Design Concept of Fast Spectrum Pulse Reactor with Packed Core of Coated Dilute Fuel Particle.

Abstract

A fast neutron pulse reactor that can provide high neutron fluence with relatively short pulse half-width is proposed, which has a core constituted of uranium or plutonium nitride diluted with titanium nitride, formed into particles coated with titanium nitride and packed without moderator. Dilution of the fuel kernel is shown to enhance the neutron fluence obtainable within the allowable maximum fuel temperature. Titanium nitride possesses high heat capacity, which also enables large neutron fluence before attainment of the allowable maximum fuel temperature. As fuel, 233U and 239Pu have the advantage over 235U of permitting criticality to be attained with lower fuel enrichment. The maximum fluence obtainable with a fuel composition of 239Pu enriched to 0.6 and diluted to 0.11 (239PuN+238UN)/(239PuN+238UN+TiN) volume is 3x1016 n/cm2, which is 50 times what has been indicated for a conventional fast pulse reactor. The pulse width is significantly longer than that of the above-mentioned conventional reactor, but if necessary it can be shortened down to roughly equal value by adopting non-diluted fuel, at the expense of only reducing by half the obtainable neutron fluence.