Abstract: A method of controlling the system pressure in a power generating system, having a turbine-generator and a BWR, that modulates the core thermal power of the reactor while maintaining the main turbine control valves in a constant steady position is described. The core thermal power may be adjusted by adjusting the control rod density within the reactor core or by adjusting the flow rate through the reactor which may be accomplished by modulating the speed of variable frequency recirculation pumps or by modulating recirculation flow control valves. The method includes transferring the power generation system from normal turbine control valve modulation pressure control to core thermal power modulation pressure control. Additionally the method includes modifying the bypass valve closure bias and the power control bias to accommodate the variances from core power modulation pressure control over normal pressure control.

Abstract: A system for measuring water level includes a reactor pressure vessel containing a core and steam separator assembly, with the vessel being filled with water to a nominal level above the core. A reference leg contains a column of water having a reference level disposed above the nominal level, and a first variable leg has a first tap disposed in the vessel below the reference and nominal levels. A first monitor is disposed between the reference leg and the first leg for determining differential pressure therebetween to indicate level of the water in the vessel above the first tap. A second variable leg includes a second tap in the vessel below the first tap, and a second monitor is disposed between the first and second legs for determining differential pressure therebetween to indicate level of water in the vessel between the first and second taps when the water level falls below the first tap.

Abstract: A control apparatus and method for restricting liquid flow in a liquid moving pump, usually of the centrifugal type, to prevent pump cavitation and pump prime mover overloading. The control apparatus includes sensors to detect liquid temperature and pressure at the inlet of the pump. It may further include a device such as a current transformer to develop a signal indicative of power consumed by the prime mover of the pump where the prime mover is an electrical motor. The liquid pressure and temperature indications are used to generate a specific indication of the subcooling of the liquid. The temperature indication is used to derive an indication of the instantaneous required subcooling of the pump. The subcooling indication and the required subcooling indication are introduced to a comparator. Should the subcooling of the liquid fail to exceed the required subcooling, a first control signal is generated.

Abstract: In a system, such as a water-cooled nuclear reactor, water level sensors provide signals to a control channel for control of feedwater flow and hence the water level in the pressure vessel. Rapid and fine level control is provided by comparing fluid outflow and inflow. Means are provided to block automatically the flow comparison signal from the control circuit in response to a signal characteristic of a faulted flow comparison signal. At least one redundant control channel is provided and level control is transferred thereto automatically upon excusion of the water level beyond predetermined normal upper and lower limits or in response to a rapid change in the water level control signal to avoid unnecessary shutdown in the event of a faulted channel.