ML19323H728

Forwards LER 80-023/03L-0

ML19323H728
Person / Time
Site:	Fort Saint Vrain
Issue date:	06/06/1980
From:	Warembourg D PUBLIC SERVICE CO. OF COLORADO
To:	Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML19323H729	List: ML19323H728 ML19323H733
References
P-80144, NUDOCS 8006160115
Download: ML19323H728 (6)

Text

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j! 16805 ROAD 19%

i 1 e} t PLATTEVILLE, COLORADO 80651 June 6, 1980 Fort St. Vrain Uni t No . 1 P-80144 Mr. Karl V. Seyfrit, Director Nn- 'ar Regulatory Commission Ro j art IV Office of Inspection and Enforcement 611 U.yan Plaza Drive Suita 1000 Arlington, Texas 76012 i

Re ference: 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/

80-20, 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. 50-267/80-23.

Very truly yours,

[w Don Warembourg Manager, Nuclear Production DW/cis Enclosure I

cc: Director, MIPC Y kk 8006160ll5 3

REPORT DATE: J ur. 6, 1980 REPORIABLE OCCURRENCE 80-23 ISSUE O OCCURRENCE DATE: 5 r 7. 1980 Page 1 of 5 FOP' "'. VRAIN NUCLEAR GENERATING STATION

.CdLIC SERVICE COMPANY OF COLORADO 16805 WELD COUNTY ROAD 19 1/2 PLATTEVILLE, COLORADO 80651 REPORT No. 5 0-267/80-23/03-L-0 Final IDENTIFICATION OF OCCURRENCE:

During the period from May 7, 1980, to May 17, 1980, the plant was operated with the emergency feedwater header supply to the helium circulator water turbine drives of one loop isolated on four separate occasions.

These occurrences constitute operation in a degraded mode of LCO 4.2.2(a) and are reportable per Fort St. Vrain Technical Specification AC 7.5.2(b)2.

EVENT I

DESCRIPTION:

Fo r t S t . Vraia Technical Specification LCO 4.2.2 specifies the conditions which must be met for circulator operability. Item (a) of' LCO 4.2.2 requires that emergency feedwater be available to drive the circulator water turbines, but provides that this supply may be isolated for up to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> without the helium circulators being considered inoperable.

A pressure control system is provided to control emergency feedwater flow in each loop under flow or no-flow conditions. Refer to Figure 1 for simplifieu diagram of this system. Emergency feedwater is supplied to Loop 1 and L p2 helium circulator water turbines via two sep rate flow paths ( A and ).

The main pressure control valves ( 1 and 2 ) are designed to contro feedwater pply ssure under flow conditions.- Additional pressure control valves ( and ) are provided to bleed off any leakage from the main valves to t e tur tne water drain tank under the no-flow conditions which normally exist.

During the period from May 7,1980, to May 17,1980, the emergency feedwater supply to either Loop 1 or Loo 2 wat r turbine drives was isolated via valves provided for this purpose ( 5 and 6 ) on four separate occasions, as de-scribed below.

p - -

REPORTABLE OCCURRENCE 80-23 ISSUE O

, Page 2 of 5 EVERT DESCRIPTION: (Cont'd)

Event #1 On May 7, 1980 a Plant Trouble Report was initiated, indicating that PV-21244-1 ( 4 of Figure 1) was leaking. At 1430 hours0.0166 days <br />0.397 hours <br />0.00236 weeks <br />5.44115e-4 months <br /> on May 7, with the plant operating at approximately 45% thermal power and 135 MNe, emergency feedwater header supply to Loop 2 helium circulators was iso-laced in order to determine the cause of leakage and repair the problem.

Following a weld repair to the line immediatelp downstream of this valve, the system was returned to service at 1945 hours0.0225 days <br />0.54 hours <br />0.00322 weeks <br />7.400725e-4 months <br />.

Event #2 At 2100 hours0.0243 days <br />0.583 hours <br />0.00347 weeks <br />7.9905e-4 months <br /> on May 7, 1980, with plant conditions essentially unchanged, Loop 2 emergency feedwater supply was again isolated as the system was not 'providing proper pressure control. At this time, the line downstream of PV-21244-1 was replaced, and the system was returned to service at 2315 hours0.0268 days <br />0.643 hours <br />0.00383 weeks <br />8.808575e-4 months <br />.

Event #3 On May 8,1980, with the plant operating at approximately 46% thermal power and 135 MWe, lack of pressure control was still being observed on the emergency feedwater header supply to Loop 2 circulators. t that time, it was decided that valve leakat e through PV-21244 ( 2 of Figure 1) was contributing to the pressure control problems. In order to rectify this situation, the system was isolated at 1030 hours0.0119 days <br />0.286 hours <br />0.0017 weeks <br />3.91915e-4 months <br /> on May 8 to replace the trim in PV-21244. This work was completed and the valve and system returned to service at 1300 hours0.015 days <br />0.361 hours <br />0.00215 weeks <br />4.9465e-4 months <br />.

Event #4 On May 16, 1980, a Plant Trouble Report was initiated to indicate that Loop 1 emergency feedwater pressure control valve PV-21243 was leaking (see 1 of Figure 1). At 0350 hours0.00405 days <br />0.0972 hours <br />5.787037e-4 weeks <br />1.33175e-4 months <br /> on May 16, with the plant oper-ating at approximately 47% thermal power and 130 MWe, the Loop 1 emer-gency feedwater header supply was isolated in order to repair this valve.

. Repairs were completed and the valve and system returned to service at 0830 hours0.00961 days <br />0.231 hours <br />0.00137 weeks <br />3.15815e-4 months <br /> on May 17, 1980.

The problems with the valves themselves did not render the emergency feed- -

water header supply to circulator water turbines inoperable. However, valve and line repairs necessitated isolation of the system, resulting in operation. ~

in a degraded mode of LCO 4.2.2(a) for the periods noted above. In each instance, the affected system was returned to service 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); thus, all circulators were operable during this time period.

i REPORTABLE OCCURRENCE 80-23 ISSUE O 2

Page 3 of 5 EVENT DESCRIPTION: (Cont'd) - +

l Had it been necessary during any of the instances of degraded mode operation, the circulators in the affected loop could have been operated on water turbine drive at reduced spe'ed utilizing a water supply from the emergency condensate or firewater systems.

3 CAUSE DESCRIPTION:

Events #1, #2, and #3 Isolation of the Loop 2 emergency feedwater header supply cescribed in Events

1. 1, #2, and #3 was a result of leakage in the line downstream of PV-21244-1, as well as valve leakage through PV-21244. This leakage contributed to the poor pressure control and system isolation to effect repairs resulted in operation under a degraded mode of LCO 4.2.2(a).

Event #4 Leakage between the seat ring and valve body of PV-21243 was a result of wear on the gasket. System isolation to repair the valve resulted in LCO 4.2.2(a) degraded mode operation.'

CORRECTIVE ACTION:

Events #1ar,h[,(2 l Leakage in the line downstream of PV-21244-1 was eliminated by weld repair

! and eventual replacement of the line.

Event #3 Valve leakage through PV-21244 was rectified by replacing the 2" trim with 1 3/8" trim. The valve and system were returned to service.

Event #4 Leakage through PV-21243 was eliminated by applying devcon compound to the valve gasket surface. The valve was re-assembled and. the system returned to service. ,

1 No further corrective action is anticipated or required. .l 4

4

Emerg ncy Feedwater To Backup 11 ader Bearing Water y >

@ G n To Loop 1 llelium Circulator V-211615 PV-21243 Water Turbine Drives X < >

n PV-21243-1 Q h To Turbine Water

> Drain Tank n To Loop 2 IIelium Circulator V-211616 PV-21244 Q p h. p ,

Water Turbine Drives y

/N /N y .E g P>

n a PV-21244-1

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To Turbine Water Drain Tank 8

Q R

Emergency Feedwater Pressure Control xM FICURE 1 w

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I l REPORTABLE OCCURRENCE 80-23 4 '. ISSUE O Page 5 of 5 I

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l Prepared By: ( v2 _

Cathy Q/ Hirsch

Technical Services Technician i

Reviewed By: .

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Technical Services Supervisor i

Reviewed By:

Frank M. Mathie j

Operations Manager t

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Approved By: _ MwwAm '

Don Warembourg #

l Manager,' Nuclear Production i

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