Coupled neutronics and thermohydraulics calculations with burn-up for HPLWRs

Abstract

The HPLWR (High-Performance Light Water Reactor) is the European version of the SCWR (Supercritical-pressure Water Cooled Reactor) concept, which is one of the Generation IV reactors. In this reactor the primary water enters the core of the HPLWR under supercritical-pressure condition (25 MPa) at a temperature of 280 °C and leaves it at a temperature of up to 510 °C. Due to the significant changes in the physical properties of water at supercritical-pressure the system is susceptible to local temperature, density and power oscillations. This inclination is increased by the pseudocritical transformation of the supercritical-pressure water used as primary coolant. At the Budapest University of Technology a coupled neutronics–thermohydraulics program system has been developed which is capable of determining the steady-state equilibrium parameters and calculating the related power, temperature, etc. distributions for the above-mentioned reactor. The program system can be used to optimize the axial enrichment profile of the fuel rods (e.g. in order to obtain a uniform power distribution). Since the power distribution will change with burn-up, which causes a change in the temperature and density distributions, a coupled neutronics – thermohydraulics – burn-up calculation is required. Therefore, the program system has been extended with the ORIGEN-S burn-up calculator. In the paper the developed program system and its features are presented. Parametric studies for different operating conditions were carried out and the obtained results are discussed.