05000206/LER-1982-014, Forwards LER 82-014/03L-0.Detailed Event Analysis Submitted

Forwards LER 82-014/03L-0.Detailed Event Analysis Submitted

ML20053D544
Person / Time
Site:	San Onofre
Issue date:	06/01/1982
From:	Ray H SOUTHERN CALIFORNIA EDISON CO.
To:	Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
Shared Package
ML20053D545	List: 05000206/LER-1982-014, Forwards LER 82-014/03L-0.Detailed Event Analysis Submitted 05000206/LER-1982-014-03, /03L-0:on 820429,four Snubbers Identified as Having Empty Reservoirs.Upon Further Testing,One Snubber Failed to Pass Stroke Test.Caused by Excessive Hydraulic Fluid Leakage.Snubbers Rebuilt
References
NUDOCS 8206070053
Download: ML20053D544 (3)

LER-1982-014, Forwards LER 82-014/03L-0.Detailed Event Analysis Submitted

Event date:
Report date:
2061982014R00 - NRC Website

text

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U. S. Nuclear Regulatory Commission Office of Inspection and Enforcement Region V 1450 Maria Lane, Suite 210 Walnut Creek, California 94596-5368 Attention:

R. H. Engelken, Regional Administrator

Dear Sir:

Subject: Docket No. 50-206 LER flo.82-014 San Onofre Nuclear Generating Station, Unit 1 1

This letter and the attached Licensee Event Report describe a reportable occurrence regarding the failure of a safety related snubber on the main feed water piping for steam generator C.

This LER is submitted in accordance with the reporting requirements stipulated in Section 6.9.2.b.4 of Appendix A to the Provisional Operating License No. DPR-13.

On April 29, during the 1982 Spring outage, the following snubbers were reported as having empty reservoirs: 2-SW-2-10, 2-SW-2-11, 2-SW-1-10, and 1-SW-391-3.

On May 1st these snubbers were further inspected to determine if the hydraulic port level in the reservoir was uncovered.

Two of the snubbers reported were found to have an uncovered port (1-SW-391-3 and 2-SW-2-10).

The other two were low on hydraulic fluid but were not below the hydraulic port level. All four snubbers were F

removed and tosted in accordance with Maintenance Procedures S01-1-2.10

" Routine Tests of Inaccess!ble Hydraulic Snubbers," and S01-1-2.31

" Routine Tests of Accessible Hydraulic Snubbers".

Snubber 1-SW-391-3 failed to pass the stroke test in the "as found condition";

the remaining l

snubbers were tested and determined to be operable.

Snubber 1-SW-391-3 underwent a disassembly inspection. This inspection revealed that the cause of failure was excessive wear on the piston hydraulic seal. A further examination of the snubber components showed wear of the bushing and piston rod; the snubber was reassembled with new parts and seals.

in addition, the 'O' rings in the manifold connect-lons and the seal gasket on the reservoir were replaced as a precautionary measure. The snubber was then tested with satisfactory results.

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R. H. Engelken 2

The remaining three snubbers were also disassembled and inspected for wear or signs of deterioration.

Seal gaskets were changed on the hydraulic piston seal and reservoir and new 'O' rings were installed in the connections of the manifolds.

Following reassembly the snubbers were functionally rotested with acceptable results. After this rotesting the snubbers were returned to service.

An engineering evaluation was performed on the support components (i.e.

brackets, linkage, pipe clamps and anchors) to determine if any damage had occurred to these components. All the welds on the components were visually inspected for cracks. Checks were also made on the pin connect-ors for bending and deformation.

insulation on the pipe was removed to inspect for any sign of deterioration or binding between components.

This evaluation showed that the snubber mode of failure did not adversely af fect any of the support components or the system. There was no detri-mental effect on public health and safety.

The failed snubber (1-SW-391-3) is categorized as an inaccessible snubber.

To conform with the snubber surveillance Technical Specification 4.14.A an additional 10% sample of the inaccessible snubbers was removed and functionally tested, in all cases the results of the tests were satisfact-ory.

A visual inspection of the cylinders and bushings did not show any s !gn of wear. Al! the man! fold 'O' rings arid the fluid reservoir seal 9askets were changed in this group as.a precautionary measure. The reservoir seal gaskets were replaced in all inaccessible snubbers.

In accordance with Technical Specification 4.14.A and since the failed snubber was in the inaccessible group, the current snubber inspection intervals are as follows:

Location Frequency Deviation Permitted i

Inaccessible 12 months

+ 90 days Accessible 18 months

+ 135 days Should you have any qcestion on the above, please contact me.

Sincerely, f7 DAW /h Enclosure

R. H. Engeiken cc:

U.S. Nuclear Regulatory Conrnission Office of inspection and Enforcement U.S. Nuclear Regulatory Conynission Of fice of Management information and Program Control Institute of Nuclear Power Operations (INPO)

L.F. Miller (USNRC Resident inspector, San Onofre, Unit 1)