Evaluation of Simulator Adequacy for the Radiation Qualification of Safety-Related Equipment (NUREG/CR-1184, SAND79-1787)
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Manuscript Completed: August 1979
Date Published: May 1980
Lloyd L. Bonzon and William H. Buckalew
Sandia National Laboratories
Albuquerque, NM 87185
Operated by Sandia Corporation for the U.S. Department of Energy
Research Support Branch
Office of Water Reactor Safety Research
U.S. Nuclear Regulatory Commission
Washington, DC 20555-0001
Under Interagency Agreement DOE 40-550-75
NRC FIN A-1051-0
This analysis of the response of a reactor power cable to a loss-of-coolant accident (LOCA) discusses several different possible failure mechanisms. In the first few fractions of a minute the electrical leakage currents flow and trapped electrons may discharge, inducing noise pulses into the cable. Quantitative analysis shows these effects are not serious for a power cable.
If the cable has poor heat contact with the external environment, within a few minutes radiation energy (dose) will raise the temperature from an already elevated temperature to approach the maximum service temperature for the insulators.
After a few days the accumulated dose is enough to deteriorate the cable insulation. This chemical and mechanical deterioration thus represents the ultimate failure mode of the cable.
It is noted that gamma ray simulators may understress the electrical effects and overstress the temperature effects. It is also noted that several parameters used in this study were extrapolated from the values for roughly similar materials in roughly similar environments. A final, definitive study might have to include a program to measure these parameters in the materials of interest.