IMPLEMENTATION OF THE NEUTRONICS MODEL OF HEXTRAN/HEXBU-3D INTO APROS FOR VVER CALCULATIONS
18th Symposium of AER on VVER Reactor Physics and Reactor Safety (2008, Eger, Hungary)
Spectral and Core Calculation
A new three-dimensional nodal model for neutronics calculation is currently under implementation into APROS – Advanced PROcess Simulation environment – to conform the increasing accuracy requirements. The new model is based on an advanced nodal code HEXTRAN and its static version HEXBU-3D by VTT, Technical Research Centre of Finland. Currently the new APROS is under a testing programme. Later a systematic validation will be performed. In the first phase, a goal is to obtain a fully validated model for VVER-440 calculations. Thus, all the current test calculations are performed by using Loviisa NPP?s VVER-440 model of APROS. In future, the model is planned to be applied for the calculations of VVER-1000 type reactors as well as in rectangular fuel geometry. The paper outlines first the general aspects of the method, and then the current situation of the implementation. Because of the identical model with the models of HEXTRAN and HEXBU-3D, the results in the test calculations are compared to the results of those. In the paper, results of two static test calculations are shown. Currently the model works well already in static analyses. Only minor problems with the control assemblies of VVER-440 type reactor still exist but the reasons are known and will be corrected in near future. Dynamical characteristics of the model are up to now tested only by some empirical tests.