ML19340B056
| ML19340B056 | |
| Person / Time | |
|---|---|
| Site: | Dresden, Byron, Braidwood, Quad Cities, Zion, LaSalle  |
| Issue date: | 07/26/1978 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Brian Lee COMMONWEALTH EDISON CO. |
| References | |
| NUDOCS 8010170767 | |
| Download: ML19340B056 (1) | |
Text
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JUL 261978 Docket Hos.
0-10, 50-237,.50-249, 50-254, 50-265, 50- 95, 50-304, 50-373, 50-374,40-454, 50-455, 50-456, 50-457 Comonwealth Edison Company ATTN:
Mr. Byron Lee, Jr.
Vice President P. O. Box 767 Chicago, IL 60690 Gentlemen:
The enclosed IE Circular No. 78-16 is forwarded to you for information. If there are any questions related to your understanding of the suggested actions, please contact this office.
Sincerely, James G. Keppler Director
Enclosures:
1.
IE Circular No. 78-16 2.
List of IE Circulars Issued in 1978 cc v/encis:
Mr. B. B. Stephenson,
- ntral Files Station Superintendent Director, NRR/DPM Hr. N. Kalivianakis, Director, NRR/ DOR Station Superintendent PDR gg Mr. N. Wandke, Station Local PDR Superintendent NSIC Mr. L. J. Burke, Site TIC I
Project Superintendent Anthony Roisman, Esq.
Mr. Cunnar Sorensen, Site Attorney Project Superintendent Mr. Dean Hansell, Office of acy Ge_____RJgral Mr. R. Cosaro, Froject Attor orrecc > Superintendenf.
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l U.S. NUCLEAR REGULATORY COMMISSION 0FFICE OF INSPECTION AND ENFORCEMENT REGION III July 26, 1978 IE Circular No. 78-16 LIMITORQUE VALVE ACTUATORS Description of Circumstances:
At Rancho Seco, a Limitorque Type SMB-2 motor-driven valve actuator in a safety feature system failed to function. The failure resulted 1
from clutch weer which was due to manual operation of the valve and improper heat treatment of the clutch parts. Other SMB valve actua-tors at Rancho Seco had been subjected to undue clutch wear but were still operable. Based on information obtained from the licensee and from L1=itorque Corporation, undue wear appears to be limited to
,j Type SM3-0,1, 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 power is unavailable.
To shift from motor drive to handwheel drive, the operator must manually position a clutch so that the motor is disengaged from the drive train end the handwheel is engaged. The-clutch latches into this position and cannot be manually repositioned. The next time that the motor is energized, the latch releases automatically and a spring repositions the clutch so that the motor engages the drive train.
When the clutch is repositioned, a pair of lugs on the motor-side of the clutch engages a pair of lugs on the valve-side. At the instant the lugs engage, the lugs on the motor-side are being accelerated to full speed and the lugs on the falve-side are stationary. Before the motor is energized, the relative position of the lugs is random. This initial position determines the depth 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 occurs, the edges of the lugs are chipped or upset. After the edges are sufficiently rounded, the clutch will not engage and hold for motor actuation.
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IE Circular No. 78-16 July 26, 1978 The lict.nsee estimated that the failure of the Type SMB-2 valve actuator occurred after it had been clutched 25 to 100 times. The valve which failed to function at Rancho Seco (SFV-25003) is operated by the actuator and is a safety features valve in a line connecting the borated water storage tank to a high pressure safety injection pu=p and a decay heat removal (low head safety injection) pump. The valve actuator is vited so that the valve which it controls will drive to the fully open or fully closed position once the motor is energized.
SFV-25003 is used for various routine operations during refueling, e.g.
adding barated water to the primary cooling system.
In these instances, the operator uses SFV-25003 as a throttle valve. To do this, the valve must be actuated manually, giving rise to the potential damage to the lugs as described above. This would not occur with the type of valve actuator that is clutched with the motor at rest. Likewise, a separate throttle valve for supplying borated water during routine operation:
vould preclude the need for manual operation of the subject valve
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actuator.
Limitorque Corporation has a test program in progress for determining the clutch life of Type S3a 0,1, 2, and 3 valve actuators. Results.to date are inconclusive. Pending other resolution of the problem, the licensee has stated that the ' valve will be stroked with the motor, drive to ensure that the clutch has engaged the motor following manual actuation of the valve.
All licensee and construction permit holders should consider:
For Limitorque Type SMB-0,1, 2, and 3 valve actuators with 3600 rpm motors which are useS or will be used in engineered safety systems;
- 1) The potential for failure of the actuators resulting from manual operation.
- 2) Means for minimizing manual operation and,
- 3) Procedures for verifying that the actuator is operable with the motor after manual operation.
No written response to this Circular is required. If you require additional information regarding this matter, contact the Director of the appropriate NRC Regional Office.
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IE Circular No. 78-16 July 26, 1978 LISTING OF IE CIRCULARS ISSUED IN 1978 Circular Subject Date Issued To No.
of Issue 78-01 Loss of Well Logging 4/5/78 All Holders of Source Well Logging Source Licenses 76-02 Proper Lubricating 011 4/20/78 All Holders of for Terry Turbines Reactor OLs or cps 78-03 Packaging Greater Than 5/12/78 All Holders of Type A Quantities of Reactor OLs, cps, Low Specific Activity Fuel Cycle, Radioactive Material
-Priority I Material for Transport and Waste Disposal Licenses 78-04 Installation Error That 5/15/78 All Holders of Could Prevent Closing cf Reactor OLs or Fire Doors cps
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,u-OS Inadvertent Safety Injection 5/23/78 All Holders of During Cooldown Reactor OLs or cps 78-06 Potential Common Mode 5/23/78 All Holders of Flooding of ECCS Equipment Reactor OLs or Roo=s at BWR Facilities cps 73-07 Damaged Components of a 5/31/78 All Holders of Bergen-Paterson Series Reactor OLs or 25000 Hydraulic Test cps Stand 78-08 Environmental Qualification 5/31/78
. All Holders of of Safety Related Equipment Reactor OLs or at Nuclear Power Plants cps 78-09 Arcing of General Electric 6/5/78 All Holders of Company Size 2 Contactors cps Enclosure Page 1 of 1
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IE Circular No. 78-16 July 26, 1978 LISTING OF IE CIRCULARS ISSUED IN 1978 Circular Subject Date of Issued to No.
Issue 78-10 Control of Sealed 6/14/78 All Medical Sources Used in Licensees in Radiation Therapy Categories G and G1 78-11 Recirculation M-G 6/15/78 All Holders of-BWR OLs or cps Set Overspeed Stops 78-12 HPCI Turbine Control 6/30/78' All Holders of Valve Lift Rod Bending BWR OLs or cps for plants with HPCI Terry: Turbine-78-13 Inoperability of Multiple 7/10/78 All Holders of Service Water Pumps Reactor OLs and cps except for plants located in: AL; AK, CA', FL, GA, LA, MS, SC 78-14 HPCI Turbine Reversing, 7/12/78 All Holders of BWR Chamber Hold Down Bolting OLs or cps for plants with a HPCI Terry Turbine excepting Duane Arnold and Monticello 78-15 Checkvalves Fail to 7/20/78 All Holders of Close In Vertical Reactor OLs or cps Position Enclosure Page 2 of 2
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