Assessing the Geometric Approximations in Reactor Physics Analysis of the R2 Research Reactor Fuel Assemblies for the Nuclear Energy Agency Benchmark

Abstract

The Multi-physics Pellet Cladding Mechanical Interaction Validation (MPCMIV) Benchmark, run through the OECD NEA, investigates validation of three-way coupled simulations (reactor physics, thermal-hydraulics and fuel performance) of a fuel rod elongation experiment performed at the R2 research reactor. To obtain accurate results while simulating the experiment, the R2 reactor bulk core must be modelled using reactor physics codes. This paper investigates the impact of fuel plate modelling approximation when modelling the R2 bulk-core fuel assemblies. A convention in modelling of fuel plates assemblies is to depict the curved fuel plates as flat plates without any curvature. These differences in geometry and the impact on fuel burnup, and effective lattice multiplication factor were studied using SERPENT 2. It was found that there are very small changes caused by the difference in geometry, that can be considered negligible in the context of burnup calculations and impact on the experimental fuel rod transients.