Influence of spectral history on full core calculation results
21st Symposium of AER on VVER Reactor Physics and Reactor Safety (2011, Dresden, Germany)
Spectral and core calculations
Abstract
The few-group cross section libraries, used by reactor dynamics codes, are affected by
the spectral history effect ? a dependence of fuel cross sections not only on burnup, but
also on local spectral conditions during burnup. A cross section correction method based
on Pu-239 concentration was implemented in the reactor dynamic code DYN3D.
This paper describes the influence of a cross section correction on full-core calculation
results. Steady-state and burnup characteristics of a PWR equilibrium cycle, calculated by
DYN3D with and without cross section corrections, are compared. A study has shown a
significant influence of spectral history on axial power and burnup distributions as well as
on calculated cycle length. An impact of the correction on transient calculations is studied
for a control rod ejection example.