Adjustable drives boost nuclear plant reliability
A new reactor recirculation control (RRC) adjustable-speed drive (ASD) and digital control system at the Washington Nuclear Plant 2 (WNP-2), Hanford, Wash., has improved plant reliability. Installed this year, the system also will lower plant maintenance costs and reduce personnel radiation doses during maintenance, since the new system has less equipment in high-radiation areas than its predecessor. Advances in power electronics have improved the reliability of adjustable-speed drives for large induction motors. Large ASDs have been used in gas, oil, and coal-fired plants since around 1984. Plants where these systems are installed have realized energy savings and operational improvements in precisely controlling process flow. They also have reduced motor maintenance by slowing the motors when full-power operation is not needed. WNP-2 is the first nuclear utility with a boiling-water reactor to change to digitally controlled reactor recirculation pumps. The new RRC system provides improved flow control and maneuverability, when operating the nuclear reactor at reduced power levels. It controls coolant flow through the reactor core to control power during normal operation. There are two pumps rated at 47,200 gallons per minute (gpm). Each is driven by a vertical, totally enclosed, air/water-cooled, three-phase induction motor. The motor is rated at 8,900 horsepower (hp) and 1,782 revolutions per minute (rpm) and is operated from a 6,600-volt, 60-hertz (Hz) electrical power supply. THe ASD and digital control system replaced a hydraulically operated flow control valve and analog control system for throttling pump output. The replacement also resulted in removing the low-frequency motor generator set used for startup and slow-speed operation. The flow control valve system required a shift from low to high frequency at minimum flow control valve position to prevent excess reactor power conditions from forming during pump shift. 6 refs., 2 figs.
- OSTI ID:
- 486266
- Journal Information:
- InTech, Journal Name: InTech Journal Issue: 9 Vol. 43; ISSN 0192-303X; ISSN INTCDD
- Country of Publication:
- United States
- Language:
- English
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