Neutronic design and analysis of advanced long-cycle boron-free operation of a small modular reactor core with particle type burnable poison rods

Abstract

Soluble boron in the reactor coolant plays an important role for operation of pressurized water reactors (PWRs), but it leads to several issues such as generation of a huge amount of liquid waste, complications in the primary coolant system, and corrosion of system components. This work introduces an advanced small modular reactor (SMR) core concept that can operate over a long cycle without soluble boron and with inherent safety features. The large portion of excess reactivity for compensating for fuel depletion is suppressed by using advanced particle-type burnable poison (BP) rods, and the remaining ones by the control rods with their insertion strategies. The suggested SMR core is designed to operate over a long cycle of 3.8 effective full power year (EFPY) and is coupled with a suggested control rod map and the associated insertion strategy. The superb safety characteristics of this core were confirmed using a simulation of a rod ejection accident and by showing that the core has sufficient shutdown margin and can maintain its subcriticality even at cold zero power (CZP) conditions.