ML19340B061
| ML19340B061 | |
| Person / Time | |
|---|---|
| Site: | Dresden, Quad Cities, Zion  |
| Issue date: | 12/06/1972 |
| From: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Brian Lee COMMONWEALTH EDISON CO. |
| References | |
| NUDOCS 8010170770 | |
| Download: ML19340B061 (1) | |
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UNITED STATES 7 T.'
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'l ATOMIC ENERGY COMMISSION t
OIRECTORATE OF REGULATORY OPERATIONS REGION til
- '8111 t' 799 ROOSEVELT ROAD peg GLEN ELLYN, ILLINOIS 60137 (312) 858-2e60
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December 6, 1972 i
l Comoewealth Edissa Company Docket No. h ATTN: Mr. Byron Lee, Jr.
50-237 Assistant to the President 50-249 P. O. Ben 767 50-254 Chicago, 1114=ais 60690 50-265 50-295 50-304 centlassens The attached Direeterate of Regulatory Operations Bulletin No. 72-3, "Limitorque Yalve Operator Failures " is sent to you to provida you with infstmetion we received from the Northern States Power Company and the Cemanoowealth Edison Company concerning valve operator malfunctions experienced at their respective facilities. This information may relate to the performance of similar noter operated valves at your facilities.
The Belletia also requests eertain action on your part related to this matter.
Should you have any questions concerning this mattar, we will be plassed to discuss them with you.
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Sincerely yours, l
Boyce R. Grier Regional Director i
Attaehment:
R0 Bulletia No. 72-3 bec: 10 Files DR Central Files j
PDR Local PDR 802o27o 7 7 0 N.
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1 December 6, 1972 Directorate of Regulatory Operations Bulletin 72-3 limitorcue Valve Operator Failure s Regulatory Operations recently received information relating to the malfunc-tion of electric type valve operators at two reactors.
The valve operators were identified as Limitorque Models SMB-00 and SMB-000 which are used extensively in safety related systems at a number of PWR and BWR reactor f ac ilitie s.
Subsequent investigation identified a specific production group of these models which were manuf actured between 1969 and mid-1971.
The specific deficiencies are described as follows:
Plant A Testing of valves and valve operators used in safety related systems at this facility disclosed ten valves that failed to close following a " valve full open operation" test.
The cause of failure was attributed to malfunc-tion of the valve operator torque switch due to a lack of proper clearance between the moving parts of the torque switch unit and the inability of the
" torque switch torsion spring" to return the electrical contacts to a closed position following operation of the valve.
The weak torsion spring is con-sidered a common mode of failure. Approximately 150 valves ranging up to eight inches in size were equipped with valve operators having the f aulty switches.
Plant B During a reactor startup, the inboard steam supply valve of the reactor core isolation coolant (RCIC) system failed in the open position.
Several a ttempts were made unsuccess fully to close the valve.
The f ailure was attributed to an internal torsion spring in the valve operator torque. switch which normally resets the electrical contacts.
The valve operator in question is abnilar to the units which failed at Plant A.
Two additional facilities have recently experienced similar failures since those reported at plants A and B.
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r 2-f It is requested that you determine whether valve operators of the described make, model, and vintage are installed or scheduled to be installed in your facility.
If your findings show that valves installed or scheduled to be installed are equipped with the described valve operators, please inform this of fice within thirty days, in writing, of the number of valves equipped with the valve operators, the systems in which the subject valves are in-stalled or scheduled to be installed, a description of corrective actions taken or planned, and the scheduled completion date of your corrective actions.
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