IQS and FIM Solutions of Space - Time Dynamic Benchmark Problems Simulating Accidents in Two-Phase Flow Cooled One-Dimensional Reactors

Abstract

Simultaneous solutions of coupled neutronic and thermohydraulic equations applied to two-phase flow cooled, one-directional reactor benchmark problems have been obtained by using two computer programs, one based on the improved quasistatic method, the other on the finite integration method. Two energy groups and six delayed neutron groups have been used in the neutronic equations. Different heat transfer coefficients characterize the liquid cooled and the two-phase cooled thermohydraulic regions separated by a moving boundary. Temperature and void reactivity feedbacks have been included. Space-time perturbations simulate loss of regulation. Regional power, flux shapes, and temperature and void fraction distributions have been calculated. The two computer program give very similar results, which validate both methods.