847,843. Nuclear reactors. UNITED STATES ATOMIC ENERGY COMMISSION. May 21, 1957 [May 22, 1956], No. 16064/57. Class 39(4). An engineering test reactor has a large hole through the centre of the core for high fast flux experiments. Fig. 5, shows a cross-shaped core 20 containing fuel elements 33 and having a central hole 66 and holes 67 between the arms of the cross ; control rod holes 70 are provided. The core is surrounded by a single line of Be reflector elements 76 and by Al reflector elements 77, Fig. 11 (not shown). Control rods 85 are controlled from below the core. They have lower parts containing fuel and upper parts containing absorber e.g. Cd, and have shockabsorbing tips of Fe-sheathed Al. Fuel in the rods 85 and in the fuel elements is in the form of slightly curved plates of an alloy of 12% Al with USP235/SP of 90% enrichment, in Al supports : USP233/SP or PuSP239/SP could be used. The core is supported by grids 41, 42. The core 20 and reflector 21 are contained in a vessel 22 having a carbon steel thermal shield 26 and surrounded by a pressure vessel 27 and concrete shielding 140 ; the vessels are of low carbon stainless steel. A conical deflector 32 is attached to vessel 22 but not to vessel 27. H 2 O as coolant and moderator enters at 124, flows down through the core and up over the thermal shield, and leaves at 126. The water system is of stainless steel and includes a demineralizer. In discharging, fuel elements are lifted into the top part of vessel 27 and dropped through a shoot 129 in the shielding into receptacles 131 in a transfer machine which is submerged in an adjacent canal. The machine is then rotated and the fuel lifted out and stored elsewhere in the canal. U.S.A. Specification 2,831,806 is referred to.
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