05000267/LER-1980-047, Forwards LER 80-047/03L-0

Forwards LER 80-047/03L-0

ML19347A941
Person / Time
Site:	Fort Saint Vrain
Issue date:	09/24/1980
From:	Warembourg D PUBLIC SERVICE CO. OF COLORADO
To:	Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML19347A942	List: 05000267/LER-1980-047, Forwards LER 80-047/03L-0
References
P-80335, NUDOCS 8009300556
Download: ML19347A941 (7)

LER-1980-047, Forwards LER 80-047/03L-0

Event date:
Report date:
2671980047R00 - NRC Website

text

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a-j pubHe Service Compcny

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16805 ROAD 19%

J PLATTEVILLE, COLORADO 80651

.m September 24, 1980 Fort St. Vrain Unit No. 1 P-80335 Mr. Karl V. Seyfrit, Director Nuclear Regulatory Commission Region IV Office of Inspection and Enforcement g

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/

80-47, Preliminary, submitted per the requirements of Technical Speci-fication AC 7.5.2(b)2.

Also, please find enclosed one copy of the Licensee Event Report for Reportable Occurrence Report No. 50-267/80-47.

Very truly yours, Ah Don Warembourg Manager, Nuclear Production DW/cis Enclosure cc: Director, MIPC

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8009800 3

5 5C

r REPORT DATE:

September 24. 1980 REPORTABLE OCCURRENCE 80-47 ISSUE O OCCURRENCE DATE:

August 25. 1980 Page 1 of 6 FORT ST. VRAIN NUCLEAR GENERATING STATION PUBLIC SERVICE COMPANY OF COLORADO 16805 WELD COUNTY ROAD 191/2 PLATTEVILLE, COLORADO 80651 REPORT No. 50-267/80-47/03-L-0 Preliminary IDENTIFICATION OF OCCURRENCE:

During the performance of the regularly scheduled hydraulic snubber surveil-lance,16 snubbers were found to be inoperable which put the plant into a degraded mode of LCO 4.3.10.

Nine of these inoperable snubbers could not be repaired within the 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> in which continued reactor operation is allowed by the LCO, thus a plant shutdown was required. This is reportable per Fort St. Vrain Technical Specification AC 7.5.2(b)2.

EVENT

DESCRIPTION

On August 25, 1980, while operating at 50% thermal power and 150 MR electri:al power, maintenance personnel performing a regularly scheduled hydraulic snub-ber surveillance identified 16 inoperable snubbers. This put the plant in a degraded mode of LCO 4.3.10, in which a 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> period of continued plant operation is allowed for repair of inoperable snubbers. Nine of the inoper-able snubbers could not b-repaired during this period and the 36 hour4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> orderly shutdown period was entered.

A planned maintenance shutdown period was scheduled to bsgin August 30, 1980, and a decision was made to begin the shutdown a day early August 29, 1980, and to complete repair of the inoperable snubbers during this maintenance

period, t

The sequence of events for this period were as follows:

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REPORTABLE OCCURRENCE 80-47 ISSUE O l

Page 2 of 6 EVENT

DESCRIPTION

(Cont'd)

Date Time

_ Event Later Part N/A Normal plant operations at approximately 50% re-of August actor power and 150 MW electrical.

8-25-80 N0800 Began snubber surveillance.

1230 H0S 36 dect.ared impaired. Beginning of 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> contiraed. reactor operction period as H0S 36 could not be repaired within this period [per paragraph (b) of LCO 4.3.10].

8-28-80 1230 End of 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> continued reactor operation per-iod. Orderly shutdown begun. Beginning of 36 hour4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> allowed for orderly shutdown [per para-graph (c) of LCO 4.3.10).

8-29-80 0830 Turbine load and reactor power were being reduced as part of the orderly shutdown. At this time, I

the 24VDC power for the EHC control system was l

l lost and electrical maintenance personnel began I

I I

investigating the cause before the turbine was I

I I

taken off line.

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i 1330 Turbine runback to about 50 MR electrical load I

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occurred due to maintenance work. Resulting I

feedwater upset caused one circulator in each I

loop to trip. The turbine was manually taken off I

line at this time and preparations made to test the turbine's overspeed trip.

1545 Overspeed trip test completed.

1740 Shutdown completed, reactor manually scrammed.

8 80 0030 End of 36 hour4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> orderly shutdown period.

Dayshift Beginning of scheduled maintenance shutdown.

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REPORTABLE OCCURRENCE 80-47 ISSUE O Page 3 of 6 EVENT

DESCRIPTION

(Cont'd)

The 16 inoperable snubbers were as follows:

Snubber Problem BFS 412 Out of tolerance on travel.

CRS 144 Out of tolerance on travel.

CRS 262 Out of tolerance on travel.

H0S 36 Out of tolerance on travel.

H0S 56 Out of tolerance on travel.

HOS 86 Out of tolerance on travel.

HRS 129 Mounting brackets installed wrong.

HRS '$d Out of tolerance on travel.

HRS 351 Reservoir obstructing travel.

MSS 27 Out of tolerance on travel MSS 29 Out of tolerance on travel.

MSS 191 Out of tolerance on travel.

MSS 249 Out of tolerance on travel.

MSS 257 Out of tolerance on travel.

MSS 375 Out of tolerance on travel.

MSS 421 Bent piston rod.

CAUSE

DESCRIPTION:

An analysis of the surveillance results revealed the following reasons for inoperable snubbers.

Improper Adjustment - 13 of the 16 inoperable snubbers were due to the constant support hangers (spring hangers) not being properly adjusted for the hot position; these hangers were not carrying the appropriate load in the hot position, which in turn affected the stroke position of the various hydraulic snubbers.

o REPORTABLE OCCURRENCE 80-47 ISSUE O Page 4 of 6

CAUSE

DESCRIPTION: (Cont'd)

Snubbers Affected BFS 412 H0S 56 MSS 29 MSS 27 CRS 144 H0S 86 MSS 191 MSS 257 CRS 262 HRS 158 MSS 249 MSS 376 H0S 36 Improper Installation - HRS 129 mounting brackets were installed 90*

from the specified position binding the pipe when movement occurred.

Reservoir Out of Position - H0S 351 reservoir had been forced from its correct position, and prohibited snubber movement due to interference with an adjacent pipe.

Snubber Damaged - MSS 421 had c bent piston rod making it inoperable.

The bent rod was due to a loose pipe clamp that shif ted position.

CORRECTIVE ACTION:

The immediate corrective actions were:

Repair snubbers when possible during the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> continued operation period. The following were corrected.

HRS 129 - Mounting brackets were removed and replaced in the cor-rect position.

HRS 351 - Reservoir was repositioned and locking nut secured.

MSS 421 - Replaced with a certified replacement snubber.

CRS 144 - Snubber adjusted for proper stroke length.

H0S 86 - Snubber adjusted for proper stroke length.

MSS 27 - Snubber adjusted for proper stroke length.

MSS 249 - Snubber adjusted for proper stroke length.

Checked and recorded the hot position of snubbers and hangers.

Began an orderly shutdown at the end of the allowed 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> continued reactor operation period.

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REPORTABLE OCCURRENCE 80-47 ISSUE O Page 5 of 6 CORRECTIVE ACTION:

(Cont'd)

The followup corrective actions included:

Continued repair of the affected snubbers during the maintenance shut-down period. The following were corrected.

BFS 412 - Modified for the proper stroke lenth.

CRS 262 - Modified for the proper stroke length.

MSS 191 - Mounting brackets shimmed to give snubber proper stroke length.

HRS 158 - Mounting brackets shimmed to give snubber proper stroke leng-h.

MSS 29 - Snubber adjusted for proper stroke length.

MSS 257 - Snubber adjusted for proper stroke length.

MSS 376 - Snubber adjusted for proper stroke length.

HOS 36 - Mrunting bracket pas repositioned to give snubber proper stroke length.

HOS 56 was inoperable at hot position but no problem could be identified when the system shutdown. This will be investigated when the plant is returned to power.

Public Service Company submitted a request for relief from LCO 4.3.10 for a periou of 60 days following return to power to allow the time required to check and re-adjust hangers while at the hot position. This work will be carried out such that no more than 15% of a given line snubber shall be inoperable (P-80304, dated September 8,1980).

The surveillance interval has been adjusted to 31 days per SR 5,3.8.

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REPORTABLE OCCURRENCE 80-47 ISSUE O Page 6 of 6 Prepared By:

Asa B. Reed Technical Services Technician Reviewed By:

. W A ahm Technical Services Supervisor Reviewed By:

N.

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Frank M. Mathie Operations Manager Approved By:

)'U [MA.L4.+ m L<,0 N /f 7)n Don Warembourg g/

Manager, Nuclear Production