05000267/LER-1979-015-03, /03L-0 on 790507:during Routine Surveillance Testing,Setpoint of Pcrv Rupture Disc M-11702 Found to Be 826 Psig.Caused by Calibr Drift.Disc Recalbr

/03L-0 on 790507:during Routine Surveillance Testing,Setpoint of Pcrv Rupture Disc M-11702 Found to Be 826 Psig.Caused by Calibr Drift.Disc Recalbr

ML19259C151
Person / Time
Site:	Fort Saint Vrain
Issue date:	06/06/1979
From:	Gahm J PUBLIC SERVICE CO. OF COLORADO
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML19259C146	List: 05000267/LER-1979-015, Forwards LER 79-015/03L-0 05000267/LER-1979-015-03, /03L-0 on 790507:during Routine Surveillance Testing,Setpoint of Pcrv Rupture Disc M-11702 Found to Be 826 Psig.Caused by Calibr Drift.Disc Recalbr
References
LER-79-015-03L, LER-79-15-3L, NUDOCS 7906120414
Download: ML19259C151 (4)

LER-1979-015, /03L-0 on 790507:during Routine Surveillance Testing,Setpoint of Pcrv Rupture Disc M-11702 Found to Be 826 Psig.Caused by Calibr Drift.Disc Recalbr

Event date:
Report date:
2671979015R03 - NRC Website

text

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REPORT DATE:

June 6, 1979 REPORTABLE OCCURRENCE 79-15 ISSUE O OCCURRENCE DATE:

May 7, 1979 Page 1 of 3 FORT ST. VRAIN NU"I, EAR GENERATING STATION PUBLIC SERVICE COMPANY OF COLORADO P. O. BOX 361 PLATTEVILLE, COLORADO 80651 REPORT No. 50-267/ 79-15 /03-L-0

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2 Final IDENTIFICATION OF OCCURRENCE:

During a routine surveillance calibratian check performed on May 5,1979, the

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setpoint of the PCRV rupture disc assembly M-11702 was found to be 826 psig.

Since this setpoint is higher than the 812 psig + 1% allowable by Fort St.

Vrain Technical Specification LSSS 3.3.2(c), it is being reported per Fort S t.

Vrain Technical Specification AC 7.5.2(b)l.

EVENT

DESCRIPTION

With the reactor shutdown and depressurized for refueling, low set rupture disc, M-11702, was removed from service for a scheduled surveillance calibra-tion bench test.

The "as found" pressure setpoint was 826 psig. The accep-tance criterion of LSSS 3.3.2(c) requires the set pressure to be 812 psig +

1% (804 psig to 820 psig).

Refer to Figure 1.

Before the test gas pressure is applied the cutter, 1

is removed and a s ville washers, ($)pecial ring is installed to limit the travel of the Bel e-These washers snap over when the set pressure is reached.

Ad ustment of the set pressure is made by positioning of the threaded ring, 3

When the set pressure is reached, the diaphragm and washers travel ew thousandths of an inch, which produces an audible " thump".

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CAUSE

DESCRIPTION:

The rupture disc being out of tolerance was caused by calibration drif t over the two years it had been in service since its last calibration surveillance.

CORRECTIVE ACTION:

The rupture disc was calibrated to 812 psig and returned to service.

No further corrective action is anticipated or required.

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REPORTABLE OCCURRENCE 79-15 ISSUE O Page 2 of 3 E

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Prepared by:

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Asa B. Reed

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Technical Services Technician Reviewed by:

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Frank M. Mathie Operations Manager b

Approved by:

M, Don Warembourg

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Manager, Nuclear Production 2285 095 6

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NRC FORM 366 U. S. NUCLEAR REGULATORY COMMISSION (7 77)' *

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8 60 61 DOCKET NUMBER 68 69 EVENT DATE 74 75 REPORT DATd 80 EVENT DESCRIPTION AND PROBABLE CONSEQUENCES O'o l During refueling shutdown, while performing routine surveillance testing of PCRV rup-l o

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ture disc M-ll702 its setpoint was found to be 826 psig.

This is outside the 812 l

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g sig + 1% allowed by Fort St. Vrain Technical Specification LSSS 3.3.2(c) and is p

g being reported per Fort St. Vrain Technical Specification AC 7.5.2(b)l.

The reactor ;

o s I l had not been overpresSurized during this surveillance interval and there was no l

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47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h i io Cause of the problem was calibration drif t.

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proper setpoint and returned to service. No further corrective action anticipated or 1 l required.

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