Revisiting the Integrated Pressurized Thermal Shock Studies of an Aging Pressurized Water Reactor
The Integrated Pressurized Thermal Shock (IPTS) studies were a series of studies performed in the early-mid 1980s as part of an NRC-organized comprehensive research project to confirm the technical bases for the pressurized thermal shock (PTS) rule, and to aid in the development of guidance for licensee plant-specific analyses. The research project consisted of PTS pilot analyses for three PWRs: Oconee Unit 1, designed by Babcock and Wilcox; Calvert Cliffs Unit 1, designed by Combustion Engineering; and H.B. Robinson Unit 2, designed by Westinghouse. The primary objectives of the IPTS studies were (1) to provide for each of the three plants an estimate of the probability of a crack propagating through the wall of a reactor pressure vessel (RPV) due to PTS; (2) to determine the dominant overcooling sequences, plant features, and operator actions and the uncertainty in the plant risk due to PTS; and (3) to evaluate the effectiveness of potential corrective actions. The NRC is currently evaluating the possibility of revising current PTS regulatory guidance. Technical bases must be developed to support any revisions. In the years since the results of IPTS studies were published, the fracture mechanics model, the embrittlement database, embrittlement correlation, inputs for flaw distributions, and the probabilistic fracture mechanics (PFM) computer code have been refined. An ongoing effort is underway to determine the impact of these fracture-technology refinements on the conditional probabilities of vessel failure calculated in the IPTS Studies. This paper discusses the results of these analyses performed for one of these plants.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Oak Ridge, TN
- Sponsoring Organization:
- USDOE Office of Science (SC); USNRC Office of Nuclear Regulatory Research
- DOE Contract Number:
- AC05-96OR22464
- OSTI ID:
- 6153
- Report Number(s):
- ORNL/CP-102439; 41 WO 11 9B 1; ON: DE00006153
- Resource Relation:
- Conference: ASME Pressure Vessels and Piping Conference, Boston, MA, August 1-5, 1999
- Country of Publication:
- United States
- Language:
- English
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