Gamma detector response simulation inside the pedestal of Fukushima Daiichi Nuclear Power Station

Prediction of the fuel debris location and distribution inside the primary containment vessel (PCV) of the Fukushima Daiichi Nuclear Power Station is important to decide further decommissioning step and strategy. The radiation measurements in the past internal investigations have not yet provided enough information to predict fuel debris location and its distribution inside PCV. To support further measurement efforts, we simulate the detector response inside the PCV and finding possible gamma radiation unique to fuel debris. The calculation result could provide useful information for future gamma detector developments. (author)