SUMMARY

As new computer codes are developed for solving the transport equation in reactor problems, it is essential for methods developers to have at their disposal effective and robust computational benchmarks. In order to validate computational methods and reactor codes that may be used for real-world reactor problems, the benchmark configurations must be representative of realistic reactors, which implies that they must be large-scale 3-dimensional models that are highly heterogeneous both at the assembly and the core levels.

This work presents a whole-core benchmark problem based on a 2-loop pressurized water reactor with both UO2 and MOX fuel assemblies. The specification includes heterogeneity at both the assembly and core level. The geometry and material compositions are fully described and multi-group cross section libraries are provided in 2, 4, and 8 group formats. Simplifications made to the benchmark specification include a Cartesian boundary, to facilitate the use of transport codes that may have trouble with cylindrical boundaries, and control rod homogenization, to reduce the geometric complexity of the problem. These modifications were carefully chosen to preserve the physics of the problem and a justification of these modifications is given. Detailed Monte Carlo reference solutions including core eigenvalue, assembly averaged fission distribution and selected fuel fission density distribution are presented for benchmarking diffusion and transport methods. Three different core configurations are presented namely all-rods-out, all-rods-in, and some-rods-in.