A Neutron Flux Measuring Channel Covering Ten Decades of Reactor Power with a Single Fixed-Position Detector

A new type of instrument for neutron flux measurement in reactor control systems is described. It requires only a single fixed-position fission chamber of standard design to continuously cover ten decades of neutron flux level. The wide range of coverage is achieved by utilizing both the individual pulses from the chamber and the statistical fluctuation signal developed by the overlap of individual pulses. The channel provides a logarithmic indication of neutron flux level from approximately 1 nv to 1 × 1010 nv, with period indication over the range from approximately 1 × 104 nv to 1 × 1010 nv. It also provides a range-switched linear indication of neutron flux level over the range from approximately 1 × 104 nv to 1 × 1010 nv.