Abstract
A detector probe, for detecting ionizing radiation and which is suitable for use in a nucleonic instrument usable in locations having a high ambient temperature, includes an array of radiation detectors mounted on a support and a heat pipe for cooling the detector probe. The nucleonic instrument incorporating such a detector probe is also described.
Claims
1. A nucleonic instrument for measuring a characteristic of one or more material phases within a container, comprising: at least one source of ionising radiation comprising alpha particles, beta particles, gamma radiation and/or neutrons; at least one detector probe configured for detecting said ionising radiation comprising a linear array of radiation detectors spaced apart along a heat pipe for cooling the detectors, the detectors being mounted in thermal contact with and physically supported on the heat pipe; a power source; and an electronic apparatus comprising a control unit and a signal and data processing means for calculating a characteristic of the material phases using signals generated by the detectors in response to radiation received from the radiation sources, wherein the nucleonic instrument is a level gauge or a density profiler.
2. The nucleonic instrument according to claim 1, wherein said instrument is a density profiler and further comprises a linear array of sources of ionising radiation.
3. The nucleonic instrument according to claim 1, wherein said source of ionising radiation is a source of gamma radiation.
4. The nucleonic instrument according to claim 1, wherein at least one of said heat pipes is provided with heat-dissipating means.
5. The nucleonic instrument according to claim 4, wherein said heat-dissipating means comprises a heat sink.
6. The nucleonic instrument according to claim 1, wherein said instrument is a level gauge and the source of ionising radiation is a source of gamma radiation.
7. The nucleonic instrument according to claim 1, wherein said instrument is a density profiler and the source of ionising radiation is a source of gamma radiation.
8. The nucleonic instrument according to claim 2 wherein said source of ionising radiation is a source of gamma radiation.
9. The nucleonic instrument according to claim 1, wherein said detector is selected from the group consisting of Geiger-Muller tubes and scintillation detectors.
10. The nucleonic instrument according to claim 1, wherein said heat pipe contains a liquid having a freezing point <10 C.
11. The nucleonic instrument according to claim 1, comprising two or more heat pipes joined together using a thermally conductive coupling.
12. The nucleonic instrument according to claim 1, wherein at least one of said radiation detectors is mounted on said heat pipe and separated therefrom by means of a material which is thermally conductive and electrically insulating.
Description
BRIEF DESCRIPTION OF THE DRAWING FIGURES
(1) The invention is further described, by way of example only, with reference to the accompanying drawings, which are:
(2) FIG. 1: A schematic diagram of a detector probe according to the invention;
(3) FIG. 1A: A schematic diagram of a side view of the detector probe in FIG. 1;
(4) FIG. 2: A schematic diagram of transverse section through a detector probe according to the invention;
(5) FIG. 3: A section through a second embodiment of a detector probe according to the invention;
(6) FIG. 4: A schematic diagram, partially in longitudinal section of a density profiler according to the invention;
(7) FIG. 4A: A schematic diagram of transverse section through line A-A of FIG. 4.
(8) FIG. 4B: A schematic diagram of transverse section through line B-B of FIG. 4.
(9) FIG. 5: A schematic section through a vessel in which one embodiment of a density profiler according to the invention is installed.
(10) FIG. 6: A schematic section through a vessel in which a different embodiment of a density profiler according to the invention is installed.
(11) FIGS. 1 & 1A show a detector probe 10, comprising a support incorporating a printed circuit board 12. A plurality of detectors 14 are mounted on the circuit board in a linear arrangement. A copper heat pipe 18, having water as its cooling fluid, is installed in close proximity to the detectors. A section through a detector probe is shown in FIG. 2. A circuit board 12, carrying Geiger-Mller (GM) tubes 14, is mounted on a support board 20, having a perpendicular portion to form a T-shaped cross-section. Power cables 24, carrying a high voltage supply to the GM tubes, and data cables 26 for carrying signals from the GM tubes to counting modules in a control housing, are run along the angle of the T-shaped support board. The detector probe is installed within a protective plastic tubular enclosure 30 which is then installed within a cylindrical dip pipe 34. Insulation 32 is provided between the tube 30 and the dip pipe.
DETAILED DESCRIPTION OF THE INVENTION
(12) A sectional view of an alternative embodiment of the invention is shown in FIG. 3. In this embodiment, GM tube 14 is supported on the heat pipe 18. Pad 16 is formed from Sil-Pad 1500ST thermally conductive elastomer to provide thermal contact between the GM tube and the heat pipe and also electrical insulation between them. Printed circuit boards 12A and 12B are mounted on either side of and electrically connected to the GM tube, and transport power, control signals and measurement signals between the GM tube and the power source, electrical control and signal processing apparatus housed within a separate housing. The high voltage supply circuit to power the GM tubes is carried on circuit board 12A, whilst the electrical components of the driving circuit are housed on board 12B. In this embodiment, insulation 32 is located between a protective plastic cover 30 and the components of the detector probe.
(13) FIG. 4 shows an elevation of a density profiler instrument 40 according to a preferred embodiment of the invention. The instrument comprises a steel housing, shown in section, comprising a support structure 58 and a domed cover 42. The housing contains at least a high voltage generator 52, data loggers, counters, signal processing means and data processors 54, means for supplying power to the voltage generator 56 and electrical equipment and means for transmitting information between the data processors and an external location. A layer of insulation 60 is packed between the electrical equipment contained in the housing and the support bracket 61 to which the dip tubes 44, 46 and 48 are mounted. Further insulation 62 is provided around the inside walls of the housing. A source array is housed in tube 44 and two detector probes are housed in tubes 46 and 48. The tubes are braced together for stability by braces 50. FIG. 4B shows a transverse section through the instrument along lines B-B. The domed cover 42 in which the electronic and power equipment are housed is located directly above the tubes 44, 46 and 48, supported on a flange 58 which bears onto metal shroud 69. A heat sink 66 is supported between the support structure 58 and the top of the source and detector arrays. The heat sink includes sockets 67 for receiving the upper ends of heat pipes which pass through the detector probes. The heat sink has fins 68 for assisting with the dissipation of heat from the heat sink. An expanded metal shroud 69 surrounds and protects the heat sink. Electrical connections, including power and data cables pass between the components in the housing and detector probes housed in tubes 46 and 48 through the conduit 64.
(14) FIG. 4A shows a transverse section through the instrument along lines A-A and shows the configuration of the tubes 44, 46, 48 relative to each other and the housing 42.
(15) FIG. 5 shows a vessel 74 containing a liquid 76. A density profiler passes through a flanged aperture in the vessel. The density profiler has two detector probes housed in tubes 46 and 48. Each detector probe comprises a heat pipe 18a, 18b which extends above the top of the tube in which the probe is housed. The domed cover 42 in which the electronic and power equipment are housed is located directly above the tubes 44, 46 and 48, supported on supports 64 through which power and data cables pass. The heat pipes are angled in the region of the supports 64 in order to accommodate the dome 42. The portion of the heat pipe external to the detector probe tube is provided with fins 68 in order to more rapidly dissipate heat from that portion of the heat pipe.
(16) FIG. 6 depicts an alternative embodiment of a profiler in which the power source and electronic components are housed in a box 70 located away from the top end of the detector and source arrays. One or more cables 72 communicate between box 70 and the detector probes in order to carry power and electrical signals. The heat pipes 18 extend from the detector probes as before but need not be bent in this embodiment. The number and location of cooling fins 68 may be varied according to the requirements of the location. The heat pipes may or may not be angled in this embodiment.
