Report ANL-7224, Argonne National Laboratory, 1967. — 47 p.Conventionally the wide range of neutron flux that must be monitored in a nuclear reactor has required systems that use two or more types of detectors placed at various locations relative to the reactor core. When such systems are used, suitable discrimination against unwanted gamma,
alpha, and noise signals can be difficult to achieve over the entire range of neutron flux. A neutron-detection system that uses a single fixed-position neutron detector to continuously monitor up to ten decades of reactor power has been assembled and tested. Superior gamma discrimination, compared
to conventional systems, was realized over the entire neutron-flux range.
A conventional counting technique was used to cover the source and low intermediate ranges, and a statistical chamber current fluctuation technique, sometimes referred to as a "Campbelling System" or "Mean Square Voltage System," was used to monitor the intermediate and power ranges. Sufficient linear overlap of the two output signals was experimentally verified, thus demonstrating the continuous monitoring feature.
A mean chamber current measurement was included as part of the system and could have been used for the linear high-power trip signals. With more sophisticated equipment, period trip signals could also have been generated over the entire neutron-flux range.
