(A) study on soluble-boron-free APR1400 core using non-conventional 3-D burnable absorbers

Abstract

A conceptual Soluble-Boron-Free (SBF) Pressurized Water Reactor (PWR) has been investigated on the APR1400 reactor core by introducing innovative Burnable Absorbers (BA). The Centrally-Shielded Burnable Absorber (CSBA), which is the spherical shape of gadolinia (Gd$_2$O$_3$) placed at the center of each fuel pellet, was implemented along with the fuel pin stack. The Burnable Absorber Integrated Guide Thimble (BigT) was additionally utilized, which is a coated B$_4$C in the surfaces of the Guide Thimble (GT). The designs of fuel assemblies (FAs) were optimized by the combination of both BAs to achieve an SBF APR1400 reactor core using two-batch fuel management. Safety parameters such as Coolant Temperature Coefficient (CTC) and Fuel Temperature Coefficient (FTC), and the control rod worth were analyzed from the optimized SBF APR1400 reactor core. It is shown that the SBF APR1400 reactor core can achieve a cycle length of 630 effective full power days with an average discharge burnup of 45.4 MWD/kgU, while the reactivity swing is less than 1,000 pcm with a reasonable power profile with 3D peaking values less than 2.5. The SBF APR1400 reactor core also provides enough shutdown margin at the cold zero-power condition. All of the neutronic calculations were performed using the SERPENT 2 Monte Carlo code with nuclear data library ENDF/B-VI.