Comparisons between the measured and calculated by KASKAD neutron-physics characteristics of the cores WWER-1000/320 at Kozloduy NPP during the fuel campaign

The report shows comparisons of calculation results by code package KASKAD and experimental data for the last cycles of Kozloduy NPP Unit 5 and Unit 6. The results are related to:-critical boric acid concentration during the cycles;-assemblies relative power distribution (restored and calculated fields) in the core at different moments of operation. The comparisons of relative power distribution in the assemblies are performed: 1)between the SVRK restored Kq's fields and BIPR-7A calculated ones and 2) using PIR-A code of KASKAD and SVRK measured data. The comparisons of the assemblies' relative power distribution show a sufficient agreement for Unit 5, cycle 14, but for Unit 6, cycle 13 there are many discrepancies between the calculated and restored by SVRK relative power coefficients by assemblies. When compared to PIR-A restored Kq's all absolute errors enter in BIPR-7A passport limits. There is not agreement between BIPR-7A passport limits for some groups of TVSA assemblies when compared the calculated to SVRK restored Kq's. The measured boric acid concentration differs by more than 0.40g/kg from the corresponding calculated one to the end of cycles. This leads to a longer actual fuel cycle than the predicted one by more than 3% as it is in BIPR-7A passport. (authors)