Fracture evaluation of surface cracks in light water reactor pressure vessels under pressurized thermal shock loading

Abstract

AbstractThe evaluation of pressure vessel integrity affected by pressurized thermal shock (PTS) events caused by emergency cooling due to a small leak break is being addressed. Comprehensive numerical and experimental investigations were performed at MPA Stuttgart and the HDR plant.During cold water feeding necessary to maintain core cooling under accident conditions, high temperature gradients arise which cause thermal stresses in the walls near the inner surface of the reactor pressure vessel (RPV). Supposing there are flaws in the inner wall the thermal stresses can increase the stress intensity considerably compared with the stresses caused by internal pressuse. st the same time, the fract/fre toughness of the ferritic reactor pressure vessel matenalls reduced through the coolmg process. Therefore, the possibility of stable or unstable crack growth cannot be ruled out.This paper describes numerical and experimental investigations with large-scale heavy section specimens with circumferential and semi-e...