Application of Discontinuity factors in C-PORCA 7 code
20th Symposium of AER on VVER Reactor Physics and Reactor Safety (2010, Hanasaari, Espoo, Finland)
Spectral and Core Calculations
Abstract
1.6 Application of Discontinuity factors in C-PORCA 7 code
Istv?n P?s, Tam?s Park?
Paks NPP Ltd
E-mail:pos@npp.hu
S?ndor Patai Szab?
TS-Enercon Ltd
Abstract
During last years there were up-rated the reactor power up to 1485 MW and new fuel
types have been utilised at the Paks NPP. To fulfil the demand of the accuracy and
correctness of on-line core monitoring and off-line core analysis the HELIOS/C-PORCA
models have been modernised as well. The main step of this developing process was to
change the mathematics of the 3D two group diffusion model on the basis of hybrid finite
element method. The upgraded mathematics gave very good results comparing the C-PORCA
calculations against mathematical benchmarks and measurements of different units and
cycles of NPP Paks and Mohovce.
As a final step of the modernisation process the application of flux discontinuity
factors has been made. In the frame of VVER community the usage of this parameter in core
analyses codes is very unusual in contrast with codes for the same purpose in western
countries.
In this paper both the reason of the introduction of discontinuity factors into
HELIOS/C-PORCA models and its effect on the accuracy of calculation are also presented.
We tried to emphasise which kind of codes and which kind of reactor-physical parameters can
be influenced mainly by discontinuity factors. The method of the calculation of flux
discontinuity factors in fuel and non-fuel regions of the core is also described.
As the most important effect of the utilisation of this parameter was that almost all
fittings in C-PORCA code based on in-core measurements have became needless.