QUALIFICATION OF THE FRENCH APOLLO2.8/CEA2005V4 CODE PACKAGE ON ABSORBER CLUSTERS IN 17X17 PWR TYPE LATTICES THROUGH THE CAMELEON PROGRAM

摘要

This paper details the experimental validation of B_4C, Ag-In-Cd (AIC) and Hf-absorber clusters reactivity worths in 17x17 PWR lattices. This validation is performed through several configurations of the CAMELEON experimental program, using the newly qualified APOLLO2.8/CEA2005v4 French code package. After a general presentation of the CAMELEON program that took place in the EOLE critical Facility in Cadarache, one describes the new APOLLO2.8/CEA2005v4 code package relying on the deterministic transport code APOLLO2.8 with the method of characteristics (MOC), and its new CEA2005V4 library based on the latest JEFF-3.1.1 nuclear data evaluation, used in both reference 281 group SHEM-MOC scheme and REL2005 optimized 26groups scheme. Comparisons with the reference TRIPOLI-4 Monte Carlo code are made for reactivity and absorber worth. For critical masses, the average Calculation-to-Experiment (C-E) discrepancies on the k^r of unclustered cores are (240 ± 70) pcm and (370 ± 130) pcm for the reference 281 group MOC and optimized 26 group MOC schemes respectively. For pin-by-pin radial power distributions, the REL2005 results are close to the experimental values, with maximum (C-E)/E discrepancies of the order of 3%, i.e., in the experimental uncertainty limits. Absorber worths are overestimated by 1.2% to 3.6% with deterministic codes, if proper 3D correction, taking into account axial buckling variation, is applied on 2D keff. These results are consistent with the Monte Carlo analysis. The calculations demonstrate the good knowledge of B4C and AIC cross sections, and an overestimation of the natural Hf capture cross section by about 3% in the JEFF3.1.1 evaluated nuclear data library.