Hitachi, Ltd.

Hitachi Engineering Co., Ltd.

Tetsuya Miyakawa

Toichi Shida

Kimiko Isono

Hitoshi Sakuma

Naoshi Tanikawa

A reactor core coolant flow rate control system for a BWR type nuclear power plant in which electric power is generated by a turbine-driven generator driven by a steam turbine rotating under the work of a main steam generated from a cooling water recirculated through a boiling water reactor includes an internal pump driving unit comprised of an electric motor driven by an electric power generated by the turbine-driven generator, a fluid coupling for transmitting an output torque of the electric motor and a variable-frequency generator whose rotation number is changed in accordance with the torque transmitted by way of the fluid coupling, a fluid coupling control signal generating unit for generating a fluid coupling control signal for the fluid coupling in response to at least one of deviation in a load and a rotation speed of the turbine-driven generator and deviation in a rotation speed of the internal pumps, and a plurality of internal pumps for recirculating the cooling water. Each of the internal pumps is connected to the variable-frequency generator of the internal pump driving unit and driven by an output power of the variable-frequency generator. Rotation number of the internal pump changes in dependence on the rotation number of the variable-frequency generator. The fluid coupling changes a transmission efficiency for the torque transmitted to the variable-frequency generator from the driving motor in response to the fluid coupling control signal.

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Hitachi, Japan

Tetsuya Miyakawa