Scenario 2: Radioisotopes, Radioactivity & the Hazards of Alpha, Beta and Gamma Radiation
A radioisotope is a derivative of a chemical element that has an unstable nucleus and emits radiation while it decays to a stable form. (An isotope being an alternative of a chemical element that has a different atomic mass)Radioactivity is the emission of particles from the nuclei as a result of nuclear instability.
Radioisotopes decay and emit radiation, specifically alpha (α) rays, beta (β) rays and gamma (γ) rays. In rare cases, the decay of these radioisotopes (eg. uranium or radium) may result in the production of high speed neutrons which get released during nuclear fission. (Hawkhill, 2007)
The following image illustrates the respective deflections of the particles.
The differing deflections is due to the differing charges and the mass of the particles. α particles are positively charged and much larger, thus the angle of deflection would be smaller and in a different direction as compared to β particles which are significantly lighter and negatively charged, thereby resulting in a larger angle of deflection in the opposite direction. γ particles do not contain a charge, thus there is no angle of deflection when the particle passes through the magnetic field.
The differing penetrating powers of the respective particles is illustrated in the image below.
The order of penetrative power is as follows: α < β < γ, with α being of the lowest penetrative power and γ having the highest penetrative power.
Alpha (α) radiation: Releases α particles that are identical in mass and charge with a 4He nucleus and are the largest amongst the 3 types of particles. They generally carry more energy than γ or β particles, and release that energy quickly while passing through tissue.
> α particles can be stopped by a thin layer of light material, e.g. a sheet of paper, and cannot penetrate the outer, dead layer of skin. Therefore, they do not damage living tissue when outside the body.
>However, if inhaled or swallowed, they emit relatively large amounts of ionizing energy which are detrimental to living cells.
> Contains extensive destructive power but only within a short range.
> When in contact with rapidly dividing membranes and living cells, it can cause maximum damage.
> Possibly one of the main reasons for lung cancer.
Beta (β) radiation: Releases β particles that are identical in mass and charge with a 22Na atom
> A thin sheet of aluminum can stop β particles but these particles are able to penetrate the dead skin layer, potentially causing burns. Thus they pose as a serious direct or external radiation threat and can be lethal depending on the degree of exposure.
> Radiation hazard is the greatest when β particles are ingested or inhaled.
> If there is damage inflicted on the generative cells of the ovaries or testes by β particles, the damage may be hereditary. It can only occur when β radiation has contributed to the mutation of the gene pool.
Gamma (γ) radiation: High-energy electromagnetic radiation emitted by certain radioisotopes during nuclei transition from a higher to a lower energy state. The gamma (γ) rays have high energy and a short wave length.
> All γ rays emitted from a given isotope have the same energy, which is a characteristic that enables scientists to identify which gamma emitters are present in a sample.
> γ rays are able to penetrate tissue deeper than α or β particles, but leave a lower concentration of ions in their path to potentially cause cell damage.
> It is the most useful type of radiation in the medicinal field. However, it is also the most dangerous due to its high penetrative power which thereby allows penetration through thick and large materials.
> It has the ability to damage living cells, causing the cell to slow down by transferring its energy to surrounding cell components.
Prudent Practices in the Laboratory: Handling and Management of Chemical Hazards. (2011). Washington, DC: The National Academies Press
Tangen, L. (Ed.). (2006) Handling radioactive waste. Retrieved from Norwegian University of Science and Technology website: http://www.ntnu.no/hms/retningslinjer/HMSR35E.pdf
> All γ rays emitted from a given isotope have the same energy, which is a characteristic that enables scientists to identify which gamma emitters are present in a sample.
> γ rays are able to penetrate tissue deeper than α or β particles, but leave a lower concentration of ions in their path to potentially cause cell damage.
> It is the most useful type of radiation in the medicinal field. However, it is also the most dangerous due to its high penetrative power which thereby allows penetration through thick and large materials.
> It has the ability to damage living cells, causing the cell to slow down by transferring its energy to surrounding cell components.
References:
Ellis, J. G. & Riches, N. J. (1978). Safety and Laboratory Practice. UK: The Macmillan Press Ltd.
Gibbs, K. (2011). Deflection of α, β, γ particles in a magnetic field [Digital Image]. Retrieved from http://www.schoolphysics.co.uk/age14-16/Nuclear%20physics/text/Magnetic_deflection_of_radiations/index.html
Hawkhill Associates. (2007). Radiation [DVD]. Madison, WI: Hawkhill Associates, Inc.
Images Scientific Instruments. (2007). Penetration Power of Radioactivity [Digital Image]. Retrieved from http://www.imagesco.com/articles/geiger/build_your_own_geiger_counter.html
Nave, C., R. (2011). Radioactivity. Retrieved from http://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/radact.html
Ellis, J. G. & Riches, N. J. (1978). Safety and Laboratory Practice. UK: The Macmillan Press Ltd.
Gibbs, K. (2011). Deflection of α, β, γ particles in a magnetic field [Digital Image]. Retrieved from http://www.schoolphysics.co.uk/age14-16/Nuclear%20physics/text/Magnetic_deflection_of_radiations/index.html
Hawkhill Associates. (2007). Radiation [DVD]. Madison, WI: Hawkhill Associates, Inc.
Images Scientific Instruments. (2007). Penetration Power of Radioactivity [Digital Image]. Retrieved from http://www.imagesco.com/articles/geiger/build_your_own_geiger_counter.html
Nave, C., R. (2011). Radioactivity. Retrieved from http://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/radact.html
Prudent Practices in the Laboratory: Handling and Management of Chemical Hazards. (2011). Washington, DC: The National Academies Press
Tangen, L. (Ed.). (2006) Handling radioactive waste. Retrieved from Norwegian University of Science and Technology website: http://www.ntnu.no/hms/retningslinjer/HMSR35E.pdf
United States Environmental Protection Agency. (2011). Radiation Protection: Health Effects. Retrieved from http://epa.gov/radiation/understand/health_effects.html
Labels: alpha radiation, beta radiation, gamma radiation, hazards, radioactivity, radioisotopes, scenario 2
posted by Michelle, Bernadette, Shanna, Karen, Su Wei, Shi Ting @ 16:42
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