Analysis of the Long Term Interaction Between Molten Core And Dry Concrete At Fukushima Daiichi Unit 1

The latest investigations of Fukushima Daiichi Uni 1 have demonstrated that corium attack to the pedestal walls and pedestal floor has occurred in Fukushima Daiichi Unit 1 to a certain extent. The results of past analytical benchmarks such as the OECD/NEA BSAF project were in agreement with this finding. However, the latest investigation do not show evidence of unlimited MCCI which is one of the main discrepancies from the BSAF project. More recently a MCCI benchmark as been launched in the context of the OECD/NEA ARC-F project. In the benchmark, common geometry, boundary and initial conditions have been selected among all the participants. The results show an improved agreement among different codes for what concerns overall erosion, corium temperature and hydrogen generation, however the unlimited erosion is still predicted by all codes. It is considered that this behavior might be the result of improper boundary conditions or modeling (e.g. interfacial temperature and effective heat transfer coefficients) In this paper, a summary of the overall results and a discussion of modeling and boundary conditions is done to disclose the results of the activity and the future steps to be taken in the OECD/NEA FACE project.