Radon Nuclides and Radon Generators

Abstract

The radon element is the heaviest and the only naturally occurring radioactive noble gas. As a member of uranium and thorium decay chains, it is formed instantaneously and belongs to the naturally occurring radioactive materials (NORM). The long-lived radon isotope, the 222 Rn, is radiobiologically the most important one. It is present in subsoil and groundwater and permeates to the surface, where it may become health risk during the long-term inhalation. Proper testing of drinking water and building materials is also required to monitor radon concentrations below legal limits. Thus, the need of radon determination as well as the preparation of its isotopes arises for its use as a calibration source for the environmental and workplace monitoring in the NORM as well as other industries. Further, the radon isotopes currently appear in various research fields, including radionuclide progeny preparation and their use is experiencing renaissance. An overview of radon characteristics, its physical and chemical properties, as well as radon isotope preparation methods including the radionuclide generators and their use is given here. Radon isotope use for tracing, medical, geochemical and other purposes is also discussed.Keywords: radon, thoron, actinon, generator, decay chain, radioactive deposits, Rn, noble gas Historical introductionSoon after the discovery of radium by Curie et al. [1], the radioactivity of thorium by Schmidt [2] and the discovery of actinium by Debierne [3], it was found that all of these radioactive elements activate their surroundings and emit formerly unknown radioactive gases. Curie and Curie discovered that objects exposed to radium samples got activated and the half-life of the gained radioactivity was approximately 1 month [4], even though clear interpretation of this discovery remained unknown. Similarly, radioactive gas evolution was observed © 2017 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.in samples of thorium and uranium [5][6][7][8][9]. Rutherford and Dorn interpreted the emanated activity from thorium and radium compounds as new chemical substances. Rutherford and Owens reported that the gas released from thorium had the half-life of about 1 min. Radioactive gas release from actinium samples was reported by Debierne soon after [10]. All the three gases (originating from radium, thorium and actinium) were found as chemically inert and were classified as noble gases [11]. Further studies on emanation gases lead to better understanding of their physical and chemical properties as well as their nature, for example, their condensation at low temperatures [12]. Many experiments were performed in order to determine the atomic mass of the emanation. In 1910, among others, Ramsay and Gray collected radium emanation gas to measure its densit...

Preparation of multi-purpose radon emanation sources

“…Radon generators can be produced from crystalline, amorphous and porous materials but their emanation power can vary in wide range. In general crystalline materials show lower emanation power-few percent-while the emanation power of porous materials can reach close to 100% in certain cases [12].…”

Indoor Air Radon Concentration in Premises of Public Companies and Workplaces in Latvia

“…When the radon nucleus decays, it releases an alpha particle with 5.49 MeV of energy, and the nucleus transforms to 218 Po. Polonium atoms are metals and tend to stick to surfaces they come in contact with, e.g., a dust particle in the air, a wall, or the inside of the lungs [ 11 , 12 , 13 ].…”

“…That is why it is the second leading cause of lung cancer in humans after cigarette smoking. However, there is no known threshold concentration below which no risk exists [ 11 , 12 , 14 , 15 ]. Radon alpha emissions in the long term can have an adverse effect on the health of the population.…”