Patent GB-1027095-A (GB)
Title: Swimming pool reactor
Inventor: DUPUY GERARD
IPC: G21C19/20
Filed: 1964-10-27
Abstract: 1,027,095. Nuclear reactors. COMMISSARIAT A L'ENERGIE ATOMIQUE. Oct. 27, 1964 [Oct. 30, 1963], No. 43794/64. Heading G6C. A swimming pool reactor comprises a core formed by vertical fuel elements placed near the bottom of a mass of water, means being provided to produce a rising flow of cooling water through the core, vertical channels being pierced in a neutron-absorbing mass of material in extension of each fuel element position, and locking rods being provided in sliding fit within the channels and which each have means providing a releasable connection to a fuel element and a releasable member for retention by a locking plate outside the swimming pool. As shown in Figs. 1a, 1b, a duct 5 supplies cooling water to a casing 4 from which it flows up through a caisson 6 over ;juxtaposed fuel elements 7 and into a chimney 8 from whence it is removed through a duct 9. At the top of the casing 4 is a water chamber 10 connected to a suction duct 11. The water flowing in the chamber 10 serves to cool experimental apparatus such as that indicated by the reference numeral 12 which are placed outside the reactor core and rest on a grid 13 forming the ceiling of the chamber 10. The caisson 6, which serves to withstand the water pressure produced in the core by the load loss of the cooling water flow over the fuel elements and to screen gamma radiation from the core, carries a metal pigeon-hole system 14, the holes of which receive the fuel elements, experimental apparatus and control elements. The chimney 8 prevents water from the core from overflowing into the remainder of the swimming pool while allowing experiments to be performed in the reactor core. One such experiment is represented by the reference numeral 15. Since the water rises through the core, the load loss therein is added to the static water head in the swimming pool. In order to prevent the fuel elements and experimental apparatus from being raised by the upward thrust of the cooling water, they are rigidly connected to locking rods 16, the locking being controlled manually from a control room 17 below the swimming pool. The rods 16 reach the control room 17 through a cylindrical block 18 formed by two metal plates 19, 20 interconnected by vertical tubes 21 through which the rods 16 pass. The space between the tubes 21 and the plates 19, 20 is filled with heavy sand 22 based on barytes to protect the operators in the room 17 against ionizing radiations from the core. Each rod 16 has at the top a cylindrical sleeve to which a fuel element 7 is locked by means of a bayonet system (not shown). Two control elements 27, 28 are shown in Fig. 1b, each moving inside a square-section sheath 29, 30 which bears against the top surface of the block 18 and is maintained upright by a grid 31 rigidly secured to the chimney 8. The control elements 27, 28, each comprise a fuel element 32, an absorbent element 33 and a counter-weight 34 (which counters the upward thrust of the rising flow of cooling water), and can be moved inside their respective sheaths on guide carriages 35, 36 and 37. The control mechanisms for the elements 27, 28 are located in the room 17. The element 27 is controlled mechanically by a motor 27b and the element 28 hydraulically by a system 28b. A fuel element or experimental apparatus may be replaced in any position in the core by a control element, or vice versa, and a description is given of the various stages in such a replacement.