Zohlednění různé provozní historie při přípravě makroskopických dat pro celozónové výpočty

Abstract

This thesis explores the impact of various operating histories on the preparation of macroscopic nuclear data for full-core nuclear reactor simulations, specifically focusing on the VVER-1000 reactor model. Using the Serpent2 code for nuclear data preparation and the PARCS code for full-core calculations, the study investigates how different operational histories affect the macroscopic data preparation, neutron spectra, and operational parameters, which are critical for accurate nuclear reactor simulations. The calculations follow material, geometry, and operational data specifications of the first campaign presented by the X2 Khmelnitsky benchmark. Traditional methods of PWR calculations typically employ the construction of a single macroscopic data library with cycle-averaged parameters. This method works well for constant reactor operations; however, new types of reactors have the possibility of frequent power changes to satisfy the electrical grid's demands for so-called load-following operations. This thesis explores the level of improvement brought by a library accounting for history effects compared to an average library. Results at the lattice level demonstrate that variations in operational histories influence the neutron spectrum and therefore the atomic densities of nuclides in the spent nuclear fuel. The implementation of history cases in full-core calculations showcased a non-negligible influence on the calculation of thencritical boron concentration, primarily in the latter half of the campaign. On the other hand, almost no difference was observed in the calculations of power distribution.

This thesis explores the impact of various operating histories on the preparation of macroscopic nuclear data for full-core nuclear reactor simulations, specifically focusing on the VVER-1000 reactor model. Using the Serpent2 code for nuclear data preparation and the PARCS code for full-core calculations, the study investigates how different operational histories affect the macroscopic data preparation, neutron spectra, and operational parameters, which are critical for accurate nuclear reactor simulations. The calculations follow material, geometry, and operational data specifications of the first campaign presented by the X2 Khmelnitsky benchmark. Traditional methods of PWR calculations typically employ the construction of a single macroscopic data library with cycle-averaged parameters. This method works well for constant reactor operations; however, new types of reactors have the possibility of frequent power changes to satisfy the electrical grid's demands for so-called load-following operations. This thesis explores the level of improvement brought by a library accounting for history effects compared to an average library. Results at the lattice level demonstrate that variations in operational histories influence the neutron spectrum and therefore the atomic densities of nuclides in the spent nuclear fuel. The implementation of history cases in full-core calculations showcased a non-negligible influence on the calculation of thencritical boron concentration, primarily in the latter half of the campaign. On the other hand, almost no difference was observed in the calculations of power distribution.