Feasibility of a very-low-boron core design for APR1400 with 24-month cycle length

Abstract

Next-generation pressurized water reactors (PWRs) require higher flexibility in operation strategy and more efficiency for environmental and sustainable system. The use of soluble boron for controlling excess reactivity during the cycle should be minimized and various cycle operation strategy should be available for cycle scheme flexibility. Moreover, low-boron operation is advantageous for passive load-following operation in PWRs. The standard Advanced Power Reactor 1400MWe (APR1400) core is designed for an operation cycle of about 18 months with one-third of the fuel assemblies replaced during each refueling outage. To realize very low-boron operation of APR1400 (APR1400-VLB), an innovative burnable absorber (BA) concept, Centrally-Shielded Burnable Absorber (CSBA), is applied. CSBAcan readily optimize the self-shielding effect associated with the depletion rate of the BA, thus reactivity hold-down is effective during the cycle. On the other hand, a new fuel loading scheme is proposed to extend the cycle length from 18 months to 24 months. The study presented here describes a scoping analysis for technical feasibility of 24-month APR1400-VLB core. All neutronic analyses is performed using the Monte Carlo Serpent 2 code and ENDF/B-7.1 library.