U-601931, Special Rept:On 920109,diesel Generator 1A Tripped Due to Reverse Power.Caused by Improper Manual Loading Following Synchronization W/Offsite Power.Dg 1A Manually Started to Demonstrate Operability Per Surveillance Procedure 9080.01

Special Rept:On 920109,diesel Generator 1A Tripped Due to Reverse Power.Caused by Improper Manual Loading Following Synchronization W/Offsite Power.Dg 1A Manually Started to Demonstrate Operability Per Surveillance Procedure 9080.01

ML20092A734
Person / Time
Site:	Clinton
Issue date:	02/05/1992
From:	Spangenberg F ILLINOIS POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
U-601931, NUDOCS 9202100261
Download: ML20092A734 (3)

Text

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RE.100c February 5, 1992 10CTR50.36 Docket No. 50 461 Document Control Desk

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Subjecti Special Report

Non valid Test Failure of Division 1 Ri e e cl _Ee ne r a t o r a t C1 i n t orJ.cy31.Aat10fL_(GH) -

Dear Sir:

CPS Technical Specification 4.8.1.1.3 requires all diesel generator failures valid or non valid, be reported to the Nuclear Regulatory Connaission (NRC) pursuant to Technical Specification 6.9.2, SpECIAl.

rep 0RTS,,within thirty days. Due to-a-trip of the Division 1 Diesel Generator (DGIA) during surveillance testing on January 9,1992, this Special~ Report is~being submitted in accordance with CPS Technical Specification 4.8.1.1.3 to provide the.information required by Regulatory cuide 1.108,--Revision 1, *Porlodic Testing of Diesel Generator Units Used as Onsite Electric Power Systems at Nucioar Power Plants", Regulatory Position C.3.b.

Rascription'of Event At approximately 1525 hours0.0177 days <br />0.424 hours <br />0.00252 weeks <br />5.802625e-4 months <br /> on January 9.1992, DG1A was manual j started to demonstrate its operability por survol11ance procedure 9080.01, " Diesel cenerator 1A (IB) Operability.Hanual". During thu surveillance test, DGIA reached the-required oltage'and frequency within the time specified by the Technical Specifications. . llowever. -at

, 1528 hours0.0177 days <br />0.424 hours <br />0.00253 weeks <br />5.81404e-4 months <br /> inunediately following synchronization of D01A with offsite power and closure of the output breaker. DCIA tripped due to reverse

-power. DGIA was declared inoperable. At 1533 hours0.0177 days <br />0.426 hours <br />0.00253 weeks <br />5.833065e-4 months <br />, D01A's output-

-breaker was reset.

At 1709 hours0.0198 days <br />0.475 hours <br />0.00283 weeks <br />6.502745e-4 months <br />,tDGIA was manually' started to confirm ltho suspected cause-of the reverse power trip. DGIA'was successfully synchronized with ofinite power at.1716 hours0.0199 days <br />0.477 hours <br />0.00284 weeks <br />6.52938e-4 months <br /> and run at full load for_approximately 19 minutes without any abnormalitics noted. The successful--maintenance run confirmed that the reverse power trip of Do1A was caused by improper As a manual', loading result it:was following concluded synchronization'with that DCIA had been restored offsite-power; to operable status

.at 1533 hours0.0177 days <br />0.426 hours <br />0.00253 weeks <br />5.833065e-4 months <br /> when its output breaker-was reset.

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=At 1849 hours0.0214 days <br />0.514 hours <br />0.00306 weeks <br />7.035445e-4 months <br />, DGIA was manually started to demonstrate its operability per surveillance procedure 9080.01. DGIA was successfully syn:hronized with offsite power and fully loaded. The surveillance test was successfully completed at approximately 2020 hours0.0234 days <br />0.561 hours <br />0.00334 weeks <br />7.6861e-4 months <br />. No difficulties were experienced in synchronizing or loading DG1A subsequent to the reverse power trip. As a result, it has been concluded that the reverse power trip was caused by operating error. In accordance with Regulatory cuide 1.108, Regulatory positie- C.2.e(2), this trip has been classified as a non valid failure.

Corrective Actio.ng As discussed above, the reverse power trip of DG1A has been attributed

, to operating tror. . Survcillanco procedure 9080.01 currently contains a caution statement wh.tch reminds the operator to be prepared to raise diesel generator load' to at least 200 KV iimnediately af ter diesel generator output breaker closure. loading the diesel generator immediately after closing its output breaker will prevent a reverse

. power trip.

Synchronizing and loading a diesel generator is a routine procedure but it does require n.certain degree of operator technique. Synchronizing the diesel generator involves: (1) adjusting the diesel generator's voltage with-its voltage regulator contro1' switch so that the diesel generator's output voltage in slightly lower than the offsite power voltage, (2) adjusting the diesel generator's speed with its governor control switch so-that the diesel generator's output frequency is slightly greater than .the off aite power frequency. and (3) closing the diesel . generator's output breal sr with its control switch as the synchroscope's pointer nears the vertical position and the synchronizing lamps become dark. Upon synchronization,'the diesel generator's load is then increased by adjuating the diesel generator's speed (i.e. ,

increasing the torque applied to the generator) using the governor control _ switch.. As stated above, load must be manually applied to the diesel generator immediately after closure of its output breaker in order to prevent " motoring" of the generator and the associated reverse power trip. At the same time, voltage regulator adjustments are also required to obtain the correct field excitation relative to the desired reactive loading / power factor. In this case, the manual load adjustment was.not mado quickly enough to prevent the reverse power trip.

The operator involved in this event is experienced and has successfully performed this evolution many times. In addition, as noted above,~the testing procedure currently contains a caution statement to remind the operator of this loading requirement. As a result, no further corrective action is considered necessary in response to this event.

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Igat Intervals The reverse power trip has been classified as a non valid failure. As of January 9,1992. DCIA had experienced six valid f ailures in the last 100 valid tests

• and one valid failure in the last twenty valid tests.

In accordance with CPS Technical Specification Table 4.8.1,1.2-1. DCIA continues to be tested at least once per 31 days.

This letter satisfies the requirements of CPS Technical Specifications 4.8.1.1.3 and 6.9.2 for submittin6 a Special Report for diesel generator failures.

Sincerely ours, 1

. . M fr it 'L4".b F. A. . iangent rg,111 Hanag' , Lice ing and l(}afety DAS/alg eci NRC Clinton Licensing Project ManaBer liRC Resident Office NRC Region III., ReSional Adtninistrator Illinois Department-of Nuclear Safety D

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. Per NRC letter ' dated l January 25, 1991, one particular test performed on May 15, 1990- is not included in this total.

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