05000373/LER-1982-036, Forwards LER 82-036/03L-0.Detailed Event Analysis Encl

Forwards LER 82-036/03L-0.Detailed Event Analysis Encl

ML20054L217
Person / Time
Site:	LaSalle
Issue date:	06/23/1982
From:	Holyoak R COMMONWEALTH EDISON CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML20054L218	List: 05000373/LER-1982-036, Forwards LER 82-036/03L-0.Detailed Event Analysis Encl 05000373/LER-1982-036-03, /03L-0:on 820606,during Performance of STP-17 Hot Line Walks,Mechanical Snubber MS14-1058S Found Damaged. Snap Ring Which Holds Snubber Together Had Become Loose. Caused by Introduction of Lateral Force on Snubber
References
NUDOCS 8207070277
Download: ML20054L217 (2)

LER-1982-036, Forwards LER 82-036/03L-0.Detailed Event Analysis Encl

Event date:
Report date:
3731982036R00 - NRC Website

text

-

A s C mm:nw311th Edison LaSa!!e County Nuclear Station i) Rura! Route #1, Box 220 c

m

Marseilles, filinois 61341 Telephone 815/357-6761 June 23, 1982 James G. Keppler Regional Administrator Directorate of Regulatory Operations, Region lli U. S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, IL 60137 i

l

Dear Sir:

Reportable Occurrence Report #82-036/03L-0 Docket #050-373 is being submitted to your office in accordance with LaSalle County Nuclear Power Station Technical Specification 6.6.B.2. (c), observed inade-quacies in the implementation of administrative or procedural controls i

which threaten to cause reduction of degree of redundancy provided in reactor protection systems or engineered safety feature systems.

i i

R. H.

k Superintend t

LaSalle County Station RHH/GW/dJp l

Enclosure cc:

Director of Inspection & Enforcement Director of Management Information & Program Control U. S. NRC Document Management Branch Inpo-Records Center File /NRC h

N 8207070277 820623 Mv%

PDR ADOCK 05000373

}{)$

S PDR

O 1.

LER HUMBER:

82-036/03L-0 l1.

LASALLE COUNTY STATION:

UNIT 1 lli. DOCKET NUMBER: 050-373/374 IV.

EVENT DESCRIPTION

During the performance of STP-17 hot line walks, mechanical snubber

.MS14-10585 was found damaged.

The snap ring which holds the snubber togethe'r had become loose, thereby allowing the snubber to have free movement but not restraining action.

V.

PROBABLE CONSEQUENCES OF THE OCCURRENCE:

The damaged snubber was installed on' drain line 1 MS14AA (2 inch) under the "B" MSIV.

The piping had gone through a thermal expansion during heatup to condition 3 This slow movement of the piping was not affected by the inoperable snubber.

During the time period the snubber was inoperable, no seismic or transient shocks o.ccurred which would have required the snubber to initiate restraining action.

VI.

CAUSE

An analysis of the inoperable snubber determined the cause of failure l

to be the introduction of a lateral force on the snubber causing the internal drive mechanism to bend.

This bending caused the snap ring holding the outer casing to become disengaged which in turn failed the snubber.

Due to the disengagement of the outer casing, the snubber failed in the free movement position and did not restrict thermal expansion of the piping.

Since failure was caused by external damage to the snubber, a generic problem with Pacific Scientific mechanical snubbers is not apparent.

Vll. CORRECTIVE ACTION:

Work Request L16262 was written and a replacement snubber was installed.

e