再処理工程におけるKrガス放出特性の調査

Investigation of release characteristics of Kr gas arising in the reprocessing process

大谷 武久; 鈴木 一之 ; 畠 勝郎; 菊池 英樹; 中村 大司; 佐本 寛孝 ; 田中 志好

Otani, Takehisa; Suzuki, Kazuyuki; Hata, Katsuro; Kikuchi, Hideki; Nakamura, Daishi; Samoto, Hirotaka; Tanaka, Yukiyoshi

東海再処理工場(TRP)では、再処理オフガス中の主要核種の挙動調査の一環として、Krガス放出特性に関する調査を実施している。Krガスは、せん断,溶解過程で全量がオフガス系へ移行し、燃料溶解の進行を確認する指標となる。TRPでは、これまでにLWR燃料(PWR,BWR)に加え、ATR燃料(UO,MOX)の4種の使用済燃料の処理実績を有する。これらの処理実績から運転管理の指標となるKrガスの放出特性に関して、燃焼度,燃料種別の影響を把握する目的で、せん断,溶解過程におけるKrガスの放出と運転との関係,SOG系,DOG系へのKr移行割合等を調査した。今回は、新たに取得したATR-UO, ATR-MOX燃料に関する調査結果をLWR燃料との比較を含め報告する。

The investigation of the behavior of krypton gas arising due to reprocessing of spent fuels has been performed at TRP. The whole amount of Kr gas transfers to the off-gas system through shearing and dissolution process, so it is applicable as an indicator to determine the progress of fuel dissolution. It is thought that the behavior of gaseous fission product, including Kr, in the spent fuels depends on burn-up and the type of spent fuels. In the reprocessing process, these deference are reflected to the migration rate of krypton gas between shearing off-gas system (SOG) and dissolver off-gas system (DOG). At TRP, four types of spent fuels (LWR; PWR, BWR and ATR; UO, MOX) were treated and examined about their release characteristics of krypton gas in order to understand the effect on burn-up and type of spent fuels. In this report, the results concerning the ATR-UO fuel and ATR-MOX fuel are discussed compared with the results of LWR fuel.