Waste high-level solid

Solid waste comes from the mining and milling of uranium ore and the sludge from spent fuel storage. It also includes contaminated equipment and structures. High-level solid waste includes the hulls from the dissolving of spent fuel, ion exchange resin, and the like. 

High-Level Solid Waste Treatment. Cladding hulls and dissolver solids are generated as wastes from reprocessing LWR fuels. The alpha activity associated with these head-end wastes is normally low, but as a precautionary measure the WTF provides an area where these wastes may be given an extended tertiary HNO3/KF/ HC1 leach. Experimental studies with mixed-oxide reactor fuels (10,11,12) suggest that actinide losses can be held to 0.01 or less if fluoride and chloride are present in the leachant. 

This description clearly indicates the problems involved in burying high-level solid wastes. 

Aqueous wastes. High-level aqueous wastes HAW (stream 5) and lAW (stream 59) are concentrated by evaporation. The condensate, containing recovered nitric acid, is recycled. Processes for converting the concentrated, unneutralized liquid wastes to solid suitable for long-term storage have not been finalized. 

High bumup of fissile material leads to a high fission product cont t in the fuel elements resulting in the formation of seminoble metal fission product alloys, which are insoluble in boiling nitric acid. The insoluble material ccmsists of mm sized metal particles of Ru, Rh, Tc, Mo, and Pd. These metal particles usually contain negligible amounts of uranium and plutonium and can be filtered as high level solid waste, HLSW. 

High level solid waste (HLSW) originates at the dissolver. The hulls from the dissolution contain activation products and small amounts of imdissolved fuel ( 0.1%). The dissolver solution contains finely divided particles of undissolved seminoble metal alloys (Ru, Rh, Mo, Pd, etc.). This suspension is treated by filtering or centrifugation prior to the solvent extraction. Past practice in the USA and the USSR has been to put the HLSW in shielded containers which are transported to and stored at a dry disposal site. In the future the same disposal is expected to be used for the HLSW as for the solidified HLLW ( 21.12). 

Residual quantities of minor actinides and fission products that are removed from the purification parts of the cycle are usually reduced in volume and then combined in the aqueous raffinate HLW stream. The cladding hulls are managed as high-level solid waste by packaging them in drums and storing the drums in a dry disposal site. 

Applicability Most hazardous waste slurried in water can be mixed directly with cement, and the suspended solids will be incorporated into the rigid matrices of the hardened concrete. This process is especially effective for waste with high levels of toxic metals since at the pH of the cement mixture, most multivalent cations are converted into insoluble hydroxides or carbonates. Metal ions also may be incorporated into the crystalline structure of the cement minerals that form. Materials in the waste (such as sulfides, asbestos, latex and solid plastic wastes) may actually increase the strength and stability of the waste concrete. It is also effective for high-volume, low-toxic, radioactive wastes. 

In conclusion, the technology of total liquefaction of apple allows to work with a continuous process with less labour and faster than with a classical one, to get a high and constant yield during the whole processing season at a very high level (93- 95%), to get a pulp with a low content of solids (about 20% in volume) which can be centrifuged instead of pressed (lower investment in equipment), to decrease the quantity of waste pomace, to decrease the production costs. Liquefaction technology allows to process different fruits with the same process, at last to liquefy fruits for which no equipment had been developed to extract the juice or for which the use of pectinases did not allow to get juice such as tropical fruits. 

Studies designed to improve the determination of environmental contaminants will continue to provide refinements and improvements in the determination of acrylonitrile. The current high level of activity in supercritical fluid extraction of solid and semisolid samples should yield improved recoveries and sensitivities for the determination of acrylonitrile in solid wastes, and the compound should be amenable to supercritical fluid chromatographic analysis. Immunoassay analysis is another area of intense current activity from which substantial advances in the determination of acrylonitrile in environmental samples can be anticipated (Vanderlaan et al. 1988). 

Can treat waste streams with high levels of suspended solids without pretreatment. 

High-level waste (HLW), intermediate-level waste (ILW), and low-level waste (LLW) are produced at all stages of the nuclear fuel cycle as well as in the non-nuclear industry, research institutions, and hospitals. The nuclear fuel cycle produces liquid, solid, and gaseous wastes. Moreover, spent nuclear fuel (SNF) is considered either as a source of U and Pu for re-use or as radioactive waste (Johnson Shoesmith 1988), depending on whether the closed ( reprocessing ) or the open ( once-through ) nuclear fuel cycle is realized, respectively (Ewing, 2004). 

Clark, W. E. Godbee, H. W. 1963. Fixation of simulated highly radioactive wastes in glassy solids. In Treatment and Storage of High Level Radioactive Wastes. IAEA, Vienna, 412-432. 

Nuclear Waste. NRC defines high level radioactive waste to include (/) irradiated (spent) reactor fuel (2) liquid waste resulting from the operation of the first cycle solvent extraction system, and the concentrated wastes from subsequent extraction cycles, in a facility for reprocessing irradiated reactor fuel and (3) solids into which such liquid wastes have been converted. Approximately 23,000 metric tons of spent nuclear fuel has been stored at commercial nuclear reactors as of 1991. This amount is expected to double by the year 2001. 

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