ML19320A926

Forwards LER 80-029/03L-0

ML19320A926
Person / Time
Site:	Fort Saint Vrain
Issue date:	07/01/1980
From:	Warembourg D PUBLIC SERVICE CO. OF COLORADO
To:	Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML19320A927	List: ML19320A926 ML19320A944
References
P-80191, NUDOCS 8007080289
Download: ML19320A926 (4)

Text

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y public Service Company

• CcHendo 16805 ROAD 19%

. . _ _.! PLATTEVILLE, COLORADO 80651 1

July 1, 1980 Fort St. Vrain Unit No. 1 P-80191 Mr. Karl V. Seyfrit, Director Nuclear Regulatory Commission Region IV Office of Inspection and Enforcement 611 Ryan Plaza Drive Suite 1000 Arlington, Texas 76012

Reference:

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

Dear Mr. Seyfrit:

Enclosed please find a copy of Reportable Occurrence Report No. 50-267/

80-29, Final, submitted per the requirements of Technical Specification AC 7.5.2(b)2.

Also, please find enclosed one copy of the Licensee Event Report for Reportable Cccurrence Report No. 50-267/80-29.

Very truly yours,

$WY Don Warembourg Manager, Nuclear Production DW/cis Enclosure cc: Director, MIPC V

Yh \

80070801N 3

e REPORT DATE: July 1, 1980 REPORTABLE OCCURRENCE 80-29 -

ISSUE O OCCURRENCE DATE: June 2, 1980 Page 1 of 3 FORT ST. VRAIN NUCLEAR GENERATING STATION PUBLIC SERVICE COMPANY OF COLORADO 16805 WELD COUNTY ROAD 19 1/2 PIATTEVILLE, COLORADO 80651 REPORT No. 50-267/80-29/03-L-0 Final IDENTIFICATION OF OCCURRENCE:

Operations personnel observed that the reactor building pressure could not be maintained subatmospheric. Subsequent investigation revealed that one reactor building louver was not closed.

This resulted in operation in a degraded mode of LCO 4.5.1 a)2 and a)3, and is reportable per Fort St. Vrain Technical Specification AC 7.5.2(b)2.

EVENT DESCRIPTION:

At 1630 hours0.0189 days <br />0.453 hours <br />0.0027 weeks <br />6.20215e-4 months <br /> on June 2,1980, with the plant operating at approximately 60%

thermal power and 172 MRe, operations personnel observed that reactor building pressure was atmospheric. This is contrary to the requirenents of LCO 4.5.1 a)2, and an investigation was initiated to determine the reason for inability to maintain subatmospheric pressure.

At 0010 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> on June 3,1980, with plant conditions essentially unchanged, l investigation revealed that one of ninety-four reactor building louvers was open. The reactor building louver system is designed to preserve reactor building integrity in the event of an over-pressure condition. This system consists of twenty groups, each group containing four to five -louvers. The system is designed to maintain the louvers in a normally-closed position via  !

an air supply to a pneumatic actuator. Operations personnel investigating l the' reactor building pressure problem discovered the open louver and determined l that the problem was due to a frozen air line. Because the air line was i frozen near the operator, the backup nitrogen supply could not be utilized  ;

to maintain the louver in the closed position. Technical Specification LCO l 4.5.1 a)3 requires that the louvers must be closed, except during approved '

surveillance testing.

. REPORTABLE OCCURRENCE 80-29 .

ISSUE O Page 2 of 3 EVENT DESCRIPTION: (Cont'd)

Technical Specifications require that the reactor building pressure be main-tained subatmospheric in order to reduce the amount of radiation released to the environment during normal operation or accident conditions. A check of radiation monitoring instrumentation by health physics personnel indicates no increase in reactor building activity above background levels during the time period in question; therefore, neither the reduction in reactor building pres-sure to atmospheric nor the louver being open resulted in any release of radio-activity to the environment.

CAUSE DESCRIPTION:

Operation in a degraded mode of LCO 4.5.1 was the result of a frozen air line to a reactor building louver pneumatic actuator. The air line had been in-stalled near the liquid nitrogen system piping. The extremely cold tempera-tures of the liquid nitrogen system, and the close proximity of the air line to the lagging of the nitrogen system piping, resulted in the freezing of a small amount of moisture within the air line. This blocked the air supply to the pneumatic actuator, thus allowing the louver to open, and contributed to the inability to maintain reactor building pressure subatmospheric.

Followup investigation by instrument personnel revealed a crack in the air line tubing. Although thawing operations had restored operability of the system, and sufficient air supply was available to hold the louver closed, the cracked tubing was replaced to insure continued system operability.

CORRECTIVE ACTION:

Operations personnel moved the air line away from the cold piping of the liquid nitrogen system and thawed out the line. This removed the block in the line, provided air supply to the pneumatic actuator, closed the louver, and returned the reactor building pressure to, subatmospheric.

Followup repair by plant instrument personnel on June 3 involved replacement of a piece of cracked tubing to the -louver pneumatic actuator.

All louvers in the affected group were subsequently checked and only the air supply ttbing for the louver referenced in this report was routed near the liquid nitrogen system piping.

A Plant' Trouble Report has been issued to reroute the tubing to the affected louver.

No further problems with louver position or reactor building pressure were obse rved.

No further corrective action is anticipated or required.

REPORTABLE OCCURRENCE 80-29 .

ISSLT 0 Page 3 of 3 Prepared By: iLI- , v Cathy C. Jtirsch Technical Services Technician Reviewed By: /_/./ . /.

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J. V.<Gahm

' Technical Services Supervisor Reviewed By: /-L 4. d \

Frank M. Mathie Operations Manager Approved By: e Yhd ,

Don Warembourg /

Manager, Nuclear Production

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