[2G10-14] Fuel Debris

[2G14] Correlation between the canister’s criticality and activity ratio of short-half-life noble-gas fission products under various fuel debris material compositions

*Eka Sapta Riyana¹, Masahiro Sakamoto¹, Taichi Matsumura¹, Kenichi Terashima¹, Keisuke Okumura¹ (1. JAEA)

Keywords:Fuel Debris Canister, Subcritical System, Non-destructive Assay (NDA), Monte Carlo Calculation, Short Half-life Fission Products

We investigated the possibility of estimating the effective neutron multiplication factor (k_eff) of the fuel-debris canister using remote gas-radioactivity measurement. The fuel-debris compositions inside a canister may vary and depend on the fuel-debris location inside the primary containment vessel and fuel-debris removal process. Our calculation result demonstrates the correlation between k_eff and the activity ratio of ⁸⁸Kr-to-¹³⁵Xe for the various fuel debris material conditions such as fuel burn-up degree before the accident of the Fukushima Daichi Nuclear Power Stations (1F), canister filling rate, water fraction, and fuel-debris type.