Hitachi-ge Nuclear Energy, Ltd.

Yukihiro Katayama

Masashi Sugiyama

Hirohisa Satomi

Shunya Morita

Kenji Tominaga

Ichirou Shimoda

A recirculation pump motor is supplied with a power from a unit auxiliary middle voltage bus through a power supply system including a first circuit breaker, a voltage source inverter, and a second circuit breaker electrically connected in series to provide a no-load operation by use of the voltage source inverter. The second circuit breaker may be multiplexed with more than one breaker electrically connected in series. An existing nuclear plant using a induction motor driving a hydraulic coupling mechanically coupled to a synchronous generator for driving the recirculation pump, such as an MfG set, may be subjected to a method of replacing the induction motor, the hydraulic coupling, and the synchronous generator with the voltage source inverter and a circuit breaker through electrically disconnection and removal.

Nuclear power plant, method of replacement in the same and method of operating the same

An adjustable speed drive system for a primary loop recirculation pump and method of control in which a first breaker is connected to an auxiliary power supply system, an inverter is connected to the first breaker, a second breaker is connected to an output of the inverter, a gate driver supplies a gate pulse to the inverter, and an inverter control portion drives the gate driver. The adjustable speed drive system is combined with a backup adjustable speed drive system. When a malfunction in a main adjustable speed drive circuit portion including the inverter and the gate driver in the adjustable speed drive system used in a normal operation is detected, the main adjustable speed drive circuit portion is switched to the backup adjustable speed drive system, and an operation of a recirculation pump motor for driving a recirculation pump that controls a flow of a reactor core is continued.

Adjustable speed drive system for primary loop recirculation pump

An adjustable speed drive system for a primary loop recirculation pump capable of keeping a PLR pump operating even if a single malfunction occurred in a main adjustable speed drive circuit portion. The drive system for the primary loop recirculation pump has a backup main adjustable speed drive circuit portion, and a breaker for switching between an incoming destination and an outputting destination of the backup main adjustable speed drive circuit portion. A control signal of an inverter control portion is switched to control an inverter included in the backup main adjustable speed drive circuit portion, and when a malfunction occurred in the adjustable speed drive main circuit, by switching to the backup main adjustable speed drive circuit portion, the primary loop recirculation pump of a nuclear reactor is continuously controlled and operated.

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Hitachi, Japan

Yukihiro Katayama