| 摘要 |
<p>1,206,733. Fuel elements. UNITED STATES ATOMIC ENERGY COMMISSION. 26 March, 1969 [10 April, 1968], No. 15740/69. Heading G6C. A fuel subassembly for a liquid metal-cooled fast nuclear reactor comprises a shroud containing a bundle of slender, elongated, parallel fuel pins, each of which includes a fuel zone and a fission-gas plenum, the ends of the fuel zones of all the fuel pins lying in parallel planes perpendicular to the axis of the subassembly, with the fuel pins being so oriented that some of the fission-gas plenums are located downstream of the fuel zones and the remainder are located upstream of the fuel zones. In one embodiment described, a group of fuel pins at the centre of the fuel subassembly have their gas plenums below the fuel while the remaining fuel pins have their gas plenums above the fuel. Two adjacent outer and inner fuel pins 15a, 15b respectively are shown in Figs. 6 to 8, both including a tube 38 enclosing PuO 2 /UO 2 pellets 40 which make up the fuel zones 13. Pellets 41 of depleted UO 2 are disposed above and below the fuel zones 13 to serve as an axial blanket while nickel rods 42 are disposed above the fuel zones 13 to serve as an axial reflector. Springs 43 are disposed above rods 42. The fuel pins differ only in the location of the fissiongas plenums 44 which are formed by stainless steel tubes 45. In the outer fuel pins 15a the plenums 44 are disposed above the fuel zones 13 between springs 43 and upper end fittings 22, while in the inner fuel pins 15b they are disposed below the fuel zones 13 between pellets 41 and lower end fittings 29. This embodiment was specifically designed for use in a reactor which required the lower end of each fuel subassembly to be tapered. Where this is not necessary, alternate rows of fuel pins may have their fissiongas plenums located on one side of the fuel zones and the remaining rows have their plenums on the other side of the fuel zones. Reference has been directed by the Comptroller to Specification 1,139,968.</p> |
