ML20009E711

Forwards Revised LER 81-008/03X-1.Detailed Event Analysis Encl

ML20009E711
Person / Time
Site:	Fort Saint Vrain
Issue date:	06/18/1981
From:	Warembourg D PUBLIC SERVICE CO. OF COLORADO
To:	Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML20009E712	List: ML20009E711 ML20009E719
References
P81169, NUDOCS 8107280381
Download: ML20009E711 (8)

Text

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puhue service company *e cenende 16805 ROAD 19%

PLATTEVILLE, COLOR ADO 80651 June 18, 1981 Fort St. Vrain Unit No. 1 P-81169 6.'

h,f c . il sl,a Mr. Karl V. Seyfrit , Director - hy,k ij S Nuclear Regulatory Commission 2 Region IV 8- JUL 2 71981 *- I Office of Inspection and Enforcement u.s.gajugn uou _--

611 Ryan Plaza Drive Suite 1000

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Arlington, Texas 76012 g Refern ce: Facility Operating License No. DP R-34 Docket No. 50-267 I

Dear Mr. Seyf rit:

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

81-008, Preliminary - Corrected and Additional Information, submit ted 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 Event Report for Reportable Occurrence Report No. 50-267/81-008.

Very truly yours ,

/ ~ Wu,J Don Warembourg Manager, Nuclear Production DW/cls Enclosure cc: Director, MIPC y6N

.5

///

8107280381 810618 PDR ADOCK 05000267 S PDR

REPORT DATE: June 18, 1981 REPORTABLE OCCURRENCE 81-008 Determined ISSUE 1 CCCURRENCE DATE: January 20, 1981 Page 1 of 7 FORT ST. VRAIN NUCLEAR GENERATING STATION PUBLIC SERVICE COMPANY OF COLORADO 16805 WELD COUNTY ROAD 19 1/2 PLATTEVILLE, COLORADO 80651 REPORT NO. 50-267/81-008/03-X-1 Preliminary - Corrected and Additional Information IDENTIFICATION OF OCCURRENCE:

l Routine surveillance testing of the primary coolant programmed I pressure scram revealed that the three pressure transmitters were out of calibration and could have allowed operation with trip setpoints less conservative than required by LCO 4.4.1, Table 4.4-1.

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

EVENT DESCRIPTION:

l While the reactor was in a shutdown condition, instrument personnel i performing the the annual calibration of the primary coolant pressure

] scram channels observed that the three pressure transmitters were out l of. calibration in the nonconservative direction. This could have l resulted in the low pressure scram trips occurring at lower pressures l than allowed by the LCO requirements.

4 l See Figure 1. The output voltage from the pressure element @ goes which supplies a measured to ll the to the pressure pressure transmitter switch high @ an@ d the pressure switch low @ signal l The high and low pressure bistables @ and @ are programmed by l circulator inlet temperature through n auctioneer circuit 5 and

[ bistable setpoint programmers @ or 7 .

i l The high pressure bistable 3 provides a trip A ignal to both loop l shutdown and steam / water dum ( of 3) circuitry U8 and a scram to l l the appropriate channel 9 . (Channel "A" in Figure 1) This trip i l circuitry is designed to provide protection in the event that

! l moisture monitor trip circuitry fails to operate a loop trip i steam / water dump and scram on high moisture levels, resulting from a t [ rupture of the seconcary coolant system.

l The low pressure bistable @ provides a scram function only @ .

l The programmed pressure temperature curve is shown in Figure 2. The l high output voltage from the pressure transmitters could have r

i

REPORTABLE OCCURRENCE 81-008 ISSUE 1 Page 2 of 7 l resulted in the low preslure m trips occurring below the allowable low l pressure curve (line UB UB ). The high pressure trips would have l occurred below the high pressure trip curve (line @ @ ) in a l conservative direction.

[ See Table 1 for "As Found", "As Left" data and equivalent pressures.

l Table 2 lists the equivalent pressure (psia), the "As Found" output j of each of the three pressure transmitters (PT's) and the l differential pressure between the expected output and the "As Found"-

1 output of each of the three PT's.

l TABLE 2 l

l PT "As Found" Output '

1 Pressure Voltage - Equivalent AP l PSIA Pressure (PSIA)

! i I l 1108 ! 1109 1 1110 1108 1 1109 1110 1 412 417 406 415 @ @ @

l l 512 521 l 521 519 I +9 +9 U1 l 550 560 561 560 ! +10 +11 +10 l l 612 622 l 624 628 l +10 +12 +16 l 621 632 5 634 632 l +11 +13 +11, l 661 670 ! 676 671 : +9 +15 +10 l

712 723 l 728 729 ! +11 +16 +17 l 720 731 : 736 -735 +11 +16 l *740 751 '

"759 744 +11 *+19 l l 812 . 823 825 818 +11 +13 l

l l @ Not applicable - PT's in tolerance.  ;

\ ,

l "See Example >

l With the circulator inlet temperatures reading correct,1y, then

i the low reactor pressure trip curve would be line' @ UB Figure l minus the aP of the particular transmitter.

! For Example:

l l Pressure = 740 psia l PT-1109 "As Found" Voltage / Equivalent Pressure = 759 psia l PT-1109 AP = +19 l Line @B' @ , Figure 2, approximately equal to 627 psia.

l Then, 627 - 19 = 608 psia for a low pressure scram to l occur from PT-1109.

l Although the low pressure trips could have occurred at a value less conservative than that established in the Technical Specifications, i

REPORTABLE OCCURRENCE 81-008 ISSUE 1 Page 3 of 7 they would not prevent the fulfillment of the functional requirements of the system.

CAUSE DESCRIPTION:

1 The high output voltages from the pressure transmitters were due to l instrument drift of the pressure transmitters.

CORRECTIVE ACTION:

The pressure transmitters were calibrated during the procedure, returned to service, and the Surveillance Test was successfully completed.

I Once a month (while the reactor is pressurized above 400 psia), on a I temporary basis, the pressure transmitter voltage outputs will be I checked against reactor pressure to determine if further instrument drift is occurring. The monthly test will be conducted until the next regularly scheduled surveillance calibration is required or until it is determined that instrumera drift is not occurring.

The results will be included in a future supplemental report.

h

a REPORTABLE OCCURREllCE 81-008 ISSUE 1 Page 4 of 7 REACTOR PRESSURE T CIRCULATOR INLET TEMPERA *URE 3h (PROPORTIONAL TO Pt. ANT LJAO)

C'4ROMEL/ CONS T AN T AN pg POTENTICMETRic TE TE THERMCCOUPLES LOCATE:

TRANSOUCER IN WELLS IN PCRV LOWER HIAD

" - - ; ; ,. INSTRUMENT DENETRail0NS t, ;) C,;j TEST MAIN CONTROL 1r y 1r ROOM PT h AMPLIFIER AMPLIFIER TT TT AMPLIFIER Pt 0 INDICATOR g AUCTIONEER SISTABLE SETPolNT ' BISTABLE SETP0 INT

.ROGRAMMER (WITH TH TM 'R0GRAMMER (wtTH MfGH AND LOW HIGH AND LOW y LIMITS) LIMITS) 1 i Pi l

SET AT 500 PSlA h " SETPolNT tNDICATOR u ir v PS L PSH

\  : P1 psp c BISTABLE SISTABLE PISTABLE g T T T TO PCRV TO LOOP TO SCRAM l RELIEF VALVE SHUT 00WN CHANNEL "A"

( INTERLCCK AND STEAM /

j (2 0F 3) WATER DUMP i

CIRCUlf (2 CF 3)

CIRCUITRY Reac:cr pressure instr =en: _ channel (:yp. fer channels 3&C)

FIGi:RE 1

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PRESSURE TRAllSMITTER CALIBRATION DATA .' .

PT 1108 _. PT 1109 PT 1110 APPLIED PRESSURE EXPECTED OUTPUT EQUIVALENT ABSOLUTE AS FOUND AS LEFT AS FOUND AS LEFT AS FOUND AS LEFT PSIG VDC PRESSURE (PSIA) VDC VDC VDC VDC VDC VDC 4

(1.5) (1.075) (10,5) 400 4.124 412 4.171 4.077 4.061 4.084 4.151 4.1 21 500 5.124 512 5.215* 5.109 5.212* 5.093 5.190 5.142 538 5.504 550 5.604* 5.493 5.610* 5.481 5.595* 5.490

'600 6.124 612 6.225* 6.102 6.245* 6.102 6.283* 6.148 1 609 6.214 621 6.321* 6.201 6.338* 6.194 6.323* 6.201 649 6.614 661 6.703* 6.611 6.761* 6.606 6.713* 6.650 l 700 7.124 712 7.236* 7.108 7.277* 7.111 7.288* 7.152 708 7.204 720 7.310* 7.182 7.357* 7.189 7.355* 7.249 728 7.404 740 7.514* 7.385 7.595* 7.399 7.438 7.421 l 800 8.124 81 2 8.235* 8.113 8.249* 8.120 8.185 8.063 i

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REPORTABLE OCCURRENCE 81-008 ISSUE 1 Page 7 of 7 Prepared By:

Asa B. Reed Tectaical Services Technician Reviewed By: ,

,4. f: Gahm p Technical Services Supervisor Reviewed By: M [s s. ,r'I, - -

Frank M. M,pt. hie p /

Operationi Manager Approved By: [ ~

Wwd .

Don warembourg 6 Manager, Nuclear Production

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