ML19329B110

Deficiency Rept Re Hpis Pump Motor Starting Torque, Supplementing 740607 Interim Rept.During Westinghouse Evaluation,Motors Would Not Pull in Required Load.Caused by Nonconformance W/B&W Specs.Pumps Returned to Westinghouse

ML19329B110
Person / Time
Site:	Davis Besse
Issue date:	02/20/1975
From:	Roe L TOLEDO EDISON CO.
To:
References
NUDOCS 8001300693
Download: ML19329B110 (2)

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%mm EDISON Docket No. 50-346 LOWELL E. ROE Vice President Facihties Ceve.coment (419) 259-5242 February 20, 1975 Dr. Donald F. Knuth, Director Office of Inspection & Enforcement U.S. Nuclear Regulatory Commission Washington, D.C. 20555

Dear Dr. Knuth:

This letter is submitted in accordance with 10CFR Part 50.55 as a consummation of the Interim Report dated June 7.1974 regarding the reported Davis-Besse Nuclear Power Station Unit No. I high pressure injection (HPI) pump motor starting torque deficiency.

Description of the Deficiency The two (2) 600 HP, 4000 volt high pressure injection pump motors supplied by Westinghouse to B&W for installation at the Applicant's Davis-Besse Nuclear Power Station Unit I were reported by Westinghouse to be in nonconformance with B&W specifications.

The B&W specification requires the motors to accelerate their drives to normal operating speed within six seconds at 707o voltage. An evaluation by We.stinghouse indicated that the motors would not pull in the required load for a voltage less than or equal to 70To of nameplate voltage under normal operating mode or under 80?o voltage using emergency conditions.

Corrective Action Taken The ipplicant directed B&W to return the HPI pump motors to Westinghouse (Buffalo) for correction of the problem. Before any repairs were made, tests were performed on an eddy current dynamometer which confirmed the torque deficiency. In order to increase the motor starting torque, the determination was then made to increase the rotor resistance.

To accomplish this, the old end rings were machined off the rotors and replaced with end rings of greater cross sectional area, fabricated from higher resistivity metal. To overcome additional he., ting from the increased resistance, an integral axial blower was added. To guarantee t' t the repairs were sufficient to meet requirements, test points were used to establish a speed torque curve at 707o cf rated voltage (2800 volts). The measured curve was used to calculate the acceleration time; which met the B&W specification six second requirement for acceleration to full speed at 70"o voltage.

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5 00SG-THE TCLEDO EDISCN COMPANY EDISCN PLAZA 300 MACISCN AVENUE TOLECO. CHO 43652 8001300ff3 g 1

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Safety implications The high pressure injection pump motors are powered from essential 4.16 KV electrical busses. These busses are normally energized from the unit auxiliary transformer, and under loss of power from this transformer, the busses are automatically energized from offsite power via the essential unit start-up transformers. Should these sources too be unavailable, the emergency diesel generators would energize the essential busses and under emergency conditions would provide conservatively adequate voltage relationship necessary for proper functioning of the high pressure injection system; that is, the time-voltage relationship to the HPI pump motors would assure system response within the requirements of the FSAR safety analysis. Thus, the safety of the plant and public were not jeopardized.

Respectively submitted, bj c/2 cc:

J. G. Keppler, Regional Directer Office of Inspection and Enforcement Region III I

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