ML20153C021
| ML20153C021 | |
| Person / Time | |
|---|---|
| Issue date: | 08/29/1988 |
| From: | Stello V NRC OFFICE OF THE EXECUTIVE DIRECTOR FOR OPERATIONS (EDO) |
| To: | Carr, Roberts, Zech NRC COMMISSION (OCM) |
| Shared Package | |
| ML20153C025 | List: |
| References | |
| NUDOCS 8808310184 | |
| Download: ML20153C021 (2) | |
Text
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t AUG 2 9 Igg MEMORANDUM FOR: Chaiman Zech Comissioner Roberts Comissioner Carr Commissioner Rogers FROM:
Victor Stello, Jr.
Executive Director for Operations
SUBJECT:
AEOD CASE STUDY REPORT "SERVICE WATER SYSTEM FAILURES AND DEGRADATIONS IN LIGHT WATER REACTORS" (AE0D/C801)
Enclosed for your information is a copy of an AEOD case study report on operational events involving service water system failures and degradations in light water reactors from 1980 to 1987 The results of the comprehensive case study indicate that service water system failures and degradations are attributable to a great variety of causes, and have adverse impact on a large number of safety-related systems and components which are required to mitigate reactor accidents. Specifically, the causes of failures and degradations include various fouling mechanisms, single failures and other design deficien-cies, flooding, multiple equipment failures, personnel and procedural errors, and seismic deficiencies. Systems and components cdversely impacted by a service water system failure or degradation include the component cooling water system, emergency diesel generators, emergency core cooling system pumps and heat exchangers, the residual heat removal system, containment spray and fan coolers, control room chillers, and reactor building cooling units.
The staff has expressed concern on the importance of service water system operating experience and possible vulnerabilities in tems of core damage potential. Some bounding estimates based on probabilistic risk assessment reveal that support systems such as the service water system can significantly impact safety if attention is not given to assuring reliable operation.
In some instances, the service water system experience identified single failure vulnerabilities (seven plants) and prompt corrective actions were taken to rectify noncompliance with our existing requirements.
Based on the results of the AE00 case study, NRR is proceeding to develop a generic letter which would incorporate recomendations developed by AEOD and Region Il to reduce the frequency and severity of service water system failures and degradations. Additionallv s the lessons learned from operating experience related to service water system prrt.co are planned to be incorporated in the Individual Plant Examination program, d
To further enhance the feedback of operational experience, the AEOD c report will be published as a NUREG document.
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8808310184 000029 PDR ORO NCXD h
Multiple Addressees I would be pleased to provide any clarification or further information that you may desire.
WI'8TFsigMn yict or St,S4 Victor Stello, Jr.
Executive Director for Operations
Enclosure:
As Stated cc w/ enclosure:
SECY OGC GPA OSP ACRS NRR RES Regional Administrators Distribution:
PDR ROAB R/F AEDD R/F EJordan JHeltemes TNovak VBenaroya JRosenthal Plam KBlack MWilliams MTaylor JPartlow EDO R/F VStello
- See previous concurrences DSP:AE00 ROAB:DSP:
D:DSP:AE0D D:DSP:AE0D DD:AE0D D:AE0D EDQ3 Plam:as JRosenthal VBenaroys TNovak CHeltemes EJordan VStello 8/ /88*
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