Abstract :
The requirements of reactor instruments demand an unusual emphasis on the philosophy of fail to safety, guaranteed power supplies in all circumstances and reliability over long periods of operation. The special advantages of transistors in the development of these instruments are simplicity of circuit and economy of power required. As a result, a greater emphasis can be placed on a.c. or pulse operation of circuits which, although inherently more complex, can be made much safer than d.c. operation. New instruments designed for the U.K.A.E.A. take their power from a d.c. supply of 50 V centre tapped or from the a.c. mains which considerably eases the provision of stand-by facilities. A description is given of a logarithmic amplifier and period meter with a wide range, fast response and no period overshoot which typifies the approach. A potentiornetric recorder and pulse counting channel are briefly mentioned.
