Effect of burnup history by moderator density on neutron-physical characteristics of WWER-1000 core
21st Symposium of AER on VVER Reactor Physics and Reactor Safety (2011, Dresden, Germany)
Spectral and core calculations
Abstract
Results of assessment of burnup history effect by moderator density on neutron physical
characteristics of WWER-1000 core are presented on example of stationary fuel loading with
Russian design FA TWSA and AER benchmark for Khmelnitsky NPP that was proposed by
TUV and SSTC NRC at 19th symposium. Assessment was performed by DYN3D code and
cross section library sets generated by HELIOS code.
Burnup history was taken into account by preparing of numerous cross section sets with
different isotopic composition each of which was obtained by burning under different
moderator density. For analysis of history effect 20 cross section sets were prepared for each
FA corresponded to each of 20 axial layers of reactor core model for DYN3D code. Four fuel
cycles were modeled both for stationary fuel loading with TWSA and AER benchmark for
Khmelnitsky NPP to obtain steady value of error due to neglect of burnup history effect.
Main attention of study was paid to effect of burnup history by moderator density to
axial power distribution. Results of study for AER benchmark were compared with
experimental values of axial power distribution for FAs of 1st, 2nd, 3rd and 4th year operation.
The work was performed in framework of orders BMU SR 2511 and BMU R0801504
(SR2611). The report describes the opinion and view of the contractor ? SSTC N&RS – and
does not necessarily represent the opinion of the ordering party – BMU-BfS/GRS and T?V
S?D.