Gamma compensated pulsed ionization chamber wide range neutron/reactor power measurement system

Claim 2

In a nuclear atomic reactor power/neutron flux measurement system of the pulsed high voltage ionization chamber type the improvement comprising: a. a single sensor system with separate chambers of neutron plus gamma and gamma-only sensitivity respectively for providing separate output voltages responsive to pulsed voltage ionization technique and including a single-pole high voltage pulser means and a charging network connected to a pulse generating timing means and delay means to provide a field-free period for ionization density build-up signal enhancement and pulsed voltage ionization collection polarization from said pulser means, and b. differential circuit means connected to receive said output voltages and to provide as a difference voltage output signal a neutron only voltage value effecting gamma field compensation, constituting a compensated pulsed ion chamber channel.

Claim 3

Apparatus according to claim 1 a. said differential circuit means including amplifier means, comparator means, and amplifier inverter means connected to receive said respective chamber output voltages and provide an amplified voltage and an amplified inverted voltage and b. a differential amplifier connected to receive said amplified voltage outputs and provide a difference output signal eliminating the effect of gamma field.

Claim 4

Apparatus according to claim 2 including a. a linear gate means connected to sample said differential amplifier difference output signal at its maximum amplitude, b. a track and hold module connected to receive the output signal of said linear gate and hold the sampled maximum voltage until the next pulse arrives at said track and hold module from said linear gate and c. voltage display means connected to receive and display the voltage level of said track and hold module.

Claim 5

In a nuclear atomic reactor power measurement system of the pulsed high voltage ionization chamber type the improvement comprising a. a single sensor system with separate chambers of neutron plus gamma and gamma-only sensitivity respectively providing separate output voltages responsive to pulsed voltage ionization technique and b. differential circuit means connected to receive said output voltages and to provide as a difference voltage output signal a neutron only voltage value effecting gamma field compensation, constituting a compensated pulsed ion chamber channel, c. a squaring functions electronic circuit for each of said chambers and an operational mode selector, d. each of said squaring functions circuits including a chamber voltage sample and hold means, routing gate means, a comparator means and a squaring circuit connected for activation from said sample and hold means, e. said routing gate means having one input connected to derive voLtage directly from its associated chamber and a second input connected to receive voltage from said squaring circuit, f. said comparator means being connected to receive inputs from said sample and hold means and from said squaring circuit and connected to provide an input to said routing gate means, g. said routing gate means being connected to provide an input to said differential amplifier and being set to switch from a signal derived directly from said sample and hold means and corresponding to a first order region of radiation fields response constituting a compensated pulsed ion chamber channel, to a second order higher radiation fields response in a squared gamma only channel mode to assure that only signals which are varying directly with the source of ionization rate will appear at the differential amplifier inputs, h. a second input to said operational mode selector being received from said squaring circuit of said gamma-only circuit, and i. said operational mode selector being operable to switch to the gamma-only squaring circuit signal which will then be responding to prompt-fission gammas, and thereby continue the linear response of the system.

Claim 6

In a nuclear atomic reactor power measurement system of the pulsed high voltage ionization chamber type the improvement comprising a. a single sensor system with separate chambers of neutron plus gamma and gamma-only sensitivity respectively providing separate output voltages responsive to pulsed voltage ionization technique and b. differential circuit means connected to receive said output voltages and to provide as a difference voltage output signal a neutron only voltage value effecting gamma field compensation, constituting a compensated pulsed ion chamber channel, c. a squaring functions electronic circuit for each of said chambers and an operational mode selector, d. each of said squaring functions circuits including a chamber voltage sample and hold means, routing gate means, a comparator means and a squaring circuit connected for activation from said sample and hold means, e. said routing gate means having one input connected to derive voLtage directly from its associated chamber and a second input connected to receive voltage from said squaring circuit, f. said comparator means being connected to receive inputs from said sample and hold means and from said squaring circuit and connected to provide an input to said routing gate means, g. said routing gate means being connected to provide an input to said differential amplifier and being set to switch from a signal derived directly from said sample and hold means and corresponding to a first order region of radiation fields response constituting a compensated pulsed ion chamber channel, to a second order higher radiation fields response in a squared gamma only channel mode to assure that only signals which are varying directly with the source of ionization rate will appear at the differential amplifier inputs, h. a second input to said operational mode selector being received from said squaring circuit of said gamma-only circuit, and i. said operational mode selector being operable to switch to the gamma-only squaring circuit signal which will then be responding to prompt-fission gammas, and thereby continue the linear response of the system.

Claim 7

Apparatus according to claim 4 including a. a high performance pulse rate system connected to operate on said neutron plus gamma sensitive chamber and to provide a third input to said operational mode selector to provide a low neutron flux measurement capability over a range of approximately 10 2 to 106 neutrons/cm2 sec, thus constituting a pulse rate mode channel.

Claim 8

Apparatus according to claim 1 wherein a. said chambers are provided with neon as a fill-gas component for fission and boron coated chambers and as a trace constituent with other gases that are neutron sensitive to provide temperature stabilization of the pulsed ionization chamber voltage signals under temperature variant conditions.

Claim 9

Apparatus according to claim 5, said operational mode selector including a. channel switch means having gated drivers for selectively connecting said respective channels to a display unit, b. operational control switch means and relay switch means, c. said operational control switch means having a first, second and third positions for manual selection of said operation mode in any of said three channel modes and a fourth position by passing the effect of said first three switch positions and placing the system in automatic operation for control by said comparators, inverters and gated drivers responsive to the relative values of output voltages from said chambers for selection between said pulse rate, compensated pulsed ion chamber and squared gamma-only channels.

Claim 10

Apparatus according to claim 5, including a. log ratemeter means connected in said pulse rate mode channel and log amplifier and operational amplifier means connected in said compensated pulse ion channel and in said squared gamma only channel for converting linear response characteristics of each channel into logarithmic response.