International Conference on Research Reactors:
Safe Management and Effective Utilization

14-18 November 2011, Rabat, Morocco

Full-core conversion of the WWR-M research reactor in Ukraine with simultaneous replacement of all remaining HEU fuel by fresh LEU fuel requires the new safety analysis of the reactor because of great decrease of the number of fuel assemblies in the core. Because of considerable increase of reactivity due to loading a fuel assembly into the core and reactivity worth of control rods, the following potential accidents are analysed for the new LEU core: incidental falling of a fuel assembly in a cell of the core and spontaneous withdrawal of a control rod group because of malfunction of electronic equipment. To provide the safety of the reactor, some limiting conditions for operation are revised. In particular, maximum allowed effective multiplication factor when all control rods are fully in and all safety rods are fully out is decreased from 0.988 to 0.977, and maximum allowed power of the reactor is decreased from 10 MW to 7 MW. The safety analysis shows that with the revised limiting conditions for operation, such the events with accompanying one additional equipment malfunction and one error of personnel do not lead to damage of fuel elements and release of radioactivity exceeding allowed level. For neutronics calculations, the MCNP code based on the Monte Carlo method is applied. Thermal-hydraulics is calculated with the PLTEMP code.

Top