ML17053B488
| ML17053B488 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 03/07/1980 |
| From: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Rhode G NIAGARA MOHAWK POWER CORP. |
| References | |
| NUDOCS 8003190267 | |
| Download: ML17053B488 (8) | |
Text
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Docket No. 50-410 UNITED STATES NUCLEAR REGULATORY COMMISSION REGION I 631 PARK AVENUE KING OF PRUSSIA, PENNSYLVANIA19406 March 7, 1980 Niagara Mohawk Power Corporation ATTN:
Mr.
G.
K.
Rhode Vice President System Project Management 300 Erie Boulevard, West Syracuse-,
New York 13202 Gentlemen:
The enclosed IE Information Notice No. 80-08, The States Company Sliding Link Electrical Terminal Block, is forwarded to you for information.
No written response is required.
If you desire additional information regarding this
- matter, please contact this office.
Sincerely, Boyce H. Grier Director
Enclosures:
1.
IE Information Notice No. 80-08 with Attachment 2.
List of Recently Issued IE Information Notices CONTACT:
S.
D. Ebneter (215-337-5296) cc w/encls:
Eugene B. Thomas, Jr.,
Esquire
ENCLOSURE 1 SSINS:
6870 UNITED.STATES Accession No.:
NUCLEAR REGULATORY COMMISSION 7912190689 OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D. C.
20555 IE Information Notice No. 80-08 Date:
March 7, 1980 Page 1 of 1 THE STATES COMPANY SLIDING LINK ELECTRICAL TERMINAL BLOCK Description of Circumstances:
On July 19,'979, the Consumers Power Company notified the Nuclear Regulatory Commission of a defect found in the sliding link electrical terminal block manufactured by the States
- Company, a subsidiary of Multi Amp Corp.
The defective terminal blocks were found at the Midland plant.
The connection between the two slotted bars on the terminal block is made by a U-shaped sliding link and spacer located between the two bars.
The top of the U-shaped link and the spacer are drilled and the bottom of the link is threaded to accept a 8-32 screw.
When the screw is tightened it binds the link, spacer and bar together to-make electrical connection.
Loosening the screw and sliding the link from between the bars breaks the connection.
The purpose of the-link is to provide easy insertion of'est instr uments, etc. into the circuit:
The defect, which has been identified in 5X of the terminal blocks checked, occurs in the form of a crack between the threaded screwhole and the side of the U-shaped link.
When the screw is tightened the crack widens and a poor or intermittent electrical connection can result.
A defective link is impossible to cinch tightly in place and is difficult to detect visually.
Attachment 1 shows-the States Company terminal block.
The defect, a crack in the bottom portion of the metal U-shaped link, is displayed in the exploded view of the terminal block assembly.
These terminal blocks are widely used in the nuclear industry and may be used as permanent installations in safety related systems.
The defective mechanical connection can cause an electrical circuit malfunction.
This Information Notice is provided to inform licensees of' potentially significant matter.
It is expected that recipients will review the informa-tion for applicability to their facili'ties.
No written response to this IE Information Notice, is required.
However, the reporting requirements as set forth in the regulations must be met. If you require additional information regarding this matter, contact the Director of the appropriate NRC Regional Office.
Attachment:
Graphic Display of Terminal Block
ENCLOSURE 2 IE Information Notice No. 80-08 Date:
March 7, 1980 Page 1 of 1 RECENTLY ISSUED IE INFORMATION NOTICES Information Notice No. 79-32 Subject Separation of Electrical Cables for HPCI and ADS Date Issued
'12/21/79 Issued to All Power Reactor Faci-lities with an Operating License (OL) or Construction Permit (CP) 79-33 Improper Closure of Primary Containment Access Hatches 12/21/79 All Power Reactor Faci-lities with an OL or CP 79-34 Inadequate Design of Safety-12/31/79 All Power Reactor Faci-Related Heat Exchangers lities with an OL or CP 79-35 Control of Maintenance and Essential Equipment 12/31/79 All Power Reactor Faci-lities with an OL or CP 79-36 Computer Code Defect in Stress Analysis of Piping Elbow 12/31/79 All Power Reactor Faci-lities with an OL or CP 79-37 Cracking in Low Presssure Turbine Discs 12/31/79 All Power Reactor Faci-lities with an OL or CP 80-01 80-02 80-03 80-04 80-05 80-06 80-07 Fuel Handling Events 8XBR Water Rod Lower End Plug Wear Main Turbine Electro-hydraulic Control System BWR Fuel Exposure in Excess of Limits Chloride Contamination of Safety Related Piping and Components Notification of Signif-icant Events Pump Fatigue Cracking 1/4/80 1/25/80 1/31/80 2/4/80 2/8/80 2/2?/80 2/29/80 All Power Reactor Faci-lities with an OL or CP All BWR Facilities with an OL or CP All Power Reactor Faci-lities with an OL or CP All BWR Facilities with an OL or CP All Power Reactor Faci-lities with an OL or CP and applicants for a CP All Power Reactor Faci-lities with an OL and applicant for OL All Power Reactor Faci-lities with an OL or CP
t Attachment to IE ormation Notice No. 80-08 ENCLOSURE 1 TO IE INFORlVlATIONNOTICE 80-
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Side View of States Company Terminal Block in Assembled Position 1r
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Exploded View of States Company Terminal Block
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