NuFuel & MMSNF 2015

First Workshop on Research into Nuclear Fuel in Europe
and Materials Modeling and Simulation for Nuclear Fuels Workshop
Karlsruhe, Germany, November 16th to 18th, 2015

Updated: Tue 08 Dec 2015, 14:27

Poster 6.3: Numerical simulation of the melt relocation behavior in fuel assembly scale structures

Susumu Yamashita, Tokushima Kazuyuki, Masaki Kurata, Hiroyuki Yoshida
  • JAEA

Abstract

We have been developing the numerical simulation method for the melt relocation for severe accidents in a fuel assembly scale. The purpose is to deeply understand each processes of the core melt progression which has not enough accuracy for numerical analyses and is to contribute the improvement of severe accident analysis codes and debris state analysis in the Fukushima accident. For example, in the process of the fuel degradation of the BWR, since the understanding for the reaction process between molten fuel and core support plate might not be enough, we are developing the numerical simulation code with experiments in simplified system. The numerical simulation code is based on a unified, phenomenological, and multiphase thermal-hydraulic simulation models. In this paper, the developed code was applied to numerical simulations of the melt behavior of the complicated fuel support structures, e.g., fuel support piece, control rod and channel box, and also applied to the melt relocation experiment as an validation of our code.From the present numerical results, the code stably worked in the complicated structures and showed in good agreement with the results of the experiment. Therefore, it was confirmed that the developed code has potential to accurate understand melt relocation behavior inside an RPV. In the near future, in order to perform the more detail simulation, we will implement the eutectic reaction model to the code and also proceed the experiment analysis.