Disposal of Waste from Nuclear Power Stations

6 Disposal of Waste from Nuclear Power Stations 

The spent fuel elements contain in addition to radioactive fission products considerable quantities of fissile uranium and plutonium, which are produced in the nuclear reactor. For a burn up, which gives the ratio of the energy produced with the nuclear fuel to the mass of heavy metals in the nuclear fuel, of e.g. 33,000 MWd per t uranium, a spent fuel, originally consisting of 3.2% 235y and 96.8% 238u, still contains 0.76% uranium, 0.9% plutonium (70% fissile) and about 3.5% of fission products. To recycle the not yet utilized and the bred plutonium, they have to be 

The precedence of reprocessing spent fuel elements to dispose of the radioactive waste was abandoned in the middle of 1994. Since then direct permanent storage has been awarded equal legal precedence to a waste disposal option on the basis of reprocessing. It is expected that the electricity industry will make increasing use of this 

Since 1994 direct permanent storage on an equal footing in the Federal Republic of Gemiany 

The conventional waste disposal in energy and economically more advantageous  

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On the other hand, there is the question of disposal of domestic and general industrial wastes. There are toxic wastes which require more careful handling. Of particular concern are radioactive wastes from nuclear power stations. With the latter, there are stringent regulations for safe disposal to minimize contamination of the land surface and neighboring surface waters. 

The last stage in the disposal of nuclear power station waste is long-term secure permanent storage of the solidified high, medium and low activity waste. Annually 5000 m- of radioactive waste is produced in the Federal Republic of Germany, of which only half comes from nuclear power stations. 

Spent fuel from nuclear power stations contains radiogenic U and Pu, and highly radioactive waste solution is produced when the spent fuel is reprocessed. This waste solution needs to be disposed of as it remains highly radioactive for a very long period. 

Liquid waste is generated in numerous places with activities <0.1 GBq/ m. Such waste is classified as low level. Some of these liquids may be clean enough to be released directly into the environment. Others are cleaned by flocculation, ion exchange, sorption, and similar processes. The general philosophy for liquid wastes is to concentrate all radioactivity to the next higher level because the waste volumes decrease in the order LLLW > MLLW > HLLW. Thus, in principle, the three kinds of wastes are reduced to two (HLLW and MLLW) and cleaned aqueous effluent. The MLLW and residues from LLLW cleaning are treated as the wastes of the nuclear power stations, i.e. concentrated and put into a disposal matrix such as concrete or bitumen (see 20.4.3). At some coastal sites it has been the practice to release the LLLW to the sea, with official permission. The nuclides of main concern are H, °Sr, Cs, Ru, and the actinides. 

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