Searching for the most optimum burnable absorbers (BAs) for AP-1000 from the neutronic, thermal-hydraulic, and solid mechanics points of view

Abstract

Because of the importance of absorber materials in regulating the reactivity of AP-1000, several materials with varied designs have been investigated to find the most optimum absorber materials from the neutronic, thermal-hydraulic, and solid mechanics perspectives. In this work, ZrB2, Er2O3, (SiO2-B2O3) and (Al2O3-B4C) were investigated as burnable absorbers (BAs) and H3BO3, Ag–In–Cd, and SS-304 as non-burnable absorbers. For the investigated BAs, the main neutronic parameters such as the fuel burn-up, axial thermal neutron flux distribution and the pin by pin distribution have been simulated. For the non-burnable absorbers, the control rod worth (CRW) and the boron concentration coefficient have been calculated. In the thermal-hydraulic analysis, the temperature distribution of the fuel, clad, coolant and the minimum departure from nucleate boiling ratio (MDNBR) have been studied. The BAs’ effects on solid mechanics analysis have emerged on both the von-Mises stress and the maximum fuel outer surface displacement.