ML19352A970

Final Deficiency Rept,Originally Reported on 810211,re Shaft Failure on Pump Supplied by Comsip,Inc.During Inhouse Testing of Pump & Motor Assembly,Pump Shaft Snapped.Caused by Excessive Force on Motor Shaft.Motor Shaft Redesigned

ML19352A970
Person / Time
Site:	Grand Gulf
Issue date:	05/26/1981
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-81-183, NUDOCS 8106020453
Download: ML19352A970 (4)

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I MISSISSIPPI POWER & LIGHT COMPANY

_. Helping Build Mississippi ,

EmihhiMiins P. O. 8 O X 16 4 0, J A C K S O N , MiSSISS1PPl 39205 '

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May 26, 198 sW --

4' / q, O ses Of fice of Inspection & Enforcement g U. S. Nuclear Regulatory Commission f- gCh.ypg h Q1 Region II ~_. l-101 Marietta Street, N.W.

Suite 3100 k6;

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Atlanta, Georgia 30303  %*'op /

Attention:

Mr. J. P. O'Reilly, Director

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SUBJECT:

Grand Gulf Nuclear Station Units 1 and 2 Docket Nos. 50-416/417 File 0260/15525/15526 PRD-81/06, Final Report Comsip, Inc. Motor Shaft Failure AECM-81/183 On February 11, 1981, Mississippi Power & Light Company notified Mr. J.

Rausch, of ycar of fice, of a Potentially Reportable Deficiency (PRD) at the Grand Gulf Nuclear Station (GGNS) construction site. The deficiency concerns the shaft failure on a pump supplied by Comsip, Inc.

It has been determined that this deficiency is reportable under 10CFR50.55(e). It is not reportable under 10CFR21 because MP&L has not accepted aay deficient items. Attached is our final response.

Yours trul

/ J. P. McGaughy, Jr.

WHU:dr ATTACHMENT cc: See page 2 30/7 s

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'53 Member Middle South Utilities System

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Mr. J. P. O'Reilly AECM-81/183 NRC Page 2 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 Conunission Washington, D.C. 20555 Mr. G. B. Taylor ,

South Miss. Electric Power Association P. O. Box 1589 Hattiesburg, MS 39401 i

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Attachment to AECM-81/183 Page 1 of 2 FINAL REPORT TO PRD-81/06 I. Description of the Deficiency During in-house testing of the pump and actor assembly of the Hydrogen Gas Analyzer Equipment being conducted as part of the investigation into Potentially Reportable Deficiency (PRD) 80/24, the pump shaft snapped.

With the spring loaded check valve in place and the discharge pressure limited to 100 psig the motor shaf t failed af ter a period of four hours opera tion.

The condition was reported to the NRC, Region V, by Consip, Inc. as a reportable condition under 10CFR Part 21.

The deficiercy is applicable t,o Units 1 and 2 II. Analysis of Safety Implication These conditions are confined to the Combustible Gas Control System (E61). Interactions with possible interfacing systems is not considerea applicable. Should the failures have occurred during plant operations, they could have adversely af fected safe operation of the system.

The Combustible Gas Control System controls the concentration of hydrogen which may be released into the Drywell and/or Containment following a postulated Loss of Coolant Accident (LOCA) and also prevents a vacuum from being drawn in the Drywell.

III. Corrective Actions Taken The supplier conducted a motor shaf t evaluation and determined that the apparent force on the motor shaf t was found to be in excess of 400 lbs. Also, te shaf t stress at the base of the shaf t extension was calculated to be approximately 35,000 psi. The supplier has redesigned the motor shaft as follows:

1. Lengthened the motor end portion of the shaf t at a diameter equal to the bearing I.D. to approximately 1.37 inches.

2. Reduced the portion of the shaf t whose diameter is 0.625 inches to about 1.62 inches. The overall shaf t length will be increased by approximately 0.31 inches.

3. Changed shaf t material to AISI 4150 (Reliance Electric Co. Class 2) with an indicated endurance limit of 4b,000 pst in place of the original AISI 1045 (Reliance Electric Co. Class 1) with the indicated endurance limit of 33,000 psi.

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Attachment to AECM-81/183 Page 2 of 2 To preclude recurrence, the supplier's system design has been changed to incorporate a spring loaded check valve between the pump discharge and suction for the purpose of limiting the pump discharge pressure.

Consip pro ided the repair packages to correct this deficiency sad siso provided a company representative to supervise the necessary Ic.rotat.

This work was accomplished on March 24th and 25th, 1981, in accordance with our constructor's Work Plans & Inspection Records.

This constitutes our final response on this deficiency.

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