Scale 6.1 Evaluation of the Effective Cross Sections of a LWR Assembly-Reflector Model with Application to the NEA TMI-1 PWR Benchmark

This paper reports some results obtained using the methodology based on the T-NEWT control module of SCALE 6.1 for the calculation of the effective, two-group cross sections for the 2-D assembly-reflector geometry of TMI-1 PWR given in NEA/NSC/DOC (2013)7 benchmark [1]. The calculation of the effective two-group cross sections of the reflector zone is performed both for a homogenized geometry and for the exact 2-D one. The effect on the results of a variation of the boron concentration in the moderator zones is also investigated. The outcomes of the reference case are then compared with those obtained from a calculation performed with the Monte Carlo code SERPENT and those (MCNP5, DRAGON) presented in the available literature for the same benchmark problem. The differences in the numerical values obtained from the various codes are also discussed.