Critical experiments on Iron-Loaded Core at the modified STACY

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

In order to understand the criticality characteristics of the fuel debris generated by the accident at the Fukushima Daiichi Nuclear Power Plant, it is essential to obtain critical experiment data that includes reactor structural materials such as iron and concrete that are considered to be contained in the fuel debris. To gather such critical experiment data, JAEA had conducted a major modification of the critical assembly STACY, and the modified STACY achieved first criticality in March 2024. In this presentation, we will discuss the experiments conducted in the modified STACY, with a particular focus on iron, which is considered to have a significant impact on criticality safety due to its strong neutron absorption effect.