ML20215E986

Forwards Case Study Rept - Effects of Ambient Temp on Electronic Components in Safety-Related Instrumentation & Control Sys. W/O Encl

ML20215E986
Person / Time
Issue date:	12/05/1986
From:	Heltemes C NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD)
To:	Layman W NUCLEAR SAFETY ANALYSIS CENTER
References
AEOD-C604, NUDOCS 8612230199
Download: ML20215E986 (2)

Text

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a December 5, 1986 AE0D/C604 Mr. William Layman, Acting Director Nuclear Safety Analysis Center 3412 Hillview Avenue P.O. Box 10412 Palo Alto, California 94303

Subject:

Case Study Report--Effects of Ambient Temperature on Electronic Components in Safety-Related Instrumentation and Control Systems The Office for Analysis and Evaluation of Operational Data (AE0D) has finalized its case study on the effects of ambient temperature on electronic components in safety-related instrumentation and control systems. The final report addresses the peer review comments provided by NRR, IE, the Regions, INP0, NSAC, Westinghouse Electric Corporation and Duke Power Company. The final report also includes the analysis and evaluation of three additional operational experiences not included in the preliminary report involving failures of electronic components due to elevated temperature. We have l enclosed a copy of our final report for your information and use as you may j deem appropriate.

l The study was initiated by an event that occurred at the McGuire Station'in June 1984, during which the plant's control area ventilation system was lost for 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />. Based on this event, and the resulting initial AE0D study, Information Notice 85-89 " Potential Loss of Solid-State Instrumentation Following Failure of Control Room Cooling" was issued to alert licensees of operating nuclear plants of the event and the NRC's concerns. Three other events were subsequently identified in which the root cause of failure of the instrumentation system was determined to be overheating of electronic components located in cabinets in a controlled environmental area. The enclosed report documents the review and evaluation of these four events.

Overheating of electronic components in safety-related instrumentation and control systems raises two concerns: (1) decreased reliability of electronic equipment due to increased failure rate of heat sensitive electronic components, and (2) the potential for common cause failure of redundant instrument channels due to extended loss of normal cooling to the cabinets in which the instruments are located. The enclosed case study report contains specific recommendations which, based on the study's findings and conclusions, address these two concerns. These recommendations are currently being reviewed by the Nuclear Regulatory Commission staff.

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9' Mr. William Layman A copy of the final case study report _and this letter are being placed in the Public Document Room at 1717 H Street, N.W., Washington, D.C. 20555.

If you have any questions regarding this report, please contact Matthew Chiramal l of my staff. Mr. Chiramal can be reached at (301) 492-4441. '

Sincerely, asummenessW C. J. N '- J C. J. Heltemes, Jr. , Director Office for Analysis and Evaluation of Operational Data

Enclosure:

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