ML19269C724
| ML19269C724 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 02/02/1979 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| Shared Package | |
| ML19269C725 | List: |
| References | |
| NUDOCS 7902120129 | |
| Download: ML19269C724 (1) | |
Text
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UNITED STATES
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NUCLEAR REGULATORY COMMISslON k,.h M I. h RELION V O
1 SUlTE 202. W ALNUT CHEEK PLAZ A s
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1990 N. CALIFORNIA DOULEVARD
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WALNUT CREEK. CALIFORNI A 94596 February 2,1979 Docket fio. 50-312 Sacramento Municipal Utility District P. O. Box 15830 Sacramento, California 95813 Attention: Mr. John J. Mattimoe Assistant General Manager Gentlemen:
This Information Notice is provided as an early notification of a possibly significant matter.
It is expected that recipients will review the information for possible applicability to their facilities.
No specific action or response is requested at this time.
If further NRC evaluations so indicate, an IE Circular or Bulletin will be issued to recommend or request specific licensee actions.
If you have questions regarding this matter, please contact the Director of the appropriate NRC Regional Office.
Sincerely, el k R. H. Engelken Director
Enclosures:
1.
IE Information Notice No. 79-01 2.
List of IE Information Notices Issued in 1979 cc w/encls:
R. J. Rodriguez, SMUD L. G. Schwieger, S!;UD 780212Ol89
UilITED STATES IlVCLEAP REGULATORY COMMISSI0tl OFFICE OF IllSPECTIO!1 Arid ErlFORCEMEllT WASHIllGT0il, D. C.
20555 February 2, 1979 IE Information flotice tio. 79-01 BERGEti-PATERS 0il HYDRAULIC SHOCK AllD SWAY ARREST 0RS (HSSA)
On December 4,1978, Rancho Seco fluclear Generating Station reported t
the failure of seven Bergen-Paterson HSSA (Snubber) units to lockup in the compression direction and the failure of one additional unit to lockup in the extension direction. These failures were identified during surveillance testing and the affected models included HSSA-3-6 HSSA-10-6 and HSSA-20-5.
When the units were disassembled, the licensee observed damage to the poppet valve and seat on the compression side of the valve blocks of the seven units that failed in the compression direction.
It was also observed that five of the seven units had the poppet spring entrapped between the poppet and the seat.
The licensee attriauted the seven failures in the compression direction to abusive handling during compression of the units for installation following testing at the previous refueling outage.
The cause of the single failure in the extension direction has not been determined.
In addition to exercising greater care in reinstallation, the licensee committed to functionally test all Bergen-Paterson snubbers subjected to transient conditions which cause either physical damage to or significant movement of piping. This testing will include verification of piston movement, lockup and bleed. The Bergen-Paterson Technical Maintenance Manual j
recommends that additional inspections should be made on units which may have participated in an unusual shock occurrence involving known damage to piping or equipment.
On January 3. 1979, the licensee reported that the decay heat removal system had
.en subjected to a transient condition in the form of a
" water h auer."
This transient, caused pipe movement great enough to damage two rigid pipe support wall attachments.
The subsequent functional testing of the affected Bergen-Paterson units revealed that one of seven units failed the lockup test.
This unit (Model flo. HSSA-3-6) was disassembled and damage to the poppet valve and seat was observed.
The damage to the poppet valves is presently being reviewed by both the licensee and Bergen-Paterson.
At this time, the cause of damage has not been completely defined nor has appropriate corrective action been determined. Other licensees have reported instances of poppet valve damage; however, the cause and extent of damage are not known at this time.
Pdge l Of 2 ed9f
.7002120059
IE Information Notice No. 79-01 February 2, 1979 This information is provided as an early notification of a possibly significant matter.
It is expected that recipients will review the information for possible applicability to their facilities. No specific action or response is requested at this time.
If further UR; evaluations so indicate, an IE Circular or Bulletin will be issued to recommend or request specific licensee actions.
If you have questions regarding this matter, please contact the Director of the appropriate NRC Regional Office.
Page 2 of 2
IE Information flotice No. 79-01 February 2,1979 LISTIflG 0F IE IriFORMATION fiOTICES ISSUED Ill 1979 Information Subject Date Issued To Notice No.
Issued An Information flotice is a new method of connunicating items of potential interest to licensees. This item, Information flotice No. 79-0',, is the first of this new form of ccmmunication.
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