Assessment of the IEA-R1 nuclear reactor using a nonstandard fuel assembly with six fuel plates of the Brazilian Multipurpose Reactor

Abstract

In order to qualify the fuel plates of the Brazilian Multipurpose Reactor (RMB), a nonstandard Instrumented Fuel Assembly (IFA) was designed and is being constructed to be burned in the IEA-R1 nuclear research reactor. IFA has fuel plates of different uranium densities (10 fixed fuel plates of 3.0 gU/cm3 – IEA-R1 standard; 6 removable fuel plates of 3.7 gU/cm3 – RMB; and a central aluminum plate). This paper is the first step to demonstrate that IEA-R1 can safely operate with this IFA. To verify the IFA thermal behavior inside the IEA-R1 core during reactor operation and certify the no power peaks occurrence, the power distribution was calculated for each fuel plate. LEOPARD and HAMMER-TECHNION codes were utilized to calculate the core thermal neutron cross section and CITATION code to calculate the core power distribution. Calculations were performed for 5 MW reactor power considering the IFA placed in a core peripheral position. The RMB fuel plates average power was 4.73 % higher compared to IEA-R1 fuel plates. This was expected due to the higher density of uranium in these plates. The power of each IFA fuel plate was compared with a fresh IEA-R1 Fuel Assembly (FA) at the same core position. The power in the IFA hottest plate is only 6.79 % higher than the correspondent IEA-R1 fuel plate. The IFA power distribution was also compared to the hottest FA of the core. The power of each IFA fuel plate was below its correspondent hottest FA fuel plate. In addition, the total IFA power is 18.40 % less than the hottest FA in the core. No significant power peaks occur in the IFA during operation. As future works, thermal–hydraulic calculations will be performed considering this calculated power distribution and no hot spots are expected.