ML20042B821

Forwards LER 82-005/03L-0.Detailed Event Analysis Encl

ML20042B821
Person / Time
Site:	Fort Saint Vrain
Issue date:	03/17/1982
From:	Warembourg D PUBLIC SERVICE CO. OF COLORADO
To:	Jay Collins NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML20042B822	List: ML20042B821 ML20042B823
References
P-82082, NUDOCS 8203260186
Download: ML20042B821 (6)

Text

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Public Service Company Cf OdlcIrade 4 _

16805 Road 19 1/2, Clatteville, Colorado 80651-9298 March 17, 1982 Fort St. Vrain Unit No. 1 e,a -

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2 RECBVED H MAR 2 51982>

Mr. John T. Collins, Regional Administrator g -7, Region IV ]6, rAc acuuss u ,

Nuclear Regulatory Commission

• 611 Ryan Plaza Drive g 8 Suite 1000 y e Arlington, Texas 76011

Reference:

Facility Operating License No. DPR-34 Docket No. 50-267

Dear Mr. Collins:

Enclosed please find a copy of Reportable Occurrence Report No. 50-267/82-005, Final, submitted per the requirements of Technical Specification AC 7.5.2(b)3.

i Also, please find enclosed one copy of the Licensee Event Report for

Reportable Occurrence Report No. 50-267/82-005.

l Very truly yours,

- f}%wbs Don Warembourg Manager, Nuclear Production DW/cis Enclosure cc: Director, MIPC ],[R@fHfRV/[5P,

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JL 8203260186 820317 PDR ADOCK 05000267 S

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REPORTABLE OCCURRENCE DISTRIBUTION Nus6er of Copies _

1 (P Tetter)

Dep ar tment o f Ene rgy - - -

San Frmcisco Operations Of fice Attn: California Patent Group 1331 Broadway Oak 1snd, California 94612

- ----- -- - -- 1 (P Letter)

Department of Ene rgy - - - - - - - - -

Mr. Glen A. Newby, Chief IITR Branch Division of Nuclear Power Development Mail Station B-107 Washington, D.C. 20545 e

1 (P Letter)

Dep attmen t o f Ener gy - - - - - - - - - - - - - - - - - - - - - - -

Attnt Project Manager 110 West A Street, Suite 460 San Diego, California 92101 1 Original of P !stter)

- --- - - - - - -- l

tr. John T. Collins, Regional Administrator Region IV Nuclear Regulatory Constission 611 Ryan Plaza Drive Suite 1000 Arlington, Texas 76011 *

- - - - - - - - - - - - 1 (P Letter)

Mr. Ge o rge Kuzmy cz - -

Nuclear Regulatory Commission 7920 Norfolk Avenue Bethesda, Maryland 20034

-- - --- ---- 1 (P !stter)

Director - - - - - - - ion and Program Control Of fice of Maagement Informat Nuclear Regulatory Cossaission Washington, D.C. 20555 1 (P Letter)

Re cor ds Cent e r -

Institute of Nuclear Power Operations 1820 Water Place Atlanta, Georgia 30339 10 (Original of FPLG Letter, two copies of FPLC Letter, Mr. Richard Phelps, FSV, CA Site Representative - - - - - - - - - - - and one copy of P Letter)

General Atomic Co g any 16864 Weld County Road 191/2 Platteville, Colorado 80651

- -- 1 (P Letter)

NRC Resident Site inspector (y

REPORT DATE: tiarch 17, 1982 REPORTABLE OCCURRENCE 82-005 ISSUE O OCCURRENCE DATE: February 15, 1932 Page 1 of a FORT ST. VRAIN NUCLEAR GENERATING STATION PUBLIC SERVICE COMPANY OF COLORADO 16805 WELD COUNTY ROAD 19 l/2 PLATTEVILLE, COLORADO 80651-9298 ,

REPORT NO. 50-267/82-005/03-L-0 Final IDENTIFICATION OF OCCURRENCE:

On February 15, 1982, with the reactor pressurized to greater than 100 psia and subcritical, a Loop 2 steam generator penetration pressure switch was found isolated which could have allowed pressure between the steam generator penetration rupture disk and the associated relief valve to be in excess of that specified in LCO 4.2.7(d). This is reportable per Fort St. Vrain Technical Specification AC 7.5.2(b)3.

EVENT DESCRIPTION:

(Footnotes ([ ) refer to Figure 1)

At 0600 hours0.00694 days <br />0.167 hours <br />9.920635e-4 weeks <br />2.283e-4 months <br />, February 15, 1982, high gas pressure in the piping betwea No. I Loop 2 steam g rator penetration interspace rupture disk 1 an safety valve 2 caused the pressure swi , set at 4.5 psig, 3 to open, tripping the Control Room alarm 4 . The operat tooK appropriate action by opening the safety stem vent valve o using the Control Room vent valve hand switch 6 . This action, while appropriate for the situation, failed to clear the alarm indication.

Since the alarm indication did not clear, at 0710 hours0.00822 days <br />0.197 hours <br />0.00117 weeks <br />2.70155e-4 months <br /> on February 15, 1982, the operator took further appropriate action by switching to the No. 2 safety sys'a . This was accomplished by using tne k valve hand switch 7 to close the 1 block valve and simultaneously open ne No. 2 block valve .

An Instrumentation Technician, calleo to troubleshoot the failure of the alarm to clear, verified proper operation of the No. 1 vent valve, thus, giving assurance that the No. 1 safety system piping had been oreviously relieved of gas pressure. Further investigation revealed the pressure switch to be in a tripped condition. The technic n lightly tapped the pressure sw *ch while opening a vent valve 10 located on the' same rack 11 the pressure switch was mountec n. This action caused the pressure switch to reset and clear the alarm. The technician pressurized and vented the pressure switch several times to observe the switching action. He verified

REPORTABLE OCCURRENCE 82-005 ISSUE O Page 2 of 4 the setpoint was properly calibrated to about 4.5 psig and that the switch was functioning smoothly. Ass. ming that the problem had been caused by a sticking switch mechanism, and that this had been corrected, the technician vented the switch, leaving it in a reset condition.

At 0015 hours1.736111e-4 days <br />0.00417 hours <br />2.480159e-5 weeks <br />5.7075e-6 months <br /> on February 16, 1982, the Loop 2 steam generator rupture disk No. I leak alarm again alerted Control Room personnel of high No. I safety ^ system gas pressure. The Reactor Operator took appropriate action by opening the vent valve, but again, the alarm failed to clear. An Equipment Operator dispatched to the No. I safety stem, discovered the pressure switch root isolation valve 12 was in a closed position. He opened the isolation valve and observed operation of the vent valve while the Reactor Operator opened it once more. The vent valve did open properly, gas pressure was relieved, and the alarm cleared.

CAUSE DESCRIPTION:

The cause for the occurrence was the root isolation valve to P3-11158 being closed for unknown reasons. There was enough leakage past the seat of the root isolation valve that the pressure switch could trip.

Although the pressure between the rupture disk and relief valve-could have exceeded the 5 psig allowed by LCO 4.2.7(d), the functional

- requirements of the system could still have been met.

CORRECTIVE ACTION:

In both instances, when the alarm was received (0600 hours0.00694 days <br />0.167 hours <br />9.920635e-4 weeks <br />2.283e-4 months <br /> on February-15, 1932, and 0015 hours1.736111e-4 days <br />0.00417 hours <br />2.480159e-5 weeks <br />5.7075e-6 months <br /> on February 16, 1982), immediate action was taken to vent the safety system to the Reactor Building atmosphere, and in both instances, operation of the vent valve was verified.

The pressure switch was tested and found to be operable and within l setpoint tolerances.

The pressure switch isolation valve was opened to the full open position.

I No further corrective action is anticipated or required.

l

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REPORTABLE OCCURRENCE 82-005

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FIGURE 1 ISSUE O Page 3 of 4 h To Atmosphere Outside Reactor Building PAH-lll58 ----] b l

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V-ll 39 )

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g Set at 475 psig i

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Local Threaded Ven t Valve yh N

Plug and Test Con-h nection HS-(2) 1116(i

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T7 Local Isolation l g Valve l

O u O k 2 O To Reactor rg > Building Atmosphere l

( V-ll29 ) ( HV-11166 )

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( M-1103 h5f System HS- b 11164 g g H V-lll64-2 )

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Puri fied Helium From Loop 2 Steam Generator Penetration Interspaces i

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LOOP 2 STEAM GENERATOR PENETRATI0fl If1TERSPACE, iiO.1 RUPTURE DISK AilD SAFETY VALVE SYSTEM T

. s REPORTABLE OCCURRENCE 82-005 4

6 ISSUE O Page 4 of 4

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4 Prepared By: ,

Paul A. Tramp /

Technical Services Technician Reviewed By:

Charles Fuller Technical Services Engineering Supervisor Reviewed By: [4 k/ A7 g

Ecwin D. Hill /

Station Manager Approved By: MwM Don Waremoourg )

Manager, Nuclear Prod Ktion l

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