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Riyana, E. S.; 坂本 雅洋; 松村 太伊知; 寺島 顕一; 奥村 啓介; 神野 郁夫
no journal, ,
The activity ratio of short half-life noble gas fission products, 
Kr to 
Xe (A(Kr/Xe)), has close relationship with the criticality (
) in the primary containment vessel (PCV) or fuel debris canister, in which fuel debris are accumulated. In this paper, we investigated the time-dependence of the A(Kr/Xe) when the k
changes according to an incident such as the change of geometry in the PCV. Our calculation shows a slow change of the A(Kr/Xe) value with the maximum or minimum values before settling in a new stable value after several hours from the change. The applicability and the suitability of the A(Kr/Xe) time-dependent measurement is discussed for the monitoring of the in PCV.
Xe, Kr) emitted by fuel debris for criticality estimationRiyana, E. S.; 坂本 雅洋; 松村 太伊知; 寺島 顕一; 奥村 啓介; 神野 郁夫
no journal, ,
Our previous study showed a linear relationship between the activity ratio of Kr to Xe and the effective multiplication factor, , in a primary containment vessel (PCV) and in a fuel debris canister. The accuracy of the activity ratio, which closely related to the accuracy of predicted , is estimated based on an existing gamma ray energy spectrum. Practical measurement method for the gamma ray from nuclides in the PCV and the fuel debris canister gas is proposed.