ML20004C344

Forwards Revised LER 79-034/03X-1.Detailed Event Analysis Encl

ML20004C344
Person / Time
Site:	Fort Saint Vrain
Issue date:	04/09/1981
From:	Warembourg D PUBLIC SERVICE CO. OF COLORADO
To:	Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML20004C345	List: ML20004C344 ML20004C347
References
P-81118, NUDOCS 8106030220
Download: ML20004C344 (5)

Text

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E public Service Company *f Odlendo 1 16805 ROAD 19%

_.),w) PLATTEVILLE, COLORADO 80651 April 9, 1981 Fort St. Vrain g { 9

Unit No. 1 ,D s P-81118 g

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Mr. Karl V. Seyfrit, Director Nuclear Regulatory Commission 'Qs w. . ; .,%

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/

79-34, 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 Repor* able Occurrence Report No. 50-267/79-34.

Very truly yours, Wus.c Don Warembourg (/

Manager, Nuclear Production DW/cis Enclosure cc: Director,lHPC '

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8106030290 3

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'l REPORT DATE: April 9, 1981' REPORTABLE OCCURRENCE 79-34 ISSUE 1

0CCURRENCE DATE: August 30. 1979 Page 1-of 4

.c MRT ST. VRAIN NUCLEAR GENERATING STATION PUBLIC SERVICE COMPANY OF COLORADO 16305 WELL COUNTY ROAD 19-1/2-PLATTEVILLE, COLORADO 80651 REPORT No. 50-26 7/ 79-34/03-X Final IDENTIFICATION OF

~ OCCURRENCE:-

On Aus.ust 30, 1979, during normal surveillance testing, the emergency diesel-generat.or day tank levels were found to be less than 500 gallons. This is a degraded mode per Fort St. Vrain Technical Specification LCO 4.6.1 and is reportable per AC 7.5.2(b)2.

EVENT DESCRIPTION:

On August 30, 1979, while at 36% thermal pcver and 105 114 electrical power, normal scheduled surveillance testing found that the high level switches on both emergency diesel generator day tanks were inoperable. The contacts ,

were in the open condition which simulated a high tank level.

See Figure 1. The level switch high (LSH), @ , opens on hi h tank lavel to de-energize the diesel transfer pump cont - 1 relay (CR), 2 . . When tank level d.acreases enough for the high level alarm to clear, the level switch high contacts close, energizing the control relay, starting the fuel oil transfer pump, and increasing tank level until the level switch high again opens on day tank high level. This action should normally maintain tank level at around 500 gallons per tank.

, With the level switch high, 1 , open, the day tank 1 vel fell to approxi-mately 350 gallons where the etel switch low (LSL 3 , contacts closed, energi ng the level switch low auxiliary rela 4 , and the control re-lay, 2 , through auxiliary relay contacts, 5 . This started the fuel .

oil transfer pump. With the high level switch open, the day tank level l cycled aroand the low switch level setpoint, approximately 350 gallons.

The original control configuration for the diesel fuel oil transfer pump was as follows: When tank level fell to the low level switch setpoint, about 350 gallons, the transfer pump would be started and fill the day  !

tank level to the high level switch setpoint, greater than 500 gallons.

This was recognized as unsatisfactory due to the possibility of the diesel generator being shut off with the day tank level less than the 500 gallons, which was the limit required by Technical Specification.

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4 REPORTABLE OCCURRENCE . 79-34 ISSUE 1

.Page 2 of 4 EVENT DESCRIPTION: (Cont' d). .

To correct the problem, the switches were rewired by Field Change Notice 2405-to the configuration described above, where the level switch high controls the transfer pump -and the level switch low acts as a backup. During post modification testing, it was discovered that.the dead band of the switches (the distance the level must rise or fall to change the switches state), was too wide to allow the tank lwel to be meintained at greater than 500 gal-lons. While'other methods ti solving the problem were being investigated, an operations order was iusued requiring the Operators to manually fill the tank until the high level alarm was received. This would assure the-500 gal-lon miMmm . level was met.

A Technical Specification change requesting the lowering of the required -

~

minimum level. from 500 gallons to 325 gallons was submitted on thrch 7,

.9 9 reference P-79056.

As an interim measure, while waiting for response from the Nuclear Regula-tory Commission on the Technical Specification change, a Change Notice was initiated, CN-1132, to replace the switches with one having a narrower dead band. This Change Notice was in progress when Amendment No. 22 to the

- Technical Specifications was issued . so' the CN-1132 was cancelled.

CAUS.E DESCRIPTION:

The level switch high setpoints were such that regardless of ' the tank levels, the contacts were open, which simulated high tank levels.

I' These switches were not normally tested, and since the high level alarms were up, it e.ppeared the day tank level control systems were operating .

properly.

CORRECTIVE ACTION:  ;

The level switch high setpoints were re-adjusted to the r, per setpoint, and the Surveillance Test revised to include testing these swa.cches. The test was successfully comoleted.  ;

, The Technical Specification change requested by Public Service Company on March 7,1979, reference P-79056, was issued by the Commission in Amendment Number 22 on October 1, '1980, allowing a minimum level of 325 gallons.  :

No further corrective action is anticipated or required. j l  :

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REPORTABLE OCCURRENCE 79-34 ISSUE 1 Page 4 of 4 -

Prepared By: _

h' Asa B. Reed /

Technical Services Rechnician Reviewed By:

[.f.Gahm

(/ Technical Sertices Supervisor Reviewed By: [ M. /V/ d b h ~

• Frank M. Mathie (/

Operations Manager Approved By: @a cs Don Warembourg (/

Manager, Nucle 7 Production l

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