Assembly of elements of the moderator solid for nuclear reactors.

摘要

913,887. Moderator structures. SOC. NATIONALE D'ETUDE ET DE CONSTRUCTION DE MOTEURS D'AVIATION. Dec. 1, 1960 [Dec. 4, 1959], No. 41381/60. Class 39 (4). A moderator structure for use in a high temperature nuclear reactor subjected to accelerations and to substantial inclinations to the vertical, e.g. a nuclear reactor used as the energy source for the propulsion of an aircraft, comprises an assembly of mutually independent moderator columns capable of expanding laterally by reason of clearances provided between adjacent columns and axially by reason of resilient guide means which also provide axial compression for giving mechanical cohesion to each column. In the embodiment shown, the columns comprise superposed elements 10, e.g. of beryllia, connected to each other by means of lugs 27. A tubular terminal member 13 at the upper end of each column embraces a sleeve 14 secured to the cover 2 of the reactor casing 1 while at the lower end of each column a terminal member 11 rests upon a support 12 secured to the lower part of the casing 1. The elements 10 in each column are pressed together by means of a helical spring 24 which abuts a shoulder 26 on the sleeve 14 to one end and a shoulder 25 on the member 13 at the other end. Longitudinal expansion is permitted by the members 13 sliding on the sleeves 14 and laterial expansion by the clearance 23 between adjacent columns. Coolant gas under pressure at a temperature around 350‹ C. enters the casing 1 through the inlet 5 and leaves at a temperature around 800‹ C. from the outlet 6, a deformable wall 7 separating the inlet zone from the outlet zone. Axial channels 15 are formed partly by central apertures in the elements 10, in which are housed fuel elements 20, and partly by bores 16 in the supports 12, bores 17 in the members 11, bores 18 in the members 13 and the bores 19 of the sleeves 14. Coolant gas enters the channels 15 through apertures 21 and leaves through apertures 22. The cover 2 is cooled by circulation of water by way of pipes 3, 4 and the casing 1 by immersion in protective water for the reactor.