Power Plant Engineering

 Fig. 13.5. A typical low-level liquid-waste storage tank with double-walled containment.
13.17.2 WASTES
The wastes associated with nuclear power can be summarized as:
1. Gaseous effluents. Under normal operation, these are released slowly from the power plants
into the biosphere and become diluted and dispersed harmlessly.
2. Uranium mine and mill tailings. Tailings are residues from uranium mining and milling
operations. They contain low concentrations of naturally occurring radio-active materials. They are
generated in large volumes and are stored at the mine or mill sites.
3. Low-level wastes (LLW). These are classified as wastes that contain less than 10 nCi
(nanocuries) per gram of transuranium contaminants and that have low but potentially hazardous con-
centrations of radioactive materials. They are generated in almost all activities (power generation, medi-
cal, industrial, etc.) that involve radioactive materials, require little or no shielding, and are usually
disposed of in liquid form by shallow land burial (Fig. 13.5).
4. High-level wastes (HLW). These are generated in the reprocessing of spent fuel. They con-
tain essentially all the fission products and most of the transuranium elements not separated during
reprocessing. Such wastes are to be disposed of carefully.
5. Spent fuel. This is unreprocessed spent fuel that is removed from the reactor core after reach-
ing its end-of-life core service. It is usually removed intact in its fuel element structural form and then
stored for 3 to 4 months under water on the plant site to give time for the most intense radioactive

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isotopes (which are the ones with shortest half-lives) to decay before shipment for reprocessing or
disposal. Lack of a reprocessing capacity or a disposal policy has resulted in longer on-site storage,
however. If the spent fuel is to be disposed of in a throwaway system (without reprocessing), it is treated
as high-level waste.