29th Symposium of AER on VVER Reactor Physics and Reactor Safety (2019, Energoland, Mochovce NPP, Slovakia)
reactor dynamics and safety analysis
J. Hádek, M. Benčík
The RELAP5-3D© computational system code includes several significant quality improvements over the “standard” versions of RELAP5 program. The most important of these are three-dimensional flow modeling capabilities and the incorporation of three-dimensional neutronic model for description of reactor kinetics. This paper deals with a detailed description of the thermohydraulic and neutronic model of the VVER-1000/320 reactor. Attention is paid to the preparation of neutronic XS data and their arrangement into the input deck of the system code. Earlier versions of RELAP5-3D© included the USER option, which allowed the preparation of neutronic XS data in the form of separate input files that communicated with RELAP5-3D© using external procedures created by the user. This is no longer possible in the latest RELAP5-3D© versions. Now, all the neutronic XS data are incorporated into the general input data file. Their structure follows a well-defined format, in our case it is a GEN-type format. The stationary tests of the reactor model were performed using the latest and older versions of the code. The results are compared, and the differences are discussed. Methodological problems that still need to be overcome are also mentioned.