Results of the trial of lead test assemblies in WWR-K reactor

Abstract

The urgency of the discussed issue is caused by the need to solve the issue of the possibility of converting cores of the research reactors to low-enriched uranium fuel. The main aim of the study is to carry out life tests of lead test assemblies with low-enriched fuel, experimental and calculation study of neutron-physical and energy parameters of a nuclear research reactor WWR-K when its core is loaded by the lead test assemblies. The methods used in the study: in-pile measurements, numerical simulation of neutron-physical processes in the reactor facilities, numerical experiments in support of in-pile tests, controlled comparative analysis of process parameters and the results of numerical experiments. The results: The authors have carried out life tests with lead test assemblies, defined the changes in technological parameters of a nuclear research reactor WWR-K due to the core conversion to low-enriched uranium fuel, confirmed the suitability of the new design of fuel assemblies for application in the WWR-K. During the testing period the optimization of fuel replacement in the core and completion of a lateral beryllium reflector is performed. It allowed receiving almost linear dependence of burning out in lead test assemblies from time and reducing considerably test duration. The tests were accompanied by control of neutrons flux level in irradiating device, of the lead test assemblies' power, of the reactor power and of coolant radioactivity level. The authors calculated uranium-235 burning out in experimental and regular assemblies of the core using three-dimensional MCU-REA code. The tests of the experimental assemblies went on from 357 to 480 days. During this time uranium-235 burning out reached from 49,7 to 60,3 %.

Keywords

• nuclear reactor
• lead test assemblies
• test
• burn-up
• life-time