Graphite-moderated reactors

Chernobyl. The most weU-known graphite-moderated reactor is the infamous Chemobyl-4, in Ukraine. It suffered a devastating accident in 1986 that spread radioactivity over a wide area of Europe. 

D. R. Poulter, ed.. The Design of Gas-Cooled Graphite-Moderated Reactors, Oxford University Press, London, 1963. 

Carbides of the Actinides, Uranium, and Thorium. The carbides of uranium and thorium are used as nuclear fuels and breeder materials for gas-cooled, graphite-moderated reactors (see Nuclearreactors). The actinide carbides are prepared by the reaction of metal or metal hydride powders with carbon or preferably by the reduction of the oxides uranium dioxide [1344-57-6] UO2 tduranium octaoxide [1344-59-8], U Og, or thorium... 

A variety of graphite moderated reactor concepts have evolved since the first aircooled reactors of the 1940s. Reactors with gas, water, and molten salt coolants have been constructed and a variety of fuels, and fissile/fertile fuel mixtures, have been used. The evolution and essential features of graphite moderated power producing reactors are described here, and details of their graphites cores are given. 

In support of the development of graphite moderated reactors, an enormous amount of research has been conducted on the effects of neutron irradiation and radiolytic oxidation on the structure and properties of graphites. The essential mechanisms of these phenomena are understood and the years of research have translated into engineering codes and design practices for the safe design, construction and operation of gas-cooled reactors. 

Gas-cooled, graphite moderated reactors have several significant advantages over other reactor designs by virtue of their inherent passive safety characteristics. These are the result of the large thermal mass of the graphite core, the high... 

CHEMTREC information network, 21 856 Chernobyl-4 graphite-moderated reactor, 17 571-572... 

Table 4. Estimated sensitivities of radioactivation analyses by irradiation in a natural uranium, graphite moderated, reactor...

The first self-sustaining nuclear reactor built by Fermi in Chicago, which came on stream in 1942, was a gas-cooled graphite-moderated reactor. 

In contrast with AGR-reactors, the high temperature reactors (HTR) currently in development, which are also gas-cooled graphite-moderated reactors, helium is the cooling gas, thereby avoiding the troublesome corrosion of graphite by carbon dioxide, according to the equation ... 

In graphite-moderated reactors another source of C is the (n, 7) reaction with C, which is present as 1.108 percent of the natural carbon in graphite ... 

A rather unique design is the pebble bed reactor, see Figure 20.3. It is a helium cooled graphite moderated reactor with a core consisting of a bed of spheres each about 6 cm in diameter. The fuel is initially based on a mixture of carbides as microspheres... 

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