| 摘要 |
1,010,524. Fuel elements. EUROPEAN ATOMIC ENERGY COMMUNITY (EURATOM). April 17, 1963 [April 17, 1962], No. 15020/63. Heading G6C. A fuel cell for a heavy water moderated nuclear reactor of the kind which is cooled by a fluid circulating under pressure in channels of the reactor formed by cold pressure tubes which receive the fuel cells, comprises a jacket 5 in which a cluster of fissile rods 3 is held by cross-members 4 secured to the jacket, a thermal insulating sheath 6 which occupies the space between the jacket 5 and a pressure tube 1 when the cell is in position in the reactor, axial movement of the sheath 6 along the jacket 5 being prevented by shoulders 7 on the jacket, and seating means at one or each end of the cell for the end of an adjacent cell, whereby several such cells may be assembled within a cold pressure tube 1 with the jackets 5 forming a continuous tube within which the cooling fluid flows. Suitable materials for the jacket 5 are beryllium, aluminium, calcined magnesium, alumina, magnesia, vitreous silica and graphite. The insulating sheath 6 may comprise alternate layers of vitreous silica and aluminium or steel sheets or bands wound in helices in overlapping fashion on the outer surface of the jacket 5, or layers constituted by thin metal sheets oxidized on both faces such as aluminium-alumina or zirconium-zirconia. The jackets 5, as shown in the embodiment of Fig. 6, have complementary seating surfaces 9 which permit a certain misalignment between adjacent fuel cells. A deflector 10 extends in the direction of the fluid flow from a peripheral annular band 12 of the cross-member 4 of one fuel cell past the complementary seating surfaces 9 and serves to prevent the hot cooling fluid from leaking between the surfaces 9 and thus coming into contact with the cold wall of the pressure tube 1. The annular bands 12 of adjacent cross-members 4 are provided with indentations in the form of intermeshing sawteeth 14 (Fig. 7) which ensure that after loading of the fuel cells, the fuel rods 3 of contiguous clusters are in alignment. |
