ML20207N223
| ML20207N223 | |
| Person / Time | |
|---|---|
| Issue date: | 01/12/1987 |
| From: | Heltemes C NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD) |
| To: | Layman W NUCLEAR SAFETY ANALYSIS CENTER |
| Shared Package | |
| ML18041A146 | List: |
| References | |
| AEOD-C605, NUDOCS 8701140060 | |
| Download: ML20207N223 (2) | |
Text
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JAN1E;3;l AE0D/C605 Mr. William Layman, Acting Director Nuclear Safety Analysis Center 3412 Hillview Avenue P.O. Box 10412 Palo Alto, CA 94303
Dear M an:
SUBJECT:
CASE STUDY REPORT - OPERATIONAL EXPERIENCE INVOLVING LOSSES OF ELECTRICAL INVERTERS 4
s The Office for Analysis and Evaluation of Operational Data (AE0D) has finalized I
its case study report on operational experience involving losses of electrical inverters. The report addresses the peer review comments provided by NRR, RES,
'lI the Regions, INP0, and Brookhaven National Laboratory. The final report also includes a brief analysis and evaluation of inverter loss events that occurred
, in calendar year 1985 which was not included in the preliminary report. We have enclosed a copy of our final report for your information and use as you ray deem appropriate.
- The study was initiated based primarily on the observation of a lack of overall
, improvement in the operational performance of safety and nonsafety-related inverters. The study indicates that events involving inverter losses raises two principal concerns: (1) increased frequency of plant transients, and (2) l, inoperable or improper functioning of both safety-related and other important plant equipment.
Based on a review of events which occurred during calendar years 1982, 1983, and L! 1984, the study concludes that at major contributing cause for inverter loss events attributed to component failures is incompatibility between the actual
. plant equipment service conditions and the service conditions assumed in the design of these units. The two factors which appear to be dominant contributors to such failures are high ambient temperature and/or humidity within inverter enclosures and voltage spikes and perturbations at inverter terminals. The study notes that these two factors have potential common cause implications.
Other contributing factors or causes are inadequate maintenance and testing procedures or inappropriate personnel actions. In addition, the study finds that technical specifications that address inverters and/or attendant buses for comparable plant designs are not consistent. Further, inverter-related operating experiences indicate that a portion of the electrical circuitry associated with the Westinghouse Solid State Reactor Protection System (SSPS) should be reassessed for acceptability. The enclosed report contains specific recommendations to address the study's findings and conclusions. These recommendations are currently being reviewed by the Nuclear Regulatory Commission staff.
8701140060 870112 PDR ORG NEXD
1 4, Nr. 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 Frank Ashe of my staff. Mr. Ashe can be reached at (301) 492-4442.
Sincerely, w n..w us c.s. w anea M<
C. J. Heltemes, Jr., Director Office for Analysis and Evaluation of Operational Data
Enclosure:
As stated Distribution:
PDR-AE0D SF AE0D CF R0AB SF ROAB CF J. Heltemes F. Hebdon S. Rubin M. Chiramal F. Ashe M. Williams K. Black W. Lanning 0FC : AE0 ROAB : AEOD:ROA% : AEOD:ROAB : AEOD:DD : AEOD : :
_ _ _ _ _ ; . . F6 {. ,_____:___ .....:____________:____....___
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- MChiramal : SRubin d : FHe : CJ temes : :
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DATE : 12/is/86 : 12/ga/86 : 12/N/86 : 12/3f/86 : 12/$h86 : :
1 0FFICIAL RECORD COPY