ML18057A981

LER 91-010-00:on 910224,unanticipated Start of 1-2 Diesel Generator Occurred During Performance of Special Test T-297, D/G 1-1 Load Reject. Event Caused by Inadequate Procedure.Procedures revised.W/910614 Ltr

ML18057A981
Person / Time
Site:	Palisades
Issue date:	06/14/1991
From:	Hillman C, Slade G CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-91-010, LER-91-10, NUDOCS 9106240346
Download: ML18057A981 (5)

Text

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consumers Power G BSlade Gelli!ral Manager

_POWERINli MICl/lliAN'S PROliRESS Palisades Nuclear Plant: 27780 Blue Star Memoria( Highway, Covert, Ml 49043

- June 14, 1991 Nuclear Regulatory Commission.

Document Control Desk Washington, DC 20555 DOCKET 50-255 - LICENSE DPR PALISADES PLANT *-

LER 91-010; EMERGENCY DIESEL GENERATOR UNANTICIPATED START DURING THE PERFORMANCE OF SPECIAL TEST T-297, "D/G 1-1 LOAD REJECT" Licensee Event Report (LER)91-010 (Emergency Dfesel Generator Unanticipated Start during the performance of Special' Test T-297, "D/G 1-1 Load Reject") is attached .. This event isc considered reportable under 10 CFR 50. 73(a)(2)(iv).

It stiould be noted that this LER is submitted greater that 30 days from the date of the event whi_ch is contrary to the requirements of 10 CFR :50. 73(a) (1).

The failure to report this event within the required 30 days is the subject of a-proposed violation and will be addressed in otir response to the proposed violation.

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Gerald B Slade General _Manager CC Administrator, Region III, USNRC NRC Resident Inspector, Palisades 1\

9106240346 910614 PDR ADOCK 05000255 A CMS /\IERGY COMPANY S Pni:;;,

NllC Fot111 . . U.1. NUCLEAll_ ltEGULATOflY C01911DION (9-83)

Al"l'llOVEO Olla NO. 3t 111-01 CM EXPlllEI: 1/31 /Ill .

LICENSEE EVENT REPORT CLER)

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ll0.731ellZIClll) I0.731111211*1 LICENSEE CONTACT fOR THll LER 1121 NAME TELEPHONE NUMBER AREA CODE Cris T Hillman, Senior Engineer 6 11(:> 7 1 61 4 - 1s 1 9 1 1 1 1

COMPL_ETE ONE LINE FOR EACH COMPONENT FAILURE DEICRllED IN THll llEPOllT 1131 CAUSE SYSTEM COMPONENT MANUFAC. SYSTEM COMPONENT MANUFAC.

TUR ER TUR ER

. I I *1 I I I I I I I I I I I I I I I I I I I I I I I I I IUPPLEMENTAL REPORT EXPECTED 1141 MONTH . DAY Y~AR EXPECTED

&UIMISSION I YES (If,,.., ~p/oro EXPECTED SUSMISSION DATE!

DATE (15)

I I I On february 24, 1991, at 0618 hours0.00715 days <br />0.172 hours <br />0.00102 weeks <br />2.35149e-4 months <br />, w*ith the Pl ant in cold shutdown, an unanticipated start of the 1-2 diesel generator occurred during the performance of Special Test T-297, "D/G 1-1 Load Reject". This test was being performed as a result of commitments made to Nuclear Mutual Limited (NML) regarding compliance with IEEE 387, Regulatory Guide 1.108 and Regulatory .

Guide 1.9 for diesel generator load rejection.

The cause of the event was an inadequ9.te procedure. No precautionary statement existed in the procedure to alert the operator that a diesel generator start may occur.

• The following corrective actions were assigned as a result of the analysis of this event:

I. Review electrical special test procedures and ~urveillance procedures to identify voltage transients which wi 11 cause diesel generator starts.* Revise procedur~s *as necessary,.

2. Replace relay 63x/LS-02P4 with a relay having a time delay such that it will ~ot actuate during a transfer of power sources to Y-01.

3. Replace PCX-02188. **

4. Review application of normally energized HFA relays on Y-01 with respect to Y-01 power transfer.

This event did not involve the failure of any systems or components.

NRC Form :lee 111-831

U.I '"UCLfAll llEGl.i~ATORV COM*llDIO..

LICENSEE EVENT REPORT (LERI TEXT CONTINUATION A""llOVEC Ca.II 1110 ll 50--01~

EXPIRES 8/J1 '115 PACILITV NAMI 111 DOCKET NU. .111121 Ll!ll N.....111111 ~AOI 131 Palisades Plant TEXT l / t - -

• _ . , , - _ . . NltC ........ .-..*a11171 EVENT DESCRIPTION On February 24, 1991, at 0618 hours0.00715 days <br />0.172 hours <br />0.00102 weeks <br />2.35149e-4 months <br />, with the Plant in cold shutdown, an unanticipated start of the 1-2.diesel generator [EK:DG] occurred during the performance of Special Test T-297, "D/G 1-1 Load Reject". This test was being performed as a result of commitments made to (NML) r~garding compliance with IEEE 387, Regulatory Guide 1.108 and Regulatory Guide 1.9.

_ The following test conditions were established for the performance of Special Test T-297:

• electrical bus 1-C was being powered by diesel generator 1-1 *with a load of approximately llOO KW Auxiliary feed pump P-8A was started as required by Special Test T-297.

immediately after the start of P-8A a voltage drop occurred causing the following events to take place: *

• Y-01 transferred from MCC~l to MCC-2

• diesel generator 1-2 started

• load shed.did not occur The final electrical load on bus 1-C following the event was approximately 1400 KW. In addition to the above events, the following plant responses were also observed:

• M0-2087, "volume control tank (VCT) outlet" closed (apparently due to a low~low level signal generated during the Y-01 transfer).

• M0-2160, "safety injection and refueling water (SIRW) to charging pumps" remained closed *

• with ch~rging pumps P-558 and P-55C oper~ting prior to the t~st, P-558 tripped (apparently on low suction pressure), however, P-55C continued to operate. (The control room operator re-opened M0-2087 to restore the suction path to the charging pumps.)

CAUSE OF THE EVENT The cause of the event was an inadequate procedure. No precautionary statement ~xisted in the procedure to alert the operator that a diesel generatrir start may occur.

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. 19-<!Jf LICENSEE EVENT REPORT ILEA) TEXT CONTINUATION ..,,... 011£0 OMll "0 Jls0.-0104 EXPl .. ES 8131 '85

'4CILITV NAMI 111 DOCKET NUMIEll IZI Ll!ll llfUMelll Ill '401 131 YEA" .. * .. :.,SIQUl .. TIAL E-. -],.11118IO"

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ANALYSIS OF THE EVENT in an effort td determine the root cause of the observed plant responses, the same test conditions that existed on February 24,* 1991 during the performance of Special Test T-297 were re-established to allow data gathering. One exception to the previous conditions was that the 1-2 diesel generator was started prior to beginning the test. *

• With the diesel generator 1-1 carrying bus 1-C and loaded to approximately 1150 KW, auxiliary feedwater pump P-8A was started. The diesel generator 1-1 output voltage immediately decreased to 83% of the starting value. This value

• is_ consistent with fhe 81% measured during Technical Specifications Surveillance Test RT-SC conducted on FebruilrY 22, 1991. Furthermo*re, a calculation (KEY-080983-1) performed by Power Resources and Systems Planning predicted a voltage drop to 77%. *

• The second level under voltage relays (127~7's) *dropped out as ~xpected and would have started the 1-2 Diesel Generator had it-not been running already.

The relays are set to actuate at 91.8% voltage with a 0.5 second time delay.

The undervoltage condition caused the Instrument AC* Bus (Y-01) to transfer to its emergency power supply. This is designed to occur at 85% voltage. The transfer of Y-01 from its normal power supply to its emergency-power supply is a break-before-make operation which de-energized Y-01 during the transfer.

The switch design is to transfer in 1/6 second (IO cycles). A manual transfer from the emergency source back to the normal source was timed and found to operate in zero cycles. However, the timer used tb measure-the transfer is designed to operate at zero voltage~ The conclusion is that the voltage on Y-

01. did not drop all the way to zero.

De-energizing Y:Ol also de-energized the 63x/LS-0204 relay. This relay causes the volume control tank (VCT) outlet valve (M0-2087) to close and the charging

• pump suctiori valv~ (M0-2160) from the Safety Injection and Refueling Water (SIRW) tank to open.

Troubleshooting of the open circuitry for M0-:2160 revealed that thevalve operated correctly. Jhe troubleshooting included actuation of relay 63x/LS-0204. The relay is normally energized with coritacts for both M0-2160 and M0-2087 open. During a transfer of Y-01, the relay de-energizes (not all the way to zero) and is 'immediately re-energized. Apparently the transient is quick enough that the contact for M0-2160 does not pick up the breaker operating coil.

During a typical momentary voltage dip scenario Y-01 is transferred twice; first to the emergency supply and, 30 seconds later, transfers back to the normal supply. While troubleshooting during the first transfer, the contact for M0-2087 did not pick up its breaker operating coil either. This was observed by the Shift Supervisor and confirmed by the Tennecomp Data Logger printout. However, both M0-2160 and M0-2087 operated correctly when relay 63x/LS-0204 was de-energized for anything longer than a transfer of Y-Ql.

This was confirmed by troubleshooting .

.. llC JOllM :IMA 111-131

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LICENSEE EVENT REPORT ILER) TEXT CONTINUATION *~ROI/EC Or.te ~o 3150--010.

EXPIRE~ 8/J1 '115

'ACILITY NAMI 111 DOCKET NUM9111 121 Liii NUll9111 111 ~AOI 131 YIAfll Palisades Plant 4 0 4.

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Qased on the results of the re-enactme~t of the events which occurred on February 24, 1991 it was concluded that:

1. The undervoltage condition should be expected when starting an auxiliary feedwater pump when diesel generator 1-1 is already carrying significant load. Diesel generator 1-2 will start, however, diesel generator 1-1 will recover voltage before load shedding occurs. * *

• 2. The instrument ac bus, Y-bl, will transfer*from its normal source to its emergency source upon sensing an undervoltage condition. The transfer will be fast, but not without an instrument ac voltage degradation. * *

. 3. The suction source sw~p for the charging pumps wtll occur if a volume control tank (VCT) lb-lo level exists. M0-2087 will close and M0-2061 will open.

4. A transfer of Y-01 will probably result in M0-2087 closing without having M0~2160 opening.

5. Charging pumps P-558 and P-55C will both trip on low suction pressure if their respective pressure setpoints are teached. P-558 might trip earlier thari it.is designed to trip.

This event is considered reportable under 10 CFR 50.73(a)(2)(iv) as an unanticipated .automatic actuation of an Engineered Safety Feature (ESF) .

. CORRECTIVE ACTION The following correcti~e actions were ~ssigned as a result of the analysis of this event: -

l.* Re~i~w elect~ical special test procedures and *surveillance procedures to identify voltage transients which will cause diesel generator starts. Revise procedures as necessary. (09/30/91)

2. Replace relay 63x/LS-0204 with a relay having a time delay such that it will not actuate during a transfer of power sources to Y-01.

(03/05/91) COMPLETE

• ~ 3. Replace PCX-02188. (03/05/91) COMPLETE 4~ Review application of normally energized HFA relays on Y-01 with respect to Y-01 power transfer. (12/01/91)

ADDITIONAL INFORMATION NONE