GB972192A - Improvements in or relating to irradiation capsules - Google Patents

Abstract

972,192. Irradiation capsules. COMMISSARIAT A L'ENERGIE ATOMIQUE. April 13, 1961 [April 13, 1960; Aug. 25, 1960], No. 13334/61. Heading H5R. An irradiation capsule comprises a tubular body adapted for insertion into a channel of a nuclear reactor, means for supporting axially within the body a sample to be investigated, and a sleeve surrounding the sample so as to form two concentric annular spaces, one between sleeve and sample and the other between the sleeve and the tubular body; these two spaces are in communication so that a gaseous filling can circulate therein; means for electrically heating the sample are also incorporated. In the form shown, the capsule comprises a hollow metal tube 1, within which is mounted upper and lower members 6, 10 of refractory material. These members are similarly shaped, having a flanged base portion on which stands a central peg 7, 13. The sample to be studied is supported between these pegs, and in Fig. 1 is a closed graphite tube 14. Also supported between members 6 and 10 is a sleeve 9 separated by an outer annular space from tube 1 and an inner annular space from tube 14. These annular spaces are connected by openings 11, 12 in sleeve 9. The graphite tube 14 has a bifilar winding 18 round it, so that it may be heated to any desired temperature, which can be measured by thermocouples 25, 26. A further thermocouple 33 is fixed to the outside of outer tube 1. After the device is assembled, with the sample in position, a cover 2 is welded to tube 1, the device evacuated, and filled with carbon dioxide. The whole device can then be inserted into a nuclear reactor, and subjected to neutron bombardment. In the modification of Fig. 4, a propeller 35 arranged below the-member 6, is rotated by the circulation of the gas in the device. At the tip of one propeller blade is a spot 40 of radio-active material, the radiation from which passes out of the device, through a hole 42 in a lead screen 41, to a detector 43. Thus the speed of revolution of the propeller, and hence the rate of circulation of the gas, can be measured. In a further modification the propeller is driven by an electric motor, so imparting forced circulation to the gas.