Abstract: The invention comprises a neutron detector (50) of very high temporal resolution that is particularly well suited for measuring the fusion reaction neutrons produced by laser-driven inertial confinement fusion targets. The detector comprises a biased two-conductor traveling-wave transmission line (54, 56, 58, 68) having a uranium cathode (60) and a phosphor anode (62) as respective parts of the two conductors. A charge line and Auston switch assembly (70, 72, 74) launch an electric field pulse along the transmission line. Neutrons striking the uranium cathode at a location where the field pulse is passing, are enabled to strike the phosphor anode and produce light that is recorded on photographic film (64). The transmission line may be variously configured to achieve specific experimental goals.

Abstract: Disclosed is a neutron detector, provided with a sealed chamber having two spaced apart electrodes, hermetically sealed in the chamber with a seal which is located in an environment of at least two decades less neutron flux than that experienced by the detector. An ionizable gas is placed within the space between the electrodes, and pressurized to a pressure above one atmosphere. A layer of a mixture of an active material and a breeding material are positioned within the chamber, the active material and breeding material being respectively U-235 and U-234, which layer has a thickness of at least 0.2 milligrams per square centimeter.

Abstract: A wide range flux monitoring assembly is provided for in-core neutron flux monitoring in a nuclear reactor vessel. The assembly comprises a fixed in-core power range monitor and a fixed in-core extended range start-up monitor which are connected to signal processing circuitry means for generating signals representative of neutron flux in the reactor vessel. The extended range start-up monitor includes a fission chamber including an anode, a cathode, a neutron sensitive material interposed between the anode and the cathode and a cable assembly for communicating electrical signals between the anode and the cathode to the signal processing circuitry means. An insulating oversheath is disposed about the extended range start-up monitor for insulating the fission chamber from reactor vessel potential. The oversheath comprises a casing having an inner wall and an outer wall and includes an insulating layer interposed between the fission chamber and the inner wall.

Abstract: Disclosed is apparatus and method which, in cooperation with an electrical system, analyzes signals generated by detectors placed in a flux field of gamma rays and neutrons. A first detector with a first sensor is coupled to the electrical system. A second detector with a second sensor is coupled to the first sensor and the electrical system. A fissile material is housed in the first detector, and is heatable by gamma ray and neutron capture to in turn heat the first sensor, which generates a first signal which is delivered to the electrical system. A non-fissile material is housed in the second detector, and is heatable by gamma ray capture to in turn heat the second sensor, which generates a second signal. The first and second signals are analyzed in the electrical system to determine the power level, neutron flux, and gamma ray flux within the flux field. Also provided is a microtechnology apparatus and method for measuring neutron flux.

Abstract: A method for fabricating a thermocouple unit for service in and about nuclear reactors and other radioactive environments. The method provides a thermocouple encapsulated within a sphere of fissile material.

Abstract: An apparatus (10, 110, 210) including a containment capsule (12, 112, 212) a support member (16, 116, 216) removably disposed within the capsule and carrying therein a solid state track recorder material (20, 120, 220) and a layer of fissile material (20, 120, 220), and means (52) on the exterior of the capsule adapted to be remotely grasped for positioning the capsule adjacent to the fuel. The capsule is lowered into close proximity to the fuel, and positioned at a predetermined location for a period of time between about one hour and one day. The capsule is withdrawn from the fuel, the support member and recording member are withdrawn from the capsule, and the recording member is processed to reveal the fission track density, which is readily correlated to fuel burnup.

Abstract: A fission chamber assembly for use in-core of a nuclear reactor with the fission chamber included within a small diameter tubular housing which is hermetically sealed at opposed ends. A signal cable end seal assembly is provided at one end of the tubular housing serving to hermetically seal the mineral insulated coaxial signal cable to the tubular housing. A second cable end seal assembly is included within the tubular housing between the signal cable end seal assembly and the fission chamber, with a hermetically sealed gas-filled reservoir defined between the spaced-apart cable end seal assemblies. These redundant seal assemblies provide an improved reliability detector for use in the reactor hostile environment.

Abstract: A portable uranium analyzer employs a neutron source and a neutron detector for carrying out an uranium assay along the surface of the earth and a gamma ray detector for carrying out a natural gamma radiation assay along the surface of the earth. The neutron source irradiates the underlying earth formation along an exploration line in either a continuous scan mode or in a plurality of fixed assay points. Prompt or delayed neutrons resulting from neutron fission of any uranium present in the formation are detected and recorded during assaying. The uranium assay and the natural gamma radiation assay are correlated to identify formations suspected of containing uranium.

Abstract: An improved long operating lifetime ionization chamber type neutron detector for use within a nuclear reactor. The chamber contains uranium U-235 as the neutron sensitive material and helium or argon fill gas. The atom rate of U-235 to fill gas is from 0.45 to 1.8 for helium, and 2.3 to 9 for argon.

Abstract: A neutron flux monitor is provided which consists of a plurality of fission counters arranged as spaced-apart point detectors along a delay line. As a fission event occurs in any one of the counters, two delayed current pulses are generated at the output of the delay line. The time separation of the pulses identifies the counter in which the particular fission event occured. Neutron flux profiles of reactor cores can be more accurately measured as a result.

Abstract: The invention relates to a process for measuring a continuous neutron flux, and to an measuring apparatus for carrying out this process. According to the invention, a probe is disposed in the neutron flux, comprising a first part defining an enclosure and a second part disposed inside the enclosure and separated therefrom by a medium whose heat conductance is known, one of said parts being made at least partially of fissile material, and the difference in temperatures between the two parts is measured at equilibrium, to deduce therefrom the power released by the fissile material, then the neutron flux. The invention is more particularly applicable to measuring the neutron flux, particularly in the core of nuclear reactors.

Abstract: An accurate determination of whether the reactivity of individual spent fuel assemblies exceeds a threshold value is made while each assembly is being transferred from the reactor core to the fuel storage rack. The reactivity of each spent assembly is compared with that of a standard assembly by comparing the subcritical multiplication resulting from insertion of a neutron source into the assemblies. The measuring apparatus preferably exteriorly resembles a control element assembly wherein one control element finger containing the neutron source is yoked to another finger containing a neutron detector. The fingers are simultaneously inserted into a standard assembly having a known reactivity and subcritical multiplication, and the resulting flux signal is recorded. Thereafter spent assemblies are sequentially measured to assure that no assembly having a subcritical multiplication greater than that of the standard is ever placed into the storage rack.