ML18059A681

LER 93-013-01:on 930427,loss of Onsite AC Power Due to Both Emergency Diesel Generator Simutanously Inoperable.Caused by Electrical Distribution Grid.Corrective Actions:Electrical Section revised.W/940210 Ltr

ML18059A681
Person / Time
Site:	Palisades, Rensselaer Polytechnic Institute
Issue date:	02/10/1994
From:	Hillman C, Slade G CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-93-013, LER-93-13, NUDOCS 9402280016
Download: ML18059A681 (5)

Text

consumers Power GB Slade General Manager

• l'OWERINli MICHlliAN'S l'ROliRESS Palisades Nuclear Plant: 27780 Blue Star Memorial Highway, Coven, Ml 49043 February 10, 1994 Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 DOCKET 50-255 - LICENSE DPR PALISADES PLANT - LICENSEE EVENT REPORT 93-013-01 ~ LOSS OF EMERGENCY ONSITE AC POWER DUE TO BOTH EMERGENCY DIESEL GENERATORS BEING SIMULTANEOUSLY INOPERABLE - SUPPLEMENTAL REPORT Licensee Event Rep_ort (LER) 93-013-01 is attached. This _supplemental* report adds information gained as the result of our review of events which occurred during the past two years and had the potential to be similar to the event reported in LER 93-013. The review revealed that one other event related to simultaneous diesel generator i noperabil ity similar to the event reported in.

. LER 93-013 occurred in 1992 and was not reported to the NRC in accordance with 10CFR50.73. As discussed with the Palisades Senior Resident Inspector, a separate LER will not be generated for this 1992 event sjnce it is included in this supplemental LER.

This event was reported in accordance with 10CFR50. 73 ( a)(2)( i )(B) as a condition prohibited by plant technical specifications in that both emergency diesel generators were simultaneously inoperable.

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Gerald* B Slade /f General*Managef CC Administrator, Region Ill, USNRC NRC Resident Inspector - Palisades Attachment

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LICENSEE EVENT REPORT (LERI I

I FACILITY NAME 11 I DOCKET NUMBER 121 PAGE 131 Palisades Plant 015101010121515 1 I OF 0I 4 TITLE 141 LOSS OF EMERGENCY ONSITE AC POWER DUE TO BOTH EMERGENCY DIESEL u~N~ .l.\JlC:i Ot. l.l'l\:J SIMULTANEOUSLY [NOPERABLE - :lJPPT.FMFN'l' 11 T Dt PffR'T' EVENT DATE 161 LER NUMBER 181 REPORT DATE 181 OTHER FACILITIES INVOLVED 181 SEQUENTIAL REVISION FACILITY NAMES MONTH DAY YEAR YEAR NUMBER NUMBER MONTH DAY YEAR N/A 0161010101 I 014 217 9 3 91 3 011 13 011 0 12 l IO 914 N/A ol61ololol I THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR I: ICh<<k ON.,,.,,,;,,. of IN following/ 1111 POWER OPERATING MOOE 181 N

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NRC Form 388AI LICENSEE CONTACT FOR THIS LER 1121 NAME TELEPHONE NUMBER Cris T. Hillman, Staff Licensing Engineer sARr,Cl°Es COMPlETE ONE LINE FOR EACH COM.PONENT FAILURE DESCRIBED IN THIS REPORT 1131 I 7 I 6 I 4 I -I 8 I 9 I 1 I 3 MANUFAC* REPORTABLE MANUFAC* REPORTABLE CAUSE SYSTEM COMPONENT TUR ER TO NPROS CAUSE SYSTEM COMPONENT TUR ER TO NPROS 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 I I I SUPPlEMENTAL REPORT EXPECTED 1141 MONTH DAY VEAR EXPECTED

- - , YES Vf y... c_,.~ EXPCTED SUBMISSION DATE! h-i ABSTRACT IJjm;t to 1400 - * *

• i.e., .,,,,roxinwtely fifteen aingl.--* typewritten liM*I I 181 NO SUBMISSION DATE 1161 I I I On April 27, 1993, at 0428 hours0.00495 days <br />0.119 hours <br />7.07672e-4 weeks <br />1.62854e-4 months <br />, with the plant operating at 100% kower, diesel 3enerator {DG) 1-1 was test started and loaded to approximately 500 Wprior to removing G 1-2 from service to gerform preventive maintenance. After ap~roximately 5 minutes of operation, the load on G 1-1 dropped to zero and DG 1-1 was dee ared inoperable. In accordance with our technical specifications, DG 1-2 was started and loaded to verify operability; however, by ~aralleling DG 1-2 to the electrical. distribution grid to accept load, DG 1-2 was a so .rendered inoperable for a ~eriod of five minutes.

Therefore, both DGs were simultaneously inoperable, Tee nical Specification 3.0.3 (plant shutdown within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />) was entered, and an Unusual Event was declared in accordance with our emergency operating procedures.- ,.

The cause of this event was paralleling DG 1-2 to the electrical distribution grid and rendering it inoperable while DG 1-1 was also inoperable. Paralleling DG 1-2 was determined to be necessary to verif~ there was no common mode failure and to ensure DG 1-2 operability~ A similar event w ich occurred in 1992 and was not reported to the NRC is discussed in the body of this LER.

• Corrective action for this includes submitting a revision to the electrical section of our technical specifications which will emulate the NUREG 1432, "Standard Technical Specifications for CE Plants," electrical section.

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U.S. NUCLEAR REGULATORY COMMISSION 19*83)

Al'PROVEO OMS NO. 3160-0104 EXPIRES: 8/31 /86 LICENSEE EVENT REPORT (LERI TEXT CONTINUATION FACILITY NAME 111 DOCKET NUMBER 121 LER NUMBER 131 PAGE 141 SEQUENTIAL REVISION YEAR NUMBER NUMBER Palisades Plant - 0 11 OF 014 EVENT DESCRIPTION On April 27, 1993, at 0428 hours0.00495 days <br />0.119 hours <br />7.07672e-4 weeks <br />1.62854e-4 months <br />; with the plant operating at 100% power, diesel generator [EK] (DG) 1-1 w*s test started prior to removing DG 1-2 from service to gerform preventive maintenance as required by Palisades Technical Specification 3.7.2i.

iesel generator 1-1 was successfully started and loaded to approximately SOOKW. After approximately 5 minutes of operation, the control room operator observed that the load on DG 1-1 was dropping from SOOKW. The.cont~o1 room operator atte~pted to restore load but could not. The control room DG "ra1se 11m1t" alarm actuated w1th zero KW on DG 1-1.

The control room operator then opened the DG 1-1 output breaker.

In accordance with Tech~ital Specification 3.7.2i, with DG 1-1 inoperable, DG 1-2 ~ust be started to verify ORerability and then shutdown, with the controls left in the automatic mode. Therefore, OG 1-2 was started as required. In addition, OG 1-2 was paralleled to the electrical distribution grid to verify the DG wquld accept and maintain an electrical load to assure that no common mode failure existed for the two diesel generators. This was considered necessary to assure operability as required by Technical Specification 3.7.2i. . .

By paralleling DG 1-2 to the Irid, .DG 1-2 was rendered inoperable in accordance with our Standard Operating Procedure SOP) 22, "Emergency Diesel Generators." When a OG is

• paralleled to the grid, the D is incapable of performing its intended safety fu~ction.

Therefore, while DG 1-2 was in the parallel mode, both DGs were simultaneously inoperable. There is no action statement in the Palisades Technical Specifications for both diesel generators being simultaneously inoperable, therefore, the plant implemented the requirement of Technical Specification 3.0.3, and an Unusual Event (UE) was declared in accordance with Emergency Implementin~ Procedure (El) 1, "Activation of the Site Emergency Plan/Emergency Classification. The UE was declared at 0428 hours0.00495 days <br />0.119 hours <br />7.07672e-4 weeks <br />1.62854e-4 months <br /> .on April 27, 1993 because of the loss of on-site emergency AC power. The UE was terminated five minutes later at 0433 when DG 1-2 was declared operable after it was no longer paralleled to the elettrical distribution grid. The pl~nt also exited the Technical Specification 3.0.3 action requirement.

• This event is reportable in accordance with 10CFR50.73(a}{2)(i)(B) as a condition *

• prohibited by plant technical specifications in that both emergency diesel generators were simultaneously inoperable. *

• _

CAUSE OF THE EVENT.

The cause of this event was paralleling DG 1-2 to the electrical distribution grid and rendering it inoperable while DG 1-1 was also inoperable. Paralleling DG 1-2 was determined to be necessary to verify there was no common mode failure and to ensure DG 1-2 operability.

ANALYSIS OF THE EVENT Palis~des Standard Operating Procedure (SOP} 22, "Emergency Diesel Generators," provides direction to the operators concerning d1ese1 generator test start in~ and electrical -

loading. In that procedure, the operators are given options regard1ng the starting and loading of a diesel generator depending upon whether or not one of the DGs is inoperable. DG 1-1 had been successfully started to verify operability and was being electrically loaded when it failed. Jn accordance with the technical specifications and

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NRC F0<m 388A U.S. NUCLEAR REGULATORY COMMISSION 19-831 APPROVED OMB NO. 3160-0104 EXPIRES: 8/31 /86 LICENSEE EVENT REPORT (LERI TEXT CONTINUATION FACILITY NAME 111 DOCKET NUMBER 121 LER NUMBER 131 PAGE 141 SEQUENTIAL REVISION YEAR NUMBER NUMBER Palisades Plant ol 1 I 3 - o I1 QI J OF the procedure, the opposite. DG (DG 1-2) was started to verify operability. Since DG 1-1 failed when it was accepting electrical load, the operators followed SOP 22, Step 4.1.lc, which requires that DG 1-2 be test started, paralleled to the electrical

• distribution grid, electrically loaded, and declared inoperable. In accordance with SOP 22, Step 4.1.lc.2, DG 1-2 was declared inoperable because it was paralleled to the grid.

Therefore, with DG 1-1 inoperable because it failed to maintain electrical load and DG 1-2 inoperable because it was paralleled to the electrical distribution grid, both diesel generators were simultaneously inoperable. . * .

For this event, the operators could not confirm whether the inability of DG 1-1 tb maintain load was a diesel generator problem or an electrical distribution system

• problem, therefore, simply starting DG 1-2 would not have verified its operability. In this instance, starting and loading of DG 1-2 was procedurally required to verify that a common mode failure did not exist.

Subsequent investigation as to the cause of the DG 1-1 failure determined that the fuel oil booster pump had experienced excessive wear. The wear on the fuel oil booster pump caused reduced pumping capacity and air intrusion into the pump casing, resulting in starving DG 1-1 as it became loaded. .

• NUREG 1432, "Standard Technical Specifications for CE Plants," Section 3.8.1 discusses diesel generator LCOs. In the "Required Actions" section, with one DG inoperable, the plant would have had 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to determine whether the second DG was inoperable because of a common mode failure. *Therefore, had Palisades implemented standard technical specifications, we would have had 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to perform the common mode failure testing, would not have entered the Technical Specification 3.0.3 action statement, and would not have a reportable occurrence. In addition, the Standard Technical Specifications allow for the (simultaneous) inoperability of two DGs, with a required action to restore one DG to operable status within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />. Again, had we implemented standard technical .

specifications, we would have had 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> to restore the second DG to operable status,

• would not have entered the Technical Specification 3.0.3 action statement, and would not have a reportable occurrence.

Safety Signifitanc~

The safety significance of this event is small because the operators were aware that DG 1-2 would be rendered inoperable by their actions, in accordance with SOP 22. The plant was in a stable, operating condition at the time of the event, and there were no

• unplanned acti~ities in progress. DG 1-2 had been verified operable with no apr.arent common mode failure, therefore, DG 1-2 could have been restored to an "operable' status in accordance with SOP 22.

CORRECTIVE ACTION A corrective action for this event is to submit a revision to the electrical section of the Palisades Technical Specifications. One of the changes that will be included is a revision to the action statement(s) regarding diesel generator operability which emulates NUREG 1432, "Standard Technical Sp~cifications for CE Plants," Section 3.8.1.

~R;:; Form 3e8A U.S. NUCLEAR REGULATORY COMMISSION (9-831 APPROVED OMB NO. 3160-0104 EXPIRES: B/31 /B6 LICENSEE EVENT REPORT (LERI TEXT CONTINUATION FACILITY NAME 111 DOCKET NUMBER 121 LER NUMBER 131 PAGE 141 SEQUENTIAL REVISION YE.AA NUMBER NUMBER Palisades Plant 011 13 011 0 I 4 OF 014 The cover l~tter to LER 93013 stated that we would review other potential Licensee Event Reports over the last two* years to determine if an NRC required report had been missed.

Our review revealed that one. other event related to simultaneous diesel generator inoperability occurred on May 6, 1992 and was not reported as required by 10CFRS0.73.

The event is summarized below:

• On May 6, 1992, during the performance of TSSP M0-7A-1, "Emergency Diesel Generator,"

DG 1-1 was declared inoperable because of voltage control problems. In accordance with SOP 22, DG 1-2 was test started, lo~ded onto its respective bus, and was also declared inoperable. Therefore, both DGs were simultaneously inoperabl~ and Technical Specificatiori 3.0.3 was ~ntered. * *

• The May 6, 1992 event was not reported to the NRC because an incorrect determination was made that thii ivent was a "planned evol~tion" and was, therefore, not reportable. The determination was apparently made without further review of 10CFR50~72 which clearly indicates that "pre-planned sequences" are applitable to ESF actuations. Although the starting of the EDG is considered an ESF actuation, rendering it inoperable and having a condition with both diesel generators simultaneously inoperable is not within the scope of that reporting condition; Guidance in Draft NUREG-1022, Rev. 1, pertaining to 10CFR50.72(b)(l)(ii) (which, althou~h it is draft guidance, is considered applicable for this event) indicates that entry into Technical Specification 3.0.3, or its equivalent, is a condition that is considered outside the bounds of the plant design basis and, therefore, a non-emergency one-hour report is required. A 30-day report is also required in accordance with 10CFR50.73(a)(2)(ii). . __

An additional corrective action resulting from the discovery of this second unreported event is that, beginning January 1, 1994, the plant Licensing group will review all corrective action documents for 10CFRS0.72 and 10CFRS0.73 reportability.

ADDITIONAL INFORMATION Licensee Event Report (LER) 93001 reported a similar occurrence of both diesel .

generators being simultaneous inoperable. The cause of the event reported in LER 93001 was personnel. error and is not related to the event reported herein.