Radioactive Waste Treatment

NRC), 17 528, 532, 539, 597-598. See also NRC safety goal radioactive waste treatment under,... 

Potential applications for CA-CDI technology include the purification of boiler water for fossil and nuclear power plants, volume reduction of liquid radioactive waste, treatment of agricultural wastewater containing pesticides and other toxic compounds, creation of ultrapure water for semiconductor processing, treatment of wastewater from electroplating operations, desalination of seawater, and removal of salt from water for agricultural irrigation. 

Dmitriev, S. A., Stefanovsky, S. V., Knyazev, I. A. Lifanov, F. A. 1995. Characterization of slag product from plasma furnace for unsorted solid radioactive waste treatment. Materials Research Society Symposium Proceedings, 353, 1323-1332. 

Dozol, J.F., Bohmer, V., McKervey, A. et al. 1997. New macrocyclic extractants for radioactive waste treatment Ionizable crown ethers and functionalized calixarenes. Report EUR-17615. 

Casnati, A., Sansone, F., Dozol, J.F. 2001. New calyx[4]arene-monobenzo- and dibenzo-crown-6 as cesium selective ionophores in the radioactive waste treatment Synthesis, complexation and extraction properties. J. Inch Phenom. Macro. Chem, 41 (1-4) 193-200. 

J.-F. Dozol, V. Bohmer, M. A. McKervey, F. Lopez-Calahorra, D. N. Reinhoudt, M. J. Schwing, R. Ungaro and G. Wipff, New macrocyclic extractants for radioactive waste treatment Ionizable crown ethers and functionalized calixarenes, EUR-OP Reference CG-NA-17615-EN-C (EUR-17615), European Commission, Nuclear Science and Technology, Luxembourg, 1997. 

A.S. Wagh, D. Singh, and S.Y. Jeong, Chemically bonded phosphate ceramics for stabilization and solidification of mixed wastes, Hazardous and Radioactive Waste Treatment Technologies Handbook (CRC Press, Boca Raton, FL, 2001), pp. 6.3.1-6.3.18. 

Calcinm glectrowinning in piutniiium production. A potential application of inorganic membranes in radioactive waste treatment is in the industrially practiced direct oxide reduction process. In this process plutonium oxide is calciothermit y reduced to plutonium in the presence of calcium chloride according to the following reaction ... 

Radioactive waste treatment applications have been reported [3-9] for the laundry wastes from nuclear power plants and mixed laboratory wastes. Another interesting application of reverse osmosis process is in decontamination of boric acid wastes from pressurized heavy water reactors (PHWRs), which allows for the recovery of boric acid, by using the fact that the latter is relatively undissociated and hence wdl pass with water through the membrane while most of the radioactivity is retained [10]. Reverse osmosis was evaluated for treating fuel storage pool water, and for low-level liquid effluents from reprocessing plants. 

In radioactive waste treatment, significant operational aspects include the following. Since the operation requires the use of high pressures, there is a need to ensure control of the activity release from possible leaks. As with evaporation, pretreatment of the feed may be necessary to prevent scaling, and where dirty waters are to be fed directly it would be advisable to consider the use of equipment with larger membrane flow channels, which would permit periodic foam ball cleaning of the membrane surface. 

Membrane Processes Employed for Liquid Radioactive Waste Treatment.850... 

MEMBRANE PROCESSES EMPLOYED FOR LIQUID RADIOACTIVE WASTE TREATMENT... 

The RO process was implemented at the Institute of Atomic Energy, Swierk. The wastes collected there, from all users of nuclear materials in Poland, have to be processed before safe disposal. Until 1990 the wastes were treated by chemical methods that sometimes did not ensure sufficient decontamination. To reach the discharge standards the system of radioactive waste treatment was modernized. A new evaporator integrated with membrane installation replaced old technology based on chemical precipitation with sorption on inorganic sorbents. Two installations, EV and 3RO, can operate simultaneously or separately. The membrane plant is applied for initial concentration of the waste before the evaporator. It may be also used for final cleaning of the distillate, depending on actual needs. The need for additional distillate purification is necessitated due to entrainment of radionuclides with droplets or with the volatile radioactive compounds, which are carried over. 

The processes of UF and enhanced UF for low and intermediate-level radioactive waste treatment were studied at INCT, Poland. Liquid radioactive wastes originating mainly form application of radioisotopes are collected from all of Poland at Institute of Atomic Energy, in Swierk. They contain various radioactive substances (total specific activity <10 kBq/m ) and ballast non-active salts (concentration <5 g/dcm ), as well. In the solution, small radioactive ions such as H CrO, ... 

FIGURE 30.15 Radioactive waste treatment by UF/complexation. (Reprinted from Zakrzewska-Trznadel, G. and Harasimowicz, M.,... 

In Table 30.15, decontamination factors for different processes for low- and medium-level radioactive waste treatment are shown. Membrane distillation with its high decontamination factors is a competitive method in this field. However, it has to be mentioned that these high-decontamination factors are achieved from low-volatile solute after adequate pretreatment. 

The elaboration of proper pretreatment methods, application of antisealants, and minimization of secondary wastes created during cleaning cycles are of great importance. At present the research work on use of pressure-driven processes for radioactive waste treatment is focused on following issues ... 

Despite of some technical and process limitations, membrane techniques are very useful methods for the treatment of different types of effluents. They can be applied in nuclear centers processing low- and intermediate-level liquid radioactive wastes or in fuel reprocessing plants. All the methods reported in the chapter have many advantages and can be easily adapted for actual, specific needs. Some of them are good pretreatment methods the other can be used separately as final cleaning steps, or can be integrated with other processes. Membrane methods can supplement or replace techniques of distillation, extraction, adsorption, ion exchange, etc. Evaluation of membrane processes employed for liquid radioactive waste treatment is presented in Table 30.17. 

Chmielewski, A.G., Harasimowicz, M., and Zakrzewska-Trznadel, G., Membrane technologies for liquid radioactive waste treatment, Czech. J. Phys., 49, 979, 1999. 

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