A nuclear reactor coolant circulation pump system with a pump (8), and a power supply system (10-17) for its operation and control. The power supply includes an DC/AC converter (11) with its controller (17) for adjustment of the AC voltage to frequency ratio connected in series between the AC bus bar (1) and the pump. Also in series is a AC/DC converter and controller (13) and a superconducting energy store (14) which with its controller (13) is responsible for controlling the DC supply. An excitation voltage is applied from an activator (14) that is linked via the system control unit (16) to the reactor circulation system so that the power supply to the pump can quickly be adjusted to a reactor shut down or power output interruption.
