Modelization of Corium from Fukushima-Daichi Powerplant Using PANTHERE Codes

This study is about radioprotection in the case of the Fukushima-Daiichi Nuclear Power Plant accident that happened in 2011. It focusses on the retrieval of the corium in the core of the reactor. OAKRIDGE created a project that also responds to the international call of IRID (International Research Institute for Nuclear Decommissioning). The concept is based on the rapid pneumatic transfer of closed capsules that contain debris of corium. This project is now focused on the utilization of developed computing software that can be experimented on the dose rate of corium based on previous works. This software is called PANTHERE. With PANTHERE, we can propose multiple methods of online attenuation calculation with the dose rate (DED H*(10) in mSv/h, KERMA in the air in mGy/h,flux-dose in particles/cm2/s or energy fluencies in MeV/cm2/s). With PANTHERE, we modelized the corium and ran a corium retrieval simulation based on a point of observation to calculate the dose rate of corium inside the capsule inside the BWR Fukushima reactor. After that, we also modelized the trajectory of the capsule from when it is inside the RPV (Reactor Pressure Vessel) until when it is inside the storage system in SFP (Spent Fuel Pool). The highest dose rate given by the calculation was $3.24\times 10^{-3}$ rnSv/h.