Abstract: A neutron flux radiation detector is provided that utilizes neutron radiation induced nonlinear acoustic behavior in water, with the resultant mixing of two ultrasonic signals in transit through the liquid, to provide a measure of ambient radiation levels. Nonlinear elastic properties are imparted to the water by the presence of microcavities which are formed when high-energy neutrons collide with the waters atomic nuclei.The detector employs an ultrasonic transmitting transducer which is driven simultaneously at two different frequencies. The acoustic output is transmitted through a container housing a pool of distilled water. Only when radiation is present will the acoustic signals in transit through the water undergo harmonic distortion and "mix", thereby generating sum and difference frequencies. These sum and difference frequencies are then sensed using a separate receiving transducer, and are identified as a measure of the ambient radiation level.

Abstract: A method is disclosed for determining the concentration of fission products in the reactor coolant of a liquid metal cooled nuclear reactor. Reactor coolant is bypassed at constant temperatures and constant velocity through a flow sampling system containing a sampling tube. After a period of time, the sampling tube is isolated and removed from the bypass system; the liquid metal coolant is removed from the tube; and, the radionuclides deposited on the sampling tube are measured by gamma spectroscopy. The concentration of fission products in the reactor coolant is then determined from the measured radioactivity of the deposited nuclides.

Abstract: A method of measuring neutron radiation within a nuclear reactor is provided. A sintered oxide wire is disposed within the reactor and exposed to neutron radiation. The induced radioactivity is measured to provide an indication of the neutron energy and flux within the reactor.

Abstract: A method of detecting stacks with leaky fuel elements in a liquid-metal-cooled reactor, consisting in that prior to withdrawing a coolant sample, gas is accumulated in the coolant of the stack being controlled, the reactor being shut down, separated from the sample by means of an inert carrier gas, and the radioactivity of the separated gas is measured. An apparatus for carrying out said method comprises a sampler in the form of a tube parallel to the reactor axis in the hole of a rotating plug and adapted to move along the reactor axis. Made in the top portion of the tube are holes for the introduction of the inert carrier gas and the removal thereof together with the gases evolved from the coolant, while the bottom portion of the tube is provided with a sealing member.

Abstract: The present invention concerns a neutron dosemeter particularly applicable to the dosimetry of fast neutrons. According to the invention there is provided a composite detector material consisting of at least two fissile elements, the fission cross-section versus neutron energy response curves of which combine to match the kerma versus neutron energy response of a known biological material.

Abstract: Methods are disclosed for measuring simultaneously the thermal neutron lifetime of the borehole fluid and earth formations in the vicinity of a well borehole. A harmonically intensity modulated source of fast neutrons is used to irradiate the earth formations with fast neutrons at three different intensity modulation frequencies. Intensity modulated clouds of thermal neutrons at each of the three modulation frequencies are detected by a single spaced detector and the relative phase shift of the thermal neutrons with respect to the fast neutrons is determined at each of the three modulation frequencies. These measurements are then combined to determine simultaneously the thermal neutron decay time of the borehole fluid and the surrounding earth formation media.

Abstract: A method is disclosed for measuring the thermal neutron decay time of earth formations in the vicinity of a well borehole. A harmonically intensity modulated source of fast neutrons is used to irradiate the earth formations with fast neutrons at three different intensity modulation frequencies. The tangents of the relative phase angles of the fast neutrons and the resulting thermal neutrons at each of the three frequencies of modulation are measured. First and second approximations to the earth formation thermal neutron decay time are derived from the three tangent measurements. These approximations are then combined to derive a value for the true earth formation thermal neutron decay time.

Abstract: A method is provided for determining the dose value of neutrons leaving a body as thermal and intermediate neutrons after having been scattered in the body. A first dose value of thermal and intermediate neutrons are detected on the surface of the body by means of a first detector for neutrons which is shielded against thermal and intermediate neutrons not emerging from the body. A second detector is used to measure a second dose value of the thermal and intermediate neutrons not emerging from the body. A first correction factor based on the first and second values is obtained from a calibration diagram and is applied to the first dose value to determine a first corrected first dose value.