Fission chamber detector system for monitoring neutron flux in a nuclear reactor over an extra wide range, with high sensitivity in a hostile environment

摘要

A fission chamber detector system for monitoring neutron flux density in a nuclear reactor utilizes a unique coaxial cable carried through a flexible metal hose to provide sufficient signal quality to allow a preamplifier and signal conditioning unit for amplifying and conditioning neutron signal pulses produced by the fission chambers to be far enough away from the fission chambers as to be located outside of the containment vessel for the reactor. Reactor power and rate-of-reactor-power-change signals produced for overlapping power ranges from a countrate circuit and a mean square voltage circuit are aligned by a voltage controlled switch and a slave switch without causing spurious transients in the rate-of-change signals. Power signal indications are provided over 12 decades. The preamplifiers include an input stage that enables the preamplifiers to be controlled remotely to either pass or inhibit neutron signal pulses to an amplifier stage from the fission chambers, and to pass test signals to the amplifier stage.