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UNITED STATESNUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATIONWASHINGTON, D.C. 20555

December 14, 1993

NRC INFORMATION NOTICE 93-96: IMPROPER RESET CAUSES EMERGENCY DIESELGENERATOR FAILURES

Addressees

All holders of operating licenses or construction permits for nuclear powerreactors.

- Purpose

The U.S. Nuclear Regulatory Commission (NRC) is issuing this informationnotice to alert addressees to the potential for an emergency diesel generator(EDG) to fail to start on demand or to trip during operation due to improperexecution of the reset operation at the conclusion of the previous run. It isexpected that recipients will review the information for applicability totheir facilities and consider actions as appropriate to avoid similarproblems. However, suggestions contained in this information notice are notNRC requirements; therefore, no specific action or written response isrequired.

Description of Circumstances

H.B. Robinson

In August of 1987 at the H.B. Robinson plant, startup trips occurred on theKA" EDG. With the assistance of a vendor representative, several steps weretaken in an effort to preclude such trips, including replacement of thegovernor, replacement of the governor oil, replacement of sticky fuelinjection pumps, checking of injection pump timing, and rebalancing fuel racksettings. In February of 1988, startup trips were again experienced. It wasconcluded, after detailed inspection of the latch mechanism parts, that therewas a possibility of wear on the tip of the latch, which may have been acontributing factor to the trips. These parts were replaced with new parts.

On June 3, 1992, during the performance of a test activity, the TAw EDGtripped on mechanical overspeed after the engine had been operatingapproximately one half hour. After detailed consideration of possiblescenarios for the trips and considering prior actions taken, it was determinedthat the most probable cause was a failure to properly reset the tripmechanism after the previous run. It was concluded that operations personnelapparently were unaware of the importance of moving the reset lever throughits full travel. In addition, resettirg was difficult for shorter individualsdue to the location of the reset lever, which is positioned over the exhaust

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<-N 93-96December 14, 1993Page 2 of 3

manifold. Operations personnel were subsequently trained on the proper methodfor actuating the reset lever. Also, a step was provided to permit easieraccess to the lever.

Duane Arnold

On June 11, 1993, while the Duane Arnold plant was operating at 85 percent offull power, the 'A" EDG tripped approximately 3 seconds after the initialstart signal during an operability surveillance test. An evaluation wasconducted by the licensee of possible EDG trip causes, including occurrence ofan actual overspeed condition, failure of the overspeed mechanism, actuationof the emergency stop pushbutton, failure of the emergency stop pushbutton,latch assembly not fully latched, latch assembly failure, mechanical tripmechanism failure, and annunciator circuit or trip lever microswitch failure.It was concluded that the most probable cause of the trip was that the latch

--assembly was not fully engaged from the previous reset operation and enginestartup vibration unlatched the trip mechanism. Less than complete engagementof the latch assembly could be caused by an inadequate reset operation.Corrective actions adopted by the licensee included procedure revisions toensure a more positive latching operation, improved physical access to thereset lever, and operator training.

The procedure revision directs operators to perform the reset operation asecond time following the initial resetting of the trip. The second reset issomewhat easier to perform and should ensure that the latch is fully engagedin the event that the initial latching sequence resulted in a partiallylatched condition. Verification that the latch is fully seated isaccomplished by checking that the reset lever subsequently moves freely.

Discussion

In response to experience with previous trips during fast starts, the dieselmanufacturer for both plants, (Coltec/Fairbanks Morse Engine Division), hadpreviously issued a service information letter (SIL, Volume A, Issue 25, datedAugust 1, 1991) addressing a revised overspeed trip adjustment. The SILrecommended that the overspeed trip setting be raised from the range of 112 to115 percent to the range of 115 to 117 percent. In light of events thatoccurred at H.B. Robinson and Duane Arnold, the manufacturer has now advisedthese licensees that proper resetting of the trip mechanism would be enhancedby slowly moving the reset lever fully to the reset position and back, twice.The inadvertent partial reset latching operations described above may alsooccur on other units having similar mechanical trip mechanisms.

- IN 93-96December 14, 1993Page 3 of 3

This notice requires no specific action or written response. If you have anyquestions about the information in this notice, please contact one of thetechnical contacts listed below or the appropriate Office of Nuclear ReactorRegulation (NRR) project manager.

Brian K. Grimes, DirectorDivision of Operating Reactor SupportOffice of Nuclear Reactor Regulation

Technical contacts: Larry(404)

Garner, RII331-4663

Chris(319)

G. Miller,851-5111

RIII

Walter P. Haass, NRR(301) 504-3219

Attachment:List of Recently Issued NRC Information Notices

Att'achmentIN 93-96December 14, 1993Page 1 of 1

LIST OF RECENTLY ISSUEDNRC INFORMATION NOTICES

Information Date ofNotice No. Subject Issuance Issued to

93-93

93-92

91-21,Supp. 1

89-77,Supp. 1

93-91

Storm-Related Loss ofOffsite Power Eventsdue to Salt Buildupon Switchyard Insulators

Unauthorized ForcedEntry into the Pro-tected Area at ThreeMile Island Unit 1 onFebruary 7, 1993

Inadequate Control ofReactor Coolant SystemConditions During Shutdown

Plant Improvements toMitigate Common Depend-encies in ComponentCooling Water Systems

Inadequate QualityAssurance Program ofVendor SupplyingSafety-Related Equipment

Debris in ContainmentEmergency Sumps andIncorrect ScreenConfigurations

Misadjustment BetweenGeneral Electric 4.16-KVCircuit Breakers and TheirAssociated Cubicles

12/13/93

12/09/93

12/08/93

12/07/93

12/07/93

12/03/93

12/03/93

All holders of OLs or CPsfor nuclear power reactorslocated close to a largebody of salt water.

All holders of OLs or CPsfor nuclear power reactors.

All holders of OLs or CPsfor nuclear power reactors.

All holders of OLs or CPsfor nuclear power reactors.

All holders of OLs or CPsfor nuclear power reactorsand all recipients ofNUREG-0040, license Con-tractor and Vendor Inspec-tion Status Report' (WhiteBook).

All holders of OLs or CPsfor nuclear power reactors.

All holders of OLs or CPsfor nuclear power reactors.

. OL = Operating LicenseCP - Construction Permit

IN 93-96December 14, 1993Page 3 of 3

This notice requires no specific action or written response. If you have anyquestions about the information in this notice, please contact one of thetechnical contacts listed below or the appropriate Office of Nuclear ReactorRegulation (NRR) project manager.

Brian K. Grimes, DirectorDivision of Operating Reactor SupportOffice of Nuclear Reactor Regulation

Technical contacts: Larry(404)

Garner, RII331-4663

Chris(319)

G. Miller,851-5111

RIII

Walter P. Haass, NRR(301) 504-3219

Attachment:List of Recently Issued NRC Information Notices

*SEE PREVIOUS CONCURRENCE

OFFICE VIB/DRIL* | REGION III* REGION II* VIB/DRIL* VIB/DRIL*

NAME WHaass CHiller LGarner UPotapovs LNorrholm

DATE 09/09/93 09/09/93 08/30/93 09/10/93 09/15/93

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OFFICIAL RECORD COPY WULUMMNT NAME: VJ-V0.1N

IN 93-XXDecember xx,Page 3 of 3

1993

This notice requires no specific action or written response. If you have anyquestions about the information in this notice, please contact one of thetechnical contacts listed below or the appropriate Office of Nuclear ReactorRegulation (NRR) project manager.

Brian K. Grimes, DirectorDivision of Operating Reactor SupportOffice of Nuclear Reactor Regulation

Technical contacts: Larry Garner, RII(404) 331-4663

Chris(319)

G. Miller, RIII851-5111

Walter P. Haass, NRR(301) 504-3219

Attachment:List of Recently Issued NRC Information Notices

*SEE PREVIOUS CONCURRENCE

OFFICE VIB/DRIL* REGION III* REGION II* VIB/DRIL* | VIB/DRIL*

NAME WHaass CMiller LGarner I UPotapovs LNorrholm

DATE 09/09/93 09/09/93 08/30/93 09/10/93 09/15/93

TECH ED* DRIL/NRR* FEEKB/NRR* OGCB/DORS* C:OGCB DORS* |D:DORS/NRR

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IN 93-XXNovember xx,Page 3 of 3

1993

This notice requires no specific action or written response. If you have anyquestions about the information in this notice, please contact one of thetechnical contacts listed below or the appropriate Office of Nuclear ReactorRegulation (NRR) project manager.

Brian K. Grimes, DirectorDivision of Operating Reactor SupportOffice of Nuclear Reactor Regulation

Technical contacts: Larry Garner, RII(404) 331-4663

Chris(319)

G. Miller, RIII851-5111

Walter P. Haass,(301) 504-3219

NRR

Attachment:List of Recently Issued NRC Information Notices

r III.1,*SEE PREVIOUS CONCURRENCE

OFFICE VIB/DRIL* REGION I* REGION II* VIB/DRIL* VIB/DRIL*

NAME WHaass CMiller LGarner UPotapovs LNorrholm

DATE 09/09/93 109/09/93 08/30/93 09/10/93 9/15/93

TECH ED* DRIL/NRR* EEKB/NRR* OGCB/DORS* C:OGCB/DORS D:DORS/NRR

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IN 93-XXOctober xx, 1993Page 3 of 3

This notice requires no specific action or written response. If you have anyquestions about the information in this notice, please contact one of thetechnical contacts listed below or the appropriate Office of Nuclear ReactorRegulation (NRR) project manager.

Brian K. Grimes, DirectorDivision of Operating Reactor SupportOffice of Nuclear Reactor Regulation

Technical contacts: Larry Garner, R11(404) 331-4663

Chris G. Miller, RIII(319) 851-5111

Walter P. Haass, NRR(301) 504-3219

Attachment:1. List of Recently Issued Information Notices

*SEE PREVIOUS CONCURRENCE

OFFICE VIB/DRIL* REGIONX* REGION II* VIB/DRIL* VIB/DRIL*

NAME WHaass CMiller LGarner UPotapovs LNorrholm

DATE 09/09/93 09/09/93 08/30/93 09/10/93 09/15/93

TECH ED* DRIL/NRR* | EEKB/NRR* |OGCB/DORS C:OGCB/DORS D:DORS/NRR

DGable CERossi CBerlinger PCWen10| GHMarcus BKGrimes

09/14/93 09/20/93 10/21/93 1 11/10/93 11/ /93 11/ /93OFFICIAL RECORD COPYDOCUMENT NAME: INEDGST.wen

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IN 93-XXOctober xx, 1993Page 3 of 3

This notice requires no specific action or written response. If you have anyquestions about the information in this notice, please contact one of thetechnical contacts listed below or the appropriate Office of Nuclear ReactorRegulation (NRR) project manager.

Brian K. Grimes, DirectorDivision of Operating Reactor SupportOffice of Nuclear Reactor Regulation

Technical contacts: Larry Garner, RII(404) 331-4663

Chris G. Miller, RIII(319) 851-5111

Walter P. Haass, NRR(301) 504-3219

Attachment:1. List of Recently Issued Information Notices

*SEE PREVIOUS CONCURRENCE

OFFICE VIB/DRIL* REGION I* REGION II* VIB/DRIL* VIB/DRIL*

NAME WHaass CMiller LGarner UPotapovs LNorrholm

DATE 09/09/93 09/09/93 08/30/93 1 09/10/93 09/15/93

TECH ED* DRIL/NRR* J EEKB/NROM OGCB/DORS C:OGCB/DORS D:DORS/NRR

DGable CERossi CBerlinger PCWen GHMarcus BKGrimes

09/14/93 09/20/93 10/13/93 10/ /93 10/ /93 10/ /93OFFICIAL RECORD COPYDOCUMENT NAME: INEDGST.wen

IN 93-XXOctober xx, 1993Page 3 of 3

Discussion

The staff is continuing its review of the above events with the manufacturerof the diesel engines, Coltec/Fairbanks Morse Engine Division, to arrive at amore detailed and consistent set of procedures to assure a positive latchingoperation. In addition, it should be noted that other diesel enginemanufacturers may have similar mechanical trip mechanisms, and licenseesshould be aware that potential inadvertent partial reset latching operationsmay also occur on those units.

This notice requires no specific action or written response. If you have anyquestions about the information in this notice, please contact one of thetechnical contacts listed below or the appropriate Office of Nuclear ReactorRegulation (NRR) project manager.

Brian K. Grimes, DirectorDivision of Operating Reactor SupportOffice of Nuclear Reactor Regulation

Technical contacts: Chris G. Miller, RI at Duane Arnold(319) 851-5111

Larry Garner, R11(404) 331-4663

Walter P. Haass, NRR(301) 504-3219

Attachment:1. List of Recently Issued Information Notices* SEE PREVIOUS CONCURRENCE

OFFICE VIB/DRIL REGION I REGION II VIB/DRIL VI5/YOL

NAME WHaass CMiller LGarner UPotapovs 1; R holm

DATE 9 / 9/93* 9/9/93* 8/30/93* 9/10/93* l C//) /93

COPY YES NO YES NO YES NO YES NO 6 NODOC

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IN 93-XXOctober xx, 1993Page.4 of 3

Attachment:

1. List of Recently Issued Information Notices

* SEE PREVIOUS CONCURRENCE

OFFICE VIB/DRIL REGION I REGION II VIB/DRIL VIB/DRIL

NAME WHaass CMiller LGarner UPotapovs LNorrholm

DATE 9 / 9/93* 9/9/93* 8/30/93* 9/10/93* / /93

COPY YES NO YES NO YES NO YES NO YES NO

DOC

OFFICE TECH EDITOR DRIL/NRR OGCB/NRR EELB/NRR DORS/NRR

NAME a 44, CERossi GMarcus CBerlinger BGrimes

DATE 7 / 9 / /93 / /93 / /93 / /93

COPY YES NO YES NO YES NO YES NO YES NO

DOC

U-II IEODCP DouetNm:G\NDSOFFICIAL RECORD COPY Document Name: G:\INEDGST

IN 93-XXOctober xx, 1993Page 3 of 3

Discussion

The staff is continuing its review of the above events with the manufacturerof the diesel engines, Coltec/Fairbanks Morse Engine Division, to arrive at amore detailed and consistent set of procedures to assure a positive latchingoperation. In addition, it should be noted that other diesel enginemanufacturers may have similar mechanical trip mechanisms, and licenseesshould be aware that potential inadvertent partial reset latching operationsmay also occur on those units.

This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please contactone of the technical contacts listed below or the appropriate Office ofNuclear Reactor Regulation (NRR) project manager.

Brian K. Grimes, DirectorDivision of Operating Reactor SupportOffice of Nuclear Reactor Regulation

Technical contacts: Chris G. Miller, RI at Duane Arnold(319) 851-5111

Larry Garner, RII(404) 331-4663

Walter P. Haass, NRR(301) 504-3219 a.?

Attachment:1. List of Recently Issued Information Notices '� CL1-e

OFFICE VIBDRIL E VIBD VIB/DRIL

NAME WHaass amfil F 4It _f arne r A UPot V LNorrholm

DATE 9/ 9/93 ?9//93 93 / /93 93/ /93

COPY Y NO E NO Y NO YE NO YES NOD o c_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

OFFICE DRIL/NRR OGCB/NRR EELB/NRR DORS/NRR

NAME CERossi GMarcus CBerlinger BGrimes

DATE I /93 I /93 I /93 I /93

COPY YES NO YES NO YES NO YES NODO .J__ __ _ _ _ _ _ _ _ ___ ., __ __ __ _ _ . ___________A _ _ i_ __ _ _ _ _ _DO-CIA EODCP ouetNm:G\NDS

MFICIAL RECORD COPY Document Name: 6:\INEUGST