[2E15-20] SMR, Accident Evaluation Models & Power Distribution Estimation

[2E19] Advancement of the spent fuel pool temperature evaluation in Onagawa NPPs

*Yuhei Hamada¹, Iichi Kimura¹, Hiroaki Seino¹, Hiroaki Kikkawa¹, Tomoya Shindo¹, Kenta Matsuura¹, Masashi Shimanaka¹, Toshiaki Wakabayashi¹ (1. Tohoku-EPCO)

Keywords:Spent fuel pool, Decay heat, Heat dissipation, Heat balance, Temperature evaluation

Conventionally, the spent fuel pool temperature has been predicted by conservative evaluation model which the pool temperature rises linearly.
By contrast, it was confirmed that the rate of temperature increase gradually decreased when the cooling of the pool was temporarily stopped due to maintenances.
Therefore, for the purpose of improving the evaluation model, we constructed a realistic evaluation model considering the heat balance, and collected various data at Onagawa Unit 1 and 3 without pool cooling.
As a result, the pool temperature converged sufficiently below the limit value specified in the safety regulations in the fuel storage state of prolonged shutdown. In addition, the evaluation results were in good agreement with the actual temperature.