ML20127H512
| ML20127H512 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 12/06/1972 |
| From: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Wachter L NORTHERN STATES POWER CO. |
| References | |
| IEB-72-03, IEB-72-3, NUDOCS 9211180532 | |
| Download: ML20127H512 (3) | |
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UNITED CTATO3 1.j g
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I ATOMIC ENERGY COMMISSION g Q' A Q',
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DIRECTOR ATE OF REGULATORY OPERATIONS b
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799 ROOStVELT ROAD tcu.pu m t OLEN ELLYN ILLINOIS 60137 Olh 8502660 December 6, 1972 1
Northetu 8tatse Fewer Ceapany Decket No. 50-263 A!TW: Wr. Lee Wachter, Vice President Fever Producties 419 Nisellet Hall Minneapolis, Minnesota 54401 Gentlemen:
The attached Directorate of Regulatory Operationa Bulletin No. 72-3, "Limitorque Valve Operator Failures " is sent to you to provide you with information we received from the Northern States Power Company and the 4
Commonwealth Edison Company concerning valve operator malfunctions esperienced at their respective facilities. This information may relate to the performance of similar motor operated valves at your facilities.
i The Bulletin also requests certain action on your part related to this matter.
Should you have any questions concerning this matter, we vill be pleased 3
to discuss them with you, i
Sincerely yours, l
l Boyce H. Grier j
Regional Director l
Ateachment:
I R0 Bulletin No. 72-3 1
bcct RO Files DR Central Files ___
l PDR l
Local PDR l
I 9211180532 721206 3a PDR ADOCK 05000263 qP G
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December 6, 1972 Directorate of Regulatory l
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Operations Bulletin 72-3 4
j Limitorque Valve Operator Fattures 4
i 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 FWR and BWR reactor facilities.
Subsequent investigation identified a specific production group of these mode (s which were manufactured 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 ter valves that f ailed to close following a " valve this f acility dir 1:
4 full open operat m" f "h. cause of f ailure was attributed to malfunc-
.ran
'uitch due to a lack of proper clearance tion of th7 va lvr. oyet u i between the movint aytv n sad torque switch unit and the inability of the
" torque switch tot s t n
- hg" to return the ciectrical contacts to a closed position following operatien of the valve.
The weak torsion spring is con-sidered a coucon mode of failure. Approximately 150 valves ranging up to eight inches in size wero (quipped with valve operators having the f aulty switches.
Plant B l
During a reactor startup, the inboard steam supply valve of the reactor core isolation coolant (RCIC) system failed in the open position.
Several attempts i
l were made unsuccessfully to close the valve. The f ailure was attributed to an l
internal torsion spring in the valve operator torque switch which normally l
resets the electrical contacts.
The valve operator in question is similar 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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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 findingt show that valves installed or scheduled to be installed are equipped with the described valve operators, plesse inform this office 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 aetions.
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