ML19249B962
| ML19249B962 | |
| Person / Time | |
|---|---|
| Site: | Vermont Yankee File:NorthStar Vermont Yankee icon.png |
| Issue date: | 08/14/1979 |
| From: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Groce R VERMONT YANKEE NUCLEAR POWER CORP. |
| References | |
| NUDOCS 7909070153 | |
| Download: ML19249B962 (1) | |
Text
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NUCLEAR REGULATORY CCTiMISSION I
REGION I
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,o KING OF PRUSSIA, PENNSYLVANI A 19406 Docket No. 50-271 I 4 U73 Vermont Yankee Nuclear Power Corporation ATTN:
Mr. Rohrt H. Grace Licensing Engineer 20 Turnpike Road Westborough, Massachusetts 01581 Gentlemen:
This Circular is provided as an earl / notification of a possible significant matter.
It is expected that recipients will review the information for pos-sible applicability to their facilities.
No specific action or response is requested at this time.
If further NRC evaluations so indicate, an IE Bul-letin will be issued to recommend or request specific licensee actions.
If you have questions regarding this matter, please contact the Director of the appropriate NRC Regional Office.
Sincerely, Mokugy
[' p/Boyce H. Grier Director
Enclosures:
1.
IE Circular No. 79-17 2.
List of IE Circulars Issuad in the Last 6 Months cc w/encls:
W. F. Conway, Plant Superintendent Ms. J. Abbey, Technical Secretary A. Z. 30isman, Natural Resources Defense Council 790907o(53 1LT 0 ZS
ENCLOSURE 1 UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 IE Circular No. 79-17 Date:
August 14, 1979 Page 1 of 1 CONTACT PROBLEM IN 58-12 SWITCHES ON GENERAL ELECTRIC METALCLAD CIRCUIT BREAKER 5 The General Electric Company, Switchgear Department in Philadelphia, reported to the NRC on July 3, 1979, an intermittent contact problem in SB-12 switches.
This intermittent contact problem will cause a lack of continuity through the "a" contact of the switch that is used to energize the trip coil of the circuit breaker.
Investigation disclosed that a die used to form a hale in the contact arms of the switch had worn, resulting in elongated holes.
This condition could permit the contact bridge member to move laterally relative to the contact arm, occasionally resulting in improper "a" cor, tact wipe.
The worn die has been corrected, and all switches shipped on or after July 1, 1979, include this correction.
A review of the history of these components indicates that switches shipped in the time period of August 1, 1978 to July 1, 1979, could have this problem.
The trip coil and auxiliary switch portion of the trip circuit is monitored for continuity by a red light on the front door of the switchgear.
This light is lit when the breaker is closed and the control circuits are energized.
If the red light is lit, this indicates that the "a" contacts of the switch are closed, and that a trip signal will trip the breaker.
Based on the above, the licensees are advised to do the following:
1.
Insure that all General Electric Company Metalclad Circuit Breakers shipped to your facilities during the period from August 1, 1978 to July 1, 1979 and used in or affecting the operation of safety related equipment are furnished with new SB-12 control switches as promptly as possible.
2.
Pending replacement of 58-12 control switches adm.-istrative controls should be initated to assure the red light which demonstrates contact continuity, is lit and remains lit each time these circuit breakers are closed.
No written response to this circular is required.
If you require additional information regarding this subject, contact the Director of the appropriate NRC Regional Office.
L
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ENCLOSURE 2 IE Circular No. 79-17 Date:
August 14, 1979 Page 1 of 2 LISTING OF IE CIRCULARS ISSUED IN LAST SIX MONTHS Circular Subject First Date Issued To No.
of Issue 79-03 Inadequate Guard 2/23/79 All Holders of and Training / Qualification Applicants for and Falsified Training Special Nuclear Records Material Licenses in Safeguards Group I 79-04 Loose Locking Nut on 3/16/79 All Power Reactor Limitorque Valve Facilities with an Operators OL or CP 79-05 Moisture Leakage in 3/20/79 All Power Reactor Stranded Wire Facilities with an Conductors OL or CP 79-06 Failure to Use Syringe 4/19/79 All Holders of and Bottle Shields in Medical Licenses Nuclear Medicine Except Teletherapy Licenses 79-07 Unexpected Speed 5/2/79 All BWR Power Reactor Increase of Reactor Facilities with an Recirculation MG Set OL or CP Resulted in Reactor Power Increase 79-08 Attempted Extortion-5/18/79 All Fuel Facilities Low Enriched Uranium and Licensed Reactors 79-09 Occurrences of Split 6/22/79 All Materials Priority or Punctured Regulator I, Fuel Cycle and Diaphragms in Certain Operating Reactor Self-Contained Licensees Breathing Apparatus
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2 IE Circular No. 79-17 Date:
August 14, 1979 Page 2 of 2 LISTING 0F IE CIRCULARS ISSUED IN LAST SIX MONTHS Circular Subject First Date Issued to No.
of Issue 79-10 Pipefittings Manu-6/26/79 All Power Reactor factured from Facilities with an Unacceptable Material OL or CP 79-11 Design / Construction 6/27/79 All Applicants for, Interface Problem and Holders of cps 79-12 Potential Diesel 6/28/79 All Power Reactor Generator Turbo-Facilities with an charger Problem OL or CP 79-13 Replacement of Diesel 7/16/79 All Power Reactor Fire Pump Starting Facilities with an Contactors OL or CP 79-14 Unauthorized Procure-7/16/79 All Medical Licensees ment and Distribution except Teletherapy Medi-of Xenon-133 cal Licensees, and all Licensed Radiopharr.a-ceutical Suppliers 79-15 Bursting of High Pres-8/8/79 All Materials Priority sure Hose and Malfunc-I, Fuel Cycle and Opera-tion of Relief Valve "0" ting Power Reactor Ring in Certain Se' Licensees Contained Breathing Apparatus 79-16 Excessive Radiation 8/16/79 All Radiography Exposures to Members Licensees Of The General Public And A Radiographer e;i