Resolution of Generic Safety Issues: Item C-1: Assurance of Continuous Long-Term Capability of Hermetic Seals on Instrumentation and Electrical Equipment ( NUREG-0933, Main Report with Supplements 1–35 )
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DESCRIPTION
Historical Background
This NUREG-04713 item was developed because of concerns regarding the long-term capability of hermetically-sealed instruments and equipment which must function in postaccident environments. Certain classes of instrumentation incorporate seals. When safety-related components within containment must function during post-LOCA accident conditions, their operability is sensitive to the ingress of steam or water.
Safety Significance
If the seals should become defective as a result of personnel errors in the maintenance of such equipment, such errors could lead to the loss of effective seals and the resultant loss of equipment operability. The establishment of a basis for confidence that sensitive equipment has a seal during the lifetime of the plant is needed.
Possible Solutions
The NRC has undertaken a program to reevaluate the qualification of all safetyrelated electrical equipment at all operating reactors. As part of this program, more definitive criteria for environmental qualification of safety-related electrical equipment have been developed by the staff. The Division of Operating Reactors' "Guidelines for Evaluating Environmental Qualification of Class 1E Electrical Equipment in Operating Reactors" (DOR Guidelines) were completed in November 1979. The Guidelines are intended as a screening device to catch those pieces of equipment which might have qualification problems. In addition, for reactors under licensing review, the staff has issued NUREG-0588.19 The staff intends to evaluate the qualification of all electrical safety equipment in operating plants pursuant to the Guidelines. If problems arise, the staff shall resolve them using NUREG-058819 as a guide for their judgment.
On May 27, 1980 the NRC issued Commission Memorandum and Order CLI-80-2146 ordering that the above two documents form the requirements which licensees and applicants must meet in order to satisfy those aspects of 10 CFR 50, Appendix A, GDC-4, which relate to the environmental qualification of safety-related electrical equipment. The order established an implementation schedule which set a goal that all safety-related electrical equipment in all operating plants be qualified to the DOR Guidelines or NUREG-058819 by no later than June 30, 1982.
CONCLUSION
This item has been RESOLVED. Requirements have been established and implementation is underway.
REFERENCES
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