isotopes capable of being readily transformed directly or indirectly, into fissionable material by the absorption of neutrons, particularly uranium-238 and thorium-232
When these fertile materials capture neutrons, they are converted into fissile plutonium-239 and uranium-233, respectively.
Thermal power stations and other combustion installations with a heat output of 300 megawatts or more and nuclear power stations and other nuclear reactors (except research installations for the production and conversion of fissionable and fertile materials, whose maximum power does not exceed 1 kilowatt continuous thermal load).
Nuclear fission fuels are classified as fertile or fissile by the behaviour or their nuclei in fission reactions. The fertile fuels are those whose nuclei, if they react with a neutron, will be likely to capture it and undergo transmutation into the nuclei of fissile fuels. Uranium-238 is them most commonly used fertile fuel. It decays on absorption of a neutron and loss of a beta-particle into plutonium-239.
