United Kingdom Atomic Energy Authority

British Gas Plc

Cogent Limited

Malcolm R Wormald

Colin G Clayton

Bruce C Tofield

Thomas W Conlon

Bruce W Thomas

James Asher

George B Huxtable

Lionel G Sanders

A tool suitable for borehole logging, including production oilwell borehole logging, contains a radioisotope neutron source (14), a fast neutron detector (15) and a gamma-ray detector (16). Gamma-ray detection events are selected for building spectra by coincidence or anticoincidence with detection of the associated neutron. In a development, additional information is derived from identification of which of a series of time intervals encompasses detection of a neutron after detection of a gamma-ray.

Analysis using neutrons

An analysis method and system for analyzing coal or other material causes the material to be bombarded with neutrons from a source, and this generates gamma rays from the material which are detected by a detector. The detector has scintillators which generate light when a gamma ray is detected, the light being detected by photomultipliers. Each gamma ray generates two other gamma rays, which may both be wholly absorbed in one or the other scintillator, or one absorbed in one scintillator and one in the other. By analyzing these events, the spectrum of gamma rays may be obtained, giving the composition of the material. One preferred detector has an array of scintillators and coincident gamma ray detection events in three adjacent scintillators detected by detecting if a primary scintillator detector event is coincident with detection events in the other two scintillators. For each detection event, one of the scintillators is selected as a primary scintillator, and two other scintillators, on opposite sides of the primary scintillator, are selected. The detection event in the selected primary scintillator is compared with the detection events in the two other selected scintillators to determine coincidence. In another embodiment, two gamma detectors of differing properties are used, with each detector having a plurality of scintillators. Coincident events are detected in one detector and anticoincident events in the other.

Coal analysis

A method of inspecting the cover of a buried pipeline comprising the operations of irradiating the inner wall of the pipeline with neutrons from a radioactive source carried by a vehicle traversing the pipeline, measuring the intensity of ionizing radiation within the pipeline arising from nuclear interactions occuring within the cover of the pipeline and its surroundings due to the neutrons emitted by the source, and recording the measured intensity of the said ionising radiation together with data representative of the position of the vehicle along the pipeline. Apparatus for carrying out the method also is described.

Inspection of buried pipelines

A corrosion monitoring probe consisting of a housing for mounting a piece of radioactive material in a surface of a body the corrosion of which is to be measured so that the radioactive material is exposed to the same corrosive environment as the surface of the body, and means for measuring the intensity of ionizing radiation emitted by the radioactive material. The housing also contains a reference source of ionizing radiation and means for exposing a radiation detector which forms part of the means for measuring the intensity of ionizing radiation emitted by the radioactive material alternately to the radioactive material and the reference source of ionizing radiation.

Corrosion monitoring probe

A method for determining the gold content of an auriferous material, comprising the operations of irradiating a body of the material with neutrons and determining the intensity of .gamma.-rays having an energy of 279 keV arising from the reaction .sup.197 Au (nn') .sup.197.sbsp.m Au.fwdarw.279 keV. Apparatus for carrying out the method also is described.

Analysis of gold-containing materials

A monitor for determining the ash content of coal in wagons consisting of a structure including means for irradiating each wagon as it passes the structure with a known dose of neutrons, means for detecting and measuring the intensities of .gamma.-rays emitted by ash-forming elements in the coal, and means for providing an indication of the concentration of the ash-forming elements. There also are included interlocks for ensuring that the neutron source is only operated when a loaded wagon is in the appropriate position.

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Abingdon, United Kingdom

Malcolm R Wormald