United States Nuclear Regulatory Commission - Protecting People and the Environment

Performance of Metal and Polymeric O-Ring Seals in Beyond-Design-Basis Temperature Excursions (NUREG/CR-7115)

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Publication Information

Manuscript Completed: November 2011
Date Published: April 2012

Prepared by:
Jiann C. Yang
Edward J. Hnetkovsky

National Institute of Standards and Technology
Engineering Laboratory
Gaithersburg, Maryland 20899

Felix Gonzalez, NRC Project Manager

NRC Job Code N6550

Office of Nuclear Regulatory Research
U.S. Nuclear Regulatory Commission
Washington DC 20555-0001

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This report documents the beyond-design-basis thermal exposure test results of the performance of one type of metallic seal and two different polymeric compound (ethylene-propylene and polytetrafluoroethylene) seal designs typically used in spent fuel transportation packages. Fifteen tests were conducted using a small scale-model package made of stainless steel SS 304 filled with helium initially pressurized at either 5 bar or 2 bar at room temperature. The test package was then exposed in an electric furnace to temperatures equal to or over the specified maximum operating temperatures of these seals for a pre-determined period (typically 9 h). The pressure drop technique was used to determine if leakage occurred during thermal exposure. A total of fifteen tests, twelve used metallic seals, two used ethylene-propylene compound, and one used polytetrafluoroethylene, were performed. Leakage was observed in some of the thermal exposure tests. The time when leakage occurred varied. The overall goal of the project is to provide insights to the performance of these seals when exposed to beyond-design-basis temperature conditions that could result due to a severe fire.

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