ML20082H529
| ML20082H529 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 11/23/1983 |
| From: | Tucker H DUKE POWER CO. |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, NUDOCS 8312010200 | |
| Download: ML20082H529 (3) | |
Text
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h lh DUKE POWER GOMPANY P.O. HO X 3 31tM)
CHAMLOTTE, N.C. 28242 HAL H. TUCKEH TELEPHONE 83ll0ygg (704) 07:F4838 vnos pasament November 23,$k'8)
.Mr. James P. O'Reilly, Regional Administrator U. S. Nuclear Regulatory Commission Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30303 Re: Catawba Nuclear Station Units 1 and 2 Docket Nos. 50-413 and 50-414
Dear Mr. O'Reilly:
Pursuant to 10 CFR 50.55e, please find attached Significant Deficiency Report SD 413-414/83-16.
j Very truly yours,
/hd B. Ddc Hal B. Tucker LTP/php Attachment cc: Director INFO Records Center Office of Inspection and Enforcement Suite 1500 U. S. Nuclear Regulatory Commission 1100 circle 75 Parkway Washington, D. C. 20555 Atlanta, Georgia 30339 NRC Resident Inspector Mr. Robert Guild, Esq.
Catawba Nuclear Station Attorney-at-Law P. O. Box 12097 Palmetto Alliance Charleston, South Carolina 29412 213515 Devine Street Colu-bia, South Carolina 29205 FFirf ay copy S E 27 8310.010200 831123 f/
PDR ADOCK 05000413 S
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JP0/HBT/LTP Nov:mber 23, 1983 Duke Power Company Catawba Nuclear Stction Report Number: SD 413-414/83-16 Report Date: November 23, 1983 Identification of Deficiency: Potential. deficiency in capstan springs in safety related Pacific Scientific mechanical snubbers. Deficiency identified October 3, 1983.
Initial Report: On October 25, 1983, Mr. Virgil Brownlee of NRC Region II, Atlanta, Georgia was notified of this deficiency by Messrs. D. M. Collings, R. D. Carroll, L. M. Coggins and T. L. Utterback of Duke Power Company, Charlotte, North Carolina 28242.
Supplier and/or Component: PSA-1 and PSA-3 mechanical snubbers manufactured by Pacific Scientific Company.
==
Description:==
Mechanical snubbers are used to restrain safety related piping and other components during seismic and other dynamic events.
If either of the tangs at the ends of the capstan spring in a Pacific Scientific snubber should break off, the snubber would not perform its expected restraining action during an earthquake or other dynamic event.
This could lead to over-stressing of the restrained component.
The usual process for forming capsts' springs occurs prior to the age-hardening process. Some size 1 and size 3 capstan springs were formed after aging, resulting in high residual stresses. During the subsequent plating operation, some springs developed cracks at the root of the tang. Approximately 8500 snubbers were assembled with springs which may have these cracks.
During pre-service functional testing at the Callaway Station, four size 1 snubbers failed to activate and were found to have broken tangs.
Subsequent P-T examination of over 200 springs, returned from the field, indicates conservative cracked and broken tang rates of 33% and 1.6%, respectively, for size 1 snubbers. Cracked and broken tang rates for size 3 snubbers are 4% and approximately 0%, respectively.
Analysis of Safety Implications:
ITT-Grinnell records (Pacific Scientific Company snubbers were bought through ITT-Crinnell) indicate that 109 size 1 snubbers and 78 size 3 snubbers were shipped to Catawba Nuclear Station (109 + 78 = 187 total).
Had this situation not been discovered, it is probable that a small number of the suspect snubbers would not have performed their expected restraining action during a design basis event. This might have led to overstressing of the restrained components.
4 E
JP0/HBT/LTP November 23, 1983 Corrective Action: Of the 187 suspect snubbers shipped to Catawba, 85 have been located on the site. Of these, 22 had been installed. As of November 22, 1983, 18 of the 22 installed suspect snubbers had been removed.
Four (4) located suspect snubbers remain installed.
As they are located or removed, suspect snubbers are being placed on hold.
The four (4) located suspect snubbers will be removed by December 31, 1983.
The search for the 102 snubbers (187 - 85) will continue.
Assurance that suspect snubbers are not installed in Unit 1 will be obtained before fuel loading, and in Unit 2 by June 30, 1984. L