Level gauge using neutron irradiation
AssigneeCommonwealth Scientific and Industrial Research Organization
InventorPlackottu J. Mathew
Life of this patent
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Abstract
Measurement of the level of materials in bins, hoppers, and the like is effected by a neutron monitoring technique. A sensor is located to move substantially vertically in a guide located in or near the bin or hopper. The sensor contains a fast neutron source, a detector of thermal neutrons, and a moderator-containing material in the vicinity of the detector. In a preferred form of the sensor, the neutron source and thermal neutron detector are separated by lead and cadmium screening, and the moderator-containing material is a sheath of polyethylene around the detector. With sensors of this type, material levels may be sensed whether the material contains a neutron moderator or not.
Claims8
Apparatus for determining the level of a material in a container, said apparatus comprising;
- (a) generally vertical guide means extending between the base and the top of the container;
- (b) a sensor positioned within said guide means;
- (c) means for moving said sensor along said guide means;
- and
- (d) means for monitoring the position of the sensor within the guide means;
- said sensor comprising
- (i) a source of fast neutrons;
- (ii) a detector for thermal neutrons, and
- (iii) a sheath of a moderator-containing material surrounding said detector;
- whereby thermal neutrons produced by irradiation of the material by said fast neutrons and thermal neutrons produced by irradiation of said moderator-containing material by neutrons reflected by the said material are detected by said detector when said sensor is positioned within said guide means at a level which is not substantially higher than the level of the material in the container.
A method for determining the location of the top surface of a material stored in a container, said material neither comprising nor containing a neutron moderating element, said method comprising the steps of
- (a) irradiating said material with fast neutrons;
- (b) monitoring the thermal neutrons generated in a neutron-moderating medium by the action of fast neutrons scattered by said material, said neutron-moderating medium being located in the vicinity of said material;
- and
- (c) moving said neutron-moderating medium substantially vertically within the levels of the top and bottom of said container and noting the level at which there is a discontinuity in the production of said thermal neutrons.
Dependencies are inferred from the claim text.