Nuclear reactor materials processing

The Idaho Chemical Processing Plant is a versatile, multipurpose facility used for recovering highly enriched uranium from a variety of fuels in naval propulsion, research, and test reactors. Materials processed [Al] include aluminum-alloyed, zirconium-alloyed, stainless steel-based, and graphite-based fuels. The West Valley plant, although designed primarily for low-enriched uranium fuel from power reactors, also processed plutonium-enriched and thorium-based fuels. It is the only U.S. plant to have reprocessed fuel from commercial nuclear power plants. 

Most zirconium is used as an oxide in commercial applications. Only a few percent is converted to the metal and used in chemical process industries because of its excellent corrosion resistance, while a special grade of zirconium is used in the nuclear industry. There are no official statistics for the production and consumption of zirconium metal. The annual global production capacity is estimated approximately at 85001, and total production/consumption is about 7000 t/year. The main applications of zirconium metal are for the nuclear energy and chemical process industries. About 85% of zirconium metal, 5000-6000 t/year, is used in the nuclear industry. Commercial-quality zirconium still contains 1 -3% hafnium. This contaminant is unimportant except in nuclear applications. For nuclear reactor materials, the zirconium metal should have a very low hafnium content of less than 0.01 wt%. Most Zr metal is produced by the reduction of the zirconium (ZrCy chloride with magnesium metal in the Kroll process. 

A number of special processes have been developed for difficult separations, such as the separation of the stable isotopes of uranium and those of other elements (see Nuclear reactors Uraniumand uranium compounds). Two of these processes, gaseous diffusion and gas centrifugation, are used by several nations on a multibillion doUar scale to separate partially the uranium isotopes and to produce a much more valuable fuel for nuclear power reactors. Because separation in these special processes depends upon the different rates of diffusion of the components, the processes are often referred to collectively as diffusion separation methods. There is also a thermal diffusion process used on a modest scale for the separation of heflum-group gases (qv) and on a laboratory scale for the separation of various other materials. Thermal diffusion is not discussed herein. 

Department of Energy - has sponsored analyses of its reactors and process facilities, the risks of the breeder reactor, the risk of nuclear material transportation and disposal, and the risks of several fuel cycles. 

Carbon is a relatively inert element chemically and is used in its graphitic and pre-graphitic forms as a construction material under a variety of corrosive conditions. Modern uses include heat exchangers in chemical plants, consumable electrodes in a variety of metallurgical processes and the components of rocket motors and the moderators of gas- and litiuid-cooled nuclear reactors. The demand for carbon products at the present time is I0 t/year. 

The heart of the nuclear reactor boiler plant system is the reactor core, in which the nuclear fission process takes place. Nuclear fission is the splitting of a nucleus into two or more separate nuclei. Fission is usually by neutron particle bombardment and is accompanied by the release of a very large amount of energy, plus additional neutrons, other particles, and radioactive material. The generation of new neutrons during fission makes possible a chain reaction process and the subsequent... 

The energy produced in a nuclear reactor vessel is the result of a nuclear fission (atom splitting) process that occurs when sufficient nuclear material is brought together (critical mass). Under these circumstances, a chain reaction occurs and an external supply of neutrons is not required. A nuclear fuel control rod system raises or lowers the nuclear fuel (which is contained within fuel rods) inside the reactor vessel. 

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Either MA or MM processes drop under more general class of solid-state amorphization reactions, SSAR. Amorphization by irradiation of solids was observed yet in the era of study of materials for nuclear reactors. In 1962, Bloch [88] amorphized UgFe by exposing it to fluxes of nuclear fission fragments. Others obsawed amorphization... 

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