ML19343B501
| ML19343B501 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point, Perry, Grand Gulf, Susquehanna, Limerick, River Bend, Clinton, Allens Creek, Skagit, Black Fox, Hartsville, Phipps Bend  |
| Issue date: | 12/08/1980 |
| From: | Sherwood G GENERAL ELECTRIC CO. |
| To: | Stello V NRC OFFICE OF INSPECTION & ENFORCEMENT (IE) |
| References | |
| REF-PT21-80-331-000 NUDOCS 8012240089 | |
| Download: ML19343B501 (3) | |
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SYSTEMS DIVISION GENERAL ELECTRIC COMPANY.175 CURTNER AVE., SAN JOSE, CALIFORNIA 95125 MFN 212-80 MC 682, (408) 925-5040 December 8, 1980
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?Q Office of Inspection and Enforcement ~
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' Washington, D. C. 20555 Attention:
Victor Stello, Jr., Director Gentlemen:
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SUBJECT:
REPORTABLE CONDITION GROUNDING OF FLEXIBLE CONDUIT This is to advise you of a reportable defect under 10CFR Part 21 as reported to Mr. Wayne Reinmuth, by Walter H. D'Ardenne, ManageT Safety Evaluation Programs on December 3, 1980.
This defect is a potential for reactor protection system flexible conduit to develop hot shorts if improperly grounded.
The defect was judged reportable on December 1, 1980.
Attached is the report of the defect and the action to rectify the issue.
The aff,ected projects arp Limerick 1 & 2,,Susquehanna ) & 2, Hanford 2, Grand Gulf 1 & 2, Clinton 1 & 2,, Perry 1 & 2, River Nipe Mile Point 2,ille A1, A2, 81, & B2, Phipps Bend 1 & 2, Skagit 1 &
Bend 1 & 2, Hartsv 2, Allens* Creek, and Blal-k Fox 1 & 2.
General Electric will inform the affected utilities of the defect and advise them of the corrective action.
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(.cGlennG.Sherwood, Manager Safety & Licensing Operation GGS:1m/1340 Attachment cc:
Mr. J. F. McAllister Mr. U. Potapovs, N.RC Region IV 0
s PGCC Flexible Ccnduit Grounding Flexible conduit is used to encicse electrical conductors in various fail-safe (deenergize to operate) circuits which are part of the Reactor Protection System (RPS).
These include RPS, Nuclear Steam Supply Shutoff System (NSSSS) and Neutron Monitoring System (NMS) logic.
One of the purposes of the flexible conduit is to provide.a low resistance path to ground under certain short-circuit conditions.
This insures that upstream fuses will melt and thereby prevent " hot shorts" which have the potential for preventing the. co.mpletion of a protective function.(de-c,.;.. energizing varicus circuits).
The flexible conduit in questioh'i's~0 sed?T/T
' on all Power Generation Control Complex (PGCC) installations.
Specifically.
- it is flexible conduit that runs frcm a panel on a specific floor section, is routed in the floor section, and finally is terminated in a termination cabinet at the end of that floor section.
The flexible conduit is contained ir. PGCC equipment designed and supplied by the Control and Instrumentation Department of the General Electric Company in San Jose, California.
The nature of the defect is the' potential loss of solid metallic grounding of the flexible conduit either at the termination cabinet or at the panel.
This has the potential for preventing operation of fail-safe (deenergize to operate) logic associated with the Reactor Protection System.
The condition has been observed at the Hanford 2 site.
A check of conduit resistance with an ohmmeter indicated essentially zero resistance to ground.
However, this is not considered adequate in that the measure-ment does not account for high values of short-circuit current, casual contact grounding of conduit touching panel steel, and long-term oxidation of the conduit surfaces.
In a typical termination cabinet installation the conduit is firmly attached with a locking ring to a termination module.
This is an acceptable ground connection; however, the termination module is ultimately mounted on a painted (high electrical resistance) surface.
There has l
been no procedure to insure that paint is removed from panel surfaces before termination modules are mounted.
There also has been no procedure to check that the termination module makes a low resistance connection to the panel steel.
The corrective action to provide positive grounding of the PGCC conduit, will be implemented prior to the fuel load of the affected projects.
The schedule for development and issue of procedures to implement the corrective action will be provided by January 31, 1981.
GGS:1m/1342 12/8/80 S
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