ML20003D787

Part 21 Rept Re Comsip,Inc Motor Shaft Failure,Initially Reported on 810211.Pump Shaft on Pump & Motor Assembly of Hydrogen Gas Analyzer Equipment Snapped.Redesign Proposed. Determined Not Reportable Per 10CFR21

ML20003D787
Person / Time
Site:	Grand Gulf
Issue date:	03/13/1981
From:	Mcgaughy J MISSISSIPPI POWER & LIGHT CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
REF-PT21-81-383-000 10CFR-050.55E, 10CFR-50.55E, AECM-81-108, PT21-81-383, PT21-81-383-000, NUDOCS 8104010011
Download: ML20003D787 (4)

Text

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PRELIMINARY EVALUATION OF THE' ATTACHED DORTi TES LEAD RESPONSIBILITY FOR FOLLOWJP AS SFDhN BELOW:

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l' I MISSISSIPPI POWER & LIGHT COMPANY Helping Build Mississippi k ' .k P. O. B O X 16 4 0, J A C K S O N, MISSISSIPPI 39205

1. ,$[ Sic [NUd@ March 13, 1981 Office of Inspection & Enforcement U. S. Nuclear Regulatory Commission 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-81/06, Interim Report #1, Comsip, Inc. Motor Shaft Failure AECM-81/108 On February 11, 1981, Mississippi Power & Light Company notified Mr. J.

Rausch, of your office, 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 Consip, 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 any deficient items. Attachcd is our interim response. We expect to submit a final response by August 14, 1981.

Yours truly f J. P. McGaughy, Jr.

p ATR:mt ATTACHMENT cc: See page 2 Member Middle South Utilities System

.c ~ Ml=lfSIPPI POWER O LIGHT COMPANY Mr. J. P. O'Reilly AECM-81/108

. NRC Page 2 1

! cc: Mr. N. L. Stampley Mr. R. B. McGehee 3

Mr. T. B. Conner

Mr. Victor Stello, Director Office of Inspection & Enforcement U. S. Nuclear Regulatory Commission ' '~

i Washington, D.C. 20555' Mr. G. B. Taylor l South Miss. Electric Power Association P. O. Box 1589 Hattiesburg, MS 39401 I

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Attachment to AECM-81/108 Page 1 of 2 INTERIM REPORT #1 TO PRD-81/06 I. Description of the Deficiency During in-house testing of the pump and motor assembly of the Hydrogen Gas Analyzer Equipment being conducted as part of the investigation into Potentially Reportable Deficiency (PRD) 80/24, the pump shaf t anapped.

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 fou'r hours operation. -

i The condition was reported to the NRC, Reg ~ ion V, by Comsip, Inc. as a reportable condition under 10CFR Part 21.

The deficiency is applicable to Units 1 and 2.

II. Analysis of Safety Implication These conditions are confined to the Combustible Gas Control System (E61). Interactions with possible interf acing systems is not considered applicable. Should the failures have occurred during plant operations, they could have adversely affected 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 i

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 shaft was found to be in excess of 400 lbs. Also, the shaft stress at the base of the shaft extension was calculated to be approximately 35,000 psi. The supplier ha: proposed a redesign of the motor shaft as follows:

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

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

3.

Shaft material to be AISI 4150 (Reliance Electric Co. Class 2) with an indicated endurance limit of 48,000 psi in place of the original AISI 1045 (Reliance Electric Co. Class 1) with the indicated endurance limit of 33,000 psi.

To preclude recurrence, the supplier's system design will incorporate a spring loaded check valve between the pump discharge and suction for the purpose of limiting the pump discharge pressure.

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