EFFECT OF FUEL BURNUP HISTORY ON NEUTRON-PHYSICAL CHARACTERISTICS OF WWER-1000 CORE
23rd Symposium of AER on VVER Reactor Physics and Reactor Safety (2013, Štrbské Pleso, Slovakia)
Advances in spectral and core calculation methods
Usually during few-group cross section library preparation for using in WWER macro
calculations the change of nuclide concentration during fuel burnup is defined under
invariable and averaged over whole core characteristics (power, fuel and moderator
temperature, moderator density etc.). In reality conditions of fuel burnup are changing and
this factor effects on fuel nuclide content (so called spectral history effect). For accounting of
real burnup history it?s necessary to take into consideration the dependence of cross sections
on not only burnup, but also on history of neutron spectrum during fuel burnup.
In given report results of analysis of fuel burnup history effect on neutron-physical
characteristics of WWER-1000 core with use of DYN3D code are presented. In DYN3D code
the method of using of the local Pu-239 concentration as an indicator of burnup spectral
history is realized. Calculating studies are performed for the four first fuel loadings of 2nd
unit of Khmelnitsky NPP and stationary fuel loading with TWSA. Effect of fuel burnup
history is presented both on macro characteristics of reactor core (boron acid concentration,
fuel campaign duration, reactivity coefficients) and on local values of burnup and power.
The work was performed in framework of orders SR 2511 and R0801504 (SR2611)
under German BMU support.