Definition - What does Yellowcake mean?
Yellowcake is a concentrated uranium powder obtained from uranium ore and is the result of the initial processing of uranium prior to transforming it into fuel. It emits low levels of radiation and has a very long half-life. It is the form of Uranium that precedes U3O8, also known as Uranium octaoxide concentrate.
Safeopedia explains Yellowcake
Although yellowcake itself emits very low levels of radiation, it can give off toxic gases including radon during storage. In 2014, the NRC released a series of guidelines aimed at preventing the build-up of gases in yellowcake storage drums. OSHA is currently considering comment in order to revise the existing uranium exposure limits to be applied in uranium mining and manufacturing processes. Primary concerns surrounding yellowcake are inhalation of the dust and the potential effects of skin contact.