Heat Transfer in the Rod Bundles and Thermal Analysis of Constor RBMK Cask Under Normal Storage Conditions

Abstract

For demonstrating the safety of the casks intended for spent nuclear fuel transport and storage, the maximum temperature of the nuclear fuel rod cladding must be defined. For the gas filled CONSTOR RBMK metal-concrete cask developed jointly by GNB (Germany) and AOOT NPO CKTI (Russia) for RBMK-1000/1500 assemblies (Russian design) storage and transport the thermal analysis has been carried out for normal and fire accident conditions of operation. This paper is devoted to the description of the method applied to the analysis of heat transfer in the basket with assemblies disposed in the cask cavity. The combined analytical and numerical method for heat transfer calculation in the cask cavity based on a two-zone model of heat transfer inside the assembly has been developed and verified by means of the tests performed with an electrically heated bundle model consisting of 127 rods. One of the main features of the method is the real multi-rod assembly substitution by a homogenous heat-releasing bar with effective heat conductivity enclosed in the heat-conducting casing which models the basket tube.