Abstract
AbstractIn the lifetime prediction and extension of a nuclear power plant, a reactor pressure vessel (RPV) has to demonstrate the exclusion of brittle fracture. This paper aims to apply fracture mechanics to analyse the non‐uniform cooling effect in case of a loss‐of‐coolant accident on the RPV integrity.A comprehensive framework coupling reactor system, fluid dynamics, fracture mechanics, and probabilistic analyses for the RPVs integrity analysis is proposed. The safety margin of the allowed RTNDT is increased by more than 16°C if a probabilistic method is applied. Considering the non‐uniform plume cooling effect increases KI more than 30%, increases the failure frequency by more than 1 order of magnitude, and increases the crack tip constraint due to the resulting higher stress. Thus, in order to be more realistic and not to be nonconservative, 3D computational fluid dynamics may be required to provide input for the fracture mechanics analysis of the RPV.
Highlights
The reactor pressure vessel (RPV) in a nuclear power plant is not replaceable and its integrity determines the lifetime of the nuclear power plant
Brittle fracture initiated by postulated or existing cracks may occur under pressurized thermal shock (PTS) loading and this is generally considered to be the major threat to RPV integrity
Based on the output of RELAP5 and GRS-MIX, the thermal mechanical and fracture mechanics analysis is performed by FAVOR, whereas the thermal mechanical analysis based on computational fluid dynamics (CFD) results is performed using the w
Summary
The reactor pressure vessel (RPV) in a nuclear power plant is not replaceable and its integrity determines the lifetime of the nuclear power plant. Besides the 3D CFD calculations, an analytical method to consider the local effect of cooling plumes is achieved by the code GRS-MIX [26], which uses an empirical model to calculate the local heat transfer coefficients (HTC) and water temperatures Both structural and fracture mechanics analyses are performed with the finite element method (FEM). Due to the significance and nuclear safety, a lot of work has been done concerning the safety assessment of RPVs under accident scenarios [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22] Both deterministic and probabilistic integrity analysis of a RPV subjected to PTS transients considering uniform RPV cooling have been performed by linear elastic (LEFM).
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