ML20097B041
| ML20097B041 | |
| Person / Time | |
|---|---|
| Site: | Fermi  |
| Issue date: | 08/27/1984 |
| From: | Jens W DETROIT EDISON CO. |
| To: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| 76, EF2-69662, NUDOCS 8409130478 | |
| Download: ML20097B041 (2) | |
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Vice President V
Nuc!es Operawns Fnemi-2 '
0400 North D:ne Hi?way n _ pia ssoiso August 27, 1984 Newport, Mchegan 48t06 EF2-69662 Mr. James G.
Keppler Regional Administrator U.
S.
Nuclear Regulatory Commission Region III 799 Roosevelt Road Glen Ellyn, Illinois 60137
Dear Mr. Keppler:
Reference:
(1)
Fermi 2 NRC Docket No. 50-341 (2)
- Letter, D.
A.
Wells to J.
G.
- Keppler, August 30, 1982, EF2-59390 (3)
- Letter, D.
A. Wells to J.
G.
- Keppler, December 28, 1982, EF2-61525
Subject:
Final Report of 10CFR50.55(e) Item 76 "Limitorque Limit Switch Rotor Failures" This is Detroit Edison's final report concerning Limitorque limit switch rotor failures.
Item 76 was originally reported as a potential deficiency on July 31, 1982, and subsequently documented in References (2) and (3).
Description of Deficiency While performing standard maintenance procedures on motor operated valves, maintenance personnel discovered sixteen cracked limit switch rotors in QA Level I Limitorque motor operators.
The cracks appear to have originated at the split pin that secures the limit switch rotor to the gear box shaft.
The rotor makes and breaks the contacts for the limit switches.
The limit switch deenergizes the operator when the valve is in its open or closed position, depending on the direction of valve stem travel.
l 8409130478 B40827 AUG 31 )984 d
PDR ADOCK 05000341 Vt g
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4
+0' 2.l Z Mr. James G..Keppler
.EF2-69662 August 27, 1984 Page 2 s
Analysis of Safety Implications-Failure of the rotor.could result;in the motor continuing'to run until the motor fails.: Valves in safety related' systems would remain either open or closed, depending'on the direction of-valve stem travel.. ' The-motor operators; could fail to per--
form their ' intended safety function.
Corrective Action The following actions were taken to correct this deficiency and prevent recurrences o
An inspection of.the QA Level I operators wastmade and the results documented-in NCR 83-280 for operators inside primary containment and.NCR 83-283 for operators outside primary containment.
o Field Modification Request (FMR) #S-5190 was written to require replacement of the limit. switch assemblies on Limitorque operators inside the primary containment.
FMR #S-5717 was written to_ replace.the defective limit-
-l switch assemblies identified in the inspection on l
operators outside the primary containment.
o To prevent the possibility' of damage.due to mis-handling or improper installation. of the split pin, the entire limit switch assembly, not just the rotor, wasi replaced as a unit.
o Procedure CAIO. 000.006 requires a -final. inspection of the Limitorque limit switch; rotors by Startup personnel-after refurbishment..In addition, ongoing startup activities, including CAIO and preoperational testing have not identified any more Limitorque limit switch rotor failures.
This is Detroit Edison's final report on this item.
If you have questions concerning this matter,'please contact Mr. Lewis P.
Bregni, (313) 586-5083.
Sincerely, i
cc:
Mr.
P.
M.
Byron' Mr.
R.
C.
DeYoang Mr.
R.
C. Knop 4
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