Aerosols uranium

Yang, Y., Xiao, S., Zhang, Y. et al. (2013). In situ detection of trace aerosol uranium using a handheld photometer and solid reagent kit. Anal. Methods 5,4785-4789. 

By far the largest use of hydrogen fluoride is in the manufacture of fluorocarbons which find a wide variety of uses including refrigerants, aerosol propellants and anaesthetics. Hydrogen fluoride is also used in the manufacture of synthetic cryolite, Na3AIFg, and the production of enriched uranium. 

Stanley JA, Edison AF, Mewhinney JA, et al. 1978. Inhalation toxicology of industrial plutonium and uranium oxide aerosols II. Deposition, retention and dosimetry. Health Phys 35(6) 888. 

Stanley JA, Edison AF, Mewhinney JA. 1982. Distribution, retention and dosimetry of plutonium and americium in the rat, dog and monkey after inhalation of an industrial-mixed uranium and plutonium oxide aerosol. Health Phys 43(4) 521-530. 

Si(Li) spectroscopy, with the capability of simultaneous quantitative analysis of 72 elements ranging from sodium through to uranium in solid, liquid, thin film and aerosol filter samples. The penetrating power of protons allows sampling of depths of several tens of microns, and the beam itself may be focussed, rastered or varied in energy. The use of a proton beam as an excitation source offers several advantages over other X-ray techniques, for example there is a higher rate of data accumulation across the entire spectrum which allows for faster analysis. 

Theoretical unattached fractions of RaA using average aerosol concentrations and count median diameters as found in track and trackless Canadian uranium mine are presented in Table III. The reported uranium mine aerosol properties are N 120,000 particles/cm3 and CMD = 0.069 ym for a trackless mine and N =... 

Busigin, A., A.W. van der Vooren and C.R. Phillips, Measurement of the Total and Radioactive Aerosol Size Distributions in a Canadian Uranium Mine, Amer. Ind. Hyg. Assoc. J. 42 310-314 (1981). 

Bigu, J., Radon Daughter and Thoron Daughter Deposition Velocity and Unattached Fraction Under Laboratory-Controlled Conditions and in Underground Uranium Mines, Aerosol Sci., 16 157-165 (1985). 

Radon-222, a decay product of the naturally occuring radioactive element uranium-238, emanates from soil and masonry materials and is released from coal-fired power plants. Even though Rn-222 is an inert gas, its decay products are chemically active. Rn-222 has a a half-life of 3.825 days and undergoes four succesive alpha and/or beta decays to Po-218 (RaA), Pb-214 (RaB), Bi-214 (RaC), and Po-214 (RaC ). These four decay products have short half-lifes and thus decay to 22.3 year Pb-210 (RaD). The radioactive decays products of Rn-222 have a tendency to attach to ambient aerosol particles. The size of the resulting radioactive particle depends on the available aerosol. The attachment of these radionuclides to small, respirable particles is an important mechanism for the retention of activity in air and the transport to people. 

The characteristic feature of the uranium exploration industry is the radioactivity of all wastes. The quality of these wastes, such as radon, radioactive aerosols, and dust emitted to the atmosphere, depends on mine production and the radioactive budget in the mines. For example, middle range mine exploring the ores with n x 10 1-10 2% of U content emits to the atmosphere up to 8 x 1010 Bq/day of radon. 

Bigu J. 1985. Radon daughter and thoron daughter deposition velocity and unattached fraction under laboratory-controlled conditions and in underground uranium mines. J Aerosol Sci 16 157-165. 

The release of 131I and other fission products in reactor accidents has been considered in the previous chapter. In the Windscale accident, the temperature in the fire zone reached an estimated 1300°C and 8 tonne of uranium metal melted. Over 25% of the 1311 in the melted fuel escaped to atmosphere. In the Chernobyl accident, the fuel was U02, the temperature exceeded 2000°C, and about 25% of the total reactor inventory of 131I was released to atmosphere, as vapour or particulate aerosol. In the Three Mile Island accident, 131I remained almost completely in the reactor coolant. The activities of 131I released in reactor accidents, including that at Chernobyl, have totalled much less than the activities released from weapons tests (Table 2.3). 

The particle size of Pu aerosols is very variable, depending on the mode of formation. In Fig. 5.2, curves A, B and C show size spectra obtained by Carter Stewart (1971) in laboratory experiments on the oxidation of Pu metal in air. In controlled oxidation at temperatures below the ignition point (about 500°C), scaly, friable, oxide particles were produced, with median diameter increasing with temperature. Few particles less than 1 jum in diameter were found. When the delta alloy of Pu was used, the oxide was more adherent, and the particle size larger. Increase of particle size with increase of temperature was also found in laboratory oxidation of uranium metal (Megaw et al., 1961), and was ascribed to sintering of the oxide layer. 

This experiment presents the measurement of uranium with an inductively coupled plasma mass spectrometer (ICP-MS). In this system, a nebulizer converts the aqueous sample to an aerosol carried with argon gas. A torch heats the aerosol to vaporize and atomize the contents in quartz tubes. The atoms are ionized with an efficiency of about 95% by an RF (radiofrequency) coil. The plasma expands at a differentially-pumped air-vacuum interface into a vacuum chamber. The positive ions are focused and injected into the MS while the rest of the gas is removed by the pump. The ions are then accelerated, collected, and measured as a function of their mass. Losses at various stages, notably the vacuum interface, result in a detection efficiency of about 0.1 %, which is still sufficient to provide great sensitivity. The amounts of uranium isotopes in the sample are determined by comparisons to standards. Because different laboratories have different instruments, the instructor will provide instrument operating instmctions. Do not use the instrument until the instructor has checked the instrument and approved its use. 

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