Reactor Types, Moderators, and Coolants

Generally, reactors that use light water as their coolant require low-enriched uranium (LEU usually of 2%-5% U) as fuel while graphite gas-cooled reactors and heavy water reactors are normally operated with fuel in which the uranium is of natural isotopic composition. 

It should be noted that there are less common reactor types like the liquid metal fast breeder reactors (LMFBR) and molten salt reactors (MSR) in which fast neutrons are responsible for most of the fission reactions and the coolant can be a liquid metal (e.g., sodium or lead) or the molten salt itself. 

Electrical power backtx)pknt to power internal components 

FIGURE 1.15 A schematic of a generic nuclear power plant. (From World Nuclear Association, http //www.world-nuclear.org/info/Nuclear-Fuel-Cycle/Power-Reactors/Nuclear-Power-Reactors/, accessed July 26,2014. With permission.) 

Pellets into fuel rods and fuel assemblies 

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