GB1256450A - Improvements in and relating to fission chambers - Google Patents

Abstract

1,256,450. Ionization chambers. COMMISSARIAT A L'ENERGIE ATOMIQUE. 3 Feb., 1970 [3 Feb., 1969], No. 5176/70. Heading H1D. In a pulse type fission chamber comprising a casing 1 which serves as a cathode, an anode 3 within the casing, electric wiring 8 connected to the anode, and hermetic sealing means 4, 5, 6 providing a hermetic seal between the casing and the wiring, the anode 3 is made of Ti and the sealing means comprises an alumina insulator 4 and is welded using a Ag-Cu eutectic to the casing and the wiring. The anode 3 is locked by a screw 9 on to a threaded portion 7 of a Ti member 5 welded at 12 to the insulator 4 and at 13 to a flexible stainless-steel wire 8 brazed into a hollow terminal 10. A collar 6 of Ti is welded at 14 to the insulator 4 and at 15 to the cathode 1 which is made of Ti or any metal weldable thereto, e.g. Zr, Nb, or Mo, and is closed by a plug 2 of similar metal. The chamber may be slid into a sleeve having resilient members which grip the cathode 1 and terminal 10. In an alternative embodiment (Fig. 2, not shown), designed for operation at high temperatures, e.g. 450‹ C., the cathode 1 is welded directly to the insulator 4. A cap is welded to one end of the insulator and to the wire 8 which is located in the insulator 4 by further insulators. Fissile material, e.g. 90% enriched uranium, is deposited on the anode and/or cathode. The chamber is degassed by heating before use, when the degassed Ti acts as a getter to absorb any traces of oxygen or water vapour in the filling, which may be argon.