SCALE 6.1.3 Evaluation of the Heavy Reflector Effective Cross Sections for a GEN III PWR System and a Serpent 2.1.23 Model Comparison

This paper reports some results obtained using the methodology based on the T-NEWT control module of SCALE 6.1.3 modular code system for the calculation of Assembly Discontinuity Factors (ADFs) and homogenized two group condensed effective heavy reflector cross sections in the central and peripheral zones of a GEN III PWR core. A preliminary study has been carried out to verify the different quantitative neutronic behaviour between a heavy and a standard reflector. Afterwards, it analyzes the effect of different geometric and material assembly/reflectors models – homogeneous, homogenized slabs and heterogeneous – on the effective cross sections numerical results. The impact of the use of 2 or 8.5 assemblies coupled with the central reflector zone on the effective cross sections values is also investigated. The results of heavy central reflector effective cross sections data were then compared with those obtained on the peripheral region of a GEN III core. Finally, a cell data calculation has also been carried out on a 2x2 color-set to investigate a 2-D effect, in the reflector angle region, on the effective cross section results. The outcomes of the T-NEWT reference case are at last compared with those obtained with the Serpent 2.1.23 code.