Nuclear fission cesium from

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). 

The anthropogenic radionuclides of most concern are those produced as fission products from nuclear weapons and nuclear reactors. The most devastating release from the latter source to date resulted from the April 26, 1986, explosion, partial meltdown of the reactor core, and breach of confinement structures by a power reactor at Chernobyl in the Ukraine. This disaster released 5 x 107 Ci of radionuclides from the site, which contaminated large areas of Soviet Ukraine and Byelorussia, as well as areas of Scandinavia, Italy, France, Poland, Turkey, and Greece. Radioactive fission products that are the same or similar to elements involved in life processes can be particularly hazardous. One of these is radioactive iodine, which tends to accumulate in the thyroid gland, which may develop cancer or otherwise be damaged as a result. Radioactive cesium exists as the Cs+ ion and is similar to sodium and potassium in its physiological behavior. Radioactive strontium forms the Sr2+ ion and substitutes for Ca2+, especially in bone. 

After more than 400 atmospheric nuclear test explosions and the fallout from Chernobyl, Cs became the most frequently released nuclear fission product throughout Central Europe. Cesium behaves like potassium it has a ubiquitous distribution inside the body, especially in soft tissues. In the gastropod Helix pomatia the biological half-time after a single 24-h dietary dose was 2.5 days for the short-lived component and 28.5 days... 

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... 

From these two main groups of the Periodic System of Elements, only the elements bromine, iodine, rubidium and cesium are produced by nuclear fission to an extent worth mentioning. Iodine and cesium are of particular interest during plant normal operation as well as in accident situations, because of their comparatively high fission yields, their enhanced mobility in the fuel at higher temperatures and the radiotoxicity of some of their isotopes. Both elements are often summarized under the term volatile fission products their similar properties justify their treatment in the same context, despite pronounced differences in their basic chemical behavior. 

Alkali metals (K, Rb, Cs) behave similarly and sometimes one is accumulated preferentially when another is deficient. A similar case is made for Sr and Ca (Whicker and Schultz 1982a). The most important alkali metal isotope is Cs because of its long physical half-life (30 years) and its abnndance as a fission prodnct in fallout from nuclear weapons and in the inventory of a nuclear reactor or a fuel-reprocessing plant. Cesium behaves much like potassium. It is rapidly absorbed into the bloodstream and distribnted throughout the active tissues of the body, especially muscle. The P and y radiation from the decay of Cs and its daughter, Ba, result in essentially whole-body irradiation that harms bone marrow (Hobbs and McClellan 1986). 

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. 

Spent fuel from a reactor contains unused uranium as well as plutonium-239 which has been created by bombardment of neutrons during the fission process. Mixed with these useful materials are other highly radioactive and hazardous fission products, such as cesium-137 and strontium-90. Since reprocessed fuels contain plutonium, well suited for making nuclear weapons, concern has been expressed over the possible capture of some of this material by agents or terrorists operating on behalf of unfriendly governments that do not have a nuclear weapons capability. 

Separation of Actinides from the Samples of Irradiated Nuclear Fuels. For the purpose of chemical measurements of burnup and other parameters such as accumulation of transuranium nuclides in irradiated nuclear fuels, an ion-exchange method has been developed to separate systematically the transuranium elements and some fission products selected for burnup monitors (16) Anion exchange was used in hydrochloric acid media to separate the groups of uranium, of neptunium and plutonium, and of the transplutonium elements. Then, cation and anion exchange are combined and applied to each of those groups for further separation and purification. Uranium, neptunium, plutonium, americium and curium can be separated quantitatively and systematically from a spent fuel specimen, as well as cesium and neodymium fission products. 

Cesium, on the other hand, is toxic to plants in anything but trace amounts, whereas indications are that Cs+ ions impair the activity of potassium-binding sites in proteins. Excess cesium can be found in the air and in soils as a by-product of nuclear testing and spent nuclear fuels. Radioactive cesium 137, which results from the fission of uranium 235, decays by emission of a... 

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. 

Design the chlorination unit of the benzene hexachloride plant discussed in Chaps. 3 to 6 to utilize gamma-ray energy from typical spent-fuel elements of nuclear-power reactors and from cesium 137 isolated from fission products. Make a comparative economic study. 

Cesium 137 is an artificial radionuclide used in clinical, industrial, and research applications and one of the main radioactive products of fission reactions taking place in nuclear reactors. The possibility that the anomalous radioactivity derived from active nuclear plants can be rule out as the i Cs was not accompanied by the other radionuclides produced during fission. Towards the end of April 1998, an incident occurred at the Algeciras steel works in southern Spain with emissions of Cs coming from a radioactive source no longer in use. This source ended up in the foundry. The fact that the presence of Cs was interrupted for a week and then resumed is not unusual as the transport and soil deposition of air-dispersed pollutants is strictly linked to wind and precipitation. The levels of radioactivity were negligible and many times below every alarm threshold, but the bee matrix promptly revealed the presence, albeit minimal, of Cs... 

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