ML18012A553

LER 97-002-00:on 970207,main FW Isolation Valves Inoperable Due to Cold Weather Conditions.Monitored Steam Tunnel Temp Once Per 12 H shift.W/970310 Ltr

ML18012A553
Person / Time
Site:	Harris
Issue date:	03/10/1997
From:	Donahue J, Verrilli M CAROLINA POWER & LIGHT CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
HNP-97-058, HNP-97-58, LER-97-002-01, LER-97-2-1, NUDOCS 9703140100
Download: ML18012A553 (8)

Text

CATEGORY 1 REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:9703140100 DOC.DATE: 97/03/10 NOTARIZED: NO DOCKET

. FACIL:%0-400 Shearon Harris Nuclear Power Plant, Unit 1, Carolina 05000400 AUTH. NAME AUTHOR AFFILIATION VERRILLITM. Carolina Power & Light Co.

DONAHUE,J.W. Carolina Power a Light Co.

RECIP.NAME RECIPIENT AFFILIATION

SUBJECT:

LER 97-002-00:on 970207,main FW isolation valves inoperable due to cold weather conditions. Monitored steam tunnel temp once per 12 h shift.W/970310 ltr.

DZSTRZSDTZON CODE: ZE22T COPIES RECEIVED:LTR l ENCZ SIZE:

TITLE: 50.73/50.9 Licensee Event Report (LER), Incident Rpt, etc.

E NOTES:Application for permit renewal filed. 05000400 G

RECIPIENT COPIES RECIPIENT COPIES

"

ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD2-1 PD 1 1 LE,N 1 1 INTERNAL: ACRS 1 1 /aPDp'RA 2 2 AEOD/SPD/RRAB 1' CE 1 1 NRR/DE/ECGB 1 1 NRR/DE/EELB 1 1 NRR/DE/EMEB 1 1 NRR/DRCH/HHFB 1 1 NRR/DRCH/HICB 1 1 NRR/DRCH/HOLB 1 1 NRR/DRCH/HQMB 1 1 NRR/DRPM/PECB 1 1 NRR/DSSA/SPLB 1 1 NRR/DSSA/SRXB 1 1 RES/DET/EIB 1 1 RGN2 FILE 01 1 1 D EXTERNAL: L ST LOBBY WARD 1 1 LITCO BRYCETJ H 1 1 NOAC POORERW. 1 1 NOAC QUEENER,DS 1 1 NRC PDR 1 1 NUDOCS FULL TXT 1 1 N

NOTE TO ALL "RIDS" RECIPIENTS:

PLEASE HELP US TO REDUCE WASTETH CONTACT THE DOCUMENT CONTROL DESK, ROOM OWFN SD-S(EXT. 415-2083) TO ELIMINATE YOUR NAME FROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEEDl FULL TEXT CONVERSION REQUIRED TOTAL NUMBER OF COPIES REQUIRED: LTTR 25 ENCL 25

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Carolina Power 8 Light Company HarA Nadear Plant PO Box 165 New Hill NC 27562 MAR 10 1997 U.S. Nuclear Regulatory Commission Serial: HNP-97-058 ATTN: NRC Document Control Desk 10CFR50.73 Washington, DC 20555 SHEARON HARRIS NUCLEAR POWER PLANT UNIT 1 DOCKET NO. 5(h400 LICENSE NO. NPF-63 LICENSEE EVENT REPORT 7-002-00 Sir or Madam:

In accordance with Title 10 to the Code of Federal Regulations, the enclosed Licensee Event Report is submitted. This report describes a period when the Main Feedwater Isolation Valves were determined to be inoperable due to c'old weather conditions.

Sincerely, J. W. Donahue Director of Site Operations Harris Plant MV Enclosure c: Mr. J. B. Brady (HNP Senior NRC Resident)

Mr. L. A. Reyes (NRC Regional Administrator, Region II)

Mr. N. B. Le (NRC - NRR Project Manager) 9703i40i00 970310 05000400 PDR 8

ADOCK PDR llilitItiigiim swQ

~ ~

State Road 1134 New Hill NC

NRC FORM 3SS U.S. NUCLEAR REGULATORY COMMLSSION APPROVED BY OMB NO. 31604104 (505( EXPIRES 04/30/98 ESTDtATED BURDEN Nl RESPONSE TO COMPLY WITH TIBS MANOATN BIFORMAMN COLLECTION REDDEST: 500 HRS. REPORTED LESSNS LEARNED AR LXCENSEE EVENT REPORT (LER) SICNFNATED INTO THE ICENSWB PROCESS ARD RD BACK TD INDUSTRY.

FORWARD COMMENTS RE6ARDW6 BURDEN ESTIMATE TO THE BNNMATOI ARO RECORDS MANA6EINNTBRANCH IT4 FSSL US. NUCLEAR RBRRATOllT COMMBSOL (See reverse for required number of WAIUNRTOIL OC 20555(Oil. ARO TO THE PAPERWORK REOUCTOI PRONCT 0156 digits/characters for each b(ockl OIDTL OFHCE OF MANACEMENTARO BUDCET. WASHBRITOIL DC 205CL FACRITY NAME I 1) FACE ISI Harris Nuclear Plant Unit-1 50%00 1 OF3 TITLE ISI Inoperable Main Feedwater Isolation Valves caused by cold weather conditions.

EVENT DATE (6) LER NUMBER (6) REPORT DATE l7) OTHER FACILITIES INVOLVED(8)

FACIUTY NAME DOCKET NUMSEA SEOUENTIAL REylSION MONTH OAT TEAR NUMBER NUMBER K FACIUTY NAME DDCKET NUMeoi 2 7 97 97 002 00 3 10 97 05000 OPERATINQ THIS REPORT IS SUBMITTED PUR SUANT TO THE REQUIREMENTS OF 10 CFR %1 (Check one or morel l11)

MODE (9) 20.2201(b) 20.2203(e)(2)(v) 50.73(e) l2) (i) 50.73(e) (2)(viii)

POWER 20.2203(e) (1) 20.2203(s) (3) li) 50.73(s)(2) (ii) 50.73(e) (2) (x)

LEVEL (10) 20.2203(e) l2) li) 20.2203(s)(3) (ii) 50.73(e) (2) (iii) 73.71 20.2203(s) (2) lii) 20.2203(s) l4) 50.73(e)(2)((v) OTHER 20.2203(e) (2) lm) 50.36(c)(1) 50.73(s) (2) lv) spoofy In Abstract bolo W or In NRC Form 366A 20.2203(e)(2)(IY) 50.36(c) (2) 50.73(s)(2)(YII)

LICENSEE CONTACT FOR THLS LER l12)

Michael Verrilli Sr. Analyst - Licensing (919) 362-2303 COMPLETE ONE UNE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT l13)

REPORTABLE REPORTABlE COMPONENT MANUFACTURER CAUSE SYSTEM COMPONENT MANUFACTURER TO NPROS TO NPROS VF FAN J127 SUPPLEMENTAL REPORT EXPECTED (14) MONTH OAT TEAR EXPECTED YES SUBMISSION (If yes, complete EXPECTED SUBMISSION DATE). X No DATE (16)

ABSTRACT (Umit to 1400 spaces, i.o., e pproximstely 15 single-spaced typewritten lines) (16)

On February 7, 1997, with the plant operating in Mode 1 at 100% power, investigation determined that cold weather conditions resulted in the Main Feedwater Isolation Valves IMFIVs) being potentially inoperable during a period from January 17, 1997 through January 20, 1997. The MFIVs serve as containment isolation valves and are required to stroke closed in 10 seconds or less to provide feedwater isolation in the event of a main steam line break or spurious opening of a feedwater regulating valve. Based on purchase specification documents and discussions with the MFIV vendor, a minimum operating temperature of 60 degrees exists to ensure that the MFIVs will stroke in the required 10 seconds. The MFIV actuators are hydraulic to open and shut with nitrogen pressure, but even the shut sequence utilizes hydraulic oil operation. Therefore, with actuator temperature below 60 degrees the hydraulic oil may be too viscous to provide a valve stroke time of 10 seconds or less. This condition was identified when a nearby instrumentation line was found frozen and brought into question the operability of the safety-related MFIVs. (The frozen instrument line had no adverse effect on plant operation.)

This event was caused by a combination of inadequate design and improper functioning of the HVAC system that serves the Steam Tunnel (area that MFIVs are located in). The steam tunnel HVAC supply fans IS64 Fan and S65 Fan) take a suction from the outside atmosphere and exhaust directly into the area of the MFIVs. They are designed with an automatic low ambient temperature shutoff at 30 degrees, but plant process computer data indicates that the fans continued to operate with outside temperatures well below the 30 degree setpoint. Even if the fans had shutoff as designed at 30 degrees, temperatures in the area of the MFIVs would still have been well below the minimum MFIV actuator operating temperature of 60 degrees.

Corrective actions include monitoring the steam tunnel temperature locally once per 12-hour shift and the manually securing the S64 and S65 fans if necessary. Temporary heaters have also been placard in the steam tunnel for use

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION fAOUir nAME ln FACE rn nGWWAAL ranratn ranratn Sheainn Harris Nndear Plant ~ Unit ¹1 50400 2 OF 3 97 - 002 - 00 TEXr Ar mes 2A222 A 2<<r<<r<<t <<22 <<ARes2r22r222 2r rrrrn hnr Jaarl (rri EVENT D CRIPTIONr On February 7, 1997, with the plant operating in Mode 1 at 100% power, investigation determined that technical 4.6.3 had been violated. Specifically, cold weather conditions resulted in thc Main Fccdwater Isolation Valves

'pecification (MFIVs) being potentially inoperable during a period fiom January 17, 1997 through January 20, 1997. Thc MFIVs serve as containment isolation valves and are required to stroke closed in 10 seconds or less to provide feedwater isolation in the event of a main steam linc break or spurious opening of a feedwatcr regulating valve. This isolation function will prevent excessive Reactor Coolant System cooldown and/or Containment over pressurization.

Based on purchase specification documents and discussions with the MFIV vendor, a minimum operating temperature of 60 degrees exists to ensure that the MFIVs will stroke in the required 10 seconds. The MFIV actuators are hydraulic to open and shut with nitrogen pressure, but even the shut sequence utilizes hydraulic oil operation. Therefore, with actuator temperature below 60 degrees the hydraulic oil may be too viscous to provide a valve stroke time of 10 seconds or less.

This condition was identified when a nearby instrumentation line for the C" main feedwater bypass line flow transmitter was found frozen and brought into question the operability of the safety-related MFIVs. (The frozen flow transmitter instrument line had no adverse affect on plant operation.) Investigation into this condition revealed deficiencies in the design and operation of the HVAC system that serves the steam tunnel area where the MFIVs are located. The steam tunnel HVAC supply fans (S64 Fan and S65 Fan) take a suction from the outside atmosphere and exhaust directly into thc area of the MFIVs. They are designed with an automatic low ambient temperature shutoff at 30 degrees, but archived plant process computer data indicates that the S65 fan continued to operate with outside temperatures well below the 30 degree setpoint.

The "C" MFIV actuator is positioned directly in the exhaust path of one of the S65 Fan duct openings and is approximately 10 feet above the area where thc flow transmitter line was found frozen. A review of data taken since the event shows that temperatures in the area of thc MFIV actuators run approximately 15 to 20 degrees greater than the location of the frozen instrument line. Based on this, using a simplistic engineering approach, the temperature of all three MFIV actuators would have been below the 60 degree minimum operating limit and were therefore potentially inoperable (incapable of performing containment isolation function in 10 seconds).

CAUSE:

This event was caused by a combination of inadequate design and improper functioning of the steam tunnel HVAC system.

The steam tunnel HVAC supply fans (S64 Fan and S65 Fan) take a suction from the outside atmosphere and exhaust directly into the area of the MFIVs. They are designed with an automatic low ambient temperature shutoff at 30 degrees, but plant process computer data indicates that the fans continued to operate with outside temperatures weil below thc 30 degree setpoint. Even if the fans had shutoff as designed at 30 degrees, temperatures in the area of the MFIVs would still have been well below the minimum MFIV actuator operating temperature of 60 degrees.

SAFIHV SIGNIFICANCE:

There were no adverse safety consequences associated with this event. This is based on engineering review arid probabilistic safety analysis performed for Harris Plant LER ¹96-006, (submitted April 24, 1996) which determined that the failure of a MFIV to perform its containment isolation function was non-safety significant. The potential consequences of a MFIV failing to close are over-filling the affected Steam Generator and subsequent over-cooling of the Reactor Coolant System. This would be mitigated by plant design features (tripping of the main feedwater pumps or automatic closure of the feedwater regulating valves), or by operator intervention to control the main feedwater system.

This is being reported per 10CFR50.73.a.2.i.B as a violation of Technical Specifications.

PREVIOUS SIMILAR EVENTS:

There have been no other previous reports submitted related to MFIVs being rendered inoperable due to cold weather conditions. LER 96-006 (referenced above) was submitted due to a MFIV valve stem failure that occurred during surveillance testing.

0 LICENSEE EVENT REPORT (LER)

TEXT CONTINUATlON fArbUTT aAEIE n) EEa kQlbra rbr PAEE Q saaornAE rruMbta rnnrbra Shearon Harris Nudear Plant - Unit Nl 50&0 3 OF 3 97 - 002 - 00 TEXT rP ear peer ir IIroiwb est ahfcinal'ayie el ANC f<<e Jb&V rill ORRE ACTIONS COMPLETED:

1. When outside atmosphere ambient temperature is less than 65 degrees, steam tunnel temperatures are being locally monitored once per shift by Operations personnel.

2. Temporary heaters have bmn placed in the steam tunnel to be used as needed for temperature control.

CORRECrIVE ACTIONS PLANNED:

Additional investigation and troubleshooting will be performed on the steam tunnel HVAC system to ensure proper operation and that adequate temperatures are maintained during cold weather conditions. These planned actions will be completed by October 1, 1997.

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