858,991. Nuclear fuel elements. GENERAL ELECTRIC CO. Feb. 24, 1959 [March 25, 1958], No. 6325/59. Drawings to Specification. Class 39(4). In a nuclear reactor fuel rod, fertile Th232 is incorporated with fissionable U233. With this material, conversion of fertile to fissionable isotopes occurs with neutrons above 10 e.v. and fission is effected by neutrons below 0À05 e.v.. In the embodiment, the fuel rod is surrounded by a shield which excludes from the rod those neutrons having energies between 0À05 and 10À00 e.v. This reduces the formation of Pa234 from Pa 233, the required reaction being the formation of Th233 from Th232 by neutron capture, Th233 to Pa233 by #-decay, and Pa233 to U233. The formation of Pa234 reduces the neutron flux density. The shield material may be a mixture of plutonium isotopes or U238 from which the plutonium isotopes are produced. The fuel rod may be formed either of a sintered material or a slurry.
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