Method of preparation of a composite guide tube for nuclear reactor, and devices for the practical application of same

摘要

1,028,268. Tube Joints; composite tubes. COMMISSARIAT A L'ENERGIE ATOMIQUE. Jan. 28, 1963 [Jan. 31, 1962], No. 3420/63. Headings F2G and F2P. [Also in Division G6] A composite guide tube for a nuclear reactor (Fig. 1, not shown) is made by causing powder 2 to adhere to the external surface of an inner tube 1, of sintered Mg or Al, for example, and then compressing the powder to a predetermined value and holding it in position by means of an envelope tube 3, of Mg containing 0.6% by weight Zr, for example. The annular space between the inner tube and the envelope tube may be filled with the powder by vibration, following which the envelope tube is narrowed by means of a drawing operation to compress the powder to the desired value. Alternatively, the powder may be mixed with a binding agent such as camphor dissolved in acetone and projected on to the inner tube by means of a spray gun. The inner tube is then placed in a drying oven and the camphor sublimated, after which the tube bearing the powder is fitted inside the envelope tube and the narrowing operation effected as before. The composite guide tube which is thus obtained is subjected to at least one cycle of both internal heating at a temperture higher than the operating temperature of the nuclear reactor and external cooling so as to produce diametral and axial deformations which introduce a clearance between the powder and the inner tube. This clearance permits relative sliding between the inner and envelope tubes without any drawing of one tube by the other. Two such composite tubes may be joined together (Fig. 2, not shown) by providing the inner tube 1a of one guide tube with an inner screw-thread 6a which screws on to an outer screw-thread 6b on the inner tube 1b of the other guide tube. When the screw-threads 6a, 6b are screwed home, the respective envelope tubes 3a, 3b are brought flush to within a few tenths of a millimetre at 7. The tubes 3a, 3b have portions 8a, 8b of slightly reduced thickness around which a band 9 of Zr or stainless steel is wound, this being tightly applied against the tubes and either spot-welded or crimped on to itself so as to form a sleeve which prevents the powder from escaping through the annular opening 7.