ML20092D985
| ML20092D985 | |
| Person / Time | |
|---|---|
| Site: | Fermi  |
| Issue date: | 06/08/1984 |
| From: | Jens W DETROIT EDISON CO. |
| To: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| 103, EF2-68538, NUDOCS 8406220240 | |
| Download: ML20092D985 (3) | |
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Wayne H. Jens Vice Prewlent
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FM isar Operatar,is Detroit
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- C! son Sw=r-aune e, 1984 EP2-68536 x
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Mr. James G. Kepple Regional Administrator Region III U.
S.
Nuclear Regulatory Commission
- 79) Roosevelt Road Glen Ellyn, Illinois 60137
Dear Mr. Keppler:
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Reference:
(1)
Fermi 2 tiRC Docket !!o. 50-341 (2)
Le t te r,
D. A. Wells to J. G.
- Keppler, October 30, 1983, EP3-65291
Subject:
Final Report of 10CFR50.55(e) Item 103
" Capstan Spring Tang Cracks on PSA-1 and PSA-3 Mechanical Snubbers" This is Detroit Edison's final report concerning Pacific Scientific capstan spring tang cracks in PSA-1 and PSA-3 mechanical snubbers.
Item 103 was originally reported as a potential deficiency on September 30, 1383, and subsequently documented in Reference (2).
Description of Deficiency As stated in Reference (2), Daniel International notified Detroit Edison of the potential deficiency af ter several failures (4 of 7) had occurred during testing of PSA-1 shock arrestors at the Callaway Station.
The deficiency was identified as cracks in the capstan springs which, according to a metallurgical report, were produced by hydrogen induced cracking during the silver plating process.
The source of the defective springs was traced to a new subvendor with whom Pacific Scientific has since discontinued as a vendor.
Pacific Scientific identified by serial number a total of 67 potentially deficient PSA-1 and PSA-3 units that were shipped to the Fermi 2 site.
The following units were identified:
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f F.r. James G. Keppler June 8, 1984 EP2-68538 Page 2 A.
34 PSA-1 Snubbers with serial numbers 18641 thru 18658 19577 thru 19580 21946 thru 21957 B.
33 PSA-3 Snubbers with serial numbers 20957 thru 20989 Upon receipt of this information Field llanger Engineering began a program to cross. correlate the seria1' numbers of the potentially defective snubber with the Edison pipe support mark number.
The installation status of each snubber was determined which expedited the return of the-snubber to the vendor.
Analysis of the Safety Inplications Mechanical snubbers are installed on safety related-piping systems to mitigate pipe stresses during strong vibratory motion (eg. earthquake).
The capstan spring cracks, if left-undetected, could have propagated during the "High Cycle" cyclic loading causing the springs to fail, thereby preven-ting the snubber from functioning as designed.
Improper snubber operation could cause the pipe stresses, resulting from.such loadings, to exceed their design limits.'.
Corrective Action The snubbers were returned to the vendor in two groups.
The first group consisted of twenty four snubbers, (13 PSA-1 and-11 PSA-3).
The capstan springs in this group were subjected to magnetic particle examination and determined to be acceptable.
The springs were. reinstalled in-their original snubbers and tested. _'All. units passed the acceleration, lost motion, breakaway and running friction tests.
The second' group consisted of-forty three units (21.PSA-1 and 22 PSA-3).
The capstan springs in this group were subjected to a. magnetic particle examination with four being rejected.
.These.four capstan springs:were. replaced.
The' snubbers were re-assembled and subjected to acceleration, lost motion, breakaway:and running friction tests.
All. units successf ully.
completed their tests.
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Mr. James G. Keppler June 8, 1984 EF2-68538 Page 3 All units have been returned to.the Fermi 2 site and those units required ~ to complete the.necessary pipe support configurations have been installed.
Units not associated with a particular pipe support are. retained'in=the warehouse as spare units.
This is considered the final report'on this item as th'is item is no longer considered a significant deficiency and is ready for NRC review and closure.
If you have questions concerning this matter, please contact Mr. Lewis P.
Bregni at (313) 586-5083.
Sincerely,
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Mr.
P.
M. Byron Mr.
R.
C.
DeYoung Mr.
R.
C. Knop 1
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