RELAP5/MOD2 Split Reactor Vessel Model and Steamline Break Analysis

A split reactor vessel model for the RELAP5/MOD2 computer code is developed in an attempt to realize more realistic predictions of asymmetrical transients in a two-loop nuclear power plant. Based on this split reactor model, coolant mixing processes within the reactor vessel are examined. This study evaluates the model improvements in terms of thermal-hydraulic simulations of the reactor core inlet fluid condition and the consequent core behavior. Furthermore, the split reactor vessel model is introduced into an integral RELAP5/MOD2 power plant model, and a steamline break analysis is performed to determine the influence of the boron concentration in the boron injection tank on accident consequences.