抄録
Among comprehensive collaborative works with CEA, Framatome, JAEA, MHI and MFBR for design and R&D within the framework of French project of Advanced Sodium Technological Reactor for Industrial Demonstration (ASTRID), a core catcher design study has been conducted since 2016. The design strategy of ASTRID for Core Disruptive Accident (CDA) is to achieve in-vessel retention. In this strategy, discharged molten-fuel from the core during CDA could become solidified particle debris by fuel-coolant interaction in the lower sodium plenum, and then the debris could form a bed on a core catcher located at the bottom of the reactor vessel. Coolability evaluations for the debris bed are necessary for the design of the core catcher. The purpose of this study is to evaluate the coolability of the debris bed on the core catcher for the ASTRID design. For this purpose, as a first step, the coolability calculations of the debris beds formed both in short term and later phase have been performed by modeling only the debris bed itself. Thus, details of core catcher design and decay heat removal system are not described in this paper. In all the calculations, coolant temperature around the debris bed is a parameter. The calculation tool is the debris bed module implemented into a one-dimensional plant dynamics code, Super-COPD. The evaluations have shown that the debris beds formed both in short term and later phase are coolable by the design which secures sufficient coolant flow around the core catcher located in the cold pool.
