United States Nuclear Regulatory Commission - Protecting People and the Environment

Response of Rubber Insulation Materials to Monoenergetic Electron Irradiations (NUREG/CR-3532, SAND83-2098)

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Publication Information

Manuscript Completed: November 1983
Date Published
: November 1983

Prepared by:
W.H. Buckalew, F.J. Wyant, G.J. Lockwood
Sandia National Laboratories
Albuquerque. New Mexico 87185
Operated by Sandia Corporation
for the U.S. Department of Energy
Under Contract No. DE-AC04-76DP00789

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

Under Interagency Agreement DOE 40-550-75

NRC FIN A-1051

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The electron charge disposition in ethylene-propylene rubber (EPR) insulation specimens irradiated with monoenergetic electrons has been investigated. Studied was charge disposition in slab and cylindrical (cable) geometries. For each geometry, charge behavior was observed as a function of environment, electron energy, and surface termination. Under certain conditions, charge was accumulated and spontaneous breakdown did occur during irradiation in the vacuum environment; however, no evidence of breakdown was observed during ambient air exposures. Based on these experiments, it is concluded that electron charge buildup and breakdown is not apt to occur in EPR rubber insulation exposed to electrons from a LOCA radiation environment provided that the insulation is in contact with an ionized medium. The results can probably be applied to other organics and it appears that the LOCA beta spectra need not be precisely duplicated in insulation-radiation qualification tests.

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