ML19319C125

Final Deficiency Rept Re Hpis Pump Motor Starting Torque.Two Hpis Pump Motors Found in Nonconformance W/B&W Specs.Rotor Resistance Increased,Increasing Motor Starting Torque.Axial Blower Added,Overcoming Addl Heating

ML19319C125
Person / Time
Site:	Davis Besse
Issue date:	02/20/1975
From:	Roe L TOLEDO EDISON CO.
To:
Shared Package
ML19319C120	List: ML19319C125 ML19319C131
References
NUDOCS 8001310485
Download: ML19319C125 (2)

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TOLEDO EDISON Docket No. 50-346 LOWELL E. ROE me. m. ee .

Fecauties Devotooment (419) 259-5242 February 20, 1975 Dr. Donald F. Knuth, Director Office of Inspection & Enforcement U.S. Nuclear Regulatory Commission Washingm, D.C. 20555

Dear Dr. Knuth:

This letter is submitted in accordance with 10CFR Part 50.55 as a consummation of the Interin. 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 h The two (2) 600 HP, 4000 volt high pressure injection pump motors supplied by Westinghous? to B&ui fe, i=ta!!ation at the Applica.nt's Davis-Beue 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 70% voltage. An evaluation by Westinghouse indicated that the motors would not pull in the required load for a voltage less than or equal to 70%

of nameplate voltage under normal operating mode or under 80% voltage using emergency conditions.

Corrective Action Taken The Applicant 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_thq rotors and replaced with end rings of greater cross sectional area, fabricated from higher resistivity metal. To overcome additional heating from the increased resistance, an integral axial blower was added. To guarantee that the repairs were sufficient to meet requirements, test points were used to establish a speed torque curve at 70% of rated voltage (2800 volts). The measmed curve was used to calculate the acceleration time; which met the B&W specification six second requirement for acceleration to full speed at 70% voltage.

8001310 f T'HE TOLEDO EDISON COMPANY EDISON PLAZA 300 MADISON AVENUE TOLEDO. OHIO 43E%2 t -

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! Safety Implications l l The lugh 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 tids transformer, the busses are automatically energized from offsite power via the essentiai unit start-up transformers. Should these sources too be unavailable, j 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 IIPI pump motors would assure system response within the requirements of the l FSAR safety analysis. Thus, the safety of the plant and public were not jeopardized.

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! Respectively submitted, bj c/2 cc:

J. G. Keppler, Regional Director

Office of Inspection and Enforcement Ilegion III i

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