ML20126M588

Special Rept SR-92-003:on 921207,EDG a Failed to Reach Rated Speed & Voltage in Less than or Equal to 10 S.Caused by Failure to Properly Secure Turning Gear Brackets.Control Brackets for Turning Gear Interlock Valves Adjusted

ML20126M588
Person / Time
Site:	Waterford
Issue date:	01/06/1993
From:	Packer D ENTERGY OPERATIONS, INC.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
SR-92-003, SR-92-3, W3F1-93-0105, W3F1-93-105, NUDOCS 9301110044
Download: ML20126M588 (6)

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D. F. Packer r,m y u n,y P!.VV,(p+ Ia! :V wa s cr3 W3F1-93-0105-A4.05 QA January 6, 1993 U.S. Nuclear Regulatory Commission Attn: Document Control Oesk Washington, D.C.

20555

Subject:

Waterford 3 SES Docket No. 50-382 License No. NPF-38 Reporting of Special Report Gentlemen:

Attached is Special Report Number SR-92-003-00 for Waterford Steam Electric Station Unit 3.

This Special Report is submitted per Technical Specifications 4.8.1.1.3 and 6.9.2 and Regulatory Guide 1.108.

Very truly ypur,

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Ge.1eral Manager - Plant Operations DfP/CJT/sst Attachment cc:

J.L. Milhoan, NRC Region IV G.L. Florreich' J.T. Wheelock - INPO Records Center R.B. McGehee N.S. Reynolds NRC Resident Inspectors Office Administrator - LRPO 9301110044 930106 PDR' ADOCK 05000392

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.c SI SPECIAL REPORT SR-92-003-REPORTABLE OCCURRENCE On December 7,1992, at 1304 hours0.0151 days <br />0.362 hours <br />0.00216 weeks <br />4.96172e-4 months <br />, Emergency Diesel Generator (EOG)_ ' A' was started per Operating Procedure OP-903-068 to demonstrate the operability of the diesel in 4 cordance with Technical Specification-(TS) 4.8.1.1.2.

The EDG started in 11.7 seconds.

The-TS requires that the EDG reach rated speed and voltage in less than or equal to 10 seconds. This event is classified as a valid failure in accordance with Regulatory Guide 1.108 and is reported in accordance with TS 4.8.1.1.3.

This failure is the third failure in the last 100 valid tests.

INITIAL CONDITIONS Plant Power:

100*4 Mode:

1 Procedures Being Performed Specific to this Event:

OP-903-068, "Emer9ency Diesel Generator And' Subgroup g

Relay Operability Verification" i

0P-903-115, " Train A Integrated Emergency Diesel Generator / Engineering Safety Features Test" Technical Specification LC0's in Effect Specific to this Event:

None Major Equipment Out of -Service Specific to this Event:

None

' #P EVENT DESCRIPTION On December 7,-1992, while performing the EDC 4'monthlhsurveillanceper.-

OP-903-068, the EDG failed to start-in less-t.ian or equal'toL10 seconds.

The EDG was declared inoperaele at 1304 hours0.0151 days <br />0.362 hours <br />0.00216 weeks <br />4.96172e-4 months <br /> and troubleshooting was' initiated to determine the cause. The turning gear-interlock-valves' control brackets were 'not properly positioned t'o depress the valves' plungers 1/8" as_ recommended by ;the Cooper-Bessemer vendor-manual. This

. condition prohibited' control air from passing through the right bank interlock valve and restricted flow through the -left bank interlock valve.

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Unrestricted flow through at least one interlock valve is required to achieve the less than or equal to 10 second start requirement.

EVENT CHRONOLOGY (dates and approximate times of occurrences)

October 28, 1992 1613 Installed new turning gear interlock valves EGA-303A and EGA-304A per Work Authorization (WA) 01101900. OP-903-ll5 Diesel

' A' Lockout test is satisf actorily performed to verify operability.

November 10, 1992 1330 EDG 'A' is manually started per OP-903-068.

The EDG starts in 5.8 seconds and carries load for 61 minutes.

November 19, 1992 1800 Installed new control air regulator, EGA-408A, per WA 01102906.

2041 OP-903-068 timed start is performed to verify operability.

The EDG starts in 9.75 seconds.

The start evaluation data sheet and an operator note of the slow start is forwarded to the operations clerk for transmittal to the System Engineer for evaluation.

December 7, 1992 1304 During Enginetred Safety Feature Actuation Signal (ESFAS)

Module Start per OP-009-002, EDG 'A' starts in 11.7 seconds.

The EDG is declared inoperable. The System Engineer is natified immediately.

1358 A troubleshoot ESFAS Test Module Start is performed to assess the cause of the late start. The EDG starts in 10.36 seconds.

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s-1422- - A second troubleshoot ESFAS-Test. Module Start -is performed.

The-EDG starts in 10.22 seconds.. It is observed that no airs is leaving the right bank air receiver._ WA 01103555 is-generated to determine the cause of:the problem.-

1500.While troubleshooting, it was determined that the turning gear interlock valves' control brackets (one per valve) were not fully depressing the valves' plungers. WA 01103555 was returned to maintenance planners-for additional instructions.

1755 The control brackets for the turning gear interlock valves are adjusted per WA 01103555. OP-903-115 Diesel 'A' Lockout Test-is performed. An ESFAS Test Module Start is performed per:0P-009-002.

The EDG starts in 6.05 seconds.

u; 2003 EDG 'A' is declared operable.

CAUSAL FACTORS Entergy Operations, Inc. believes-that the rcr cause of this event was the failure to properly secure the turning gear brackets _ thatf make contact with the turning gear interlock valve plungers.

Each bracket was secured

- to the turning-gear frame with two-5/16" bolts _and washers.- The washers-were found to be inappropriate in--that their outer diameters are smaller than' standard washers. This condition can_ result in poor surface area contact between the washers and-the bracket and facilitate slippage. The-inappropriate washers were only.found on EDG_'A'.

The washers:on EDG 'B' were' verified to'be standard size.

Furthermore, there is no vendor recommended torque' requirement-for the 5/16" bolts.. Consequently, the_

bolts were not; torqued.

Thus,.it appears that engine vibration caused the_ turning gear _ bracket to-slide during the successful start and load run on November 10, 1992.

These brackets must be positioned such that-they_ depress the plungers =of

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the turning gear: valves 1/8" with the turning gear fully diser 39ed. With

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the plungers in this position, control air passes through the interlock-valves and_ supplies the air start solenoid valves with' control-air.

Upon initiation of a start ~ signal, the starting ~ air solenoid valves open-and allow Control' air to open the air start valve which supplies starting air

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1 to the diesel.

l Additionally, a causal factor and a non-causal factor were identified.

The causal factor is that the inappropriate washers appeared to be those originally supplied with the diesel.

The non-causal factor is-that. no actions were taken to address the 9.i5 second start on November 19, 1992.

CORRECTIVE MEASURES The control brackets for the turning gear interlock valves were adjusted to assure that they depress the turning gear interlock valve plungers one-eight inch.

EDG

'A_' was successfully started in 6.05 seconds.

Condition

' Identifications (CIs) were initiated to assure that the turning gear interlock valve bracket bolts are properly torqued and that the bolts.are fitted with the proper size washers.

The Cooper-Bessemer drawing, KSV-55-2, will be revised to provide torque values-for_ the turning gear interlock _- valve bracket bolts.

System Engineering will evaluate.the method by which the EDG System Engineer-is notified of-EDG start times.

Furthermore, UNT-005-020, " Post' Maintenance Testing," will be reviewed and revised as-appropriate to provide additional guidance on the post maintenance tests that should.be perfonned following maintenance on EDG starting and control circuits. -These actions

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will be completed by April 30, 1993.

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-SAFETY SIGNIFICANCE-E This event is classified as a valid failure since EDG 'Adid not' reach v

L rated speed and voltage in'less than or equal to 10 seconds as required by

-the TS.

This failure is the third failure in the last 100 valid tests and f

the current surveillance test interval is at least once per 31 days. An 4

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.E ennineering evaluation of this event determined that the EDG would have'-

performed its safety function and that the health and safety'of the public:

-and plant personnel-were not compromised.

SIMILAR EVENTS No previous similar events were identified.

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