Cesium removal from nuclear

Z. Asfari, C. Bressot, J. Vicens, C. Hill, J.-F. Dozol, H. Rouquette, S. Eymard, V. Lamare and B. Tournois, Cesium Removal from Nuclear Waste Water by Supported Liquid Membranes Containing Calix-bis-brown Compounds, in ACS Symposium Series 642 (Anaheim CA, April 2-6, 1995), eds. R. A. Bartsch and J. D. Way, American Chemical Society, Washington, DC, Editon edn., 1996, pp. 376-390. 

Cesium Removal from Nuclear Waste Water by Supported Liquid Membranes Containing Calix-bis-crown Compounds... 

Bonnesen, P. V., Delmau, L. H., Haverlock, T. J., Levitskaia, T. G., Sachleben, R. A., Sloop, F. V., Jr., and Moyer, B. A. Science to Applications, Development of the Caustic-Side Solvent Extraction Process for Cesium Removal from Savannah River Waste, Proc. 9th Biennial Intemat. Conf. Nuclear and Hazardous Waste Management (Spectrum 2002), Aug. 4-8, 2002, Reno, Nevada. 

Approximately 25—30% of a reactor s fuel is removed and replaced during plaimed refueling outages, which normally occur every 12 to 18 months. Spent fuel is highly radioactive because it contains by-products from nuclear fission created during reactor operation. A characteristic of these radioactive materials is that they gradually decay, losing their radioactive properties at a set rate. Each radioactive component has a different rate of decay known as its half-life, which is the time it takes for a material to lose half of its radioactivity. The radioactive components in spent nuclear fuel include cobalt-60 (5-yr half-Hfe), cesium-137 (30-yr half-Hfe), and plutonium-239 (24,400-yr half-Hfe). 

Another application for adsorption of metal impurities is in the nuclear power industry. Radioactive cesium is one of the compounds that is difficult to remove from radioactive waste. This is because ordinary resins and zeolites do not effectively adsorb radioactive cesium. In 1997, lONSlV lE-911 crystalline silicotitan-ate (CST) ion exchangers were developed and effectively used to clean up radioactive wastes in the Melton Valley tanks at Oak Ridge [268, 269], CST was discovered [270] by researchers at Sandia National Laboratories and Texas A M University, with commercial manufacture carried out by UOP. 

Cobalt-60 is made by exposing ordinary inexpensive cobalt in an atomic reactor. Strontium-90 is a fission product in nuclear power plants and has a higher beta radiation than cobalt-60. Cesium-137 is a fission product found in all nuclear reactors and must be removed from time to time to maintain efficiency. Evidently large quantities of strontium-90 and cesium-137 will be available in the year to come. 

Finally, both upper and lower rim substitution have been used to produce a class of macrocycles referred to as calixarene-crown ethers, or calixcrowns. One simple example is shown here (103). These receptors combine characteristics of the crown ethers and calixarenes, and have been intensively studied for metal ion extraction, in particular, for the removal of cesium from nuclear waste. ... 

Once the radioactive fission products are isolated by one of the separation processes, the major problem in the nuclear chemical industry must be faced since radioactivity cannot be immediately destroyed (see Fig. 10-7c for curie level of fission-product isotopes versus elapsed time after removal from the neutron source). This source of radiation energy can be employed in the food-processing industries for sterilization and in the chemical industries for such processes as hydrogenation, chlorination, isomerization, and polymerization. Design of radiation facilities to economically employ spent reactor fuel elements, composite or individually isolated fission products such as cesium 137, is one of the problems facing the design engineer in the nuclear field. 

There are many examples of the studies on SLM for nuclear applications in the literature. SLMs were tested for high-level radioactive waste treatment combined with removal of actinides and other fission products from the effluents from nuclear fuel reprocessing plants. The recovery of the species, such as uranium, plutonium, thorium, americium, cerium, europium, strontium, and cesium, was investigated in vari-ons extracting-stripping systems. Selective permeation... 

Vicens and coworkers (Chapter 26) report the use of novel calix-fcw-crown ether compounds as carriers in a supported liquid membrane system for the removal of cesium from nuclear waste water. Decontamination factors of greater than 20 are obtained in the treatment of synthetic acidic radioactive wastes. Very good stability (over 50 days) and high decontamination yields are achieved. 

Removal of Radioactive Materials from Nuclear Waste Streams. ELMs have potential for the removal of radioactive materials such as strontium, plutonium, cesium, uranium, and americium from nuclear waste streams. Eroglu et al. (57) reported an ELM system for the extraction of strontium, which is shown in Table XHI. They extract about 92% of Sr " " from a feed containing 100 mg/L Sr " by the use of D2EHPA as the extractant. 

Bonnesen, P.V., Haverlock, T.J., Engle, N.L., Sachleben, R.A., Moyer, B.A. 2000. Development of process chemistry for the removal of cesium from acidic nuclear waste by calix[4]arene-crown-6 ethers. In Calixarene Molecules for Separations. Lumetta, G.J., Rogers, R.D., Gopalan, A.S. Eds. ACS Symposium Series Vol. 757, American Chemical Society, Washington, DC, pp. 26-44. 

PAN-KCoFC and PAN-4A composite adsorbents were prepared for the removal of cesium and strontium ions from acidic nuclear waste solutions. High porous spheri( composite adsorbents could be prepared using a dual nozzle technique. The acid and radiation stability tests showed that the both composite adsorbents were stable against acid solutions higher than pH - 2 and radiation dose less than 1.89 MGy, respectively. Adsorption tests showed that the PAN-KCoFC was selective for cesium ion and the PAN-zeolite 4A was for strontium ions, respectively. The ion exchange equilibrium isotherms were obtained and evaluated for the binary systems. 

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