Yellowcake is a type of uranium concentrate powder that is produced from uranium ore. It is an intermediate step in the processing of uranium for use in nuclear fuel. The powder is typically yellow or brown in color, which is how it gets its name. Yellowcake contains a high percentage of uranium, usually around 70-90%. It is not directly usable as fuel but must be further processed into uranium hexafluoride before it can be enriched for use in nuclear reactors or nuclear weapons. The production and handling of yellowcake are regulated due to its radioactive properties.