Automatic Control System of the PEGGY Reactor

The paper describes the automatic control system designed to replace the previous system of the Peggy reactor. The main characteristics of the system are that it permits - change-over at a constant period of 20 s from an initial to a final power differing by a factor of as much as 106; - accurate stabilization of the power, the change from a transient to a stabilized state being made automatically. The equipment consists of a d.c. linear amplifier, with automatic range commutation from decade to decade, and an assembly of circuits for producing from the signal emitted by the amplifier a signal proportional to the logarithm of the power over six decades. A constant power period is achieved by adjusting the logarithm of the power to a value provided continuously by an electronic programmer which produces a voltage gradient with a slope corresponding to the period of 20 s and a saturation value equal to the logarithm of the power required. When the power approaches the value required, a voltage comparator switches the system to a stabilized state by adjusting the linear power value to the preset value by conventional methods. At the beginning of a transient state the system also functions in reverse, enabling the reactor to pass from a stabilized state to a transient state. The control system also makes it possible to approach the required power level from above or below. The author discusses the principles underlying the design of the equipment. (author)