05000267/LER-1981-060, Forwards LER 81-060/03L-0.Detailed Event Analysis Encl

Forwards LER 81-060/03L-0.Detailed Event Analysis Encl

ML20011A631
Person / Time
Site:	Fort Saint Vrain
Issue date:	10/22/1981
From:	Warembourg D PUBLIC SERVICE CO. OF COLORADO
To:	Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML20011A632	List: 05000267/LER-1981-060, Forwards LER 81-060/03L-0.Detailed Event Analysis Encl 05000267/LER-1981-060-03, /03L-0:between 810922-1013,emergency Feedwater to Loop 1 Helium Circulator Water Turbine Drives Was Isolated on Three Occasions.Caused by Leakage Between Seat Ring & Valve Body Pressure Control Valve
References
P-81253, NUDOCS 8110290205
Download: ML20011A631 (6)

LER-1981-060, Forwards LER 81-060/03L-0.Detailed Event Analysis Encl

Event date:
Report date:
2671981060R00 - NRC Website

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October 22, 1981 OCTg 8 b2 Fort St. Vrain

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Unit No. 1 odlgge P-81253

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'.ctd' j't OCT 2 61981 Mr. Karl V. Seyfrit, Director l'\\

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Nuclear Regulatory Commission Region IV Office of Inspection and Enforcement 611 Rycn Plaza Drive Suite 1000 Arlington, Texas 76012

Reference:

Facility Operatt.ng Licr-a No. DPR-34 Docket No. 50-267

Dear Mr. Seyfrit:

Eaclosed please find a copy of Reportable Occurrence Report No. 50-267/81-060, 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 Occurrence Report =No. 50-267/81-060.

Very truly yours, A nwk Don Warembourg

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Manager, Nuclear Production DW/cls Enclosure cc.

Director, MIPC si.

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1 (P Letter)

San Irancisco Operatione Office Attn:' California Patent Group

' 1333? Broadway.

Oakland, California 94612 Dep ar tmen t o f Ene rgy - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

1 (P Letter)

Mr. Glen A. Newby, Chief

.HTR Srsuch' Division of Nuclear Power Development Mail Station 5-107 Vaehington, D.C.

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1 (P Letter)

Attn - Project Nanager 110 West A Street, Suite 460 San Diego, California 92101 1 (original of P Letter.

Mr. Karl V. Seyfrit. Director Region IV and Copy of I.ER)

Office of Inspection and Enforcement Nuclear Regulatory Countisaton 611 Ryan Plaza Drive Suita 1000 Arlington, Texas 76012

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Office of Management Information and Program Control U. S. saclear Regulatory Cosumission Washington, D.C.

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Mr. B ill Lave lee - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

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Nuclear Safety Analysis Center 3412 Hillview Avenue F. O. Box 10412 Palo Alto, California 94303 1

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REPORT DATE:

October 22, 1981 REPORTABLE OCCURRENCE 81-060 ISSUE O OCCURRENCE DATE:

September 22, 1981 Page 1 of 4 FORT ST. VRAIN NUCLEAR GENERATING STATION PUBLIC SERVICE COMPANY OF COLORADO 16805 WELD COUNTY ROAD 19 1/2 PLATTEILLE, COLORADO 80651-9298 REPORT NO. 50-267/81-060/03-L-0 Final IDENTIFICATION OF OCCURRENCE:

During steady state power operation, the emergency feedwater header supply to Loop 1 helium circulator water turbine drives was isolated on three separate occasions between September 22, 1981, and October 13, 1981. This is a degraded mode of LCO 4.2.2 and is reportable per Fort St. Vrain Technical Specification AC 7.5.2(b)2.

EVENT

DESCRIPTION

Event #1 On September 22, 1981, with the plant operating at 70% thermal. power and 243 MWe, excessive leakage through PV-21243 necessitated isolation of emergency feedwater to Loop 1 helium circulator water turbine drives to effect repairs. Refer to Figure 1 for simplified' diagram of this system.

A pressure control system is provided to control emergency feedwa er flow to each of the circulator pelton wheel supply headers and B under flow and no-flow conditions.

contra s supply header pressure.

l Under flow conditions, 21243 1 Under no-flow conditions, PV-2 243-1 U3 is provided to relieve excess header pressure to the turbine water drain tank in the event DV-21243 leaks through.

In this instance, leakaga through.PV-21243 was in excess of the capabilities of PV-21243-1,_and increased Loop 1 supply header pressure.

This dio not, in itself, render the emergency feedwater to Loop 1 ci rc ulators inoperable.

A Plant Trouble Report was initia ed, and the emergency feedwater was isolated ahead of PV-21243 5 at 0010 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> on -September 22, 1981.

Repairs were made to PV-1243, and pelton drive water system was restored to service at 2140 hours0.0248 days <br />0.594 hours <br />0.00354 weeks <br />8.1427e-4 months <br /> on September 22, 1981.

Event #2 Valve leakage increased again, and on September 29, 1981, at 1100 hours0.0127 days <br />0.306 hours <br />0.00182 weeks <br />4.1855e-4 months <br />, PV-21243 was isolated again and the valve stroke was lengthened in an attempt to reduce the leakage. The valve was returned to service at 1150 hours0.0133 days <br />0.319 hours <br />0.0019 weeks <br />4.37575e-4 months <br />.

l REPORTABLE OCCURRENCE 81-060 ISSUE O Page 2 of 4 Event #3 On October 12, 1981, at 1000 hours0.0116 days <br />0.278 hours <br />0.00165 weeks <br />3.805e-4 months <br />, PV-21243 was isolated again for repairs.

The valve was repaired and returned to service on October 13, 1981, at 0830 hours0.00961 days <br />0.231 hours <br />0.00137 weeks <br />3.15815e-4 months <br />.

The pelton drive water system was returned to operation 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(a) in each event.

Had it been necessary during these periods, the affected helium circulators could have been operated at reduced speed utilizing a water supply from the emergency condensate or firewater systems.

CAUSE

DESCRIPTION:

Excessive leakage through PV-21243 required isolation of emergency feedwater to Loop i helium circulators to effect repairs.

The

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leakage was due to wear on the gasket surface between the seat ring and the valve body.

CORRECTIVE ACTION:

Event #1 The gasket surface in the valve body of PV-21243 was built up by applying devcon compound to eliminate leakage.

The valve was re-assembled, and the system returned to service.

Event #2 The valve stroke was lengthened.

Event #3 The valve disc and-seat ring were replaced.

The valve was re-assembled and returned to service.

A Plant Trouble Report has been written to have this valve rebuilt during the upcoming maintenance shutdown.

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' ergency Feedwater To Backup p

eader Pearing Water O

To Loop 1 llelium Circulator V 211615 1

PV-2124 3 Water Turbine Drives bN/

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To Turbine Water

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PV-21244 To hop 2 IIelium Circulator ygg h

V-211616 Q

Water Turbine Drives j

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To Turbine Water O

Drain Tank O

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Emergency Feedwater Pressure Control 7

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REPORTABLE OCCURRENCE 81-060-ISSUE O-

- Page 4 of 4 Prepared By:

Asa Reed Technical Services Technician Reviewed By:

/k Charles Full'er Technical 3ervices Engineer p Supervisor i

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Reviewed By:

Edwi n D.Wi 11' ~/

Station Manager l

l Approved By:

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Don Warembourg f/

Manager, Nuclear Production i

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