ML20206U905

Rev 1 to Employee Concern IN-85-228-001, Improper Handling of Snubbers

ML20206U905
Person / Time
Site:	Sequoyah
Issue date:	05/16/1986
From:	Denny R, Lagergren W, Shepherd P TENNESSEE VALLEY AUTHORITY
To:
Shared Package
ML20206U867	List: ML20206U863 ML20206U880 ML20206U905 ML20206U937
References
IN-85-288-001, IN-85-288-001-R01, IN-85-288-1, IN-85-288-1-R1, NUDOCS 8610080451
Download: ML20206U905 (5)

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TENNESSEE VALLEY AUTHORITY SEQUOYAH NUCLEAR PLANT

""- --- GENERIC CONCERN TASK FORCE EMPLOYEE CONCERN # IN-85-288-001  !

Subject:

Improper Handling of Snubbers

, Date 'of Investigation: April 25,;1986 Investigator: [ Lh / Y"8[~ [h i P. L. Sheph(rd Date Reviewed By: _ .b. 4W /_ N "M-8 b R. C. enny M Date l Approved By: bi ,

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., 4/25/86 I. BACKGROUND Sequoyah Nuclear Plant (SQN) Generic Concern Task Force has identified the following potential generic issue:

Improper Handling of Snubbers This issue was generated from an employee concern communicated to Quality Technology Company (QTC) in response to the Watts Bar Employee Concern Program. The specific concern # IN-85-288-001 was expressed to QTC as follows: ~

Snubbers are not handled properly and are not adjusted and installed in accordance with the manufacturer's recommended practices of protecting them in waterproof coverings, storing and carrying them compressed, and adjusting their paddles only while they are held vertical. Construction department concern; CI has no more information.

II. SCOPE The secpe of this investigation was directed toward the verification of the occurrence of this concern at SQN and assessment of impact on SQN performance.

A. During the course of the investigation, discussions were held with cognizant personnel in Mechanical Maintenan'ce, Power Stores, -

Modifications Branch, and Design Services' sections of NUC PR.

B. Answers to these guestions were discussed:

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1. What are the manufacturer's recommended practices for handling,"

adjusting and installation of snubbers.

2. Do any manufacturers recommend:

a. Protecting snubbers with waterproof coverings,

b. Storing and carrying snubbers compressed, ,,

c. Adjusting snubber paddles only while tlue snubber is held vertical.

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4/25/86 III.

SUMMARY

OF FINDINGS Through discussions with NUC PR personel, which included some who had worked in Construction during initial snubber storage, handling, and installation, the allegation of improper handling of snubbers at SQN was substantiated.

1. Even though an attempt was made by Construction to store snubbers inside, some of them may have been stored outside.

Currently, all snubbers are stored inside by SQN Power Stores where thef are kept under controlled conditions.

Mechanical snubbers are stored at SQN Power Stores in the compressed position, but only because the vendor packages the snubbers during shipment in the compressed position.

During a telecon between Individual #1, of SQN Mechanical Maintenance, and Individual #2, of Pacific Scientific on January 8, 1986, the following was verified:

l l The vendor, Pacific Scientific, does not specify storage ,

4 and/or handling requirements concerning the position of -

i mechanical snubbers.

I The end-plug is sometimes referred to in the field as the 2.

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" paddle." The vendor, Pacific Scientific, lists on " good practice" of placing the a'r restor in a vertical position on a  !

table to make end-plug adjustments. MI-6.13A does not use this '

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" good practice," but paragraph 6.3.2.4 provides sufficient instructions and precautions to propprly rotate rthe 'end-plug or

" paddle." The advice provided by the vendor is intended to help in preventing possible damage to internal components of '

mechanical snubbers which could occur if the support cylinder

• was completely removed from the housing assembly.

3. TVA, Division of Construction, Seguoyah Nuclear Plant Inspection Instruction No. A-3, " Inspection and Cycling of i Shock Suppressors," Revision 6 dated December 29, 1980 (Reference 45) required that all snubbers be cycled and documented during installation. Twenty two II A-3 documents were randomly sampled in two systems to verify that cycling was

. documented as completed.

SI-162.2 requires that replacement snubbers and snubbers which l have repairs that might affect the functional test results will .

be tested to meet the functional test criteria before installing in the unit.

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SUMMARY

OF FINDINGS (continued) l There has been an SI-162.2 inspection performed during each l unit refueling outage. There have been three unit one and two l I

unit two refueling outages. All five of these data packages were reviewed for failures that could be attributed so i storage / installation damage. There were 858 snubbers inspected with 44 failures (5.1%). Twelve of these failures (1.4%) could have been caused by improper storage resulting in failure due l to rust or corrosion and 10 of these failures (1.ZL) could have '

- been caused by improper end paddle,y,otation during installation. The remainder of the failures were not related to possible storage / installation damage.

Summary: Storing mechanical snubbers in the compressed or extended -

position or any position in between does not affect the operability l a

of mechnical snubbers. Rotation of the " paddle" is seldom required. Whenever this adjustment is made, the suppo'rt cylinder is kept engaged with the housing assembly. There is no cause for moving the support cylinder ii. a linear direction. The adjustment is rotational only, and many times this adjustment is made with the

, snubber installed while both ends are pinned or fixed in place. .

This concern is only applicable to site PSA 1/4 and PSA 1/2 l mechanical snubbers because of their specific design. This concern is not relative to other PSA snubber sizes. Post-maintenance tests are always performed on new snubbers or snubbers repaired to the extent that snubber operability might be affected as-discussed in the scope of SI-162.2. .-

IV " CONCLUSIONS AND RECOMMENDATIONS.... .......... .,,,,.,, , , , , , ,

A. Conclusions s Although the concern of " improper handling of snubbers" was substantiated at SQN, the accumulated evidence indicates that initial testing and periodic surveillance testing would have detected any damage that would have prevented the snubbers from performing their intended safety function.

B. Recommendations -

None I

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'.- 4/25/86 DOCUMENTS REVIEVED AND REFERENCES

1. Seguoyah Nuclear Plant Surveillance Instruction SI-162.1, " Snubber Visual Inspection (Hydraulic and Mechanical)," Revision 7,

2. Seguoyah Nuclear Plant Surveillance Instruction SI-162.2, " Snubber Functional Testing (Hydraulic and Mechanical). " Revision 4.

3. Sequoyah Nuclear Plant Administrative Instruction AI-36, " Storage, Handling, and Shipping of QA Material, " Revision 8.  :

4. Seguoyah Nuclear Plant Maintenance nstructionMk'-6.13A,"Removaland Reinstallation of Hydraulic and Mechanical Snubbers," Revision 2.

5. TVA, Division of Construction, Seguoyah Nuclear Plant Inspection Instruction No. A-3, " Inspection and Cycling of Shock Supressors,"

Revision 6 dated December 29, 1980.

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