ML18051B092
| ML18051B092 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 09/21/1984 |
| From: | Heltemes C NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD) |
| To: | Harold Denton, Deyoung R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE), Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML18051B093 | List: |
| References | |
| AEOD-E423, NUDOCS 8410290114 | |
| Download: ML18051B092 (2) | |
Text
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September 21, 1984 MEMORANDUM FOR:
Richard C. *De Young, Di rector FROM:
SUBJECT:
Office of Inspection and Enforcement Harold R. Denton, Director Office of Nuclear Reactor Regulation Regional Administrators C. J. Heltemes Jr., Director Office for Analysis and Evaluation of Operational Data FAILURE OF LARGE HYDRAULIC SNUBBERS TO LOCK-UP AEOD/E423 An engineering evaluation report on failure of large, hydraulic snubbers to lock-up is enclosed.
The snubbers that failed were all attached to steam generators.
At Palisades, all 16 steam generator snubbers were determined to have been inoperable (would not lock-up) since initial operation of the plant more than 10 years ago.
Fufther investigation revealed that at least 13 plants have experienced similar snubber failures with snubbers supplied by five different manufacturers.
The primary safety issue is that failure of these large snubbers to perform their design function to restrain motion of large components during seismic or dynamic events could potentially result in an unanalyzed accident outside the plant design basis.
The causes for snubber failure to operate were determined to include deficien-cies over. a very broad spectrum of activities involving design, manufacture, functional qualif~cation, service aging, and inadequate surveillance.
The primary issue with service aging appears to be rubber seals that fail to retain hydraulic fluid after a period of seven years.~ However, it is evident that many failures were detected during the first tests conducted in response to new technical specification requirements implemented in the last two years at some plants.
In contrast, there are still 25 plants that have not imple-mented these new technical specifications and 23 of these plants have been in service for a time frame that equals or exceeds the snubber seal shelf life of seven years.
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NRC FORM 318 1101801 NRCM 0240 OFFICIAL RECORD COPY U.S. GPO 1983-400-247_
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-i M~ltiple Addressees As an initial effort, the Office of Inspection and Enforcement is requested to issue an information notice to promptly disseminate this information about these snubber failures.
Additionally~ we believe there should be agency consideration to expedite implementation of technical specification changes for those plants that have not yet responded to the generic letter on this subject (Reference 5 of the enclosed engineering evaluation report).
We understand this effort would involve the Office of Nuclear Reactor Regulation and the Regional Offices because each has responsibility in this area on a plant specific basis.
AEOD is also considering initiation of a case study.
However~ we believe there may be greater benefits *in terms of timely and effective action, as well as efficient use of resources, if the problem could be addressed by an industry group as a generic issue.
t~e suggest that the appropriate program offices consider such an approach to resolve this issue.
Enclosure:
As stated cc:
R. B. Minogue, RES bee w/encu:
NRG PDR v.
ROAB CF AEOD RF EBrown KSeyfrit Tippol ito CHe1temes Original Signed bYJ C. J. Heltemes, Jr,,
C. J. Heltemes, Jr., Director Office for Analysis and Evaluation of Operational Data 1.-
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