Influence of Neutron Irradiation and Post-Irradiation Annealing on Mechanical Properties and Fracture Toughness of the Anticorrosive Cladding for VVER-Type Reactors: Part 1. Mechanisms of Embrittlement and Recovery of Cladding Properties

—The influence of neutron irradiation and post-irradiation annealing on the fracture toughness of anticorrosive cladding material for reactor pressure vessels with different phosphorus and δ-ferrite content was investigated. The effect of the annealing temperature on the degree of degradation and recovery of the weld metal was considered. The processes during annealing exerting both positive and negative effects on recovery of the cladding properties were studied. The results of the research can be used for justification of the resistance to brittle fracture of reactor pressure vessels after annealing.