Cobalt radioactive

Cobalt in nature consists of one single isotope, Co. By irradiation with neutrons in a nuclear reactor the radioactive isotope Co is obtained. It is a strong y-radiator with a half-life of 5.27 years. This radiation is of the same type as X-rays, and for this reason °Co is used against cancer in cobalt therapy , a special form of radiotherapy. The radiation is also used for sterilizing medical equipment. 

In radiotherapy the radiation energy destroys tumor cells that are later replaced by fresh tissue. Two different methods of treatment are available cobalt therapy and treatment with X-rays, generated in linear accelerators. The latter equipment is technically very sophisticated and complicated. It can be used only in large hospitals with advanced expertise, both medical and technical. In contrast, cobalt therapy is simple and suitable for small hospitals and medical services in developing countries. For 

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Radioactive cobalt, Co, produced by bombarding stable Co with low energy neutrons, has appHcation in radiochemistry, radiography, and food steriliza tion (26-28) (see FoOD PROCESSING RADIOISOTOPES STERILIZATION TECHNIQUES). 

A 1.40-g sample containing radioactive cobalt was kept for 2.50 a, at which time it was found to contain 0.266 g of 67Co. The half-life of 67Co is 5.27 a. What percentage (by mass) of the original sample was f,Co ... 

Further work on nickelocene and cobaltocene was done by Ross , who synthesized the respective compounds using Ni, Ni and " Co, which decay be E.C., jS and a fully converted isomeric transition, respectively, all producing radioactive cobalt isotopes. The results showed retentions, after sublimation, of 84%, 83% and 80%, respectively. The composition of the unsublimable residue was largely CoCp2, except for the highly converted "Co, where only 30% CoCpj could be detected. This was interpreted as showing that by internal conversion the molecules are totally destroyed, by the same sort of argument as was used by Riedel and Merz . 

In order to dissipate the recoil energy Mossbauer was the first to use atoms in solid crystal lattices as emitters and also to cool both emitter and absorber. In this way it could be shown that the 7-ray emission from radioactive cobalt metal was absorbed by metallic iron. However, it was also found that if the iron sample were in any other chemical state, the different chemical surroundings of the iron nucleus produce a sufficient effect on the nuclear energy levels for absorption no longer to occur. To enable a search for the precisely required absorption frequency, a scan based on the Doppler effect was developed. It was noted that a velocity of 102 ms-1 produced an enormous Doppler shift and using the same equation (7) it follows that a readily attainable displacement of the source at a velocity of 1 cms-1 produces a shift of 108 Hz. This shift corresponds to about 100 line-widths and provides a reasonable scan width. 

Although B12 can be assayed biologically in mice, chicks, and rats, especially with the use of radioactive cobalt, the microbiologic method of assay is preferred because it is economical and sensitive. One serious drawback of bacterial Bi2 assay procedures is the lack of specificity and sensitivity. The extreme sensitivity (1 X 10 12 g) and relative freedom of stimulation in blood, serum, and urine make protozoa the choice assay tools (B17, F3, H19). The most specific is O. malhamensis (B17, F3) Euglena is known to be stimulated by pseudo-B12 (F2). Serum and blood from normal subjects have a growth-promoting effect on Euglena (M12) above that seen with Ochromonas. The reason for such... 

Apart from these three facts, nuclear astrophysicists take pains to point out that the rate at which the luminosities of SNla events decline, once beyond the maximum, is commensurable with the decay of radioactive cobalt-56, son of nickel-56, atomic nucleus of noble lineage as we know. This is a common factor with gravitational collapse supernovas. SNla light curves are explained through the hypothesis that half a solar mass of nickel-56 is produced when one of these white dwarfs explodes. 

The most imporant use of cobalt is in the manufacture of various wear-resistant and superalloys. Its alloys have shown high resistance to corrosion and oxidation at high temperatures. They are used in machine components. Also, certain alloys are used in desulfurization and hquefaction of coal and hydrocracking of crude oil shale. Cobalt catalysts are used in many industrial processes. Several cobalt salts have wide commercial apphcations (see individual salts). Cobalt oxide is used in glass to impart pink or blue color. Radioactive cobalt-60 is used in radiography and sterihzation of food. 

Sediments in the Mississippi River were accidentally contaminated with a low-level radioactive waste material that leaked from a nuclear power plant on the river. Pore water concentrations of radioactive compounds were measured following the spill and found to be 10 g/m over a 2-mm depth. The water contamination was 30% radioactive cesium ( Cs), with a half-life of 30 years, and 70% radioactive cobalt ( °Co), with a half-life of 6 years. Objections by the local residents are preventing clean-up efforts because some professor at the local state university convinced them that dredging the sediments and placing them in a disposal facility downstream would expose the residents to still more radioactivity. The state has decided that the sediments should be capped with 10 cm of clay and needs a quick estimate of the diffusion of radioactive material through the clay cap (Figure E2.8.1). If the drinking water limit (10 g/m ) is reached at mid-depth in the cap, the state will increase its thickness. Will this occur ... 

Frolova, L.K. (1960). Some aspects of radioactive cobalt behaviour in the fish organism (In Russian). Zhumal Obshchey Biologii 21,301-305. 

Besides, radioactive cobalt is a common radionuclide in liquid wastes from nuclear facilities, and natural erionite is a good exchanger for 60Co2+. Studies carried out with this material reveal its possibilities in the elimination of radioactive cobalt from solutions [73], The exchange of 232Th4+ in natural clinoptilolite and mordenite from liquid solutions has also been studied [74], All these peculiarities of natural zeolites make it suitable to be exploited as natural barriers for the migration of radionuclides and, consequently, natural zeolite deposits can be potential sites for a radioactive waste repository [19]. These materials have also been employed for the removal of radionuclides from polluted areas in places where nuclear power station accidents have occurred or where... 

In addition to its many uses in medical and physiological research, radioisotopes are used in therapy, and in agricultural and industrial research. Radioactive cobalt, for example, became available for the treatment of deep-seated cancer. This isotope of atomic weight 60 loses half its radioactivity in about five days and is more than 300 times as powerful as radium. It is taking the place of radium and X-ray therapy in many hospitals. 

Compare the chemical properties of radioactive cobalt-60 to those of ordinary cobalt. 

A radiological dispersal device (RDD) explodes, contaminating 10 square miles with radioactive cobalt (Co-60). The highest measured radiation level is about 10 meters from the site of the explosion and it reads about 150 mrem/hr. The average radiation dose through the affected area is 5 mrem/hr, and about 500,000 people live and work in this area. The device itself consisted of 1,000 pounds of explosive, set off near City Hall. 

Almost all elements found in nature can now be made radioactive. Radioactive potassium and phosphorus are used as tracers to measure how effectively plants take up fertilizer from soil. Radioactive iodine is applied in nuclear medicine to diagnose and treat thyroid problems. Radiation treatment for cancer therapy uses radioactive cobalt, which is made by irradiating ordinary cobalt with neutrons. 

Cyanombalamln Radioactive Cobalt ( Co) Capsules, USP. Cyanocobalamin Co capsules contain cyanocobaJ-amin in which some of the molecules contain radioactive cobalt ( Co), Each microgram of this cyanocobalamin preparation has a specific activity of not less than 0.02 MBq (0.. i Ci). The USP cautions that in making dosage calculations one. should correct for radioactive decay. The radioactive half-life of Co is 270 days. 

Cyanocobalamin Co Solution, USP. Cyanocobalamin Co solution has the same potency, dosage, and use as described under Cyanocobalamin Radioactive Cobalt ( Co) Capsulc.s. USP. It is a clear, colorless to pink solution that has a pH range of 4.0 to S.S. 

Cyanocobalamin Radioactive Cobalt ("Co) Capsules, USP. Cyanocobalamin ""Co capsules are the counterpart of cyanocobalamin Co capsules in potency, dosage, and use. They differ only in radioactive half-life, which is S.27 years. 

Stolen radioactive sources, specifically Co (radioactive cobalt), have caused injuries elsewhere, including Juarez, Mexico, and Thailand. Within the United... 

The stability of complexes formed with chloride, citrate, oxalate, and many metal-organic complexes, however, may increase (AW ° > 0) or decrease (AW ° < 0) with increasing temperature. Complexes formed with OH and EDTA are generally less stable at elevated temperatures. For example, the complex formed between EDTA and radioactive cobalt is... 

In a famous experiment in 1957, Chien-Shiung Wu subjected a supercooled sample of radioactive cobalt-60 to an electromagnetic field, causing the nuclei to emit electrons in just two directions, north and south (where the north to south direction is defined as the direction with respect to which the nucleus is rotating anticlockwise). She found that more electrons were being emitted from the south end of the nucleus than from the north. 

Once cobalt is formed by neutron capture, it can itself become the target for neutron capture, a process by which it is converted to radioactive cobalt-60 ... 

Vitamin B12 is water soluble vitamin that can be derived from oysters, salmon, liver, and kidney. At the core of the complex structure of vitamin B12 is a cobalt ion. Suggest a way that radioactive cobalt-57 could be used to determine which tissues of the body adsorb the most vitamin B12. 

There is no critical mass in a fusion bomb, and the force of the explosion is limited only by the quantity of reactants present. Thermonuclear bombs are described as being cleaner than atomic bombs because the only radioactive isotopes they produce are tritium, which is a weak /S-particle emitter (ti = 12.5 yr), and the products of the fission starter. Their damaging effects on the environment can be aggravated, however, by incorporating in the construction some nonfissionable material such as cobalt. Upon bombardment by neutrons, cobalt-59 is converted to cobalt-60, which is a very strong 7-ray emitter with a half-life of 5.2 yr. The presence of radioactive cobalt isotopes in the debris or fallout from a thermonuclear explosion would be fatal to those who survived the initial blast. 

Radioactive cobalt ( Co) is produced by exposing samples to neutrons in a reactor. What is the maximum number of curies that can be obtained from 1 g of cobalt exposed to a thermal-neutron flux of 10 n/(cm s) How long must the cobalt be exposed to obtain an activity of 1 Ci/g ... 

The HTGR fuel contains no metallic structure, but impurities in the graphite fuel blocks result in the production of relatively small amounts of radioactive cobalt and nidcel, as listed in Table 8.12 [HI, P3]. The total activity from metallic contaminants in HTGR fuel is considerably lower than that in the fuels from light-water and breeder reactors. 

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