Barrier Integrity Research Program (NUREG/CR-6861, ANL-04/26)

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Publication Information

Manuscript Completed: November 2004
Date Published: December 2004

Prepared by:
D.S. Kupperman, S.H. Sheen, W.J. Shack, and D.R. Diercks
Argonne National Laboratory
9700 South Cass Avenue
Argonne, Illinois 60439

P. Krishnaswamy, D. Rudland, and G.M. Wilkowski
Engineering Mechanics Corporation of Columbus
Columbus, Ohio 43221

M. Srinivasan, NRC Project Manager

Prepared for:
Division of Engineering Technology
Office of Nuclear Regulatory Research
U.S. Nuclear Regulatory Commission
Washington, DC 20555-0001

NRC Job Code Y6869

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Abstract

In response to the vessel head event at the Davis-Besse reactor, the NRC formed a Lessons Learned Task Force (LLTF). Four action plans were formulated to respond to the recommendations of the LLTF. The action plans involve barrier integrity, stress corrosion cracking (SCC), operating experience, and inspection and program management. One part of the action plan on barrier integrity is an assessment to identify potential safety benefits from changes in requirements pertaining to leakage in the reactor coolant system (RCS). In this report, experiments and models were reviewed to identify correlations between crack size, crack-tip-opening displacement (CTOD), and leak rate in the RCS. Sensitivity studies using SQUIRT (Seepage Quantification of Upsets In Reactor Tubes) were carried out to correlate crack parameters, such as crack size and CTOD, with leak rate for various types of crack configurations in RCS components. A database that identifies the leak source, leak rate, and resulting actions from RCS leaks discovered in U.S. light water reactors was developed. For each leak event, the database provides information on what equipment detected the leakage, how it was determined that the leakage was through the pressure boundary, and what caused the leakage. The sensitivity, reliability, response time and accuracy of each type of leakage detection system were evaluated. Acoustic emission crack monitoring systems for the detection of crack initiation and growth before a leak occurs were also considered. New approaches to the detection of a leak in the reactor head region by monitoring boric-acid aerosols were also considered. Infrared spectroscopy could be used for this purpose. The focus of the report is on the available technologies.