Text

LER 90-006-00:on 891027,discovered Unverified Assumption in App R Safe Shutdown Analysis.Caused by Fire Protection Program Failure to Provide Detailed Procedural Instructions for Operator Actions.New Procedures developed.W/900810 Ltr
	ML18038A319
Person / Time
Site:	Nine Mile Point
Issue date:	08/10/1990
From:	Beller R, Firlit J; NIAGARA MOHAWK POWER CORP.
To:	; NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
	LER-90-006-01, LER-90-6-1, NMP70166, NUDOCS 9008240177
	Download: ML18038A319 (18)
	v • d • e

ACCELERATED DISIBUTION DEMONSTRATION SYSTEM I

REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:9008240177 DOC.DATE: 90/08/10 NOTARIZED: NO FACIL:50-220 Nine Mile Point Nuclear Station, Unit 1, Niagara Powe 05000220 AUTH. NAME AUTHOR AFFILIATION BELLER,R.

FIRLIT,J.F.

RECIP.NAME AFFILIATION'OCKET Niagara Mohawk Power Corp.

Niagara Mohawk Power Corp.

RECIPIENT

SUBJECT:

LER 90-006-00:on 891027,unverified assumption in App R safe shutdown analysis.

W/9 ltr. D DISTRIBUTION CODE IE22T COPIES RECEIVED'LTR 50.73/50.9 Licensee Event Report (LER),

ENCL L ncident Rpt, etc.SIZE'ITLE:

NOTES:

RECIPIENT COPIES }RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL D PDl-1 LA 1 1 PD1-1 PD 1 1 MARTIN,R. 1 1 D INTERNAL: ACNW 2 2 ACRS 2 2 AEOD/DOA AEOD/ROAB/DS P 1 .12 AEOD/DSP/TPAB 1 1 2 NRR/DET/ECMB 9H 1 1 NRR/DET/EMEB9H3 1 1 NRR/DLPQ/LHFB11 1 1 NRR/DLPQ/LPEB10 1 1 NRR/DOEA/OEAB11 1 1 I4RR/DREP/PRPB11 2 2 NRR/DST/SELB 8D 1 1 NRR/DST/SICB 7E 1 1 N SPLB8D1 1 1 NRR/DST/SRXB 8E 1 1 - GAL 1 1 RES/DSIR/EIB 1 1 FILE'2'GN1 01 1. 1 EXTERNAL EGGG BRYCE g J H 3 3 L ST LOBBY WARD 1 1

~ LPDR 1 1 NRC PDR 1 1 NSIC MAYS,G 1 1 NSIC MURPHY,G.A 1 1 NUDOCS FULL TXT 1 1 R I

D A

D D

NOTE TO ALL "RIDS" RECIPIENTS:

PLEASE HELP US TO REDUCE WASTE! CONTACT THE DOCUMENT CONTROL DESK, ROOM Pl-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 34 ENCL 34

'II'IASARA.

U SKNAWK NINE MILE POINT NUCLEAR STATION/P.O. BOX 32, LYCOMING.N.Y. 13093/TELEPHONE (315) 343-2110 NMP70166 August ]p , 1990 United States Nuclear Regulatory Commission Document. Control Desk Washington, DC 20555 RE: Docket No. 50-220 LER 90-06 Gentlemen:

In accordance with 10 CFR 50.73, we hereby submit the following voluntary Licensee Event Report: LER 90-06.

This report was completed in the format designated in NUREG-1022, Supplement 2, dated September 1985.

Very truly yours, oseph F. Firlit Vice President Nuclear Generation JFF/DS/lmc ATTACHMENT ZC Regional Administrator, Region I Sr. Resident Inspector, W. A. Cook g (775'46 9008200177 900'"10 PDR ADOCK 05000220 S PDC

il

NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (64) 9) APPROVED 0MB NO. 3'I 500104 EXP IR 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 (F430), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555, AND TO THE PAPERWORK REDUCTION PROJECT (31500104), OFFICE OF MANAGEMENTAND BUDGET. WASHINGTON, DC 20503.

FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6) PAGE (3)

YEAR SEQUENTIAL "<<OP REVISION NUM ER '<<PB NUMSER Nine Mile Point Unit 1 o 5 o'o o 220 90 0 6 0 0 0 2OF 07 TEXT /// more 4/rece /4 rer)rr/rerL Iree tChdonel HRC Form 366A'4) (IT)

I. DESCRIPTION OF CONDITION On October 27, 1989, with Nine Mile Point; Uni.'t 1 (NMP1) in cold shutdown and the core off-loaded, assumption made on the Appendix R Safe Shutdown Analysis (SSA) it was discovered that an could not be verified. Specifically, operator actions to complete specific load shedding; to ensure battery capacity to start -a Diesel Generator (DG) at the conclusion of the 8 hour9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months Appendix R scenario; was not identified in applicable 'procedures. This condition was identified during corrective actions, being carried out as part of the NMPl Restart Action Plan (RAP), Specific Issue 18 (125 VDC system concerns).

The NMP1 Appendix R SSA, Rev. 0 and Rev. 1, dated October 1982 and September 1985, respectively, describes NMP1's ability to satisfy the specific requirements of 10CFR50 Appendix R Section III.G. The event in question's any postulated fire that has the potential to cause a loss of both emergency diesel generators (concurrent with a simultaneous Loss Of Off-Site Power;.(LOOP) for-up to 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months )..

The analysis credits the redundant ec((ergency condenser -system as providing hot shutdown capability automatically (via the shutdown supervisory control system) for up to eight hours without make-up and the Reactor Protection System (RPS) Motor Generator (MG) Sets powered from the Station's 125 VDC battery system for monitoring the shutdown process.

There are two long term safe shutdown functions which are dependent upon the availability of the 125 VDC system as a pait of Niagara Mohawk Power Corporation's (NMPC's) defense-in-depth approach for addressing potential Appendix R fire events. These two functions are:

1. Minimum required process monitoring instrumentation, and

2. The ability to start a diesel generator following'repairs.

In order for the 1500 amp-hour batteries to survive the full eight hours, it was necessary to perform load shedding, actions within the early stages of an Appendix R event. The load shedding requirements were contained in the 115 KV Power Failure Special Operating Procedure (N1-SOP-1 and Nl-SOP-5). These procedures did not provide specific guidance on which loads to shed. Instead, a "target" of 100 amps for Battery 11 and 460 amps for Battery 12 was considered adequate to meet the design basis load shedding objectives. Nl-SOP-1 and Nl-SOP-5 did not provide a specific time frame for the required load shedding objectives. Battery load profile calculations were not performed to verify that, the load shedding targets and the times required to achieve these load sheds assumed by the Appendix R SSA would have ensured sufficient battery NRC Form 366A (64)9)

NRC FORM 366A (64)9)

U.S. NUCLEAR REGULATORY COMMISSION e APPROVED 0MB NO. 31500104 EXPIRES. 4/30/92 ESTIMATED BURDEN PER RESPONSE TO COMPLY FORWARD WTH THIS LICENSEE EVENT REPORT (LER) INFORMATION COLLECTION REQUEST: 50.0 HRS.

COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS TEXT CONTINUATION AND REPORTS MANAGEMENT BRANCH (P430). U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555, AND TO 1HE PAPERWORK REDUCTION PROJECT (31S041104), OFFICE OF MANAGEMENTAND BUDGET, WASHINGTON, DC 20503.

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

YEAR SEOVENTIAL I43: REVISION NUMBER '?Yr? NVMSER Nine Nile Point Unit l o s o o o 2 2090 0 06 00 03 OF 0 7 TEXT /IImore 4/reoe b squired. oee alien@ HRC %%drrn 36SA'4/ (IT) capacity existed to start a diesel generator following the postulated 8-hour Appendix R scenario. The 1500 amp-hour battery load profile calculations performed in August 1988 (NMPC Calc.

125DC-Batt-11-ES) demonstrated that a 30-minute time frame to complete the target load shed would have satisfied the battery capacity requirements imposed by the postulated 8-hour Appendix R scenario for station battery 11 only. Current battery calculations indicate that the 1500 amp-hour Battery 12 would have only survived for three minutes under assumed normal loads. Therefore, the electrical maintenance supervisor would have directed all Damage Repair Procedure (DRP} actions for restoring a diesel generator.and providing 125 VDC safe shutdown loads to be performed at battery board 11. Consequently this analysis focuses on the capability to restore,and restart a diesel generator from station battery 11.

To reach the 100 amp discharge rate for Battery 11, the operators would have to shed battery charger MG Set 161, computer MG Set'167, and individual non-essential instrumentation and control loads.

Credit. was taken for the operators plant systems knowledge and operator training to..provide the necessary guidance to remove the.

non-essential battery loads.

Current industry', standards regarding the level of procedural guidance required to achieve the procedural objectives have .

increased since the issuance of Nl-SOP-1 Rev. 5, 6, and Nl-SOP-5 Rev. 0, 1, and 2. In the past many procedures were less specific and certain procedural objectives were satisfied by crediting operator training. I Since these procedures did not specify which loads were required to be shed in order to re'ach the 100 amp discharge current within the required time frame, the assumed eight-hour. battery capacity cannot be demonstrated. Also, NMPC is unable to provide documentation to support the operator training assumption.

II. CAUSE OF CONDITION The cause of 'this condition was the Fire Protection Program's failure to provide detailed .procedural instructions for implementing operator actions credited. by the Appendix R Safe Shutdown Analysis.

Since the detailed procedural instructions were not provided, procedures Nl-SOP-1 and Nl-SOP-5 were potentially insufficient to mitigate the postulated Appendix R fire scenario(s).

technical content of the existing loss of 115 KV power Special If the Operating Procedures (SOP) was questioned, the need to identify NRC Form 366A (669)

NRC FOAM 366A US. NUCLEAR REGULATORY COMMISSION APPROVED OMB NO. 31504)104 (64) 9)

EXPIRES: 4/30/92 ESTIMATED BUADEN PER RESPONSE TO COMPLY WTH THIS LICENSEE EVENT REPORT (LER) INFORMATION COLLECTION AEQUEST: SOJ) HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS TEXT CONTINUATION AND AEPORTS MANAGEMENT BRANCH IP4)30), U.S. NUCLEAR REGULATOAY COMMISSIONWASHINGTON, DC 20555, AND TO 1'HE PAPERWOAK REDUCTION PROJECT (31S04)104). OFFICE OF MANAGEMENTAND BUDGET, WASHINGTON, DC 20503.

FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6) PAGE (3)

YEAR 5E DUE NTIAL i:P:. REVISION NVM ER <<??II NUMBER Nine Mile Point Unit 1 0 5 0 0 0 2 P P 9 0 0 0 6 90 04 OFp 7 TEXT ///IINuE 4/>>44 /4 mqu/md, u44 EddR4u>>/ HRC %%dmI 3///AS / (12) specific load shedding actions and required time frames would have resulted. This would have mandated the development of duty cycles (load profiles) and capacity calculations required 'to ensure an eight hour battery capacity.

III. ANALYSIS OF CONDITION Due to changes to the Special Operating Procedures that now specify the required load shedding steps (and equipment location),

time frame, and the operator training on these procedures, the'equired NMPC is unable to provide conclusive documentation that the actions assumed in the Appendix R SSA would have occurred. Since the operator bias (revised procedures and training) would support the postulated load shedding actions, this issue as a voluntary LER.

NMPC feels it prudent to report As described above, the event in question is an Appendix R fire which causes the loss of both diesel generators, or prevents their initial operation, coincident with LOOP. The 'LOOP, combined with the lack of diesel generators results in a station blackout, and requires the operators to enter and implement the 115 KV Power Failure Procedure.

The NMP1 Safe Shutdown Analysis credits operator load shedding actions under the guidance criteria of the 115 KV Power Failure Special Operating Procedure. In order to achieve the desired battery discharge rate (100 amp), the operator is credited with removing all nonessential instrumentation loads (which are not required to monitor the Safe Shutdown Process). The first operator action in this direction would be to trip the major non-essential loads, e.g., battery charger MG Set 161 and computer MG Set 167.

This would have reduced +he load on Battery 11 to approximately 190 amps.

It is NMPC's contenti'on that the operators would have continued reducing loads by removing all non-essential instrumentation (by the removal of fuses and tripping of breakers from instrument and control loops) until the 100 amp goal was reached. 'It is not conclusive whether these actions would have been taken within a sufficient time frame to ensure eight-hour battery capacity.

Battery calculation 125 VDC-Battery-App-R shows that after shedding MG Sets 161 and 167, without shedding any loads off the RPS MG Set instrumentation busses, Battery approximately 5.18 hours2.083333e-4 days 0.005 hours 2.97619e-5 weeks 6.849e-6 months . Time lines used to evaluate the tasks ll capacity is sufficient for described in the DRP's and field walkdowns indicated that the steps required to restore and restart a diesel generator can be completed N AC Form 366A (64)9)

A f

NRC FORM366A U.S. NUCLEAR REGULATORY COMMISSION (649)

O APPROVED OMB NO. 3)504)04 EXPIRES: E/30/92 ESTIMATED 8UADEN PER AESPONSE TO COMPLY WTH THIS LICENSEE EVENT REPORT (LER) INFORMATION COLLECTION REQUEST: 50.0 HRS. FOAWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE AECORDS TEXT CONTINUATION AND AEPOATS MANAGEMENT BRANCH (F430). U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555, AND TO 1HE PAPERWORK REDUCTION PROJECT (31504104). OFFICE OF MANAGEMENTAND BUDGET. WASHINGTON, OC 20503.

FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6) PAGE (3)

YEAR SEQUENTIAL :~P/o REVISION NUMSER 4% NUMSER Nine IIi1e Point Unit 1 p g p p p 2 2 0 9 0 006 0 0 05 oF 0 7 TEXT //f more <<eoe/e r//I/red. Iree atdhkwol HRC Form 36843/ (12) within 4.5 hours5.787037e-5 days 0.00139 hours 8.267196e-6 weeks 1.9025e-6 months . Additional actions would still be required to initiate cold shutdown within the prescribed eight hours in accordance with the DRPs.

The abo've analysis of an incomplete load shedding which provides 5.18 hours2.083333e-4 days 0.005 hours 2.97619e-5 weeks 6.849e-6 months of capacity for Battery 11, still assumes MG Sets 161 and 167 are shed within 15 minutes. NMPC cannot'ocument this assumption in an unbiased fashion. Although NMPC feels that this would have occurred, and furthermore feels that load shedding to reach 100 amps at 30 minutes would also have been performed, the operators would have been made aware of a battery capacity problem from the remote battery voltage indication at the Control Room.

Even if no load shedding occurred, the operator would eventually lose all RPS instrumentation. This is because the AC output from RPS MG Set 162 has an under frequency protective breaker which trips the AC output. Although Engineering calculations to show when this point would have been reached have not been performed; the larger the load on a battery, the more quickly the voltage would drop, and decreasing voltage would eventually cause the AC output frequency to drop to the set 'oint of the protective breaker. At this point the .operators . would lose all RPS instrumentation (Reactor Coolant System pressure level can be monitored locally). NMPC considers it credible that the operators would note the loss of instrumentation and quickly identify the

~

under-voltage problem (battery voltage is monitored in the Control Room) and shed all remaining loads on Battery 11. This would have preserved adequate capacity to restart a diesel indefinitely (with all loads shed) until the diesel generator DRPs were complete and the diesel could be restarted. 'MPC feels that adequate capacity would be preserved regardless of whether the under-frequency trip occurred at high load or at the "target" load of 100 amps since a diesel start requires a'aximum load of only 60.amps.

Therefore, NMPC concludes that there was no adverse safety-consequences to the lack of detailed load shedding procedures because:

Operator knowledge was sufficient to ensure load shedding to preserve a battery capacity of 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months . Thus, the battery would have the capacity required to start a Diesel Generator at the end of the 8 hour9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months Appendix R scenario.

2. Operators would have continued load shedding below the 190 amps necessary to achieve a 5.18 hour2.083333e-4 days 0.005 hours 2.97619e-5 weeks 6.849e-6 months capacity while the DRPs credit a diesel start at 4.5 hours5.787037e-5 days 0.00139 hours 8.267196e-6 weeks 1.9025e-6 months ; and NRC F onn 386A (889)

1' NRC FORM 366A (64)9)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION t U.S. NUCLEAR REGULATORY COMMISSION APPROVED 0MB NO. 31500104 E XP I R ES: 4/30/92 ESTIMATED BURDEN PER RESPONSE TO COMPLY WTH THIS INFORMATION COLLECTION REQUEST: 500 HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS AND REPORTS MANAGEMENT BRANCH (P430), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555, AND TO 1HE PAPERWORK REDUCTION PROJECT (31500104). OFFICE OF MANAGEMENTAND BUDGET, WASHINGTON, DC 20503, FACILITY NAME (1) DOCKET NUMBER 12) PAGE (3)

LER NUMBER (6)

YEAR SEQUENTIAL ?? SI REVISION NUMSER ?'A5 NUMSER Nine Mile Point Unit 1 0 5 0 0 0 9 0 0 6 0 0 '06 oF 0 7 TEXT /// more SPece b mr/er)erL See er/I/r)/one/H/I C %%dmr 3//SA'4/ ( 17) 3,. Even if no load shedding occurred, operators would have had unmistakable evidence of a battery capacity problem (via the MG Set 162 AC output trip) well before battery capacity decreased to the level which would impact the ability to start

'a diesel, and would have shed all remaining loads on Battery 11.

IV. CORRECTIVE ACTION NMPC has acknowledged certain programmatic and/or isolated deficiencies in some of NMP1 s Station Operating Procedures. NMPC has committed to upgrading the quality and detail of the station procedures. As a result, new Procedure Writers Guides (AP-2.0, AI-1.0) were developed, and many procedures have been revised and updated in accordance with the new guidelines.

The 115KV Power Failure Special Operating Procedure (Nl-SOP-5) was revised to incorporate the Appendix R load shedding. assumptions that were questioned during the RAP Specific Issue 18 effort. A new special operating procedure "Station Blackout" (Nl-SOP-18) was

~

developed to mitigate the effect of an Appendix R Station Blackout event as postulated in the Appendix R Safe Shutdown Analysis. This procedure specifies the non-essential loads, the location of these loads, and the time frame at which these loads are required to be shed to satisfy the Appendix R and Station Blackout submittals.

To ensure that the post repair safety margin (2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months ) assumed to be provided for the DRPs will be maintained, to resolve. other 125VDC system deficiencies and to ensure the 125VDC System will satisfy all NMPl design basis commitments, NMPC replaced the two 1500 amp-hour batteries with two 2300 amp-hour batteries.

To ensure compliance to Appendix R as well as other NMPl analysis and commitments, NMPC performed detailed load profile calculations for the 1500 amp-hour and the new 2300 amp-hour station batteries.

NRC Form 366A (64)9)

NRC FORM 366A US. NUCLEAR REGULATORY COMMISSION (6'4)9) APPROVED OMB NO. 31500104 5 XP I A ES: 4/30/92 LICENSEE EVENT REPORT (LER) ESTIMATED BURDEN PEA RESPONSE TO COMPLY WTH THIS INFORMATION COLLECTION REQUEST: 500 HRS. FORWARD COMMENTS REGARDING BUADEN ESTIMATE TO THE RECORDS TEXT CONTINUATION AND REPORTS MANAGEMENT BRANCH (F430). U.S. NUCLEAR REGULATOAY COMMISSION, WASHINGTON, DC 20555, AND TO THE PAPERWORK AEDUCTION PROJECT (31500104)..OFFICE OF MANAGEMENTAND BUDGET, WASHINGTON, DC 20503.

FACILITY NAME (1) DOCKET NUMBER (2) LEA NUMBER (6) PAGE (3)

YEAR SEQUENTIAL >he<i REVISION

@ NVM SA NVMSSA Nine Mile Point Unit,l o s o o o 220 9 0 0 0 6 0 0 OF 0 7 TEXT /I/ more <<woe /4 I/or'reIL oee er/I//oooo/NRC Form 35543/ ()7)

V. ADDITIONAL INFORMATION A. Identification of components referred to in this LER:

IEEE 803 IEEE 805 COMPONENT FUNCTION SYSTEM ID Emergency Diesel Generator DG EK Battery BTRY EJ Emergency Condenser System NA BL Battery Board BYBD EJ Motor Generator Set MG EF Reactor Protection System (RPS) NA JC B. Failed components: none.

C. Previous similar events: none.

NRC Form 355A (669)

I 1

ML18038A319

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