Development of a coupled PARCS/RELAP5 model of the Ringhals-3 PWR

This paper deals with the development of a coupled PARCS/RELAP5 model of the Swedish Ringhals-3 pressurized water reactor. The stand-alone PARCS and RELAP5 models are first presented. On the neutronic side, the dependence of the material constants on history effects, burnup, and instantaneous conditions is accounted for, and the full heterogeneity of the core is thus taken into account. The reflectors are also explicitly represented. On the thermal-hydraulic side, each of the 157 fuel assemblies is modeled. The model is furthermore able to handle possible asymmetrical conditions of the flow field between the loops. The coupling between the two codes is then reported, with emphasis on the mapping between the hydrodynamic/heat structures and the neutronic nodes. Preliminary coupling tests for steady-state calculations were successfully performed and comparisons against plant measured data demonstrate a very good agreement of the model with the measurements. The coupled model will be later on used for analyzing the consequences of the power uprate planned for this reactor, via the simulation of a few limiting transients