Implementing optimisation in post-accident situation; Some lessons from Fukushima

原子力事故後の状況における最適化の実施; 福島第一原子力発電所事故の教訓に基づく考察

高原 省五  ; Crouail, P.*; Schneider, T.*

Takahara, Shogo; Crouail, P.*; Schneider, T.*

Reference level is applied to decision making for protection of the public taking into account the prevailing circumstances of the exposures under consideration. In post accident situation, as exposure conditions and radioactivity distributions change momentarily, it may be appropriate to update the reference level in a timely manner. However, before the Fukushima Daiichi Nuclear Power Plant accident, insights had been insufficient for implementing the update and the choice of reference level in post accident situation. In this study, the authors reviewed the data on evolution of the reference level and other numerical criteria which were used for making decisions on protective actions after the Fukushima accident, and also analyzed the data to get insights on confusions which were caused by the use of the reference levels. In addition, based on these insights, we made considerations about how to choose the reference level, and how to update appropriately in a timely manner.