Radiochemistry
Radiochemistry is the
Radiochemistry includes the study of both natural and man-made radioisotopes.
Main decay modes
All radioisotopes are unstable
emission decay pathways.1.
2.
3.
These three types of radiation can be distinguished by their difference in penetrating power.
Alpha can be stopped quite easily by a few centimetres of air or a piece of paper and is equivalent to a helium nucleus. Beta can be cut off by an aluminium sheet just a few millimetres thick and are electrons. Gamma is the most penetrating of the three and is a massless chargeless high-energy
-based) to reduce its intensity.Activation analysis
By neutron irradiation of objects, it is possible to induce radioactivity; this activation of stable isotopes to create radioisotopes is the basis of neutron activation analysis. A high-energy most interesting object which has been studied in this way is the hair of Napoleon's head, which has been examined for its arsenic content.[1]
A series of different experimental methods exist, these have been designed to enable the measurement of a range of different elements in different matrices. To reduce the effect of the matrix it is common to use the chemical extraction of the wanted element and/or to allow the radioactivity due to the matrix elements to decay before the measurement of the radioactivity. Since the matrix effect can be corrected by observing the decay spectrum, little or no sample preparation is required for some samples, making neutron activation analysis less susceptible to contamination.
The effects of a series of different cooling times can be seen if a hypothetical sample that contains sodium, uranium, and cobalt in a 100:10:1 ratio was subjected to a very short pulse of
Biology applications
One biological application is the study of DNA using radioactive phosphorus-32. In these experiments, stable phosphorus is replaced by the chemically identical radioactive P-32, and the resulting radioactivity is used in the analysis of the molecules and their behaviour.
Another example is the work that was done on the methylation of elements such as
In medicine PET (Positron Emission Tomography) scans are commonly used for diagnostic purposes in. A radiative tracer is injected intravenously into the patient and then taken to the PET machine. The radioactive tracer releases radiation outward from the patient and the cameras in the machine interpret the radiation rays from the tracer. PET scan machines use solid state scintillation detection because of their high detection efficiency, NaI(Tl) crystals absorb the tracer's radiation and produce photons that get converted into an electrical signal for the machine to analyze.[4]
Environmental
Radiochemistry also includes the study of the behaviour of radioisotopes in the environment; for instance, a forest or grass fire can make radioisotopes mobile again.[5] In these experiments, fires were started in the exclusion zone around Chernobyl and the radioactivity in the air downwind was measured.
It is important to note that a vast number of processes can release radioactivity into the environment, for example, the action of cosmic rays on the air is responsible for the formation of radioisotopes (such as 14C and 32P), the decay of 226Ra forms 222Rn which is a gas which can diffuse through rocks before entering buildings[6][7][8] and dissolve in water and thus enter drinking water[9] In addition, human activities such as bomb tests, accidents,[10] and normal releases from industry have resulted in the release of radioactivity.
Chemical form of the actinides
The environmental chemistry of some radioactive elements such as plutonium is complicated by the fact that solutions of this element can undergo
Movement of colloids
While binding of a metal to the surfaces of the soil particles can prevent its movement through a layer of soil, it is possible for the particles of soil that bear the radioactive metal can migrate as colloidal particles through the soil. This has been shown to occur using soil particles labeled with 134Cs, these are able to move through cracks in the soil.[16]
Normal background
Radioactivity is present everywhere on Earth since its formation. According to the International Atomic Energy Agency, one kilogram of soil typically contains the following amounts of the following three natural radioisotopes 370 Bq 40K (typical range 100–700 Bq), 25 Bq 226Ra (typical range 10–50 Bq), 25 Bq 238U (typical range 10–50 Bq) and 25 Bq 232Th (typical range 7–50 Bq).[17]
Action of microorganisms
The action of micro-organisms can fix uranium;
2 cations to uranium dioxide is that the bacteria reduce the uranyl cations to UO+
2 which then undergoes disproportionation to form UO2+
2 and UO2. This reasoning was based (at least in part) on the observation that NpO+
2 is not converted to an insoluble neptunium oxide by the bacteria.[19]
Education
Despite the growing use of nuclear medicine, the potential expansion of nuclear power plants, and worries about protection against nuclear threats and the management of the nuclear waste generated in past decades, the number of students opting to specialize in nuclear and radiochemistry has decreased significantly over the past few decades. Now, with many experts in these fields approaching retirement age, action is needed to avoid a workforce gap in these critical fields, for example by building student interest in these careers, expanding the educational capacity of universities and colleges, and providing more specific on-the-job training.[20]
Nuclear and Radiochemistry (NRC) is mostly being taught at the university level, usually first at the Master- and PhD-degree level. In Europe, substantial effort is being done to harmonize and prepare the NRC education for the industry's and society's future needs. This effort is being coordinated in projects funded by the Coordinated Action supported by the European Atomic Energy Community's 7th Framework Program: The CINCH-II project - Cooperation in education and training In Nuclear Chemistry.
References
- ^ H. Smith, S. Forshufvud and A. Wassén, Nature, 1962, 194(26 May), 725–726
- ^ N. Momoshima, Li-X. Song, S. Osaki and Y. Maeda, "Biologically induced Po emission from fresh water", Journal of Environmental Radioactivity, 2002, 63, 187–197
- ^ N. Momoshima, Li-X. Song, S. Osaki and Y. Maeda, "Formation and emission of volatile polonium compound by microbial activity and polonium methylation with methylcobalamin", Environmental Science and Technology, 2001, 35, 2956–2960
- ISBN 9781441908049.
- PMID 16213067
- ^ Janja Vaupotič and Ivan Kobal, "Effective doses in schools based on nanosize radon progeny aerosols", Atmospheric Environment, 2006, 40, 7494–7507
- ^ Michael Durand, Building and Environment, "Indoor air pollution caused by geothermal gases", 2006, 41, 1607–1610
- ^ Paolo Boffetta, "Human cancer from environmental pollutants: The epidemiological evidence", Mutation Research/Genetic Toxicology and Environmental Mutagenesis, 2006, 608, 157–162
- ^ M. Forte, R. Rusconi, M. T. Cazzaniga and G. Sgorbati, "The measurement of radioactivity in Italian drinking waters". Microchemical Journal, 2007, 85, 98–102
- ^ R. Pöllänen, M. E. Ketterer, S. Lehto, M. Hokkanen, T. K. Ikäheimonen, T. Siiskonen, M. Moring, M. P. Rubio Montero and A. Martín Sánchez, "Multi-technique characterization of a nuclearbomb particle from the Palomares accident", Journal of Environmental Radioactivity, 2006, 90, 15–28
- ^ Rabideau, S.W., Journal of the American Chemical Society, 1957, 79, 6350–6353
- ^ P. G. Allen, J. J. Bucher, D. K. Shuh, N. M. Edelstein, and T. Reich, "Investigation of Aquo and Chloro Complexes of UO22+, NpO2+, Np4+, and Pu3+ by X-ray Absorption Fine Structure Spectroscopy", Inorganic Chemistry, 1997, 36, 4676–4683
- ^ David L. Clark, Steven D. Conradson, D. Webster Keogh Phillip D. Palmer Brian L. Scott and C. Drew Tait, "Identification of the Limiting Species in the Plutonium(IV) Carbonate System. Solid State and Solution Molecular Structure of the [Pu(CO3)5]6− Ion", Inorganic Chemistry, 1998, 37, 2893–2899
- ^ Jörg Rothe, Clemens Walther, Melissa A. Denecke, and Th. Fanghänel, "XAFS and LIBD Investigation of the Formation and Structure of Colloidal Pu(IV) Hydrolysis Products ", Inorganic Chemistry, 2004, 43, 4708–4718
- ^ M. C. Duff, D. B. Hunter, I. R. Triay, P. M. Bertsch, D. T. Reed, S. R. Sutton, G. Shea-McCarthy, J. Kitten, P. Eng, S. J. Chipera, and D. T. Vaniman, "Mineral Associations and Average Oxidation States of Sorbed Pu on Tuff", Environ. Sci. Technol., 1999, 33, 2163–2169
- ^ R. D. Whicker and S. A. Ibrahim, "Vertical migration of 134Cs bearing soil particles in arid soils: implications for plutonium redistribution", Journal of Environmental Radioactivity, 2006, 88, 171–188.
- ^ "Generic Procedures for Assessment and Response during a Radiological Emergency", International Atomic Energy Agency TECDOC Series number 1162, published in 2000 [1]
- ^ Yul Roh, Shi V. Liu, Guangshan Li, Heshu Huang, Tommy J. Phelps, and Jizhong Zhou, "Isolation and Characterization of Metal-Reducing Thermoanaerobacter Strains from Deep Subsurface Environments of the Piceance Basin, Colorado", Applied and Environmental Microbiology, 2002, 68, 6013–6020.
- ^ Joanna C. Renshaw, Laura J. C. Butchins, Francis R. Livens, Iain May, John M. Charnock, and Jonathan R. Lloyd, Environ. Sci. Technol., 2005, 39(15), 5657–5660.
- ISBN 978-0-309-22534-2.