Effects of interaction between molten zircaloy and irradiated MOX fuel on the fission product release behavior

核分裂生成物の放出挙動におよぼす溶融ジルカロイと照射済MOX燃料の相互作用の影響

田中 康介  ; 三輪 周平  ; 佐藤 勇; 廣沢 孝志  ; 関根 伸一; 逢坂 正彦  ; 大林 弘 ; 小山 真一  

Tanaka, Kosuke; Miwa, Shuhei; Sato, Isamu; Hirosawa, Takashi; Sekine, Shinichi; Osaka, Masahiko; Obayashi, Hiroshi; Koyama, Shinichi

シビアアクシデント進展解析コードの高度化を目的として、化学形及び燃料と被覆管、制御棒等との高温化学反応に着目した破損燃料からの核分裂生成物及びアクチニドの放出挙動評価のための研究が開始された。本研究の一環として、核分裂生成物の放出挙動におよぼす燃料と被覆管との高温化学反応の影響を評価することを目的として、溶融被覆管と照射済MOX燃料が反応する体系での核分裂生成物の放出試験を実施した。

As a first step for obtaining experimental data on the effects of high-temperature chemical interaction on fission product (FP) release behavior, we focused on the dissolution of irradiated uranium plutonium mixed oxide (MOX) fuel by molten zircaloy (Zry), and carried out a heating test under the reducing atmosphere. Pieces of an irradiated MOX fuel pellet and cladding were subjected to the heating test at 2373 K for 5 min. The fractional release rate of cesium (specifically Cs) was monitored during the test and its release behavior was evaluated. The observation of microstructures and measurements of elemental distribution in the heated specimen were also performed. We demonstrated experimentally that the fuel dissolution by molten Zry accelerated the release of Cs from the fuel pellets.