ML20204G295
| ML20204G295 | |
| Person / Time | |
|---|---|
| Site: | Vermont Yankee File:NorthStar Vermont Yankee icon.png |
| Issue date: | 03/19/1987 |
| From: | Hebdon F NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD) |
| To: | Jordan E NRC OFFICE OF INSPECTION & ENFORCEMENT (IE) |
| Shared Package | |
| ML20204G235 | List: |
| References | |
| AEOD-E702, NUDOCS 8703260374 | |
| Download: ML20204G295 (3) | |
Text
7' March 19, 1987 MEMORANDUM FOR:
Edward L. Jordan, Director Division of Emergency Preparedness AE0D/E702 and Engineering Response Office of Inspection and Enforcement FROM:
Frederick J. Hebdon, Deputy Director Office for Analysis and Evaluation of Operational Data
SUBJECT:
M0V FAILURE DUE TO HYDRAULIC LOCKUP FROM EXCESSIVE GREASE IN SPRING PACK A recently completed AEOD engineering evaluation report on cperational data involving motor operated valve (MOV) failure due to hydraulic lockup from excessive grease in the spring pack area of the motor operator is enclosed for your information and use. The available data is applicable to Limitorque SMB motor operators.
The evidence demonstrates that hydraulic lockup has occurred and is a potential common mode failure mechanism for SMB motor operators.
-Although the parameters and conditions that cause hydraulic lockup are not fully defined or understood, the phenomenon appears related to use of EXXON NEBULA EP-0 grease which is one of two environmentally qualified greases, and.
1 seems to be_the preferred choice. The situation can be separated into two broad categories involving: (1) motor operators that were manufactured prior to approximately 1975 that need a modification kit installed to provide an external grease relief path; and (2) motor operators manufactured after 1975 that have implemented a design change to provide an internal grease relief path to prevent lockup. There appears to be a lack of awareness throughout the industry about the need for the modification kit in the earlier motor operators.
In addition, there also appears to be a lack of awareness that hydraulic lockup has occurred even in motor operators in which a design change (internal grease relief path) had been implemented to prevent such a response.
Because hydraulic lockup represents a common mode.ailure mechanism and in light of the confusing circumstances, it is recommended that IE issue an information notice to alert licensees about the phenomenon and provide a description of the events.
By separate letter, we plan to notify INP0 and NUMARC about the earlier dissemination of inaccurate information in the INP0 SER and request industry coordination to develop appropriate corrective action to alleviate hydraulic lockup. The information areas of concern include l
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identification of which type of grease (EXXON rather than Mobil) was associated with the hydraulic lockup events and operating experience that provides evidence to illustrate the design change with the internal grease relief path may not be adequate to prevent hydraulic lockup under all conditions. Thus, the guidance in the SER about the design change " negating the need for the modification kit" appears to be inaccurate and it could mislead licensees about the possible need for corrective action.
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l If you have any questions regarding the enclosed report, please contact Earl J. Brown of my staff.
Dr. Brown can be reached on x24437.
YeNdon,DeputyDirector Frede Office for Analysis and Evaluation of Operational Data
Enclosure:
DISTRIBUTION:
As stated
~ AE0D"SF ROAB CF Wlanning cc w/ enclosure:
EBrown FHebdon CJHeltemes T. Guynn, OCM J. Sniezek, DEDR0GR H. Thompson, Jr., NRR F. Miraglia, NRR R. Bernero, NRR
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T. Speis, NRR V. Rooney, NRR R. E. Martin, NRR T. Wambach, NRR M. Beaumont, W C. Brinkman, CE R. Borsum, B&W L. Gifford, GE R. Lopriore, VY D. Taylor, VY J. Osmond, VAEC P. Johnson, YAEC D. Warsing, Limitorque P. McQuillan, Limitorque B. Curry, PE J. Milito, PE B. Burdette, TVA B. Sparks, TVA R. Anderson, TTC G. Arlotto, RES B. Grimes, IE
- SEE PREVIOUS CONCURRENCE OFC
- ROAB
- ROAB:SC *
- ROAB:BC *
- AE0 :DD
_____:______"______:____________:____________:__J_______:____________:________
NAME :EBrown:nc
- MChiramal
- SRubin
- FH bdon DATE :3/ 5 /87
- 3/ 6 /87
- 3/ 6 /87
- 3/ii/87 OFFICIAL RECORD COPY
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,. If you have any questions regarding the enclosed report, please contact Earl J. Brown of my staff. Dr. Brown can be reached on x24437.
Freder N M ' Deputy Director Office for Analysis and Evaluation of Operational Data
Enclosure:
DISTRIBUTION:
As stated PDR AE0D CF MChiramal AE00 SF ROAB CF WLanning cc w/ enclosure:
EBrown FHebdon CJHeltemes T. Guynn, OCM J. Sniezek, DEDROGR H. Thompson, Jr., NRR F. Miraglia, NRR R. Berriero, NRR T. Speis, NRR V. Rooney, NRR R. E. Martin, NRR T. Wambach, NRR M. Beaumont, W C. Brinkman, UE R. Borsum, B&W L. Gifford, GE R. Lopriore, VY D. Taylor, VY J. Osmond, YAEC P.-Johnson, YAEC D. Warsing, Limitorque P. McQuillan, limitorque B. Curry, PE J. Milito, PE B. Burdette, TVA B. Sparks, TVA R. Anderson, TTC G. Arlotto, RES B. Grimes, IE OFC :ROAB e /)
- ROAB:SC'r
- ROAB:BC AEOD:DD 4p NAME :EBrow :nc
- MChiramal i :SRubin M,FHebdon
_____:____________:____________:_______V____:-___________:____________:____________:
DATE :3/ f/87
- 3/6/87
- 3/(o/87
- 3/ /87 OFFICIAL RECORD COPY l'
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