Aging Evaluation of Baffle Bolts for Reactor Internals of Qinshan Nuclear Power Plant

In order to evaluate the actual aging state of baffle bolts for reactor internals in Qinshan Nuclear Power Plant, on the basis of absorbing and summarizing the international research results on the aging mechanism of reactor internals, a criterion for judging the aging mechanism of reactor internals is established, and is used to evaluate and identify the aging mechanism of baffle bolts mainly affected by wear, stress relaxation, irradiation swelling, irradiation-promoted stress corrosion cracking and so on. Besides, according to the possible defect types caused by the aging mechanism, the underwater ultrasonic inspection technology is developed to supplement the conventional visual inspection method, so as to formulate the inspection scheme to evaluate the aging state. The evaluation results show that the baffle bolts for reactor internals in Qinshan Nuclear Power Plant are in good aging condition, and no deformation, crack and other aging failure phenomena have occurred. Practice has proved that the evaluation method is effective and can be used for the aging evaluation of PWR nuclear power plant components.