Neutronic design and analysis of a soluble boron-free small modular reactor core with GdN-CBA burnable absorber rods for load-following operations

Abstract

This paper presents a novel burnable absorber called Gadolinium Nitride-Coated Burnable Absorber (GdN-CBA), which is optimized for a soluble boron-free operation. This new burnable absorber rod was effectively adopted in designing a 180 MWth (∼54 MWe) PWR-based SMR reactor core which can be operated without soluble boron over 24-months cycle (80 % capacity factor). In particular, detailed core neutronic simulations demonstrated that the SMR core can operate during usual and unusual load-following scenarios without exceeding the constraints related to power distributions and without xenon oscillations. Additionally, the core achieved relatively high fuel discharge burnup of 33.6 MWd/kg in spite of its very compact core size, which resulted from use of an effective ZrC reflector and a three-batch fuel management scheme.