ML20010E928

First Interim Deficiency Rept Re Loss of Solid Metallic Grounding of Flexible Conduit,Initially Reported 801210. Caused by Lack of Procedure Involving Termination Modules. Final Rept by 811020

ML20010E928
Person / Time
Site:	Grand Gulf
Issue date:	08/31/1981
From:	Mcgaughy J MISSISSIPPI POWER & LIGHT CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
10CFR-050.55E, 10CFR-50.55E, AECM-81-302, NUDOCS 8109090131
Download: ML20010E928 (5)

Text

.

O -

! MISSISSIPPI POWER & LIGHT COMPANY N Helping Build Mississippi P. O. B OX 164 0. J AC K S O N, MIS SIS SIP PI 3 9 2 05 3 ,- I-

1. "f$[UTc u M]'j" August 31, 1981 7 O)

Office of Inspection & Enforcement U. S. Nuclear Regulatory Commission 9 >

)N [bD Region II 101 Marietta Street, N.W. -

6'J yi ,)

h' Suite 3100 0 Atlanta, Georgia 30303 h, S E gPg0g81981 y,s, # *?

Attention: Mr. J. P. O'Reilly, Director g

Dear Mr. O'Reilly:

' rM

SUBJECT:

Crand Gulf Nuclear Station Units 1 and 2 Ds,cket Nos. 50-416/417 File 0260/15525/15526 PRD-80/70, Interim Report #1 Flexible Conduit Grounding AECM-81/302 On December 10, 1980, Mississippi Power & Light Company notified Mr. P.

K. VanDootn, of your office, of a Potentially Rc;artable Deficiency (PRD) at the Grand Gulf Nuclear Station (CGNS) construction site. The deficiency concerns the potentiti loss of solid metallic grounding of the flexible conduit used by our NSSS Supplier in the Power Generation Control Complex (PCCC) equipment.

We have determined that this deficiency, had it remained uncorrected, could have adversely affected the safety of operations of the nuclear power plant and is reportable under the provisions of 10CFR50.55(e). Investigation is contfauing into the reportability of this deficiency under 10CFR21.

We expect to submit a final report by October 20, 1981. Attached is our interim report.

Yours truly,

,* ((y /

'[fW, u KDS:dr ATTACllMENT cc: See page 2 hD OC 00 6 S PDR Member Middle South Utilities System

1,- .

o _ .

Mr. J. P. O'Reilly ~ AECd-81/302.

NRC Page 2 f

cc: - Mr. N. L. Stampley

Mr. R. B. McGehee Mr. T. B. Conner Mr. Victor Stello, Director Office of Inspection & Enforcement U. S. Nuclear Regulatory Commission Washington, D.C. 20555 Mr. G. B. Taylor South Miss. Electric Power Association P. O. Box 1589 Hattiesburg, MS 39401 s

6 L. _ _ I

, R e -

bec: Dr. D. C. Gibbs Mr. J. Leatherman Mr. J. N. Ward Manager of BWR-6 Licensing Mr. J. P. McCaughy, Jr. General Electric Company Mr. J. D. Heaton 175 Curtner Avenue Mr. R. Trickovic San Jose, Ca. 95125 Mr. J. W. Yelverton Mr. L. F. Dale Mr. C. K. McCoy Mr. D. M. Houston Mr. T. H. Cloninger U. S. Nuclear Regulatory Commission Mr. R. A. Ambrosino Division of Licensing Mr. A. J. Iosue Washington, D. C. 20555 Mr. G. B. Rogers Mr. S. H. Hobbs Mr. L. E. Ruhland Mr. J. Ma'. ore Mr. D. L. Hunt U. S. Nuclear Regulatory Commission Mr. A. G. Wagner Division of Licensing Mr. P. A. Taylor Washington, D. C. 20555 PRD File File l

L t -

I

=-~ _. . - .

, -o

. e:

Attachment to AECM-81/302 Page 1 of 2 INTERIM REPORT NO. 1 TO PRD-80/70

1. Description of the Deficiency The flexible conduit contained in Power Generation Control Complex (PGCC) equipment, designed and supplied by General Electric, has a potential loss of solid metallic grounding at. the termination cabinet and/or the panel.

In the termination cabinet installations, the conduit is firmly attached with a locking ring to a termination module, which is an acceptable ground connection. However, the termination modulo is ultimately mounted on a painted (high electrical resistance) surface. No procedures had been issued by the manufacturer, to " sure that the paint was removed from the panel sorfaces before termination modules were mounted, or to check that the termination module made a low-renistance connection to the panel steel.

In the NSS3 this could affect the Reactor Protection System, the Nuclear Steam Supply Shutoff System and the Neutron Monitoring System. This applies to both Unit 1 and Unit 2.

One of the purposes of the flexiblo conduit is to provido a low resist-ance path to ground under certain short-circuit conditions. This insures that upstrtas fuses will melt and thereby prevent " hot shorts" which have the potential for preventing the completion of a protective function (de-energizing various circuits). There is the potential of loss of solid metallic grounding of the flexible conduit either at the termination cab-inet or at the panel. This has the potential for preventing operation of fail-safe logic associated with the Reactor Protection System. There-fore, this deficiency is reportable under the provisions of 10CFR50.55(e). The investigation into reportability under the provisions of 10CFR21 is continuing.

General Electric filed a report on this condition to the NRC under 10CFR21 on December 8,1980. This was a letter to Mr. Victor Stallo, Jr., Washington, D. C. , from Dr. Glenn G. Sherwood, Manager of Safety and Licensing Operation.

II. Approach to Resolution of the Problem The cause of the deficiency is -that there was no procedure to insure that paint was removed from panel surfaces before termination modules were mounted. Also, there was no procedure to check that the termination module makes a low-resistance connection to the panel steel. The defi-ciency affects all flexible conduit in the PGCC.

1

n. - ,-

. . - 0:

i

.. s l-Attachment to AECM-81/302 Page.2 of 2-l The NSSS vendor (General Electric) has issued Field Disposition Instruc-tions (FOI) WATPland WENY to provide a method of grounding these flexible conduits. Clamps with ground wires will- be provided to insure a positive low resistance path to ground, which will correct the deficiency.

' To prevent recurrence of the problem, GE has issued a grounding require-mer. procedure.

III. Status of Proposed Resolution The Field Disposition Instructions have been issued. Work will be com-pleted prior to fuel load.

IV. Reason Why a Final Report Will Be Delayed Mississippi Pcwer & Light has not completed the evaluation of the report-L ability of this deficiency under the provisions of 10CFR21.

V. Date When Final Report Will Be Submitted We expect to. submit our final report by October 20, 1981.

c e

l l

I

, ,-, - - ,