ML20023D501

LER 83-012/03L-0:on 830406,while Performing Functional Testing of Hydraulic Snubbers,Snubber MS-209 Failed to Lock in Tension Direction.Caused by Damaged Piston Seal Ring. Snubber Overhauled & Tested Satisfactorily

ML20023D501
Person / Time
Site:	Three Mile Island
Issue date:	05/06/1983
From:	Szczech R GENERAL PUBLIC UTILITIES CORP.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20023D497	List: ML20023D496 ML20023D501
References
LER-83-012-03L-01, LER-83-12-3L-1, NUDOCS 8305200551
Download: ML20023D501 (3)

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REPORT DATE EVENT DESCRIPTION AND PRQsAsLE CONSEQUENCES h O lOn 4/6/83, while performing functional testing of hydraulic snubbers in accordanceI

,with surveillance procedure 1303-9.9 and T.S. 4.17.4, snubber MS-209 failed to lockj g ,in the tension direction. The snubber was not called upon to mitigate any dynamic l

,o,3, g loads from any postulated event. This item is considered reportable per T.S. [

g j6.9.2.B(4). Public health and safety were unaffected. I l

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CAUSE DESCRIPTION AND CORRECTIVE ACTIONS g l The snubber failed due to a damaged piston seal-ring which was discovered _j

, , i installed backwards. The snubber was overhauled and functionally tested I

, isatisfactorily. Ten additional snubbers will be functionally tested. Mainten- i I

g l ance personnel have -been trained on proper snubber repair and overhaul.

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NARRATIVE REPORT TMI-l LER 33-012 .

EVENT DATE - APRIL 6,1983 I. Current Activities at the Time of Occurrence Functional Testing of hydraulic snubbers in accordance with Surveillance Procedure 1303-9.9 was in progress.

II. Leadin g Circumstances While performing testing of hydraulic snubbers in accordance with SP 1303-9.9, snubber MS-209 would not lock up in the tension direction.

III. Description With the exception of approximately 30 days of Hot Functional Testing in early fall, 1981, the unit has been in extended cold shutdown conditions since April, 1979. The snubber was removed'for functional testing which was being performed to satisfy Technical Specification 4.17.4 requirements.

Upon functional test to determine "as found" operability, snubber MS-209 failed to lock up in the tension direction only. This item is considered reportable under Technical Specification 6.9.2.E(2).

IV. Resultant Events If the snubber became inoperable while the plant was not in cold shutdown during 1977-79 and HFT, the inoperable snubber could have caused an increase in the probability of structural damage to the piping, resulting from a seismic or other postulated event which initiates dynamic loads. However, since there has been no earthquake or severe transient which would have caused un-restrained pipe motion under dynamic loading there are no significant occurr-ences which have taken place as a result of the snubber f ailure.

V. Previous Events of Similar Nature:

Refer to License Event Reports 80-14, 78-12, 78-11, 77-8. .

VI. Root Cause Snubber G-209 failed to lock up due to a damaged piston seal-ring which was discovered installed backwards. The snubber was last rebuilt with new seals on 5/29/75 and satisfactorily passed a functional retest in Iby , 1977.

VII. Immediate Corrcctive Action The snubber was completely overha-led (all seals replaced), functionally tested satisf actorily and reinstal ed in plant.

Long Term Corrective Action

1) Pursuant to Technical Specifications, an additional 10 snubbers will be

functionally tested. ,

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2) All ten of the above snubbers will be selected from a group o,f snubbers which have not been removed for test or rep.ir, subsequent r_o the first quarter of 1978. ,

3) Maintenance personnel who are now performing snubber repairs have re-ceived training on proper snubber repair and overhaul.

VIII. Component Failure Data ITT Grinnell, Figure 201 Hydraulic Shock and Sway Suppressor - 4" x 5" Stroke Mark No. MS-209.

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