ANALYSIS OF A TOTAL FLOW BLOCKAGE OF A FUEL ASSEMBLY IN A TYPICAL MTR RESEARCH REACTOR BY RELAP5/MOD3.3

摘要

The main aim of the following study is to perform a safety analysis of the IAEA 10 MW MTR Pool Type Research Reactor. The reactor is core cooled and moderated by downward forced circulation of light water. The transient herein considered is the related to partial and total obstruction of a single Fuel Assembly (FA) cooling channel. Such event constitutes a severe accident for this type of reactor since it may lead to local dryout and eventually to loss of the FA integrity. Two cases are analysed to emphasize the severity of the accident. The first one is a partial blockage of a single FA considering four different obstruction levels: 50%, 75%, 85% and 95% of nominal flow area. The second one is an extreme scenario consisting of total blockage of the same FA. This study constitutes the first step of a larger work which consists in performing a 3D simulation using the Best Estimate coupled code technique. However, as a first approach the instantaneous reactor power is derived through the point kinetic calculation.