Accession Number NUREG-2110
Title xLPR Pilot Study Report.
Publication Date May 2012
Media Count 77p
Personal Author C. Harrington D. Rudland
Abstract Under the auspices of an addendum to the memorandum of understanding between the Electric Power Research Institute and the U.S. Nuclear Regulatory Commissions Office of Nuclear Regulatory Research for cooperative research, a pilot study has been completed to evaluate the feasibility of developing a fully probabilistic, fracture-mechanics-based computational tool to evaluate the rupture probability of reactor coolant piping. This project, known as xLPR for Extremely Low Probability of Rupture, is initially focused on evaluating pipe rupture probabilities within Alloy 82/182 dissimilar metal welds located in lines licensed for leak-before-break (LBB) as allowed under General Design Criterion 4, Environmental and Dynamic Effects Design Bases, of Appendix A, General Design Criteria for Nuclear Power Plants, to Title 10 of the Code of Federal Regulations Part 50, Domestic Licensing of Production and Utilization Facilities. The current LBB regulatory basis does not allow for assessment of piping systems subject to active degradation mechanisms, such as primary water stress-corrosion cracking, which has been detected in some systems that have been granted LBB approval. Although the piping systems susceptible to this type of corrosion have been shown through deterministic arguments to comply with the regulations, no fully probabilistic tool currently exists to directly assess this compliance. Development of such a complex probabilistic computational tool is a daunting technical challenge, and the project team determined that a pilot study was necessary. The three key goals addressed include establishing the fundamental feasibility of such an undertaking, assessing whether the proposed organizational approach could accomplish the task, and informing the decision on the most appropriate computational platform to employ.
Keywords Corrosion
Degradation mechanisms
Extremely Low Probability of Rupture(xLPR)
Leak Before Break(LBB)
Pipe rupture
Piping systems
Water stress corrosion cracking

Source Agency Nuclear Regulatory Commission
NTIS Subject Category 94F - Tooling, Machinery, & Tools
41 - Manufacturing Technology
Corporate Author Nuclear Regulatory Commission, Washington, DC. Office of Nuclear Regulatory Research.
Document Type Technical report
Title Note N/A
NTIS Issue Number 1308
Contract Number N/A

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