Simulation of 3D hydraulic effects in the IR-8 reactor’s IRT-3M FA using ATHLET code

Abstract

This article presents the results of the calculated determination of the 3D hydraulic effects in the gaps of the fuel assembly (FA) IRT-3M. Determination 3d hydraulic effects was carried out using the one-dimensional ATHLET code. Previous work has already been done to analyze the test results hydraulic eight- and six-tube FA IRT-3M reactor IR-8. However, it has not been paid attention to the partition of hydraulic structures in the FAs in the gaps between the fuel rods in the sector in accordance with the division of thermal structures. The new improved FA model was created according to model for neutron physics calculations to create coupling calculation further. The total consumption through the FAs of the improved model changed by less than 0.01% from the base model. The obtained differences in the velocities in the flat and angular sectors will make it possible to obtain a more accurate temperature field distribution for estimation of the margin before the onset of surface boiling. The results of this work can be used in determining the permissible power of the IRT type research reactors: IR-8 at NRC KI (Moscow), IRT-MEPHI at NRNU MEPHI (Moscow), IRT-T at TPU (Tomsk) and WWR-SM at INP (Tashkent).