05000267/LER-1981-070, Forwards LER 81-070/03L-0.Detailed Event Analysis Encl

Forwards LER 81-070/03L-0.Detailed Event Analysis Encl

ML20033D271
Person / Time
Site:	Fort Saint Vrain
Issue date:	11/25/1981
From:	Warembourg D PUBLIC SERVICE CO. OF COLORADO
To:	Jay Collins NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML20033D272	List: 05000267/LER-1981-070, Forwards LER 81-070/03L-0.Detailed Event Analysis Encl 05000267/LER-1981-070-03, /03L-0:due to Mods Begun 811027,steam Generator Overpressure Protection Not in Svc Between 811028 & 1103. Mods Completed & Instrumentation Returned to Svc
References
P-81300, NUDOCS 8112070471
Download: ML20033D271 (4)

LER-1981-070, Forwards LER 81-070/03L-0.Detailed Event Analysis Encl

Event date:
Report date:
2671981070R00 - NRC Website

text

j pul)iie service conipany

• ceanurse WAydh l 16805 Road 19 1/2, Platteville, Colorado 80651-9298 November 25, 1981 Fort St. Vrain Unit No. 1 P-81300 g

4 WrdNSD.

Mr. Jchn T. Collins, Regional Administrator

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Region IV r DEC4 j

7 Nuclear Regulatory Commission

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u.s. *gim 611 Ryan Plaza Drive J' ?g, g Suite 1000 k

Arlington, Texas 76011

Reference:

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

Dear Mr. Seyfrit:

Enclosed please find a copy of Reportable Occurrence Report No. 50-267/81-070, Final, submitted per the requirements of Technical Specification AC 7.5.2(b)2.

Also, please find enclosed one copy of the Licinsee Event Report for Reportable Occurrence Report No. 50-267/81-070.

Very truly yours, h-YKmd Don Warembourg Manager, Nuclear Production DW/cis Enclosure cc:

Director, MIPC M sh 8112070471 811125 DR ADOCK 05000

REPORT DATE:

November 25, 1931 REPORTABLE OCCURRENCE 81-070 ISSUE 0 OCCURRENCE DATE: October 27, 1981 Page 1 of 3 FORT ST. VRAIN NUCLEAR GENERATING STATION PUBLIC SERVICE COMPANY OF COLORADO 16805 WELD COUNTY ROAD 19-1/2 PLATTEVILLE, COLORADO 80651-9298 REPORT NO. 50-267/81-070/03-L-0 Final IDENTIFICATION OF OCCURRENCE:

On two occasions between October 28 and November 3, 1981, the Loop 2 steam generator penetration overpressure protection instrumentation required by LC0 4.4.1, Table 4.4-2 was not in service.

This is a degraded mcde of LCO 4.4.1 and is reportable per Fort St.

Vrain Technical Specification AC 7.5.2(b)2.

EVENT

DESCRIPTION

On October 24, 1981, the Loop 2 steam generator B-2-3 interspace leakage rate exceeded the allowable limit of LCO 4.2.9.

The reactor power was reduced, and the turbine generator taken off line.

This problem had occurred before and was previously reported in Reportable Occurrence 50-267/80-030/03-L-0.

On October 26, 1981, a proposal, P-81270, was sent to the Nuclear Regulatory Commission which would allow continued operation for completion of the temperature fluctuation testine that had been in -

progress. The proposal consisted of operating the interspace for steam generator module B-2-3 separately from the remaining Loop 2 steam generator modules to permit control of the interspace pressure at slightly above cold reheat steam pressure. To effect this control change, modifications of the steam generator piping involving a rupture disk, relief valve, and plant protective system overpressure protection were necessary for the module B-2-3 penetration interspace.

On October 27, 1981, with the reactor at 0.5% power and the PCRV depressurized to less than 100 psig, the modification to steam generator module B-2-3 interspace piping was begun. On October 28, at about 0000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br />, the rupture disk was welded' into the module B-2-3 penetration interspace piping; therefore, the capability for pressurizing the' penetration existed at' that time.

However, automatic plant protective system action for an overpressurization condition had not yet been provided._for -the B-2-3 penetration.

i Therefore, operation in a degraded mode of LCO 4.4.1 occurred until the loop was shutdown at 1110 hours0.0128 days <br />0.308 hours <br />0.00184 weeks <br />4.22355e-4 months <br />'on October 28, 1981, within the 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> required.by LCO 4.4.1.

O REPORTABLE OCCURRENCE 81-070 ISSUE O Page 2 of 3 The modification was completed, and the plant rise-to power was begun.

On November 3, 1981, it hecame necessary to install a pressure gauge on a pressure sensing line of the B-2-3 penetration to provide local indication and better control of the B-2-3 penetration pressure.

This installation required the Loop 2 steam generator penetration overpressure protection instruments be disconnected at 1450 hours0.0168 days <br />0.403 hours <br />0.0024 weeks <br />5.51725e-4 months <br /> on November 3, 1981, to prevent an unnecessary loop shutdown. The gauge was installed, and the circuitry was returned to service at 1600 hours0.0185 days <br />0.444 hours <br />0.00265 weeks <br />6.088e-4 months <br /> the same day. The Loop 2 steam generator penetration overpressure protection instrumentation was out of service for 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> end 10 minutes.

CAUSE

_ DESCRIPTION:

The steam generator penetration overpressure protection instrumentation was out of service during modification of the Loop 2 steam generator penetration piping and the associated plant protective syrcem circuitry.

CORRECTIVE ACTION:

On the first occassion, the Loop 2 steam generator icop was shutdown within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />, as re uired by LC0 4.4.1.

On the second occassion, s

the modification was completed in I hour and 10 minutes, and the Loop 2 steam generator overpressurization protection instrumentation was restored to service.

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REPORTABLE OCCURRENCE 81-070 ISSUE O Page 3 of 3 4

i 4

Prepared By:

Asa B. Reed f

Technical Services Technician 1

Reviewed By:

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/d Charles Fuller Technical Services Engineering Supervisor i

Reviewed By:

bbhuQ(sq kktdtts ek-Edwin D. Hill '4 Station Manager Approved By:

/A NE 1 <.

i Don Warembourg

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