Mill tailings wastes are the residues remaining after the processing of natural ore to extract uranium and thorium. The low-level wastes can include radioactively contaminated protective clothing, tools, filters, rags, medical tubes, and many other items. NRC licensees are encouraged to manage their activities so as to limit the amount of radioactive waste they produce. Techniques include avoiding the spread of radioactive contamination, surveying items to ensure that they are radioactive before placing them in a radioactive waste container, using care to avoid mixing contaminated waste with other trash, using radioactive materials whose radioactivity diminishes quickly and limiting radioactive material usage to the minimum necessary to establish the objective. Licensees take steps to reduce the volume of radioactive waste after it has been produced.
Common means are compaction and incineration.
Approximately 70 NRC licensees are authorized to incinerate certain low-level wastes, although most incineration is performed by a small number of commercial incinerators. The radioactivity of nuclear waste decreases with the passage of time, through a process called radioactive decay. Radioactive waste with a short half-life is often stored temporarily before disposal in order to reduce potential radiation doses to workers who handle and transport the waste, as well as to reduce the radiation levels at disposal sites. Most uranium mill tailings are disposed of in place or near the mill, after constructing a barrier of a material such as clay on top of the pile to prevent radon from escaping into the atmosphere and covering the mill tailings pile with soil, rocks or other materials to prevent erosion. The remainder of the low-level waste is stored primarily at the site where is was produced, such as at hospitals, research facilities, clinics and nuclear power plants.