KIWI Ground Test Neutronics Instrumentation

Emphasis is placed on some unusual requirements for the reactor neutron power instrumentation for a rocket propulsion reactor. These are; 1) the requirement for accurate, fast automatic control over a dynamic range of many decades, 2) the unusual difficulties involved in detector location, 3) the requirement for absolute calibration prior to any chance of obtaining thermal power data. The first and third of these result from the fast startup requirement, the second from the light weight of the reactor. The instrumentation used at the Nevada Test Site is discussed in relation to these problems.