Validation of WIMS-AECL/RFSP Analysis of Moderator and Heat-Transport Temperator Reactivity Effects in Darlington Unit 2 During Commissioning

Abstract

The purpose of this analysis is to validate the calculation of reactivity effects associated with moderator temperature and heat-transport system (HTS) temperature variations relative to zone level changes in Unit 2 of the Darlington Nuclear Generating Station (DNGS). These reactivity effects were measured during Phase-B commissioning, and are here compared with calculations using the Reactor Fuelling Simulation Program (RFSP) and WIMS-AECL. This study is part of the project aimed at validating RFSP with WIMS-AECL-based data for CANDU reactor analysis. The temperature coefficients under consideration here have no safety significance, because of their small absolute magnitude, and because of the limited expected range of variation of either the coolant temperature or the moderator temperature during most accident conditions. The internal acceptance criterion at the station for the difference in coefficient value between prediction and measurement is 25%; thus the WIMS-AECL/RFSP results are acceptable.