long term storages of debris. Dry storages may be desirable in terms of costs and handlings, but it is necessary to assess generating hydrogen during storages due to radiolysis of accompanied water with debris before debris storages. AlO, SiO, ZrO, UO and cement paste pellets as simulated debris were prepared, which have various porosities and pore size distribution. Weight changes of wet samples were measured at various drying temperatures (100, 200, 300, and 1000C) using a Thermogravimetry, under helium gas flow (50 cc/min) or reduced pressure conditions (reducing pressure rate: 200 Pa in 30 min). From the results, drying curves were evaluated. There is a possibility that cold ceramics can predict drying behaviors of ceramics debris as a simulation because all of the ceramics pellets generally showed similar drying characteristics in this experiment. The cement paste pellets indicated different behavior compared to the ceramics pellets, and the drying time of the cement paste pellets was longer even in 1000C conditions. It is necessary to decide the standard level of the dry state for a drying MCCI products which may be accompanied by concrete.