ML20032C249

Final Deficiency Rept Re Potential Loss of Solid Metallic Grounding of Flexible Conduit at Termination Cabinet or at Panel,Initially Identified by IE on 801218.GE Has Issued Work Plan to Correct Defect.Ground Wires to Be Attached

ML20032C249
Person / Time
Site:	Perry
Issue date:	10/29/1981
From:	Davidson D CLEVELAND ELECTRIC ILLUMINATING CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
10CFR-050.55E, 10CFR-50.55E, 10CFR50.55E, RDC-23(81), NUDOCS 8111090553
Download: ML20032C249 (2)

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Semnct The dost Location in the Nation Dalwyn R. Davidson VICE PRESIDENT SYSTE M ENGINE ERING AND CONSTRUCYlON October 29, 1981

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Mr. James G. Keppler Office of Inspection and Enforcement

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f/ g O $ $ 'gi Director of Region III y,, "/S'gy/auw U. S. Nuclear Regulatory Commission W

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&p Glen Ellyn, Illinois 60137

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Dear Mr. Keppler:

Perry Nuclear Power Plant Docket Nos. 50-440; 50-441 Final Report - RPS Flexible Conduit Grounding in PCCC

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Installations (RDC 23(81))

This letter will serve as the final report required by 10CFR50.55(e) for the significant deficiency on the Reactor Protection System (RPS) Flexible Conduit Grounding in Power Generation Control Complex (PCCC) Installations.

This item was first identified to the NRC, Region III, Office of Inspec-tion and Enforcement by the NRC Resident Inspector, Jack Hughes, on Decem-bc. 18, 1980.

The Interim Report was submitted on January 14, 1981 to fol-low up this notification.

This report contains a description of the deficiency, an analysis of safety implications, and the corrective action taken.

Description of Dc ficiency The fle.ible conduit is contained in the PCCC equipment designed and supplied by C;neral Electric in San Jose, California. The systems involved are RPS, Nuclear Steam Supply Shutoff System (NSSSS), and Neutron Monitoring System (NMS). The flexible conduit is used to enclose electrical conductors in var-ious fail-safe circuits. The ennduit runs from a panel on a specific floor section, is routed in the floor section, and is then terminated in a termina-tion cabinet at the end of that floor section.

One of the purposes of the flexible conduit is to provide a low resistance path to ground under certain short-circuit conditiCns. The deficiency concerns the potential loss of solid metallic grounding of the flexible conduit either at the termination cabinet or at the panel. The conduit is firmly grounded K O 00 o

NOV 4 19 9 PDR

4 Mr. James C. Keppler October 29, 1981 to the termination cabinet or panel with a'locki-~ ring; however, the'cabi-net or module is ultimately mounted on a painteo (high electrical resistance) surface.

Analysis of Safety Tmplications-The fail-safe (de-energize to operate) circuits in the RPS, NSSSS. and NFS

' depend on fuses melting under short circuit conditions to provide the fail-safe function and also perform isolation. Without positive grounding of the flexible conduit that contains these circuits, the possibility exists that a conductor could be shorted to the conduit without drawing sufficient fault current to melt a fuse. While this single event would not negate the fail-safe aspects of the design, involvement of a second conductor at this time or in the future could.

In addition, this unknown ~ fault would place additional burden on the RPS power supply and create additional unwanted ambient heat.

Corrective Action General Electric has issued Field Disposition Instructions WNOJ and WRKV detailing the work to correct this deficir.ncy. Corrective action will consist of attaching a ground wire to the condi' t at one or both ends and at sixty (60) foot intervals, depending on conduit length. Adequate grounding will be veri-fied by checking with an ohm meter to verify that resistance to ground is less than four (4) ohms. This work will be performed by the site electrical contrac-tor.

Unit I work will be completed by June 1, 1982. Work on Unit 2 will be com-pleted by December 1, 1482.

Very truly yours, d

Dalwy R. Davidson Vice-President System Engineering and Construction DRD: bas cc: NRC Site Director, Office of Inspection and Enforcement U. S. Nuclear Regulatory Commission Washington, D.C.

20555 U. S. Nuclear Regulatory Commission c/o Document Management Branch Washington, D.C.

20555

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