ML20024E145

Supplemental LER 83-015/03X-1:on 830407,four Mechanical Snubbers Failed to Meet Tech Spec Surveillance Requirements. Caused by Oxidation,Mishandling,Environ Conditions & Design Flaws.Snubbers Repaired or replaced.W/830721 Ltr

ML20024E145
Person / Time
Site:	Salem
Issue date:	07/13/1983
From:	Frahm R, Zupko J Public Service Enterprise Group
To:	Murley T NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
LER-83-015-03X, LER-83-15-3X, NUDOCS 8308090277
Download: ML20024E145 (5)

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(7 771 LICENSEE EVENT REPORT

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REPORT oATE EVENT DESCRIPTION AND PROBABLE CONSEQUENCES O'o g lOn April 7, 1983, during a. routine refueling, 4 mechanical snubbers failed to meet  ;

o 3 l Technical Specification Surveillance Requirement 4.7.9c. The snubbers were located on ;

y lthe Safety Injection and Main Steam Systems and were all small bore devices of the same; gg manufacture. SubsequenttestinginaccordancewiththeTechnicalSpecificationrevealef l

o 6 l5 more degraded small bore devices. The event constituted possible operation in a l g , l degraded mode per Technical Specification 6.9.1.9b. g Iolal l l

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44 CAUSE DESCRIPTION AND CORRECTIVE ACTION: 27 R lThe failed snubbers were returned to the manufacturer for analysis. One snubber failed l l

l @ ldue to oxidation, ti'e rest were attributed to mishandling, environmental conditions, l i 7 land possible snubber design. Evaluation revealed no adverse impact on the supported l 3 3 l systems. The snubbers were repaired or replaced as necessary. Investigation of l i 4 l possible system design improvements is underway. l 7 8 9 30 sTANs* sPowEn oTwEa status @ oiss$ny' oiscovEnv oEscairtioN Surveillance Testing h

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• NAME OF PREPARER

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'_ lPublic' Service Electric and Gas Company P.O. Box E _ Hancocks Bridge, New Jersey 08038 Salem Generating Station -

July.21,-1983

-Dr. Thomas E. Murley Regional Administrator

-USNRC Region-1.

-631 Park-Avenue.

-King of Prussia, Pennsylvania 19.406

Dear Dr. Murley:

-LICENSE NO.LDPR-75.

DOCKET NO. 50-311-REPORTABLE OCCURRENCE 83-015/03X-1 SUPPLEMENTAL REPORT Pursuant to the requirements of Salem Generating Station Unit'No.,2 Technical Specifications, Section 6.9.1.9.b, we are submitting supplemental Licensee Event Report for Reportable-Occurrence 83-015/03X-1.

Sincerely yours, o - Wy 0 J. M. Zupko, Jr.

General Manager -

Salem Operations RF:ks)hf.'

CC:- Dis tribu' tion I

The Energy People 4l f4 7189 (20M) 1181 '

R'epor{ Number:-

83-015/03X-1 Report Date: 13-83

' Occurrence Date: 04-07-83

' Facility: '

Salem Generating Station Unit 2 Public Service Electric &-Gas Company Hancock's Bridge, New Jersey 08038 IDENTIFICATION OF OCCURRENCE:

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. Plant Systems - Mechanical Snubbers - Inoperable.

This report was initiated by-Incident Reports83-066 and 83-070.

CONDITIONS PRIOR TO OCCURRENCE:

- Mode 6 - RX Power 0 % - Unit load 0 MWe.

DESCRIPTION OF OCCURRENCE:

On April 7,1983, during a routine shutdown for refueling, :results of testing of.2 mechanical snubbers in accordance with Technical

- Specification Surveillance Requirement 4.7.9c revealed that the snubbers did not meet test acceptance criteria. The snubbers included one device on the Safety Injection System and another on the' Main

' Steam Drain System (Nos. 2A-SISN-105A and 2P-MSDSN-1003). Testing was performed by'Wyle Laboratories, Huntsville,LAL.

Results of additional testing received from Wyle Laboratories on-

-April 22, 1983, revealed 2 more snubbers had failed the functional tests. Both snubbers were on the Safety Injection System (Nos.

2P-SISN-104 and 2C-SISN-9). In accordance with the Technical Specifications, an additional 10% of the snubbers were tested, with the sample skewed towards.the smaller bore devices.

Five additional devices failed'the testing, including Nos. 2C-SISN-12,-

2C-SISN-14,.2A-MSA-SN-157, 2A-MSA-SN-158, and 2C-SISN-10. The snubbers were all on the Safety Injection and Main Steam Systems.

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- All snubbers which failed were small bore mechanical devices and were of the same manufacture (Pacific Scientific Co. - 1 PSA-1/2 model,'8 PSA-1/4'models). Operability of the snubbers is not necessary in Mode

- 6 since the Safety Injection and Main Steam Systems are not required to_be operable. No events initiating. unusual dynamic loading of the

,: ' systems involved had been noted during previous operation.

i  : Engineering evaluation of the impact of the-failures showed-that the.

ettached piping was not impaired as the result of the inoperability of

- the devices. This was the first testing of the devices following

plant'startup in October 1981.

APPARENT CAUSE OF OCCURRENCE:

The devices were returned to the manufacturer for determination of the i failure mechanism. Oln disassembly of the PSA-1/2 snubber, a reddish-brown, glue-like_ substance was found sticking to the inertia mass. A a

.. . . . _ _ . . _ , , , _ , _ . , . _ , . _ . _ , _ . - . , . . , - _ _ . - _ - , _ _ . . _ _ . _ . . _ . . . - . - _ . . ~ . _ _ ~ . ,

LERJ83-015/03X-1 APPARENT CAUSE OF OCCURRENCE: (cont'd)

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. ice ~cond snubber contained water inside.the device. The ball screw chaft was found bent on 5 anubbers, the torsion rod was bent on

• another,cand theLrod and-bearing assembly-was twisted on the ninth

. device. ,

The failure-of the'PSA-1/2: snubber.was+ attributed to oxidation whereas

mishandling, environmental conditions, and possible snubber design iwere-considered' responsible for-the damage to the remaining 8 devices.

'It is recognized in the industry that the small size model. snubber;is c

vulnerable to such damage.

ANALYSIS OF OCCURRENCE:

l Operability of snubbers on safety-related systems is required to ensure that the structural integrity.of^the systems is maintained during and following a seismic or other~ event-initiating dynamic loads. Operability of the Safety Injection System, as an Emergency j i

. Core Cooling System (ECCS) subsystem ensures that. sufficient emergency core cooling capability will be available in the event of a LOCA, assuming the loss of one subsystem-in accordance with single failure criteria. Each ECCS. subsystem provides long term core cooling

. . capability in the-recirculation mode. Snubbers attached to Main Steam

. System piping provide support for the Reactor Coolant System.

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! When a snubber is found inoperable, an engineering evaluation is i performed, in addition to the determination of the snubber mode of failure, in. order to determine if any safety related. component or system has been. adversely affected. The evaluation specifically shall

!~ determine whether or not the mode of failure has imparted a significant effect or. degradation on the supported component or system. .The inoperability of a snubber does not of itself imply

inoperability of the component or. system, and'the failures do not necessarily. involve any risk to the health or safety of'the public, i As noted, the mode of failure of each device was determined and ~

l ovaluation.showed no. adverse impact of-the failures on:the attached l systems. Also no events initiating unusual dynamic load were ~

involved. The occurrences therefore involved no undue' risk to the health'or safety of the public. Due to the possibility of operation in a degraded mode permitted by a limiting condition for operation,

, the. event is-reportable in accordance-with Technical Specification ~

6.9.1.9b.

CORRECTIVE ACTION:

.As stated additional' testing, determination of the failure mechanism and:evalutation of.'inoperability were performed as required by the <

Technical Specifications. All failed devices were repaired and Tsatisfactorily^ tested (with the exception of two' snubbers which were beyond; economical repair - these' devices were. replaced with new units). All snubbers were properly reinstalled in accordance with a controlled: work package. _

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. CORRECTIVE ACTION: (cont'd)

Further investigation of the failures in co-ordination with the canufacturer is being conducted. Consideration of the possible replacement of the devices with improved mechanical snubbers or rigid

+

aupports is also underway. Appropriate action will be taken upon completion of these efforts.

FAILURE DATA:

Pacific Scientific Co.

Small-bore Mechanical Snubbers

-Models PSA 1/4 and PSA 1/2 Prepared By R. Frahm f ). ( 'T# ~

S' V General' Manager -

SORC Meeting No.89-094 I

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