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

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

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.