ML18011A805

LER 95-002-00:on 950207,unanalyzed Condition Existed Re Potential of Loss of Automatic ESF Actuations & Subsequent TS 3.0.3 Entry.Caused by Both Trains of Ssps Declared Inoperable.Plant Evolutions avoided.W/950303 Ltr

ML18011A805
Person / Time
Site:	Harris
Issue date:	03/02/1995
From:	Donahue J, Verrilli M CAROLINA POWER & LIGHT CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
HO-950117, LER-95-002, LER-95-2, NUDOCS 9503080127
Download: ML18011A805 (6)

Text

RI ORITY 1 P (ACCELERATED RIDS PROCI'.SSIiCi>

REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:9503080127 DOC.DATE: 95/03/02 NOTARIZED: NO DOCKET FACIL:50-400 Shearon Harris Nuclear Power Plant, Unit 1, Carolina 05000400 AUTH. NAME AUTHOR AFFILIATION VERRILLI,M. Carolina Power & Light Co. P DONAHUE,J.W. Carolina Power & Light Co.

RECIP.NAME. RECIPIENT AFFILIATION

SUBJECT:

LER 95-002-00:on 950207,unanalyzed condition existed re potential of loss of automatic ESF actuations & subsequent I TS 3.0.3 entry. Caused by both trains of SSPS declared I inoperable. Plant evolutions avoided.W/950303 ltr. 0:

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

NOTES:Application for permit renewal filed. 05000400 RECIPIENT COPIES RECIPIENT COPIES 7 v ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD2-1 PD 1 1 LEN ,1 1 Y

INTERNAL: ACRS 1 1 AEO /SPD/RAB~ 1 1 AEOD/S PD/RRAB 1 1 FILE CENTER~02 1 1 NRR/DE/ECGB 1 1 NRR/DE/EELB 1 1 NRR/DE/EMEB 1 1 NRR/DI S P/PI PB 1 1 NRR/DOPS/OECB 1 1 NRR/DRCH/HHFB 1 1 NRR/DRCH/HICB 1 1 NRR/DRCH/HOLB 1 1 NRR/DRSS/PRPB 2 2 NRR/DSSA/SPLB 1 1 NRR/DSSA/SRXB 1 1 RES/DSIR/EIB 1 1 D; RGN2 FILE 01 1 1 0,

EXTERNAL: L ST LOBBY WARD 1 1 LITCO BRYCE,J H 2 2 NOAC MURPHY i G A 1 1 NOAC POORE,W. 1 1 NRC PDR

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1 1 NUDOCS FULL TXT 1 1 c)

U N

iOTE TO ALL"RIDS" RECIPIENTS:

PLEASF. HELP L'S TO RFDL'CE iVASTE! COiTACTTHE N'AXIE DOCL'i!EiTCONTROL DESK. ROOK! Pi-37 (EXT. 304-20S3 ) TO ELliIliATEYOL'R FROil IIL"I'IONLISTS FOR DOCL'iIEi'I'S YOL'Oi "I' L'l:.I)!

DISTRI FULL TEXT CONVERSION REQUIRED TOTAL NUMBER OF COPIES REQUIRED: LTTR 27 ENCL 27

Carolina Power 8 Ught Company Harris Nuclear Plant PCt Box 165 New Hill NC 27562

'MAR 0 3 1995 Letter Number: HO-950117 U.S. Nuclear Regulatory Commission ATTN: NRC Document Control Desk Washington, DC 20555 SHEARON HARMS NUCLEAR POWER PLANT UNIT 1 DOCKET NO. 50-400 LICENSE NO. NPF-63 LICENSEE EVENT REPORT 95-002-00 Gentlemen:

In accordance with Title 10 to the Code of Federal Regulations, the enclosed Licensee Event Report is submitted. This report fulfills the requirement for a written report within thirty (30) days of a reportable occurrence and is in accordance with the format set forth in NUREG-1022, September 1983.

Sincerely, J. W. nahue General Manager Harris Plant MV Enclosure cc: Mr. S. D. Ebneter (NRC - RII)

Mr. N. B. Le (NRC - PM/NRR)

Mr. S. A. Elrod (NRC - SHNPP)

Mr. W. R. Robinson 9503080127 950302 PDR ADOCK 05000400 113'ew S State Road Hill NC PDR

U. S. Nuclear Regulatory Commission Page 2 bc: Ms. D. B. Alexander Mr. W. R. Campbell Mr. J. M. Collins Mr. J. P. Cowan (BNP)

Mr. R. J. Duncan Ms. S. D. Floyd Mr. H. W. Habermeyer, Jr.

Mr. E. M. Harris Ms. T. A. Head (GLS File)

Mr. M. D. Hill Mr. R. M. Krich (RNP)

Mr. R. P. Lopriore (BNP)

Mr. P. M. Odom (RNP)

Mr. C. W. Martin (BNP)

Mr. R. D. Martin Admiral K. R. McKee Mr. J. P. McKone Ms. T. M. Midgette Mr. J. W. Moyer (RNP)

Mr. G. A. Rolfson Mr. R. Schlichter (BNP)

Mr. R. S. Stancil HNP Real Time Training INPO NLS File: HI/A-2D (L. M. Randall)

NRC FORM 366 U.S. NUCLEAR REGULATORY COHHISSION APPROVED BY OHB NO. 3150-0104 (5-92) EXPIRES 5/31/95 (LER) ESTIMATE RDEH PER RESPONSE TO COHPLY illTH LICENSEE EVENT PORT THIS INFORMATION COLLECTIOH REQUEST: 50.0 HRS.

FORHARD COHMENTS REGARDING BURDEN ESTIMATE TO THE INFORHATION AND RECORDS MANAGEHENT BRANCH (See reverse for required number of digits/characters for each block) (HNBB 7714), U.S. NUCLEAR REGULATORY COHHISSIOH, MASHINGTON, DC 20555-0001, AHD TO THE PAPERlSRK REDUCTION PROJECT (3150-0104), OFFICE OF MANAGEHENT AHD BUDGET HASHIHGTON DC 20503.

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

Shearon Harris Nuclear Plant-Unit ¹1 05000/400 1 OF 3 TITLE (4) Unanalyzed condition due Io the potential for loss of automatic ESF actuations and subsequent Technical S ecification 3.0.3 enI due Io declarin boih trains of SSpS ino erable.

EVENT DATE 5) LER NUHBER (6) REPORT DATE (7 OTHER FACILITIES INVOLVED (8 SEQUENTIAL REVISION FACILITY NAHE DOCKET NUMBER MONTH DAY YEAR YEAR NUHBER NUHBER HONI'H DAY YEAR 05000 FACILITY NAME DOCKET NUHBER 02 07 95 95 002 00 2 95 05000 OPERATING THIS REPORT IS SUBHITTEO PURSUANT TO THE REOUIREHENTS OF 10 CFR 5: (Check one or mor e) (11)

MODE (9) 20.402(b) 20.405(c) 50.73(a)(2)(iv) 73.71(b) 20.405(a)(1)(i) 50.36(c)(1) 50.73(a)(2)(v) 73.71(c)

POMER 100/ 20.405(a)(1)(ii) 50.36(c)(2) 50.73(a)(2)(vii) OTHER LEVEL (10) 20.405(a)(1)(iii) 50.73(a)(2)(i) 50.73(a)(2)(viii)(A) (Spec'ify in 50.73(a)(2)(viii)(B) Abstract below 20.405(a)(1)(iv) 50.73(a)(2)(ii) and in Text, 20.405(a)(1)(v) 50.73(a)(2)(iii) 50.73(a)(2)(x) NRC Form 366A)

LICENSEE CONTACT FOR THIS LER (12)

NAME TELEPHONE NUHBER (Include Area Code)

Michael Verrilli Sr. Specialist - Licensing (919) 362-2303 COHPLETE ONE LINE FOR EACH COHPONENT FAILURE DESCRIBED IN THIS REPORT (13)

REPORTABLE REPORTABLE CAUSE SYSTEH COMPONENT MANUFACTURER CAUSE SYSTEM COHPONEHT HANUFACTURER TO HPRDS TO NPRDS SUPPLEHENTAL REPORT EXPECTED (14) MONTH DAY YEAR EXPECTED YES SUB HISS ION (If yes, complete EXPECTED SUBHISSIOH DATE). X NO DATE (15)

ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines) (16)

On February 7, 1995, both trains of the Solid State Protection System (SSPS) were declared inoperable following investigation/evaluation of the postulated accident scenario described in NRC Information Notice

¹95-10. This Information Notice involved a potential loss of automatic Engineered Safety Features (ESF) actuation, due to a steam line break in the turbine building which causes electrical faults in ESF input signals. These electrical faults could result in the SSPS logic cabinet power supply fuses failing, which would in turn render an entire SSPS train inoperable. If a random single failure of the other SSPS train is assumed, no automatic protective functions would be available. This was considered to be an unanalyzed condition and was reported to the Nuclear Regulatory Commission as a 1-hour Non Emergency ENS notification. Also, declaring both trains of SSPS inoperable resulted in entering Technical Specification 3.0.3. Both of these conditions are reportable p'er 10CFR50.73. Harris Plant actions were discussed via teleconference with NRC Region II on February 7, 1995, at which time an enforcement discretion period of ten days was requested and granted. A plant modification was developed to electrically isolate and coordinate the power feeds for the SSPS logic cabinets. Installation and satisfactory testing of this modification was completed on February 15, 1995, thus exiting the discretionary enforcement period and eliminating the possibility of the postulated scenario. The cause of this condition is attributed to the original SSPS design configuration, wherein each set of SSPS logic cabinets was provided input power through a common set of fuses, and the fact that the initial design analysis did not evaluate the effect of a main steam line break in the turbine building on the Class 1 ESF-SSPS logic cabinet power supply circuits.

NRC FORM 366A (5 92)

NRC FORM 366A APPROVED BY OHB NO. 3150.0104 (5-92) EXPIRES 5/31/95 ESTIMAT URDEN PER RESPONSE TO COMPLY WITH THIS INFORMATION COLLECTION REQUEST: 50.0 HRS.

FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO LICENSEE EVENT REPORT (LER) THE INFORHATIOH AHD RECORDS MANAGEMENT BRAHCH (HHBB 7714), U.S. NUCLEAR REGULATORY COMMISSIONf WASHINGTON, DC 20555-0001, AND TO THE PAPERWORK REDUCTION PROJECT (3150-0104), OFFICE OF MANAGEMENT AND BUDGET WASHINGTON DC 20503.

FACILITY NAME (1) DXKET NUHBER (2) LER NUHBER (6) PAGE (3)

YEAR SEQUEHTIAL REVISION Shearon Harris Nuclear Plant - Unit ¹1 05000/400 2 OF 3 95 TEXT (If more space is required. use additional copies of NRC Form 366A) (17)

EVENT DESCRIPTION:

As described in NRC Information Notice IE 95-10, a new scenario was identified which could result in a failure of the Solid State Protection System (SSPS) to perform its intended design function. Specifically, the scenario involved a double-ended rupture steamline break in the turbine building. The break could occur in such a fashion that electrical conduits and junction boxes containing ESF input signals from the turbine stop valves and auto-stop oil pressure sensors might be damaged by pipe whip and/or steam jet forces. Electrical faults (shorts to ground) resulting from this damage could cause the fuses to fail in the input bays of the affected SSPS channel. Since this would disable the AC power feeds to the DC power supplies in the SSPS logic cabinets, that train of SSPS could no longer perform the Engineered Safety Feature (ESF) actuation functions to mitigate the event. If a random single failure of the other SSPS train is assumed, both trains of SSPS would be rendered inoperable. A reactor trip would occur as the SSPS de-energizes, but no ESF automatic actuations would occur.

After evaluation and investigation into this scenario and its applicability to the Harris Nuclear Plant's (HNP) design configuration and design bases, it was concluded on February 7, 1995 that HNP could be susceptible to this scenario. Following a review of this condition by the HNP Plant Nuclear Safety Committee, both trains of SSPS were declared inoperable at 1055 hours0.0122 days <br />0.293 hours <br />0.00174 weeks <br />4.014275e-4 months <br />. Shortly thereafter, the required 1-hour non-emergency ENS notification was made to the Nuclear Regulatory Commission as an unanalyzed condition per 10CFR50.72. HNP's conclusions and intended actions were discussed via teleconference with NRC Region II on February 7, 1995, at which time an enforcement discretion period of ten days was requested and granted to allow for development and installation of a plant modification to electrically isolate and coordinate the power feeds for the SSPS logic cabinets. Installation and satisfactory testing of this modification was completed on February 15, 1995, thus exiting the discretionary enforcement period and eliminating the possibility of the postulated scenario.

Cause:

The cause of this condition is attributed to the original SSPS design configuration, wherein each set of SSPS logic cabinets was provided input power through a common set of fuses and the fact that the initial design analysis did not evaluate the effect of a main steam line break in the turbine building on Class 1E ESF-SSPS logic cabinet power supply circuits.

6A (5- 2)

NRC FORM 366A U.S. NUCLEAR REGULATORY COHHISSION APPROVED BY OHB NO. 3150 ~ 0104 (5-92) EXPIRES 5/31/95 EST IMA BURDEN PER RESPONSE TO COMPLY WITH THIS INFORMATION COLLECTION REQUEST: 50.0 HRS.

FORWARD COMMENTS REGARDING BURDEN ESTIHATE TO LICENSEE EVENT REPORT (LER) THE INFORMATION AND RECORDS HANAGEHENT BRANCH (MNBB 7714), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555-0001, AND TO THE PAPERWORK REDUCTION PROJECT (3150-0104), OFFICE OF MANAGEHENT AND BUDGET WASHINGTON DC 20503.

FACILITY NAHE (1) DOCKET NUHBER (2) LER NUHBER (6) PAGE (3)

SEQUENTIAL REVISION Shearon Harris Nuclear Plant - Unit ¹1 05000/400 3 OF 3 95 002 TEXT (If more space is required. use additional copies of NRC Form 366A) (17)

SAFETY SIGNIFICANCE:

The potential concern posed no significant safety implications, based on the low probability of a Main Steam Line High Energy Break coincident with the random failure of one train of SSPS and the fact that the event is bounded by FSAR Chapter 15 DNB limits. The risk of core damage from the steamline break-SSPS failure scenario is estimated at 3.3 x 10'er reactor year, which is more than three orders of magnitude less than the annual core damage frequency for HNP due to all causes. The event frequency is only slightly above the 10'runcation limit used in the Probabilistic Safety Analysis. A reactor trip would occur during the postulated scenario when SSPS is de-energized. In an evaluation performed by Westinghouse, the reactor trip was assumed but no automatic or manual actions were credited for the first ten minutes. The conclusion reached was that FSAR Chapter 15 Accident Analysis DNB limits would remain bounding per the original licensing basis.

Additionally, control room operators would be following appropriate emergency operating procedures during the scenario and would still have the ability to manually start ESF components and position valves as needed to mitigate the accident and place the plant in a safe shutdown condition.

CORRECTIVE ACTIONS:

The following actions were taken as interim measures, prior to modification installation (c/a ¹6):

1. Optional train-related maintenance and surveillance testing was minimized and suspended where possible.

2. Plant evolutions significant to risk were avoided.

3. Operations Orders were prepared describing the condition and proper implementation of the emergency operating procedure for responding to a MSLB and the effects of possible SSPS failure. Operators on-shift were briefed on the scenario of concern, how to identify the symptoms of the scenario and the mitigating actions to take.

4. Activities in the turbine building that could result in damage to the Main Steam Lines (such as movement of loads over the high pressure turbines and piping) were restricted.

5..Lessons learned from the Salem modification installation were reviewed and incorporated into the HNP modification implementation plan.

6. A plant modification (ESR-95-00254) to electrically isolate and coordinate the power feeds for the SSPS logic cabinets was developed, installed and satisfactorily tested on February 15, 1995.

EIIS INFORMATION:

N/A NRC FORM 366A (5-92)