FERITILE FUELS

Hi guys, 
How are you? I Am fine . Hope all are doing well. Some materials are not fissionable by themselves. Yet, they can be converted as fissionable materials. They are called as fertile fuels. They absorb neutron and undergo spontaneous change to produce fissionable materials. Only U235 is available in nature. U233 and Pu 239are produced artificially. U233 is produced by nuclear reaction of thorium element. Pu239 is produced by neutron irridation of U238 and Th232 are known as fertile fuels. Thank you.