Results of the verification period 1985–1990 of the German-Swiss high converting reactor PWR-C1

Abstract A high converting reactor (HCR), the PWR-C1, is described, which was developed on the basis of the commercially proven pressurized water reactor (PWR) technology by Siemens AG Power Generation Group in cooperation with the Karlsruhe Nuclear Research Center (KfK), the Paul Scherrer Institute at Wurenlingen (PSI) and the Technical University of Braunschweig (TUBS). The essential features of the concept in comparison to the conventional Konvoi-reactor core are a triangular fuel pin lattice with a tighter pitch and a higher density of control assemblies. The main goal was a better fuel utilization, which was achieved mainly by hardening of the neutron energy spectrum. Because of the lower moderation ratio due to the tighter pitch, the neutron spectrum is shifted into the epithermal energy range, whereby the conversion rate is augmented, from 0.35 for a Konvoi-reactor core to 0.75 for a PWR-C1. The PWR-C1 concept is the result of extensive investigations of tight and very tight fuel pin lattices, concerning neutron physics, thermohydraulics, emergency cooling and mechanical design. For establishment and improvement of codes several experiments were performed in the mentioned areas; (1) the PROTEUS experiments for physics investigations at PSI Wurenlingcon, (2) the CHF experiments at Siemens Karlstein and KfK, and (3) the NEPTUN and FLORESTAN flooding experiments at PSI and KfK. All these experiments led to the validation or improvement of codes and/or the verification of calculational methods. Also methods used in conventional design activities could be improved. The investigations in mechanical design too led to results, which partly are of great use for conventional design work.