ML19220B516
| ML19220B516 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 07/26/1978 |
| From: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Herbein J METROPOLITAN EDISON CO. |
| References | |
| NUDOCS 7904260490 | |
| Download: ML19220B516 (1) | |
Text
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UNITED STATES NUCLEAR REGULATORY COMMtsslCN s.$ r
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REGIONt W'. <
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- M KING OF *RUSSI A. PENN5Y LV ANI A 1 H06 g%
July 26, 1973 Cocket Nos. 50-320 w!
50-289 Metropolitan Edison Cemaany ATTN:
Mr. J. G. Herbein Vice President - Generation
?. O. Sex 542 Reading. Pennsylvania 19603 Gentlemen:
The enclosed IE Circular No. 78-16 is forwarded to you for infor-mation. No written resconse is required.
Should you have any questions related to your understanding of this matter, please contact this office.
Sincerely,
%W.
$~
ervce H. Grier f'_ Director
Enclosures:
1.
IE Circular No. 78-16 2.
List of IE Circulars Issued in 1978 cc w/encis:
T. 3rcughton, Safety and Licensing Manager J. J. Barton, Project Manager R. C. Arncid, Vice President - Generation L. L. Lawyer, Manager - Generation Ccerations - Nuclear G. P. Miller, Sucerintendent J. P. O'Hanlen, Unit 1 Superintendent J. L. Seelinger, Unit 2 Sucerintendent - Tecnnical Supcor:
I. R. Finfrock, Jr.
Mr. R. Conrad G. F. Treweridge, Esquire Miss Mary V. Southard, Chairman, Citi: ens for a Safe Environment pr g.g
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(NO4260f 76 6
UNITED STATES NUCLEAR REGULATORY CCMMISSICN OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D. C.
20555 IE Circular No. 78-16 Date: July 26, 1978 Page 1 of 2 LIMITCRGUE VALVE ACTUATORS At Rancho Seco, a Limitorque 7.ce SMB-2 motor-driven valve actuator in a safety feature system failed to function.
The failure resulted frcm clutch wear whicn was due to manual operation of the valve and imcrocer heat treatment of the clutch parts.
Other SMS valve actuators at Rancno Seco had been subjected to undue clutch wear, but were still ccerable.
Based on information octained fecm the licensee and frcm Limitorcue Corporation, undue wear appears to be limited to Type SMS-0,1, 2, and 3 valve actuators equipped with 3600 rpm motors.
The type SMB valve actuator is provided with a handwheel so that the valve can be actuated manually in the event that pcwer is unavailable.
To shift from motor drive to hancwheel drive, the coerator must manually position a clutch so that the motor is disengaged frca the drive train and the handwheel is engaged. The clutch latches into this position and cannot be manua'lly recesitioned. The next time that the motor is energized, the latch releases autcmatically and a spring repositions the clutch so that the motor engages the drive train.
When the clutch is recositioned, a pair of lugs en the matcr-side of the clutch engages a :: air of lugs en the valve-side. At the instant the lugs engage, the lugs en the motor-side are being accelerated to full speed and the lugs on the valve-side are stationary.
Before the matar is energized, the relative ::csition of the lugs is randcm. This initial position determines the decth of engagement or bite at the instant the lugs make contact. When a full bite occurs, no damage is caused to the lugs. When a grazing bite cccurs, the edges of the lugs are chi:: ped cr uoset. After the edges are sufficiently reunced, the clutch will not engage and hold for matar actuation.
The licensee estimated that the failure of the Type SMS-2 valve actuatar occurred after it had been clutched 25 to 100 times.
The valve wnich failed to functicn at Rancho Seco (SP/-2SCO3) is operated by the actuator and is a safety features valve in a line ccnnecting ne borated water storage tank to a hign pressure safety injecticn ;umo and a decay heat removal (low head safety injection) cumo.
The valve actu
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