Module 102 The Nuclear Fuel Cycle
Yellowcake contains 70-90% by weight of
uranium oxides . The leftover mill tailings
are a concern because they still contain
some of the uranium ore . Additional
hazards exist due to the chemicals added.
It is estimated that the uranium milling in
the United States left approximately 138
million tons of mill tailings covering about
3,000 acres of land.
The yellowcake slurry is then purified by
either ion exchange or solvent extraction.
Following pur ification , the yellowcake
slurry is dried, forming a concentrated
yellowcake compound that contains 75 - 98
percent uranium. The yellow color is
caused by the addition of leaching
chemicals and their eventual removal
during the drying step. The final color can
range from yellow to orange to black
depending on the chemicals used and the
The final color is a good indicator of
solubility, and thus of biological effects if
uranium in this form is taken into the body.
Less soluble uranium compounds tend both
to remain in the body longer and to be