CFD ANALYSIS OF TEMPERATURE DEVIATIONS IN GD ASSEMBLY HEADS

S. Tóth, A. Aszódi, Budapest University of Technology and Economics, Institute of Nuclear Techniques, Hungary

22nd Symposium of AER on VVER Reactor Physics and Reactor Safety (2012, Průhonice, Czech Republic)
CFD CODES APPLICATION

Abstract

Lately a CFD model for the head part of the VVER-440 fuel assemblies with Gd burnable
poison has been developed. Using this model calculations are performed for some recent Gd
assemblies of the Paks NPP with the code ANSYS CFX. With the calculations the
temperature distributions in the assembly heads are determined and the in-core thermocouple
signals are evaluated. The computed signals are compared to in-core measured data of
Paks NPP. The study shows that the deviations between the in-core thermocouple signals and
the cross-sectional average temperatures at the measurement level depend on the burnups of
the fuel assemblies. These deviations are significant in the cases of low burnups and
negligible in the cases of higher burnups. This behavior is mainly caused by the three Gd fuel
rods near the assembly center.

Presentation / full paper