Uranium carbides compositions

Four equations and 5 independent angles have been used154 to estimate the 7S of the uranium carbide of the composition near to UC. In addition to Eq. (56) supposedly valid for the point at which a boundary between two UC grains emerges toward an argon atmosphere, also the relation... 

The purpose of this paper is to (1) document published studies of vaporization in vacuum of the Group 4 and 5 transition metal carbides and uranium carbide, and determine the temperature dependence of their equilibrium CVCs (C/MeCVC) and vaporization rates (Vecvc, g/cmzs) (2) document published studies on chemical diffusion of these carbides, and develop and compare data to a model describing the concentration dependence of the chemical diffusion coefficients and (3) develop diffusion-coupled vaporization equations which predict changes of surface composition (Cs, units of C/M and g/cm3 of C), average composition (Cavg units of C/M and g/cm3 of C), and C mass loss (M, units of g/cm2 of C). 

Two fuel forms have the potential to satisfy the GFR requirements (1) a ceramic plate-type fuel element and (2) a ceramic pin-type fuel element. The reference material for the structure is reinforced ceramic comprised of a sUicon carbide composite matrix ceramic. The fuel compound is made of pellets of mixed uranium-plutonium-minor actinide carbide. A leak-tight barrier made of a refractory metal or of Si-based multilayer ceramics is added to prevent fission products from diffusing through the clad [1]. 

For reactor fuel, the ternary uranium-plutonium-carbon monocarbide is prepared by reduction of (U, Pu)02 with graphite [FI], by melting a uranium-plutonium alloy with graphite, or by melting separately prepared individual carbides in an electric arc [K2]. Even though at low temperatures UC exists in the stoichiometric composition, the need for excess carbon for the... 

The binary systems actually and potentially important as nuclear fuel include oxides, carbides, nitrides, phosphides, and sulfides of uranium, plutonium, and thorium. An increasing amount of detailed information is becoming available on the phase equilibria of these compounds, but the relations existing between the composition (especially nonstoichiometric) and the vapor pressure (or activity) of each component are known only for a limited number of systems. 

The core comprises fuel assemblies, the moderator, and complementary nuclear safety rods (on delivery to the supporting orbit). FA consists of a bundle (O Fig. 59.12) of densely packed carbide-graphite elements and of twisted carbide FEs of different compositions based on uranium enriched up to 90%. This design allows reducing the nonuniformity of power deposition and the coolant temperature at the FA outlet. 

Ceramic abrasives and machine tools are refractory as they glow orange-hot on the job. In advanced, high-strength filament-reinforced composites, there is at least one refractory component, such as carbon or silicon carbide. The legs of a high-temperature thermocouple are also made of these two materials. Nuclear reactors use graphite, uranium oxide, and carbide. Military armor is made of refractory materials. 

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