Advanced graphite reactor

Another 14 U.K. reactors are of the advanced graphite reactor (AGR) type, utilizing slightly eturiched uranium as a fuel. The AGRs have an average age of about 13 years, and are currently owned and operated by British Energy... 

Critical and subcritical experiments, in support of the Advanced ium Graphite Reactor fASGR) program, . have been performed to determine values of material buckling for graphite assemblies fueled with slightly-enriched (3.02 wt%), uranium carbide-fuel elements. These experiments provide the first data available for comparison with results of calculations. 

The gas-cooled reactors were developed in Great Britain using CO2 as the gas coolant and graphite as the moderator with natural uranium metal as the fuel. The thermal efficiency is about 25%. With uranium enriched to 2.2% as the oxide (UO2) fuel, the thermal efficiency increased to 41% and is called the advanced gas reactor (AGR). Helium is also used in a high-temperature version. 

Compared with designs for a more advanced gas-cooled reactor, the sodium-graphite reactor appeared to offer serious technical problems combined with poor economics, which meant that it was soon dropped from the programme. 

In all studies it was assumed that the installed capacity in 1975 could be subdivided into (1) natural uranium graphite reactors (MGR) 9500 MW (2) advanced gas-cooled reactors (AGR) 8500 MW and (3) light water reactors (LWR) 17000 MW. 

Fig. 4. A typical advanced gas-cooled reactor graphite core (Hinkley Point B under construction) [11].

Kelly, B.T., The radiolytic corrosion of advanced gas-coolcd reactor graphite. Progress in Nucl. Energy, 1985, 16(1), 73 96. 

Kelly, B.T., The effect of radiolytic oxidation on the graphite moderator brick strength in advanced gas-cooled reactors, Nucl. Energy, 1984, 24(3), 265 272. 

Other newer designs include the advanced, gas-cooled reactor (AGR), Canadian deuterium reactor (CANDUR), sodium-cooled reactor (SCR), sodium-heated reactor (SHR), and fast breeder reactor (FBR). These reactors employ either natural or enriched uranium fuels that may be modified in some way (e.g., graphite-moderated fuels). 

Advanced waste form work is also being carried out in the Ceramics and Graphite Section at PNL, where high temperature gas-cooled reactor fuel technology is applied to waste solidification. Waste particles are coated with pyrolytic carbon followed by a cover coat of silicon carbide. These coated particles would then be placed in a matrix of inert material contained in a canister of yet another material. 

Neutron activation analysis is one of a small number of methods capable of multi-elemental analysis of subnanogram quantities of contaminants in semiconductors and other materials. Milligram to gram-sized samples of silicon, quartz, graphite, or organic materials are nearly Ideal for the method. The physics of the processes involved is simple, and qualitative identification of components is an Integral part of the quantitative analysis. Except for the need for access to a nuclear reactor, the equipment required is readily available commercially, and is comparable in cost and complexity to that used in other advanced analytical techniques. 

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