ML19260C702

Forwards LER 79-064/03L-0

ML19260C702
Person / Time
Site:	Fort Saint Vrain
Issue date:	01/02/1980
From:	Warembourg D PUBLIC SERVICE CO. OF COLORADO
To:	Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML19260C703	List: ML19260C702 ML19260C706
References
P-80001, NUDOCS 8001080475
Download: ML19260C702 (5)

Text

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] public service company oe conomde 16805 Weld County Road 19 1/2, Platteville, Colorado 80651 l

- O January 2, 1980 Fo rt S t. Vrain Unit No. 1 P-80001 Mr. Karl V. Seyfrit, Director Nuclear Regulatory Cot::sission 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. 50-267/79-64, Final, submitted per the requirements of Technical Specif1-cation AC 7.5.2 (b)2.

Also, please find enclosed one copy of the Licensee Event Report for Reportable Occurrence Report No. 50-267/79-64.

Very truly yours, W

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

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80010804 76

REPORI DATE: January 2,1980 REPORTABLE OCCURRENCE 79-64 ISSUE O OCCURRENCE DATE: December 5.1979 Page 1 of 4

' ORT ST. VRAIN NUCLEAR GENERATING STATION PUBLIC SERVICE COMPANY OF COLORADO 16805 WELD COUNTY ROAD 19 1/2 PLATIEVILLE, COLORADO 80651 REPORT No. 50-267/79-64/03-L-0 FINAL IDENTIFICATION OF OCCURRENCE: '

During routine surveillance of Class I hydraulic shock suppressors, thrae snubbers were determined to be inoperable.

Since reactor operation had taken place during the surveillance interval, the three snubbers are assumed to have been inoperable throughout that p eriod.

This is interpreted as operation under a degraded mode permitted by LCO 4.3.10 and is reportable per Fort St. Vrain Technical Specification AC 7.5.2(b)2, EVENT DESCIPTION:

While the reactor was in a shutdown condition for scheduled maintenance, maintenance personnel performed the routine surveillance test on the Class I hydraulic shock suppressors (snubbers). Three snubbers were determined to be inoperable. See Figure 1.

1) HRS-98.

Hot reheat snubber piston position was out of tolerance h.

2)

3) VSS-110&

VSS-lll Vent stack snubbers were installed such that the oil in the reservoi was not vering the intake holes on the snubber valves and .

The vent stack snubbers were added to the Technical Specification snubber list as a result of removal of six main steam snubbers. See Reportable Occurrence Report No. 50-267/77-41. As stated, in part, in the Event De-scription of that report, "Under the revised configuration, the thrust associated with relief valve discharge is overcome by the installation of a system of mechanical and hydraulic restraints attached to the tail piping of the main steam relief valves (i.e., outside the Class I bounda-ries) . The seismic analysis for the main steam piping system remains un-alte re d."

1703 177

REPOR1,.BLE OCCURRENCE 79-64 ISSUE O Page 2 of 4 EVENT DESCRIPTION: (Cont' d)

"Further evaluation by the licensee indicates that the function of the new system of restraints remains that of protecting the main steam piping and its associated relief valves from the effects of relief valve discharge thrust. Accordingly, these new restraints are being reclassified as safety related and those which are hydraulic snubbers are being added to the Tech-nical Specifications for operability surveillance and testing. Since these ~

restraints are attached to the relatively flexible relief valve discharge lines, their effect during a seismic event will not be reflected back into the main steam piping and the original seismic analysis remains un-altered. All analysis associated with the design of these restraints as thrust suppresors remains valid independent of the reclassification to safety related status."

CAUSE DESCRIPTION:

1) HRS-98 The piston position being out of tolerance is being attributed to thermal pipe movement such that in the " cold iron" condition, the pipe did not return to its initial position.

2) VSS-110& Incorrect installation. Following the functional test per-

3) VSS-lli formed in June,1979, the snubber was re-installed, filled, tested, and considered operable. The re-installation pro-cedure did not specifically address a check of snubber ori-entation. The bracket and pipe were both marked to correspcad to the installation prior to removal of the snubber at which tifne the orientation was considered acceptable.

The VSS-110 and VSS-111 were the only two snubbers identified as being installed incorrectly. All Class I snubbers were visually inspected as part of the surveillance test and no others were identified as being im-properly oriented.

CORRECTIVE ACTION:

1) HRS-98 The snubber was adjusted so that the piston position is with-in tolerance.

2) VSS-110&

3) VSS-111 The snubbers were re-installed with the correct reservoir /

snubber valve orientation.

The Maintenance Procedure (MP 98.1) for apair of hydraulic pipe snubbers has been revised to include a verification of proper orientation when a snubber is re-installed.

The surveil ance interval for SR 5.3.8a-X remains unchanged at 124 days.

No further corrective action is anticipated or required.

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REPORTABLE OCCURRENCE 79-64 ISSUE Q Page 3 of 4 figs. 200, 201 2 & 3 VS-110 & VSS-111, 011 in the reservoirs @

not Covering the intake hole @ on the snubber valve @ .

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1 HRS-98, Piston position out of tolerance.

FIGURE 1 1703 179

REPORTABLE OCCURRENCE 79-64 ISSUE O Page 4 of 4 Prepared By: A ,

A MicI(ael J. Ferris [

Techhical ServicesJhgineer Reviewed By:

V. Gahm Technical Services Supervisor Reviewed By: h Frank M. Mathie Operations Manager Approved By: ) [

Don Warembourg g Manager, Nuclear Production 1703 180

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