05000325/LER-1979-107-01, /01T-0:on 791212,while Performing Visual Insp of Inaccessible Snubbers,Several Snubbers Found on Safety Relief Valve F013H Tailpipe.Caused by Reactor Scram When Safety Relief Valves F013F,G & H Automatically Lifted

/01T-0:on 791212,while Performing Visual Insp of Inaccessible Snubbers,Several Snubbers Found on Safety Relief Valve F013H Tailpipe.Caused by Reactor Scram When Safety Relief Valves F013F,G & H Automatically Lifted

ML19256G192
Person / Time
Site:	Brunswick
Issue date:	12/20/1979
From:	Tollison A CAROLINA POWER & LIGHT CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19256G187	List: 05000325/LER-1979-107, Forwards LER 79-107/01T-0 05000325/LER-1979-107-01, /01T-0:on 791212,while Performing Visual Insp of Inaccessible Snubbers,Several Snubbers Found on Safety Relief Valve F013H Tailpipe.Caused by Reactor Scram When Safety Relief Valves F013F,G & H Automatically Lifted
References
LER-79-107-01T, LER-79-107-1T, NUDOCS 7912270583
Download: ML19256G192 (2)

LER-1979-107, /01T-0:on 791212,while Performing Visual Insp of Inaccessible Snubbers,Several Snubbers Found on Safety Relief Valve F013H Tailpipe.Caused by Reactor Scram When Safety Relief Valves F013F,G & H Automatically Lifted

Event date:
Report date:
3251979107R01 - NRC Website

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8 50 61 DOCK ET NUMSER 68 69 EVENT OATE 14 75 REPORT QATE 40 EVENT OESCRIPTION ANO PRC8ABLE CONSEQUENCES h l While performing PT 19.6,0.1, Visual Inspection of Inaccessible Snubbers, the follow,J o

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1) B21-34SS296,

.J g l ing snubbers were found on the safety relief valve F013H cailpipe:

i elongated hole in rodeye; 2) B21-34SS297, reservoir missing, broken shaf t, two bent J

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l rodeyes, bent extension; 3) B21-34SS298, clamp moved; 4) 321-34SS299, broken chaft, j

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o 6 l bent rodeye, clamp moved; 5) B21-34SS300, cracked weld on I-beam, clamp _ moved: 6) B21-J l 34SS336, bent extension, clamp moved, valve body damaged, broken springs; 7) B21-l

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8 i 34SS337, broken shaft, clamp rotated, extended end springs fammed into valve (cont.) 1 30 COMP.

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a ] It is believed that this damage occurred following a reactor scram on November 20,1979 jwhen safety relief valves F013F, G, and H automticallr lifted.

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1) All other safety relief valves and associated piping were checked for danace j

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2) All damaged snubbers were rebuilt and functionally tested successfully.

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LER CONTINUATION - RO# 1-79-107 Facility: BSEP Unit #1 Event Date: 12-12-79 Event Descrip_ ton and Probable Consequences (cont.)

body; 8) B21-34SS338, valve body damaged by poppet spring; 9) B21-34SS339, rodeye bent, clamp moved; 10) B21-34SS340, bent rodeye, clamp moved.

Technical Specification 6.9.1.81 Cause Description and Corrective Actions (cont.)

3) All rodeyes, extensions, clamps, and I-beams were repaired or rebuilt, de-pending on the extent of damage.

4) All welde from the relief valve inlet to the relief line entry into the torus were cleaned and inspected by PT or MT and found satisfactory.

5) All relief line vacuum breakers were inspected and tested satisfactorily.

6) The testing and rebuild history of the snubbers on the F013H tailpipe were reviewed.

There were no significant findings.

7)

The F013H valve operating history was reviewed.

There were no significant findings.

3)

Special tests have been approved to:

a) Test F0137 and H at 250 psig and inspect for damage.

F013F and H share a co==on exhaust header in the torus.

b) Test F013F and H at normal pressure (900-1000 psig) to' approximate the opening sequence occurring on November 20, 1979. Perform a tailpipe in-spection.

9)

Until permanent resolution is determined, if any pair of valves lift which share the same exhaust header, the tailpipes will be inspected.

10)

The torus modifications scheduled for 1980 will rearrange the S/RV exhaust lines in the torus such that each will have a separate tee quencher.

11)

United Engineers and Constructors has analyzed this event with the following preliminary results:

a) A normal valve discharge cannot cause the observed damage.

b) A normal valve discharge with selected inoperable snubbers cannot cause the observed damage, c) A valve discharge with a water slug in the exhaust line is not likely to cause the observed damage.

d) A valve discharge with a water slug in the exhaust line and selected in-operable snubbers could produce the obcerved damage. The water slug was postulated to be ganerated by water being driven into the line as a result of SRV "F" discharge.

e) Conclusive proof of the cause has not been determined.

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