ML19341C512

Forwards LER 81-012/03L-0

ML19341C512
Person / Time
Site:	Fort Saint Vrain
Issue date:	02/26/1981
From:	Warembourg D PUBLIC SERVICE CO. OF COLORADO
To:	Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML19341C513	List: ML19341C512 ML19341C516
References
P-81067, NUDOCS 8103030671
Download: ML19341C512 (4)

Text

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16805 ROAD 19%

Drk ~ :) PLATTEVILLE, COLOR ADO 80651 Feb ruary 26, 1981 Fort St. Vrain Unit No. 1 P-81067

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Mr. Karl V. Seyfrit, Director 7 9 IeIM0 2 bOf A Nuclear Regulatory Commission l '

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Region IV g Office of Inspection and Enforcement .A -

611 Ryan Plaza Drive Suite 1000

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Arlington, Texas .76012

Reference:

Facility Operating License No. DP R-34 Docket No. 50-26 7

Dear Mr. Seyfrit:

Enclosed please find a copy of Reportable Occurrence Report No. 50-267/

81-012, 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. 50-267/81-012.

Very truly yours,

• ~ Wwd Don Warembourg lbnager, Nuclear Production DW/cis Enclosure cc: Director, MIPC 8

81oso no67/. s 6'[

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REPORT DATE: February 26, 1981 REPORTABLE OCCURRENCE 81-012 Determined ISSUE O OCCURRENCE DATE: January 27, 1981 Page 1 of 3 i

FORT ST. VRAIN NUCLEAR GENERATION STATION l PUBLIC SERVICE COMPANY OF COLORADO

{ 16805 WELD COUNTY ROAD 191/2 j PLATTEVILLE, COLORADO 80651 i REPORT No. 50-26 7/ 81-012/03-L-0 .

Final IDENTIFICATION OF OCCURRENCE:

During performance of a scheduled Surveillance Test, six of twelve individual steam pipe rupture pipe cavity ultrasonic detector channels were found inoper-able. Since the reactor had been operated during the surveillance interval, the channels must be considered to have been inoperable when the reactor was at power.

This is interpreted as a degraded mode of LCO 4.4.1, Table 4.4-2, and is reportable per Fort St. Vrain Technical Specification AC 7.5.2(b)2.

EVENT DESCRIPTION :

On January 3,1981, while the reactor was in a shutdown condition, Surveil-lance Test SR 5.4.1.2.1j-R, Stean Pipe Rupture (Pipe Cavity) Calibration, was performed. The test requires that a calibrated ultrasonic noise source be fed to the microphone to be tested, and that the response of the channel fall between 20% and 80% of full scale meter readings at the channel % r rip module.

Data taken during the performace of the Surveillanca Test are given in Table 1.

TF_I 1 4  ! A.s .t a und As Left Location Microchene ! Raading Reading Loop 1,

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XE-93457A 5% 35%

South XE-9 34573 30% 30%

XE-93457C 5: 28%

Loop 1, XE-93455A 22% 22%

North XE-93455B 15% 22%

XE-93455C 30 30 Loop 2, XE-93456A 12% 25 South XE-93456B 35 35%

XE-93456C 15C 25 I4op 2, XE-93454A 30 30%

No rth XE-93454B 5'; 25%

XE-93454C 26% 26%

1

a REPORTABLE OCCURRENCE S1-012 ISSUE O Page 2 of 3 EVENT DESCRIPTION: (Cont'd)

Since each major channel (location) is composed of three microphones con-nected in a 2/3 trip circuit, it can be seen that all four. major channels .

were degraded *and that the case of the Loop 1 south and Loop 2 south chan-nels, two of the three individual microphone channels were degraded.

However, it must be noted that Surveillance Test SR 5.4.1.2.lf-cd5.4.1.2.lg-m, performed monthly, verifies that each channel will trip on a signal from an uncalibrated noise source. This test was performed successfully just prior to performace of SR 5.4.1.2.1j-R and indicated that a microphone showing low response to the calibrated noise source is still responsive to a louder source and may be operable.

CAUSE DESCRIPTION:

During the surveillance interval, numerous spurious " Steam Pipe Rupture (Pipe Cavity)" ultrasonic noise trips were received. In order to reduce the oc-currence of false trips, the gain of the microphones or transmitters causing the trip was reduced. The monthly performance of the functional test was i

believed to be sufficient indication of an operable channel.

A similar report, R0 80-48, was submitted concerning the "S team Pipe Rupture under PCRV" ultrasonic system which detailed the same cause as this report.

This is the first perfor=ance of SR 5.4.1.2.1j-R since that report, and since the evo ultrasonic systems have experienced the same problems, it is not unreasonable that the same reportable conditions would be found in both systems.

F CORRECTIVE ACTION:

The individual microphone and/or transmitter gain was adjusted to bring the trip module meter reading to an acceptable value for all microphones and the Surveillance Test successfully completed.

The microphone or transmitter gain will be not reduced to prevent spurious trips.

A calibration check will be perfor=ed twice a year for two years to deter-mine if there is any unanticipated system drift.

The Public Service Company Nuclear Project Department has been requested to evaluate the ultrasonic steam pipe rupture detection system.

No further corrective action is anticipated or reauired.

REPORTABLE OCCURRENCE 81-012 ISSUE O Page 3 of 3 Prepared By: . / M>

Richard R. Frost Technical Services Technician Reviewed By: / / - '_ u -

..W. Dahm

/ Technical Services Supervisor Reviewed By: ,% b/bh Frank M. Mathie Operations Manager Approved By: -

- Mu 4M Don Warembourg V Manager, Nuclear Production

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