ML19347C043

Final Deficiency Rept Re Damage to Intermediate Metallic Conduit.Caused by Improper Use & Adjustment of Threading Dies.Training Conducted Re Proper Threading Techniques & 100% Insp Performed on Threaded Metallic Conduit

ML19347C043
Person / Time
Site:	Grand Gulf
Issue date:	10/06/1980
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-80-245, NUDOCS 8010160504
Download: ML19347C043 (3)

Text

(Ttics HELD l l

MISSISSIPPI POWER & LIGHT COMPANY l

)) Helping Build Mississippi EdhMMnsag P. O. B O X 16 40, J A C K S O N. MIS SIS SI P PI 3 9 2 0 5 JAMES P. McGAUGHY, JR. Ocrober 6,1980 l assistAsst viC4 ps't$4 CENT I

Office of Inspection & Enforcement U. S. Nuclear Regulatory Cec =ission Region II 101 Marietta Street, N.W.

Suite 3100 Atlanta, Georgia 30303 Attention: Mr. J. P. O'Reilly, Director

SUBJECT:

Grand Gulf Nuclear Station Units 1 and 2 Docket Nos. 50-416/417 File 0260/15525/15526 PRD-80/20, Final Report, Damaga to Intermediate Metallic Conduit AECM-80/245

Reference:

1) AECM-80/101, 5/14/80

2) AECM-80/131, 7/5/80 Cn April 14, 1980, Mississippi Power & Light Ccmpany noti-fied Mr. F. Cantrell of your office of a Potentially Reportable Deficiency (PRD) at the Grand Gulf Nuclear Station (GGNS) con-struction site. The deficiency concerns damage to threaded me-callic conduit, two inches and larger in diameter, resulting from i= proper use and adjustment of threading dies.

We have determined that this item is reportable under 10CFR 50.55(e). Bechtel Management Corrective Action Request (MCAR)

Nu=ber 74 has been assigned to track corrective action until com-pletion. Our final report on this matter is attached.

Yours'truly,.

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st ht k Attach =ent j cc: Mr. N. L. Sta=oley Mr. Victor Stello, Director Mr. R. 3. McGehee Division of Inspection & Enforcement Mr. T. B. Conner U. S. Nuclear Regulatory Co= mission Washington, D.C. 20535 soloace5bf s Member Middle South Utilities S pum

FINAL REPORT FOR PRD-80/20 I. Description of the Deficiency Adjustable threading dies caused damage to metallic conduit at Units 1 and 2 at the. Grand Gulf Nuclear Station (GGNS). The damage resulted in sharp edges inside the conduit, which in turn damaged electrical cable being pulled through the conduit. Cable damage ranged from scrapes in the outer jacket to cuts in the insulation which exposed conductors.

This conditien was first noted on Intermediate Metallic Conduit (IMC). Further investigation revealed that the deficiency was not limited to IMC, but occurred in threaded metallic conduit, two inches and larger in diameter which was joined to conduit type l fittings. Improper adjustment and use of dull dies, along with too many threads being cut, left the conduit with a sharp, tapered end.

ll l An investigatica of conduit threaded in this manner and screwed into condulet type fittings revealed extrusions of small, sharp pieces of metal inside the conduit. The sharp pieces of metal were created when the tapered end of the threaded conduit " bottomed out" on the inner lip 'of the condulet type fitting and curled back on itself.

II. Safety Implications 3

This deficiency could tffect safety of operations at the GGNS if electrical cables supplying power or control to safety equip- ,

ment were shorted or open because of the sharp edges inside the conduit. No cases were found where this occurred. However, the possibility exists that, were this condition to have remained uncorrected, safety-related electrical cables might have been prevented frem performing their safety function. Therefore, this deficiency is reportable under 10CFR50.55(e) .

Specifically, electrical cables to RHR Loop A Test Return Valve Q1E12F024A-A were installed in conduit with this deficiency. This l

valve is normally closed and is opened remote-manually only for testing and suppression pool cooling. Our safety analysis re-vealed that a failure of the valve to open in the testing mode would not affect safety of operations. However, an undetected failure of this valve to open for post-accident suppression pool cooling could adversely affect safe shutdown of the plant.

Additicnally, failure of the valve to close during a LOCA, as-suming that the valve is open for testing or suppression pool I cooling purposes, could interfere with proper operation of the j ECCS systems necessary for safe shutdown of the plant.

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4 III. Corrective Actions Taken Mississippi Power & Light Company and the Constructor have per-formed inspections to identify where the deficiency exists. A total of fif ty-six (56) Nonconforming Reports have been issued documenting damaged metallic conduit and cable damage, as appli-cable. A Quality Control Stop Work Order #QC010 was issued on April 11, 1980 to stop installation of metallic conduit and cable pulling into metallic conduit.

This Stop Order was lifted on July 8, 1980 based on the correc-tive action steps taken as follows:

1. The extent of the deficiency was determined;

2. Training was conducted in proper threading techniques for metallic conduit. Instruction was also conducted in proper inspection criteria listed in Bechtel Procedure WP/P-E-20;

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and

3. A 100% inspection was perfor=ed on all threaded metallic conduit, two inches and larger, which was installed and accepted prior to issuance of the Stop Work Order. Sechtel Management Request (MCAR) Number 74 was assigned to track resolution of these items.

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