Status and plans for critical facility modified-STACY

Araki, Shohei   ; Arakaki, Yu; Maekawa, Tomoyuki; Murakami, Takahiko; Hasegawa, Kenta; Yoshikawa, Tomoki ; Tada, Yuta; Kamikawa, Yutaka; Sumiya, Masato; Seki, Masakazu; Aizawa, Eiju; Ishii, Junichi; Izawa, Kazuhiko ; Shiba, Shigeki*; Iwahashi, Daiki*; Gunji, Satoshi  

In the TEPCO's Fukushima Daiichi Nuclear Power Plant accident, fuel debris was formed by fuel melting and mixing with in-core structures. Although the detailed properties of the fuel debris are still unknown, it is thought to contain materials such as iron and concrete. Then, in order to understand the criticality characteristics of fuel debris, JAEA is conducting a comprehensive numerical analysis assuming the composition of fuel debris containing concrete and iron. However, integral experimental data including these materials are scarce, and the validation of the analytical results has not been fully investigated. Thus, JAEA modified the criticality facility STACY in order to obtain experimental data that will contribute to the validation. This report describes the outline and status of the modified-STACY, and the plan is also presented.