Reactor pressure vessel integrity program

Abstract

The reactor vessel report provides a technical evaluation of the effects of aging on the reactor vessel shell, lower vessel head, closure head, nozzles (and safe ends, if provided), interior attachments, and all associated pressure-retaining bolting. The evaluation is performed in accordance with the requirements of the license renewal rule, 10 CFR Part 54. This paper is based upon the B and W Owners Group report BAW-2251 (Mackay, W.H., Gross, L.B., Rinckel, M.A., Starkey, R.L., 1996. Demonstration of the management of aging effects for the reactor vessel. Report BAW-2251, Framatome Technologies, Lynchburg, VA), which was submitted to the NRC for review and approval in June 1996. The reactor vessel report demonstrates that existing utility programs adequately monitor and manage the relevant effects of aging of the reactor vessel such as cracking, loss of material, reduction in the fracture toughness of the vessel beltline material, and loss of mechanical closure integrity. The aging management programs credited include ASME Section XI, ISI, compliance to 10 CFR Parts 50.60 and 50.61, Plant Technical Specifications, and commitments to generic Nuclear Regulatory Commission communications. The aging management techniques described in this report permit continued safe operation over the period of extended operation associated with license renewal. In addition, the report includes the evaluation of three generic time-limited aging analyses: (1) fatigue of metallic components; (2) analyses and calculations performed to show compliance with NRC regulations governing reduction of fracture toughness of reactor vessel beltline materials; and (3) intergranular separations in low-alloy steel heat-affected zones under austenitic stainless steel cladding.