Our Changing Views on Reactor Instrumentation

At Chalk River emphasis has been placed on triplicated instrumentation for the reliable and safe control of nuclear reactors. Experience with the three-channel systems on the NRX and NRU reactors is given, along with some comments on the problems that have arisen. A semiconductor current amplifier, an alarm circuit and a logarithmic amplifier, are described and provide examples of instruments that meet the new design requirements. Application of solid-state digital techniques to reactor instrumentation becomes attractive when large numbers of signals have to be examined in detail. A semiconductor system is described that is capable of scanning several hundred low-level signals in less than 0.1 sec. The switching circuits used are shown. The application of these systems to plant monitoring and control is outlined.