05000272/LER-1981-059, Supplemental LER 81-059/01X-01:on 810616,during Initial Testing,Auxiliary Feedwater Pump 23 Turbine Steam Supply Check Valves 21MS46 & 23MS46 Found Damaged Internally.Caused by Steam Flow Sys Oscillations

Supplemental LER 81-059/01X-01:on 810616,during Initial Testing,Auxiliary Feedwater Pump 23 Turbine Steam Supply Check Valves 21MS46 & 23MS46 Found Damaged Internally.Caused by Steam Flow Sys Oscillations

ML20087A203
Person / Time
Site:	Salem
Issue date:	02/24/1984
From:	Rupp J, Zupko J Public Service Enterprise Group
To:	NRC OFFICE OF ADMINISTRATION (ADM)
References
LER-81-059-01X, LER-81-59-1X, NUDOCS 8403080013
Download: ML20087A203 (4)

LER-2081-059, Supplemental LER 81-059/01X-01:on 810616,during Initial Testing,Auxiliary Feedwater Pump 23 Turbine Steam Supply Check Valves 21MS46 & 23MS46 Found Damaged Internally.Caused by Steam Flow Sys Oscillations

Event date:
Report date:
2722081059R00 - NRC Website

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, . LICENSEE EVENT REPORT CONTROL BLOCK: l 1

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D ATE 7 60 DOCKET NUMBER EVENT DESCRIPTION AND PROB ABLE CONSEQUENCES h l O l 2 l l On June 16, 1981, during initial testing of Unit 2, No. 23 Auxiliary Feedwater Pump l g

turbine steam supply check valve (23MS46) was found to be damaged internally. Investit ygy,,;gation revealed similar damage to 21MS46 and to Unit 1 valves (11 and 13 MS46). Promp}

9 , g notification was made to the Commission. All valves were repaired under the super- l lO l6 l l  !

g ,; g PSE&G to investigate and determine the cause. A monthly radiography program, for all l g g ,MS46 valves, was instituted until the cause was determined and corrected. l SYSTEM CAUSE CAUSE COMP. VALVE CODE CODE SUBCODE COMPONENT CODE SUBCODE SUBCODE m

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, , l application. The system flow oscillations have been substantially reduced, and I

, 3 l plans are being made to replace the valves with ones of a different design. I I

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NAME OF PREPARER

(5 jReport? Number: 81-059/01X-1

. Report ~Date: 02/24/84-Occurrence Date: 06/16/81 Facility: _ Salem Generating Station Unit 1 Public Service Electric & Gas Company Hancock's Bridge, New Jersey 08038 LIDENTIFICATION OF OCCURRENCE:

MainESteam System - 11MS46 and 13MS46 Checks Valves - Inoperable

' CONDITIONS PRIOR TO OCCURRENCE:

LMode 5 - Rx Power 000 5.- Unit Load 0000 MWe This report summarizes the events, subsequent investigations and corrective actions involving-the-inoperability of Unit 1 and Unit 2

' Turbine Steam Supply Check Valves (11MS46, 13MS46, 21MS46 and 23MS46)

-ossociated with No. 13 and No. 23 steam driven Auxiliary Feedwater Pumps. The ir.itial. reports were documented in Unit 1 LER 81-059/01T and. Unit'2 LER 81-035/01T.

11MS46 and 13MS46-(Unit 1) supply-steam from their respective main steam lines to No.'13 Auxiliary Feedwater Pump turbine, via 1MS132 and the. turbine governor valve. Unit 2 is similar in design,'with 21MS46 and .23MS46 supplying ' steam: from their respective main steam lines to No. 231 Auxiliary Feewater Pump turbine, via 2MS132 and the turbine governor-valve.

DESCRIPTION OF OCCURRENCE:

On June 16, 1981,- during' initial testing of. Unit 2, while repairing a bonnet 11eak.on check valve 23MS46, the valve was.found to be damaged internally.- The' valve disc stud was broken and the valve disc was lying in the bottom of the. valve body. Further inspection of the valve revealed. cracks in the. disc, cracked bushings, the hinge pin was twarped and the hinge pin holes were elongated. An inspection of 21MS46 revealed similar. damage.

Due(to the' damage observed on these valves, Unit 1 check valves were also inspected. . Valve 11MS46 had a warped-hinge pin and elongated

~ hinge pin holes.. Valve 13MS46 had cracked bushings, a warped hinge pin, a broken disc stud and' elongated hinge pin holes. Prompt

notification of-these' events were madeLto the USNRC Regional Administrator in'accordance with Technical Specification 6.9 1.8.e.

'A vendor representative from Velan Valve Corporation assisted-in the inspection of.thefvalves. Velan Field Service Report, by Jack W.

Kuhner, dated ' June '18,1981, documented the inspection results. Velan aupplied the necessary1 parts; the valves =were refurbished and returned

.to an operable status.1 An inspection program was instituted that required ~the-valves to be radiographed once a month until the failure

.nechanism could be-determined and corrected.

r LER 81-05 9/01X-1 DESCRIPTION OF OCCURREECE: (cont'd)

Bolt Beranek and Newman Inc. was retained by PSE&G to investigate and determine the cause and to make recommendations for its solution.

Extensive testing was conducted with assistance from the Engineering Department and station personnel. Their findings were documented in Report # 5401, by Bruce S. Murray, dated August 1983 APPARENT CAUSE OF_0CCURRENCE:

The investigation revealed that unstable operation of the turbine governor valves (at speeds of 3600 RPM and greater) resulted in pressure fluctuations in the path of the check valves. These pressure fluctuations caused the check valve discs to repeatedly hammer themselves against their limit stops. These violent oscillations ultimately led to the fracture and distortion of the valve internal components.

Pressure fluctuations also occur when the feed pumps are started. The pressure pulses during the starting sequence are amplified by the natural oscillation (organ piping) of the steam flow in the system.

These fluctuations also cause the check valves to hammer; however, these events occur less frequently and are clearly less severe, in regards to check valve damage, than those caused by the governor.

CORRECTIVE ACTION:

The governor valves were inspected, adjusted and lubricated. The governor stability was corrected. Subsequent testing has shown that the severity and number of check valve impacts has been substantially reduced.

Although check valve damage is still being experienced, the monthly radiography inspection of the MS46 valves has proven to be very offective in identifying potential problems with the valve internals.

This has afforded early detection and timely repairs to be effected, thus assuring a high degree of reliability. This inspection program will continue until the check valve performance has been determined to be satisfactory.

Because some check valve hammer occurs due to natural oscillations of cystem flow, an investigation is still in progress for possible ways to minimize these oscillations. In addition, Design Change Requests (1SC-0630 and 2SC-0631) are being formulated to replace the check valves with ones of a different design.

-FAILURE DATA:

Velan Valve Corp.

6" Check Valves Type B14-2114 B-2TS Prepared By J._Runo 74ner%1 Mansger -

Salem Operations SORC Meeting No.89-154

E O PSEG Public Service Electric and Gas Company P.O. Box E Hancocks Bridge, New Jersey 08038 Salem Generating Station February 24, 1984 U.S. Nuclear' Regulatory Commission

-Document Control Desk Washington,-DC 20555

~

Dear Sir:

LICENSE NO. DPR-70

-DOCKET NO. 50-272 REPORTABLE OCCURRENCE 81-059/0lX-1 SUPPLEMENTAL REPORT Pursuant to'the requirements of Salem Generating Station Unit No. 1 Technical Specifications, Section 6.9.1.8.e, we are submitting supplemental Licensee Event Report for '

Reportable Occurrence 81-059/0lX-1.

Sincerely yours, J. M. Zupko, Jr.

General Manager -

Salem Operations JR:kilp6p CC: Distribution V

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- The Energy People

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