Pellet-cladding mechanical interaction analysis of heavy water fuel rods under power ramps

Abstract

A numerical simulation is used to analyze the pellet-cladding mechanical interaction (PCMI) of a heavy water research reactor (RR) fuel rods under power ramps. A mechanical simulation that best reproduces the thermomechanical behavior of the pellet-cladding system is a major industrial challenge for engineers because it involves defining operating rules that are not too restrictive but that guarantee safety requirements. The majority of currently existing codes for processing thermomechanical behavior, under irradiation, of the PCMI evolution are designed for light water reactors. This is justified by the fact that most of the world nuclear power reactor park is composed of light water reactors. However, many nuclear reactors use heavy water as coolant, e.g. type CANDU reactors. In addition to the coolant thermodynamics table which is different for the two types of codes, the conditions of use in terms of pressure and temperature in the case of RRs are less severe than those in the case of nuclear power reactors (NPRs). In this study, we used several computer codes namely MCNP5, RODBURN, FEMAXI-6, and an analytical application, developed locally, to simulate the thermomechanical behavior of the Es-Salam RR fuel rods. The fission product cross-section library that was used with the RODBURN code was produced by using the ORIGEN code fed with the neutron flux spectrum of the Es-Salam research reactor. A new approach has been developed for the PCMI analysis of a heavy water reactor by using a code originally developed for light water reactors. Operating limits have been determined when the two tables of thermodynamics of coolants are different.