05000267/LER-1979-057, Forwards LER 79-057/03L-0

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Forwards LER 79-057/03L-0
ML19210E310
Person / Time
Site: Fort Saint Vrain Xcel Energy icon.png
Issue date: 11/29/1979
From: Warembourg D
PUBLIC SERVICE CO. OF COLORADO
To: Seyfrit K
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML19210E311 List:
References
P-79288, NUDOCS 7912040320
Download: ML19210E310 (5)


LER-1979-057, Forwards LER 79-057/03L-0
Event date:
Report date:
2671979057R00 - NRC Website

text

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9 pubue service company oe conomde

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q 16805 Weld County Road 19 1/2, Platteville, Colorado 80651 N'

I November 29, 1979 Fort St. Vrain Unit No. 1 P-79288 Mr. Karl V. Seyfrit, Director Nuclear Regulatory Commission Region IV Office of Inspection and Enforcement 611 Ryan Plaza Drive Suite 1000 Arlington, Texas 76012 REF:

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

Dear Mr. Seyfrit:

Enclosed please find a copy of Reportable Occurrence Retort No. 50-267/79-57, Final, submitted per the requirements of Technical Specification AC 7.5.2(b)1 and AC 7.5.2(b)2.

Also, please find enclosed one copy of the Licensee Evene Report for Report-able Occurrence Report No. 50-267/79-57, Final.

Very truly yours,

&C

/s Don Warembourg Manager, Nuclear Production DW/alk cc: Director, MIPC

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79120403

REPORT DATE:

November 29, 1979 REPORTABLE OCCURRENCE 79-57 ISSUE O OCCURRENCE DATE:

October 30, 1979 Page 1 of 4 FORT ST. VRAIN NUCLEAR GENERATING STATION PUBLIC SERVICE COMPANY OF COLORADO 16805 WELD COUh"IT ROAD 191/2 PLATTEVILLE, COLORADO 80651 REPORT No. 50-267/ 79-57/03-L-0 Final IDENTIFICATION OF OCCURRENCE:

On October 30, 1979, during normal aurveillance testing, one of three reactor pressure transmitters was found to be out of allowable calibration tolerance limits. This resulted in operation with instrument setting less consarvative than required by LCO 4.1.1.

This is reportable per Fort St. Vrain Technical Specification AC 7.5.2(b)1 and AC 7.5.2(b)2.

EVENT

DESCRIPTION

With the reactor shut down for maintenance, instrument personnel performing routine surveillance testing found one of three reactor pressure transmitters out of calibration. The circuit's normal o eration is as follows (see Figure 1).

The sig from the pressure element 1 passed through the pressure transmitter, co the pressure switch h gh, 3, where the setpoint is programmed by c rculator inlet temperature. If the reactor pressure exceeds the programmed setpoint, the p essure switch high sends a trip to the two out of three loop trip circuits, 4

, and a single channel scram signal to the scram circuits. This trip circuitry is designed to provide protection in the event that moisture monitor trip circuitry failed to operate a loop trip and scram on high moisture levels, resulting from a rupture of the secondary coolant system. Tha resulting high pressure in the rimary coolant would generate a trip signal at the pressure switch high, 3, and provide both reactor scram signals and a preselected loop shutdown.

Although the instrument setting was less conservative than allowed by Tech-nical Specifications, it was operable and could have fulfilled the functional requirements of the system. The other two pressure trip circuits were within the limita of the Technical Specifications and provided the required protection.

With the pressure transmitter, O2 out of 11owas1e calibratio= toteraace limits, the pressure switch high, ( ), would have tripped at a pressure greater than the 107.5% of programmed pressure allowed by Fort St. Vrain Technical Specification LCO 4.4.1.

Actual trip point would have been 762 psig.

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REPORTABLE OCCURRENCE 79-57

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ISSUE O Page 2 of 4

CAUSE

DESCRIPTION:

The cause of the conditica was irstrument drif t.

CORRECTIVE ACTION:

The pressure transmitter was recalibrated and, the surveillance was success-fully completed.

We are proceeding with our plan for identifying Technical Specification instrument trip settings and the absolute limiting values for them. Our evaluation has been based on overall channel accuracy, utilizing the manufacturer's published data and the least squares method for determining accumulated accuracy.

This evaluation and the subsequent results are beinC discussed with NRR and will result in app. opriate Technical Specf.fication changes.

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REACTOR PRESSURE TRIP CIRCUIT PE 1109 (circulator Outlet Pressure 109

,Progranuned Trip Setpoint PSil O

1109 Single Channel Scram Output I

XCR 93193A D%

Other liigh Pressure Trip 7/

EUN oo 9 m O5 2/3

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5; Loop Trip Output Signal g

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FICURE 1 Z

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REPORTABLE OCCURRENCE 79-57 ISSUE O Page 4 of 4 1

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Prepared By:

Afa'B. Reed Technical Servic Technician

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Reviewed By:

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. W. Cahm

/ Technical Services Supervisor Reviewed By:

Frank M. Mathie Operations Manager b

Approved By:

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Don Warembourg U/

Manager, Nuclear Production 1472 19