ML13331B193
| ML13331B193 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 06/16/1989 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML13331B192 | List: |
| References | |
| NUDOCS 8906230007 | |
| Download: ML13331B193 (3) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RECERTIFICATION OF CHARGING PUMP MOTORS SAN ONOFRE GENERATING STATION, UNIT 1 DOCKET NO. 50-206 The following is the staff evaluation of the submittal of SCE related to the continuous rating of the charging pump motors, 700HP at 1.15 service factor, installed at SONGS-1. The rating studies and analysis are documented in a report prepared by Westinghouse Motor Company, the motor manufacturer, and submitted as Enclosure 1 to SCE letter dated December 29, 1988 (Reference 1).
The staff evaluation is based on Reference 1 and its attachments. SONGS-1 has two 600HP motors driving charging pumps with the following nameplate rating:
600HP, 4160V, 3580RPM, 3 phase, 60 Hz, 72 amps, locked KVA Code J, Insulation Class B, SF 1.15, 400C Rise at SF 1.0.
These motors were built by Westinghouse with design life expectancy of 40 years.
Due to a mechanical seizure of one of the charging pumps (the south charging pump motor), the motor windings burned out. This motor was rewound in 1972.
The charging pump power requirement is 796HP and 694HP at the two worst case accident conditions. SCE proposed a continuous rating of 700HP at 1.15 service factor and new "accident" condition requirements of 796HP for 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and 694HP for 30 days.
The staff reviewed the Westinghouse recertification report and concluded that these motors have an adequate thermal, mechanical and insulation margin con sideration to operate satisfactorily at 700HP and 1.15 service factor. This is based on the calculated total temperature rise of the windings that will be less than 920C at an ambient temperature of 270C for the new load. This temperature is within the acceptable range for the Class B (1300C) insulation used in these motors.
SCE stated that the rewound motor has a Class B insulation thus the temperature rises are within the rating of the Class B insulation. As the records and data regarding the rewinding of the south charging pump motor were not available from the motor repair facility, SCE's request to continue operation with this motor for another cycle is acceptable based on the above analysis and on the SCE commitment in their letter of December 29, 1988 to have the south charging pump motor rewound or replaced during the Cycle 11 refueling outage (end of Cycle 10).
-906230007 890616 PDR ADOCK 05000206 P
PDEC
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-2 By letters dated December 29 and 30, 1988, and February 2, 1989, the licensee provided information to the staff indicating that environmental qualification for charging pump motor G8B also could not be established based on the docu mentation currently available.
The licensee provided a safety analysis justifying continued operation and referencing 10 CFR 50.49 paragraph (i) as the basis for consideration of the analysis.
In accordance with Generic Letter (GL) 88-07, when a potential deficiency has been identified by the NRC or licensee in the environmental qualification of equipment, the licensee is expected to make a prompt determination of opera bility, take immediate steps to establish a plan with a reasonable schedule to correct the deficiency, and have written justification for continued operation which is available for NRC review. Consequently, the licensee should have followed the guidance of GL 88-07 instead of 10 CFR 50.49 paragraph (i) to address the issue of the charging pump motor qualification. Nevertheless, we have reviewed the evaluation submitted by the licensee. The deficiency identified by the licensee concerns insufficient information to specifically demonstrate that the rewound motor is qualified for the radiation environment that would result from normal operation and a loss of coolant ac ident. The anticipated radiation environment for pump motor G8B is 4.0 x 10 rads.
Although the licensee did not specifically identify the degradable materials contained in the pump motor, generic material properties and their suscepti bility to radiation damage were identified in the licensee's analysis. In addition the licensee stated that if south charging pump G8B (the pump in question5 fails, the alternative would be to rely on north charging pump G8A, which is fully qualified. Further, only one pump operates at any given time and is fully capable of providing the necessary flow to fulfill the intended safety function. Additionally, there are no credible failure modes related to the subject motor which could result in misleading information to the operator or degradation of the safety function of the redundant train. The staff, therefore, finds this justification for continued operation acceptable.
Principal Contributors: S. Saba H. Walker Date: June 16, 1989
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REFERENCES:
- 1. Letter to Document Control Desk, USNRC from M. 0. Medford, Licensing Southern California Edison Company, "Docket No. 50-206, Recertification of Charging Pump Motor Rating, San Onofre Nuclear Generating Station, Unit 1," dated December 29, 1989.