Nuclear fuel particles

Pyrolytic graphite was first produced in the late 1800s for lamp filaments. Today, it is produced in massive shapes, used for missile components, rocket nozzles, and aircraft brakes for advanced high performance aircraft. Pyrolytic graphite coated on surfaces or infiltrated into porous materials is also used in other appHcations, such as nuclear fuel particles, prosthetic devices, and high temperature thermal insulators. 

Piccinini, N., Coated nuclear fuel particles. In Advances in Nuclear Science and Technology, Vol. 8, ed. E.J. Henly and J. Lewins, Academic Press, New York, 1975, pp. 255 341. 

Lefevre, R.L.R. and Price, M.S.T., Coated nuclear fuel particles the coating process and its models, Nuclear Technology, 1977, 35, 263 278. 

Fluidized-bed CVD was developed in the late 1950s for a specific application the coating of nuclear-fuel particles for high temperature gas-cooled reactors. PI The particles are uranium-thorium carbide coated with pyrolytic carbon and silicon carbide for the purpose of containing the products of nuclear fission. The carbon is obtained from the decomposition of propane (C3H8) or propylene... 

The protection of components against nuclear radiation is a critical factor in the design of nuclear-fission components.P CVD is used extensively in this area, particularly in the coating of nuclear fuel particles such as fissile U-235, U-233, and fertile Th-232 with pyrolytic carbon. The carbon is deposited in a fluidized-bed reactor (see Ch. 4). The coated particles are then processed into fuel rods which are assembled to form the fuel elements. 

The Retention of Iodine by Pyrolytic Carbon-Coated Nuclear Fuel Particles... 

This is a relatively special technique which combines the principles of fluidized - bed heating and CVD. It is primarily used to coat powders of very fine size with suitable films for special applications. The most prominent application of this technique is in the coating of nuclear fuel particles used in high-temperature gas-cooled reactors (HTGR). A typical fluidized-bed CVD reactor is shown schematically in figure 13.4. 

These results are consistent with laboratory measurements of the effects of pH and oxidation state on the leachability of nuclear fuel particles (Kashparov et al, 2000). The increased leachability of the oxidized fuel particles may be due to (i) an increased solubility because of the change in oxidation state (ii) the higher surface area of the highly fractured oxidized particles or (iii) the diffusion of radionuclides (strontium, caesium) to grain boundaries and particle surfaces during the heating and oxidation process. 

Pyrocarbon Coating of Nuclear Fuel Particles, J. Guilleray, R. L. R. Lefevre, and M. S. T. Price... 

Fluidised-bed CVD is a special technique to coat nuclear-fuel particles for high-temperature gas-cooled nuclear reactors which was developed in the late 1950s. This technique has also been used in other applications, such as the production of biomedical components (e.g. heart valves deposited by pyrolysis carbon) and some special functional coatings on ceramic particles. 

Zirconium carbide also is a refractory compound [10]. The material has a melting point of 3450°C and is used as a coating for nuclear fuel particles such as Th02 and UO2 [10, 189, 190]. The compound is obtained by the CVD of a mixture of either ZrCU [189, 191] or ZrBr4 [190, 192] and methane (or propane) in the presence of hydrogen at 1000-1500 °C. 

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