ML20010G264

Forwards LER 81-046/03L-0.Detailed Event Analysis Encl

ML20010G264
Person / Time
Site:	Fort Saint Vrain
Issue date:	08/26/1981
From:	Warembourg D PUBLIC SERVICE CO. OF COLORADO
To:	Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML20010G265	List: ML20010G264 ML20010G271
References
P-81212, NUDOCS 8109150503
Download: ML20010G264 (5)

Text

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LE4 16805 ROAD 19%

• PLATTEVILLE, COLOR ADO 80651 Augus t 26, 1981 Fort S t. Vrain Unit No. 1 P-81212 o\ N,

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Q by ?I fir. Karl V. Seyfrit , Director h--

Nuclear Regulatory Connission Region IV 9

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o.5-Office of Inspection and Enforcement 611 Ryan Plaza Drive g/

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-s ,,N Suite 1000 Arlington, Texas 76012 Re fe rence : 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/

81-046, Final, submitted per the requirements of Technical Specif: cation AC 7. 5.2(b)2.

Also, please find enclosed one copy of the Licensee Event Report for Reportable Occurrence Report No. 50-267/81-046.

Very truly yours ,

l D Wa Manager, Nuclear Production DW/cis j Enclos ure cc: Director, MIPC 6N s

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8109150503 810826 PDR ADOCK 05000267 S PDR l { }, &

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REPORT DATE: Aucust 26, 1981 REPORTABLE OCCURRENCE 81-046 ISSUE 0 OCCURRENCE DATE: July 28. 1981 Page 1 of 4 FORT ST. VRAIN NUCLEAR GENERATING STATION PUBLIC SERVICE COMPANY OF COLORADO 16805 WELD COUNTY ROAD 19 1/2 PLATTEVILLE, COLORADO 80651 REPORT NO. 50-267/81-046/03-L-0 Final IDENTIFICATION OF OCCURRENCE:

The emergency feedwater header supply to Loop 1 helium circulatar water turbine drives was isolated for repairs with the plant operating at power. This is a cegraded mode of LCO 4.2.2(a) and is reportable per Fort St. Vrain Technical Specification AC 7.5.2(b)2.

EVENT DESCRIPTION:

On July 28, 1981, with the plant cperating at 30% power and 83 MWe, operations personnel experienced pressure control difficulties on the emergency feedwater supply header to Loop 1 helium circulator water turbines. Refer to Figure 1 for simplified diagram of this system.

Emergency feedwater is supplied to Loop 1 and loop 2 helium turbines via two separate flow p ths

( A and(

cirulator[) water

1. The main pressure control valves ( U1 and 2 )

are designed to control feedwater supply pressure unde flow conditions. Additional pressure control vavies ( 3 and 4 ) are provided to bleed off any leakage from the main control valves to the turbine water drain tank under the no-flow conditions which normally exist.

In this instanca under no-flow conditions, excessive leakage through relief valves 7 downstream of the main pressure control valve for Loop 1 caused erratic operation of the main pressure control valve.

A Plant Trouble Report was initi ted, and the emergency feedwater supply to Loop 1 was isolated 5 for repair of the relief valves at 0800 hours0.00926 days <br />0.222 hours <br />0.00132 weeks <br />3.044e-4 months <br /> on July 28, 1981. The relief valves were repaired, p.nd the system restored to service at 0140 nours on July 29, 1981, within the 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> allowed by LCO 4.2.2 without the affected helium circulators being considered inoperable.

Had it been necessary during this period, the Loop 1 circulators could have been operated on water turbine drive at recuced speed utilizing a supply from the emergency condensate or firewater systems.

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Eoergency Feedwater To llackup Ileade r Bearing Water

) To Turbir.e Water Drain Tzutk h h Q V-21522

/$g V-21542 To I,oop 1 IIelium Circulator V-211615 PV-2124 3 Water Turbine Drives

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O PV-21243-1 Q To Turbine Water

> Drain Tank n c, > To Turbine Water Drain Tank q V-2152 3 V-21543 V-211616 / / To Loop 2 IIelium Circulator -o g i P V-21244 Q /*p Q Water Turbine Drives

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To Turbine Water Drain Tank O

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Emergency Feedwater Pressure Control ,

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REPORTABLE OCCURRENCE S1-046 ISSUE 0 Page 3 of a CAUSE DESCRIPTION:

Relief valve leakage downstream of main pressure control valves necessitated isolation for repair. The relief valve leakage is attributed to normal wear.

• CORRECTIVE ACTION:

The relief valves were removed, rebuilt, bench tested, and re-installed. The emergency feedwater supply header to Loop 1 was restored to service.

No further corrective action is anticipated or required.

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REPORTABLE OCCURRENCE 81-046 ISSUE O Page 4 of 4 i

Prepared By: gu./-

Paul Moore Technical Services Technician Reviewed By: W2./'W.cjM M11't McBri'de Technical Services Manager s

Reviewed By: E[ /M d M Edwin Station Manager D. Hill f Approved By: Yd /

Don Waremoourg Manager, Nuclear Production s

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