05000318/LER-1979-007-03, /03L-0 on 790212:snubber 2-83B-2,21 Main Steam Isolation Valve Hydraulic Supply Sys,Inoperable.Caused by Slightly Bent Piston Rod.Snubber Replaced

/03L-0 on 790212:snubber 2-83B-2,21 Main Steam Isolation Valve Hydraulic Supply Sys,Inoperable.Caused by Slightly Bent Piston Rod.Snubber Replaced

ML19282B160
Person / Time
Site:	Calvert Cliffs
Issue date:	03/01/1979
From:	Davis S, Miernicki M BALTIMORE GAS & ELECTRIC CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML19282B156	List: 05000318/LER-1979-007, Forwards LER 79-007/03L-0 05000318/LER-1979-007-03, /03L-0 on 790212:snubber 2-83B-2,21 Main Steam Isolation Valve Hydraulic Supply Sys,Inoperable.Caused by Slightly Bent Piston Rod.Snubber Replaced
References
LER-79-007-03L, LER-79-7-3L, NUDOCS 7903090175
Download: ML19282B160 (2)

LER-1979-007, /03L-0 on 790212:snubber 2-83B-2,21 Main Steam Isolation Valve Hydraulic Supply Sys,Inoperable.Caused by Slightly Bent Piston Rod.Snubber Replaced

Event date:
Report date:
3181979007R03 - NRC Website

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Et E N' OATE 74 75 REFORT O ATE se EVE *.T OESCH.PTION AND P AOB A8tE CONSECLENCES h oI: ! At 1345 it was discovered that snubber 2.838-2 (21 man steam isolation I

o,3 l valve Hydraulic supoly system) was not coerable as recuired by T.S. 3.7.3.1 l

0 14 I due to a bent piston rod. The snubber was repaired and returned to service 1

Iat 1120 on 2-15-79.

All other snubbers in the system remained coerable

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0l 21 22 23 24 26 27 28 29 30 31 32 ACTION FUTURE EFFGCT SHUTDOWN ATTACHVENT NPRO-4 PRIVE COMP.

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l 7lg 33 34 36 37 40 41 42 43 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h l Snubber 2-838-2 was discovered to have a slightly bent piston rod. See j

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NAr.*Ecr[nE=AqE; S. M. Davism. J. Miernicki 301 234-7942/7960 2

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LER 79-07/31 LICENSE NO. CPR-69 DOCKET NO. 50-318 E '. NT DATE 02-12-79 REPORT DATE 03-01-79 ATTACHMENT CAUSE DESCRIPTION AND CCRRECTIVE ACTIONS:

(CONTINUED)

Snubber 2-838-2 was discovered to have a slightly bent piston rod at the point where the rod is threaded into the rod eye on the pipe clamp. This snubber was re:ently relocated under design modification FCR 78-1023. The bent rod was determined to be the result of the pipe clamp not being sufficiently tightened arcund the MSIV hydraulic supply line during this modification.

Pioe shock loading and thermal growth following the installation caused the pipe clamo to move to a point where subsecuent loading and growth damaged the snubber rod. The snubber itself remained operable in that it was able to stroke through its designed range; however, it could not effectively perform under possible seismic loadi:1gs since the configuration of the support was al tered. The snubber was therefore declared inocerable. This snubber was replaced with a qualified spare, and the support returned to the designed configuration with the pipe clamp torqued. All other snubbers on the MSIV hydraulic supply lines for both units were inspected and found to be operable.

Personnel who conduct acceptance inspections of modifications involving snubbers have been advised to examine for proper tightness of pipe clamps.

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