A CIPS risk evaluation methodology applicable for PWR

Abstract

BackgroundDuring pressurized water reactor (PWR) power operation period, corrosion products tend to deposit in the fuel boiling zone and form chalk rivers unidentified deposit (CRUD). At a certain level of CRUD, boron acid will precipitate and depress local nuclear power, causing CRUD induced power shift (CIPS) incident, however, the operation data of reactors that have undergone CIPS indicate that CRUD thickness is not the only factor affecting CIPS.PurposeThis study aims to evaluate the CIPS risk of PWR more scientifically by establishing an evaluation methodology that comprehensively considers CRUD characteristics and thermal-hydraulic condition.MethodsBased on the internal mass transfer mechanism of the porous media, a model which could simulate boron deposition process inside CRUD was established by combining the consideration of CRUD morphology. According to the simulated results, the deep causes of CIPS in Callaway and Ulchin power plants were revealed.ResultsEvaluation results show that the most important factor of CIPS in Callaway power plant is CRUD thickness which is different from the contribution of CRUD porosity to Ulchin's CIPS.ConclusionsThe CIPS risk evaluation method of this study provides theoretical evidence and supporting data for more scientific CIPS analysis.

Keywords

• pwr
• cips
• crud characteristics
• thermal-hydraulic
• boron deposition