ML17286A371

LER 90-020-00:on 900917,util Determined Overheating of Control Cabinet Could Cause Diesel Generator Failure. W/901017 Ltr

ML17286A371
Person / Time
Site:	Columbia
Issue date:	10/17/1990
From:	John Baker, Washington S WASHINGTON PUBLIC POWER SUPPLY SYSTEM
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GO2-90-176, LER-90-020, LER-90-20, NUDOCS 9010260175
Download: ML17286A371 (16)

Text

ACCELERATED DIS "BUTION DEMONSTIW. ON SYSTEM REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR

9010260175 DOC.DATE: 90/10/17 NOTARIZED: NO DOCKET ¹ FACIL:50-397 WPPSS Nuclear Project, Unit 2, Washington Public Powe 05000397 AUTH. NAME AUTHOR AFFILIATION WASHINGTON,S.L. Washington Public Power Supply System BAKER,J.W. Washington Public Power Supply System RECIP.NAME RECIPIENT AFFILIATION

SUBJECT:

LER 90-020-00:on 900917,util determined overheating of control cabinet could cause diesel generator failure.

DISTRIBUTION CODE: IE22T COPIES RECEIVED:LTR I ENCL TITLE: 50.73/50.9 Licensee Event Report (LER), Incident Rpt, etc.

U SIZE:

NOTES:

RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD5 LA 1 1 PD5 PD 1 1 ENG,P.L. 1 1 INTERNAL: ACNW 2 ACRS 2 2 AEOD/DOA 1 AEOD/DSP/TPAB 1 1 AEOD/ROAB/DSP 2 NRR/DET/ECMB 9H 1 1 NRR/DET/EMEB 7E 1 NRR/DLPQ/LHFBll 1 1 NRR/DLPQ/LPEB10 1 NRR/DREP/PRPB11 2 2 NRR/DST/SELB 8D 1 NRR/DST/SICB 7E 1 1 NRR/DST/SPLB8D1 1 NRR/DST/SRXB 8E 1 1 m8! H"- RES/DSIR/EIB 1 1 RGNS FILE 01 1 EXTERNAL EG6tG BRYCE I J ~ H 3 3 L ST LOBBY WARD 1 1 NRC PDR 1 1 NSIC MAYSiG 1 1 NSIC MURPHY I G A ~ 1 1 NUDOCS FULL TXT 1 1 NOTE TO ALL "RIDS" RECIPIENTS:

PLEASE HELP US TO REDUCE WASTE! CONTACT THE DOCUMENT CONTROL DESK, ROOM P 1-37 (EXT. 20079) TO ELIMINATEYOUR NAME FROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED!

FULL TEXT CONVERSION REQUIRED TOTAL NUMBER OF COPIES REQUIRED: LTTR 32 ENCL 32

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E ( QP Y J. D. Arbuckle 988U A. G. Hosier 968 G. C. Sorensen 280 J. W. Baker J. Barbee R: B. Barmettlor 927M 988U 1022 L; B. Hutchison R. E. Matthews C. H. HcGi lton 9270 988U 9568 R. J.

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Talbert Tupper 988U 325 S. 'L. Washington 988U H. L. Westergren 1022 R. N. Cabral J. P. Chasse .

944A 280 S. L. HcKay H. M. Honopoli 9270 1020 Docket File '68 G ~ L. Gelhaus 988U A. L. Oxsen 1023 Ops File 1313.1 927S E. HE Godfrey 1023 J. F. Peters 927S LER File 988U R. G.*Graybeal 927K J. E. Powers 927S. JDA/LB 988U K. H. Gunter 988U G. 0. Ray 1020 JWB/LB 927M

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956B L. T..Harrold 981G S. L. Scammon 988U NCR No. 290-

'ocket No. 50-397, G02-90-176 October 17, 1990 Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555

Subject:

NUCLEAR PLANT NO. 2 LICENSEE EVENT REPORT NO.90-020

Dear Sir:

Transm'itted herewith is Licensee Event Report No,90-020 for the WNP-2 Plant. This report is submitted in response to the report requirements of 10CFR50.73 and discusses the items of reportability, corrective action taken, and action taken to preclude recurrence.

Very truly 901017 yours,'010260175 PDR ADOCK 05000397 S PNU J.,W. Baker (H/0 927M)

WNP-2 Plant Manager JWB: lr Enclosur'e:

Licensee Event Report No.90-020 cc: Hr: John B. Hartin, NRC Region V Mr. C. Sorensen, NRC Resident Inspector (N/0 901A)

INPO Records Center Atlanta, GA Hs. Dottie Sherman, ANI Hr. D, L. Williams, BPA (N/0 399)

NRC Resident Inspector walk over copy E

SL Washin ton g g/g pcw+~~gqgy: JW. Baker

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FOR AttSOVALOF equi s LT Harr ld

0 WASHINGTON PUBLIC POWER SUPPLY SYSTEM P.O. Box 968 ~ 3000 George Washington Way ~ Richland, Washington 99352 G02-90-176 Docket No. 50-397 October 17, 1990 Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555

Subject:

NUCLEAR PLANT NO. 2 LICENSEE EVENT REPORT NO,90-020

Dear Sir:

Transmitted herewith is Licensee Event Report No.90-020 for the WNP-2 Plant.

This report is submitted in response to the report requirements of 10CFR50.73 and discusses the items of reportability, corrective action taken, and action taken to preclude recurrence.

Very truly yours, J. . Baker (N/D 927N)

WNP-2 Plant Nanager JWB:lr

Enclosure:

Licensee Event Report No.90-020 cc: Nr. John B. Nartin, NRC Region V Nr. C. Sorensen, NRC Resident Inspector (N/0 901A)

INPO Records Center Atlanta, GA Ns. Dottie Sherman, ANI Nr. D. L. Williams, BPA (N/D 399)

NRC Resident Inspector walk over copy 9<~/@~

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NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED OMB NO. 31600104 (64)9)

EXPIRES: 4/30/92 ESTIMATED BURDEN PER RESPONSE TO COMPLY WTH THIS INFOAMATION COLLECTION REQVESTt 60.0 HRS. FORWARD LICENSEE EVENT REPORT {LER) COMMENTS REGA4DING BURDEN ESTIMATE TO THE RECOADS AND REPORTS MANAGEMENT BRANCH (P430), U.S. NUCLEAR REGULATORY COMMISSION. WASHINGTON. DC 20555, AND TO

'HE PAPERWORK REDUCTION PROJECT (31600104I, OFFICE OF MANAGEMENTAND BUDGET. WASHINGTON, OC 20503.

FACILITY NAME (II DOCKET NUMBER (2) PA E 3 Washington Nuclear Plant - Unit 2 0 5 00 03 7~oFO TITLE (4)

DUE TO INADE()UATE DESIGN AND PROGRAOIATIC CONTROLS EVENT DATE (5) LER NUMBFR (6) REPORT DATE (7) OTHER FACILITIES INVOLVED (9)

SEOVENTIAL lo'ce FACILITY NAMES DOCKET NUMBER(S)

MONTH OAY YEAR YEAR gg NUMBER:r(oc NUMBER MONTH OAY YEAR i) 0 5 0 0 0 0 9 1 7 9 0 9 0 0 0 0 0 0 9 0 0 5 0 0 0 THIS REPORT IS SUBMITTED PURSUANT TO THE RLOUIREMENTS OF 10 CFR (): /Check one or more of the follorvinp) (11)

OP E RATING MODE (9) 20.402(B) 20.405(c) 60.73(sl(2)(lvl 73.7141)

POWER 20A06(s)(1) IB 50.36(c)(1) 60.73(sl(2) (v) 73.71(cl LFYEL (10) 9 7 20.405(s l(1 l(II) 50.36(c) (2) 50.'73(s) (2) (vll) OTHER /Specify In Aorrrect Below end In Text, NRC Form 20.405(sl(ll(lill 50.73( ~ l(2) (il 60,73(s) (2) (vli (AI 3SBA/

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NAME TELEPHONE NUMBER AREA CODE S. L. Washington, Compliance Supervisor 0 9 7 7 - 2 0 8 0 COMPLETE ONE LINE FOA EACH COMPONENT FAILURE OESC4IBED IN THIS AEPOAT (13)

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On September 17, 1990 it was determined by Plant Engineers that a single condition, overheating in the Diesel Generator Excitation Control Cabinets, could prevent the Division 1 and 2 Diesel Generators (DGl and DG2) from fulfilling their safety function. During worst case design conditions, the DG electrical equipment room would reach its design temperature of 104oF. It was determined by Plant tests that operation of the DGs, coincident with a 104oF room temperature would cause the temperature in the DG Excitation Control Cabinet to stabilize at 1360F. The Static Excitor Voltage Regulator (SEVR) manufacturer's recommended continuous operation (operation exceeding 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />) temperature is 1220F. Thus, for these conditions, operability of the SEVR is not assured and, since the SEVR controls the voltage and field of the generator, the operability of the DG also cannot be guaranteed. In November 1989, while re-evaluating the DG room heatup under design basis accident conditions, it was determined by Supply System Engineers that there was insufficient data to determine the heatup characteristics of the DG Excitation Control Cabinets. Temperature tests were then initiated to obtain the necessary data to complete the re-evaluation. Immediate corrective action was to modify applicable Plant procedures to,include instructions to remove the DG Excitation Control Cabinet doors within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> when the local DG electrical equipment room temperature exceeds 90 F during operation of the respective DG. The causes of this event are a manufacturing error in that the cabinets supplied with the DGs did NAC Form 365 (609)

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NRC FORM366A U.S. NUCLEAR REGULATORY COMMISSION (64)9) APPROVED OMB NO. 31504)104 EXPIRES: 4/30/92 5

ESTIMATED BURDEN PER RESPONSE TO COMPLY WTH THIS LICENSEE EVENT REPORT ILER) INFORMATION COLLECTION REOUEST: 50.0 HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS TEXT CONTINUATION AND REPORTS MANAGEMENT BRANCH (P4)30), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555, AND TO THE PAPERWORK REDUCTION PROJECT (31504)104), OFFICE OF MANAGEMENTAND BUDGET, WASHINGTON, DC 20503.

FACILITY NAME ('I) DOCKET NUMBER (2) LER NUMBER (5) PAGE (3)

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2 <<<< o 3 9 7 9 0 0 20 00 02>> 0 5 not have any cooling capability, and an error in the Supply System Startup Program which failed to verify that a Supply System modification to the cabinets would meet al'1 operability requirements. Further corrective action includes performing reviews to determine if other Plant safety related cabinets have a similar heat-up problem, and to determine if further modifications to the DG Excitation Control Cabinets can be made to minimize operator actions following an accident.

Plant Conditions Power Level - 97%

Plant Mode - 1 Event Descri tion On September 17, 1990 it was determined by Plant Engineers that a single condition, overheating in the Diesel Generator (DG) Excitation Control Cabinets, could prevent the Division 1 and 2 Diesel Generators (DGl and DG2) from fulfilling their safety function. During worst case design conditions, the DG electrical equipment room would reach its design temperature of 104oF. It was determined by Plant tests that operation of the DGs, coincident with a 104oF room temperature, would cause the temperature in the DG Excitation Control Cabinet to stabilize at 136oF. The Static Excitor Voltage Regulator (SEVR) manufacturer' recommended temperature for continuous operation (operation exceeding 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />) is 122oF. Therefore, during conditions where the DG electrical room temperature is 104oF and the DG is in continuous operation mode(more than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />), the operability of the SEVR cannot be assured. Furthermore, because the SEVR controls the voltage and field of the generator, the operability of the DG also cannot be guaranteed during these conditions.

In November 1989, Supply System Engineers were re-evaluating the DG room heatup under design basis accident conditions with more recent diesel heat load data.

During the re-evaluation it was determined that there was insufficient data to determine the heatup characteristics of the DG Excitation Control Cabinets.

Accordingly, temperature tests were then initiated to obtain this data.

Temperature tests performed in July 1990 in accordance with Plant Temporary Procedure TP 8.3 .162 on the control cabinets (E-CP- REPl, E-CP-REP2) for DG-1 and DG-2, at the normal ambient room temperature of 68oF, indicated the panel peak internal temperature rise was approximately 32oF. This test data was later evaluated and resulted in the September 17, 1990 conclusion that the maximum DG electrical equipment room temperature for continuous operation is 90oF.

NRC Form 366A (669)

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NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (64)9) APPROVEO 0MB NO. 31604')04 EXPIRES: 4/30/92

) ESTIMATE BURDEN PER RESPONSE TO COMPLY WTH THIS LICENSEE EVENT REPORT (LER) INFORMATION COLI.ECTION REQUEST: 500 HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS TEXT CONTINUATION AND REPORTS MANAGEMENT BRANCH (P4)30), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555, AND TO 1HE PAPERWORK REDUCTION PROJECT (3)504)104), OFFICE OF MANAGEMENTAND BUDGET. WASHINGTON, OC 20503.

FACILITY NAME ()) DOCKET NUMBER (2) LER NUMBER (6I PAGE (3)

YEAR @") SEQUENTIAL 4%2 REVISION rR% NUMBER NUMBER Washington Nuclear Plant - Unit 2 o s o o o 3 9 7 90 0 20 00 03 OF 0 5 TEXT ///more Eotce /4 rer/o/red, ore eddirionsl HRC Form 35649/ (17)

Immediate Corrective Action Applicable Plant procedures were deviated to include instructions to remove the DG Excitation Control Cabinet doors within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> when the local DG electrical equipment room temperature exceeds 90oF during operation of the respective DG.

Further Evaluation and Corrective Action A. Further Evaluation

1. This event is reportable per 10CFR50. 72(b)(2 )(iii) and 10CFR50. 73(a)(2)(v) as a single condition alone that could have prevented the fulfillment of the safety functions of DG-1 and DG-2 to shutdown the reactor and maintain it in a safe shutdown condition, remove residual heat, control the release of radioactive material, and mitigate the consequences of an accident. On September 1 7, 1990 at 1549 hours0.0179 days <br />0.43 hours <br />0.00256 weeks <br />5.893945e-4 months <br />, the Nuclear Regulatory Commission was notified in accordance with 10 CFR 50. 72(b)2 )(iii).

This event was evaluated as not reportable under 10CFR, Part21, because the Supply System previously reported this condition under the requirements of 10CFR50.55(e). [Reference Supply System Letter G02-83-924, C. S. Carlisle(SS) to J. B. Martin( NRC ) "10CFR50. 55(e)

Reportable Condition 8290 DG Exciter Control Cabinet Overheating", dated October 14, 1983.j

2. There were no structures, components, or systems inoperable prior to discovery of the condition which contributed to the condition.

3. The primary root causes of this event were 1) the cabinet design by StewartgStevenson Services, Inc. (DG1 and DG2 supplier), was less than specified to provide necessary cooling of internal components at the peak design ambient room temperature, and 2) the Supply System management programs for work practices were less than adequate to ensure that permanent modifications to the DG Excitation Control Cabinet made during Plant startup in 1983 adequately covered all design conditions.

a ~ During Plant startup testing in 1983, the SEYRs failed to operate within performance specifications because of overheating when temperatures in the cabinets exceeded the manufacturer's recommended short-time temperature limit of 158 F. This occurred at ambient room temperatures of approximately 75 F.

The DG electrical equipment room design maximum ambient temperature is 104oF ( 106oF in the Diesel Generator Contract 2808-53). Based on this design information, the SEVR vendor (a sub-supplier to NRC Form 366A (669)

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NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (689) APPROVED OMB NO. 31504)(04 E XP I R ES: 4/30/92 ESTIMATED BURDEN PER RESPONSE TO COMPLY WTH THIS LICENSEE EVENT REPORT (LER) INFORMATION COLLECTION REQUEST? 50.0 HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS TEXT CONTINUATION AND REPORTS MANAGEMENT BRANCH (P4)30), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555, AND TO THE PAPERWORK REDUCTION PROJECT (3(504)104). OFFICE OF MANAGEMENTAND BUDGET, WASHINGTON,OC 20503.

FACILITY NAME (I) DOCKET NUMBER (2) LER NUMBER (6) PAGE (3)

SEOUENTIAL x??cPA REVISION NUMBER '.:IPJI NUMBER Washin ton Nuclear Plant - Unit 2 o s o o o 39 790 0 0 00 0 4 oF0 S TEXT ///more epeee /4 I/Irked, Iree edd4bnrd HRC Fomr 3664'4/ (17)

Stewart 8 Stevenson Services, Inc.) sized static power heat sinks and selected various electronic components to allow the SEVR to be rated for continuous operation at 122 F. The SEVR vendor provided a caution in the instruction manual for the equipment ... "The (SEVR)

... is a heat producing device and must not be installed where there is no ventilation." Modifications were then made by the Supply System to the cabinets which allowed for free air convection cooling of the internal components. Thus, the original cabinet design was less than specified.

b. Identification of the cabinet design deficiency to provide adequate cooling of the internal components during startup testing resulted in modifications to the cabinet by the Supply System. The modifications consisted of installing ventilation chimneys and louvered vents to promote convection cooling. These modifications allowed startup testing to continue. However, no subsequent thermal tests and analyses were performed to determine the new temperature rise in the DG Excitation Control Cabinet due to internal components(SEVR) and the acceptability of that temperature rise under design basis conditions. Consequently, work practices were less than adequate to ensure that all design criteria were satisfied prior to placing equipment important to safety into operation.

C ~ An evaluation of the DG Excitation Control Cabinet thermal test results by Supply System Engineers indicate that with a 32 F temperature rise and the maximum continuous operating temperature for the SEVRs of 122 F, the maximum room ambient temperature allowable without additional cabinet ventilation is 90oF. It was further determined that removal of the DG Excitation Control Cabinet doors would provide adequate cooling of the SEVR at ambient temperatures above 90oF and up to the design maximum ambient room temperature of 104oF.

B. Further Corrective Action

l. A review will be performed to determine if Excitation Control Cabinets are appropriate to minimize operator actions further modifications of the DG following an accident.

2. A review will be performed exist in other safety-related cabinets.

to determine if similar heat-up characteristics NAC Form 366A (689)

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LICENSEE EVENT REPORT (LER)

O ESTIMA E XP I R ES: 4/30/92 URDEN PER RESPONSE TO COMPLY WTH THIS INFORMATION COLLECTION REQUEST: 60.0 HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS TEXT CONTINUATION AND REPORTS MANAGEMENT BRANCH IP430), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555, AND TO 1HE PAPERWORK REDUCTION PROJECT (31504104), OFFICE OF MANAGEMENTAND BUDGET, WASHINGTON, DC 20503.

FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (8) PAGE (3)

YEAR:g SSQVSNTIAI. REVISION NUMSSR NUMSSR Washington Nuclear Plant - Unit 2 0 s 0 o o 3 9 7 0 9 0 0 9 00 05 OF 0 5 TEXT ///more epeoe /4 rer/vtred, Iree edd/done/HRC Form 3884'4/ (17)

Safet Si nificance There is minimal safety significance associated with this event. Because the SEVRs are designed to operate short term (24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or less) at 158oF, the DGs would be operable for the initial stages of any event. In addition, the probability of the combination events required (loss of all offsite power requiring an extended DG run and DG electical equipment room temperatures above 90 F) is considered low.

Furthermore, the High Pressure Core Spray System DG (HPCS) would still be available. The HPCS is powered from an independent Diesel Generator which was supplied by a different vendor and was made by a different manufacturer. This DG has been designated as the Plant alternate AC source for Station Blackout. Since no event actually occurred, this situation posed no threat to the health and safety of either the public or Plant personnel.

Similar Events None EIIS Information Text Refer ence E I IS Reference

~Sstem ~Com onent Diesel Generator (DG) Excitation Control Cabinet(s) (E-CP-REP1 and CAB E-CP-REP2)

Diesel Generator (DGl and DG2) DG DG Electrical Equipment Room NB Static Excitor Voltage Regulator (SEVR(s)) 90 Generator High Pressure Core Spray System (HPCS) DG DG NRC Form 368A (669)

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