ML20084G353

Final Deficiency Rept Re Pacific Scientific Co Shock Arrestor Capstan Spring Tang.Initially Reported on 831013. Bellefonte Snubbers Will Be Replaced & Hartsville Snubbers Returned to Vendor for Repair.Springs Subj to Insp

ML20084G353
Person / Time
Site:	Bellefonte, 05000000, Hartsville
Issue date:	04/19/1984
From:	Mills L TENNESSEE VALLEY AUTHORITY
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
NUDOCS 8405070194
Download: ML20084G353 (3)

Text

,, A TENNESSEE VALLEY AUTHORITY CHATTANOOG A. TENNESSEE 374ol

! 400 C estnut Street Tower II g4 MRZ4 P 3 : 2.)3 April 19,1984 BLRD-50-438/83-55, HTRD-50-518/84-02 BLRD-50-439/83-48, HTRD-50.JL20184-02 519 U.S. Nuclear Regulatory Commission Region II Attn: Mr. James P. O'Reilly, Regional Administrator 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30303

Dear Mr. O'Reilly:

BELLEFONTE AND HARTSVILLE NUCLEAR PLANTS UNITS 1 AND 2 - DEFECTIVE PSCo SHOCK ARRESTOR CAPSTAN SPRING TANG -BLRD-50-438/83-55, BLRD-50-439/83-48, HTRD-50-518/84-02, HTRD-50-420184 FINAL REPORT S1 The subject deficiency was in tially reported to NRC-0IE Inspector Linda Watson on October 13, 1983 in accordance with 10 CFR 50.55(e) as NCR BH001. A similar condition was subsequently discovered at Hartsville Nuclear Plant and has been documented as NCR HTN NEB 8303 Enclosed is our final report for both plants.

If you have any questions, please get in touch with R. H. Shell at FTS 858-2688.

Very truly yours, TENNESSEE VALLEY AUTHORITY L. M. Mills, Manager Nuclear Licensing Enclosure cc: Mr. Richard C. DeYoung, Director (Enclosure) i Office of Inspection and Enforcement l U.S. Nuclear Regulatory Commission Washington, D.C. 20555 Records Center (Enclosure)

Institute of Nuclear Power Operations 1100 Circle 75 Parkway, Suite 1500 Atlanta, Georgia 30339 S

h O 1983-TVA 50rH ANNIVERSARY  ! ,

An Equal Opportunity Employer g

ENCLOSURE BELLEFONTE AND HARTSVILLE NUCLEAR PLANTS UNITS 1 AND 2 DEFECTIVE PSCo SHOCK ARRESTOR CAPSTAN SPRING TANG NCRs BH001 AND HTN NEB 8303 BLRD-50-438/83-55, BLRD-50-439/83-48 HTRD-50-518/84-02, HTRD-50-520/84-02 10 CFR 50.55(e)

FINAL REPORT Description of Deficiency TVA has been notified by Pacific Scientific Company (PSCo), Anaheim, l California, that two sizes of PSCo shock arrestors (snubbers), the PSA-1 }

and PSA-3, delivered to Bellefonte (BLN) and Hartsville (HTN) may have defective capstan spring tangs. According to PSCo's service report, SR83-01, " Shock Arrestor Capstan Spring Service Report," the following snubbers are affected:

PSA-1 snubbers with serial numbers: 15672 through 16921 18211 through 21160 21411 through 22060 22311 through 22710 PSA-3 snubbers with serial numbers: 21311 through 21610 24311 through 25310 25361 through 25960 27194 through 28543 The capstan spring in PSCo snubbers provides a resistance to any sudden accelerations, and allows the snubber to hold these accelerations to within specified limits. The capstan spring tang is the mechanical unit of the spring used to initiate necessary " braking" action. Report SR83-01 states that snubbers used by another utility were found to have broken or cracked capstan spring tangs, and an analysis of these springs has shown that the defects were due to stresses induced during spring forming which caused hydrogen cracking during subsequent silverplating.

Safety Implications Suspected snubbers identified by PSCo are used in various safety-related systems at BLN and HTN. If any of these suspected snubbers were defective to the point that the capstan spring tang broke, then the snubber could not mitigate the acceleration of connected safety-related piping induced by a seismic event.

This, in turn, could lead to a more severe accident than those presently analyzed in the plant's design basis.

Corrective Action -

TVA has determined that this deficiency is limited at Bellefonte to 18 snubbers, all of which were designated for use in unit 2. The specific snubbers are listed below and are scheduled to be replaced by TVA construction forces at BLN by May 31, 1984.

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PSA-1 &nubbara:- 20428 21009 PSA-3 cnubbtra 24312 24377 20999 20989 21001 21015 24325 24385 jkL *;

20997 21003 21055 24333 24390 20998 21008 24339 At Hartsville, TVA has identified 351 suspect snubbers (all PSA-1s). These are being returned to the vendor for inspection, repair, and recertification.

TVA anticipates this process will be complete by September 10, 1984.

To prevent a recurrence of this problem, PSCo has informed TVA that all capstan springs are now subjected to a magnetic particle inspection after ,

silverplating.

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