ML20083B937

Special Rept:On 910823,D23 Emergency Diesel Generator Declared Inoperable While Plant Personnel Performed Troubleshooting Activities to Resolve Discrepancy Between D23 EDG Local & Remote Kw Meters

ML20083B937
Person / Time
Site:	Limerick
Issue date:	09/18/1991
From:	Doering J PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9109250272
Download: ML20083B937 (2)

Text

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T. S. 609.2 V- .

PHILADELPHI A El.ECTRIC COM PANY LIMERICK GENER ATING ST ATION P, 0, 00X A S AN ATOG A. PENNSYLV ANI A 19464 (215) 327 1200 r at. sooo Y.!l"J.".h/."' September 18, 1991 6.....................

Docket No. 50-353 License No. NPP-85 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555

SUBJECT:

Limerick Generating Station - Unit 2 Special Report for a Valid Emergency Diesel Generator Test Failure

REFERENCE:

Technical Specifications Section 4.8.1.1.3 and 6.9.2 This Special Report is submitted pursuant to the requirements of Technical Specifications (TS) Section 6.9.2 as required by TS Surveillance Requirement 4.8.1.1.3. TS Surveillance Requirement 4.8.1.1.3 requires reporting of all diesel generator failures, valid or nonvalid, within 30 days.

The report is required to include the information recommended in Regulatory Position C.3 b of Regulatory Guide (RG) 1.108, Revision 1, August 1977, " Periodic Testing of Diesel Generator Units used as Onsite Electric Power System at Nuclear Power Plants." .

On August 23, 1991, with Unit 2 at 100% power level, the  ;

D23 Emergency Diesel Generator (EDG) was declared inoperable l while plant personnel performed troubleshooting activitled to resolve a discrepancy between the D23 EDG local and remote Kilowatt (KW) meters. The discrepancy was identified on August 1 22, 1991 during the successful performance of Surveillance Test (ST) procedure ST-6-092-313-2, "D23 Diesel Generator Operability M Test Run." As part of the preplanned troubleshooting activities,

_co$$- the D23 EDG was started at 2220 hours0.0257 days <br />0.617 hours <br />0.00367 weeks <br />8.4471e-4 months <br /> on August 23, 1991 in

'g81 accordance with System (S) Procedure S92.1.0, " Local Remote oo Manual Startup of a Diesel Generator." After the D23 EDG had E$ been running for approximately 20 minutes, its electrical output gy became very erratic (i.e., load swings of 1400 KK reaching a ,

50 maximum electrical output of 3500 KW). The Main Control Room

$$ (MCR) operator immediately reduced load and secured the D23 EDG.

D23 EDG was then declared inoperable at 2245 hours0.026 days <br />0.624 hours <br />0.00371 weeks <br />8.542225e-4 months <br /> on August 23,

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H QC 6 1991. '

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• 1M On August 24, 1991, additional troubleshooting was j}

conducted to determine the cause of the erratic electrical output [.

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U. S. Nuclear Regulatory Commission- September 18, 1991 Page 2 on D23 EDG. This troubleshooting revealed that the erratic electrical output of D23 EDG could be reproduced by tapping the electronic governor. The electronic governor was removed for inspection by Instrumention and Control personnel, and all wiring and solder-joints were found to be satisfactory. Additionally, all physical connections were inspected and tightened as required. The electronic governor was then reinstalled. The D23 EDG was started and loaded to 1100 KW for two hours without

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incident. Tapping on the D23 EDG electronic covernor would not

. initiate an erratic electrical output response. Procedure ST-6-092-313-2 was successfully performed on August 25, 1991 and the D23 EDG was declared operable at 0325 hours0.00376 days <br />0.0903 hours <br />5.373677e-4 weeks <br />1.236625e-4 months <br /> on August 26, 1991. This event is considered not to be indicative of an adverse trend due_to this event being the first incident involving the electronic governor causing erratic electrical output.

The D23 EDG failure was classified as a valid failure using the guidance in Section C.2.e.6 of RG 1.108, Revision 1, August 1977. Because this event is the first valid failure for the D23 EDG, the ST procedure frequency is not required to be changed which conforms with TS Table 4.8.1.1.2-1 and Regulatory Position C.2.d of RG 1.108, Revision 1, August 1977. However, due to the inability to recreate the erratic electrical output after

-inspection of the electronic governor, D23 EDG operability test runs will be increased to weekly until four consecutive tests are completed with no similar electronic governor problems occurring.

The D23 EDG was out of service for approximately two days as a result of this event. The D23 EDG would not have been able to provide emergency power to the Division 3 Safeguard Bus wn11e it was out of service during this time period; however, the requirements of TS Action 3.8;1.1.a were satisfied by demonstrating the operability of the remaining three emergency A.C. sources through performance of surveillance requiremont 4.8.1.1 la within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. In the event of an actual loss of

.offsite power, the three operable Unit 2 EDGa would have provided adegaate A.C. power to reach the cold shutdown condition of the Unit 2 reactor.

Should you have any questions, please contact Mr. Gil J.

Madsen at (215) 327-1200.

Sincerely, ,e il I

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cc: T. T. Martin, Administrator, Region I, LJNRC T. J. Kenny, USNRC Senior Resident Inspector, LGS i