Radioactive inert gases

Discontinuous sampling for measuring radioactivity due to the radioactive inert gas radon 222 can be carried out relatively easily following the instructions below. 

Some special points arise from the nature of the radioactive parent substance radium and the daughter radon, which is an alpha-emitting inert gas. Precautions must be taken when sampling to prevent the gas escaping from the water prior to measurement and, on the other hand, to prevent its 

In addition, consideration must be given to the fact that the decay products of radon are solids which are themselves again subject to radioactive decay. The vessels with radioactive water samples are therefore contaminated to a greater or lesser extent, so that before they are used again the radioactivity should have subsided and the vessels must be thoroughly cleaned. If the water contains dissolved radium 226, with the 

In view of the relatively short half-life of radon 222 (approx. 3.8 days) the water sample must go for radioactivity measurement as quickly as possible. The time which elapses between sampling and the first measurement must be noted. 

For determining what is known as the residual activity, water samples are filled into bottles which can be closed airtight, so that they can be analyzed for their radon content in the laboratory at a later stage, possibly after radioactive equilibrium has been established. For this, 1-litre or 2-litre glass bottles with double-bore rubber stoppers are used. 

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Both radioactive and nonradioactive (stable) inert gas atoms can be used in the DSA, although the use of radioactive inert gases is more advantageous due to their simple and sensitive detection. 

Such exclusive situation soon became a rule. Therefore, we shall have to discuss briefly some important events in the history of radioactivity studies. Now we must finish the story of radon. This name remained because radon is the longest-lived element among the radioactive inert gases. Ramsay suggested to name it niton (from the Latin for glowing) but this name did not take root. 

RANDON A naturally occurring radioactive inert gas formed by radioactive decay of radium atoms in soil and rocks and that cannot be seen, smelled, or tasted. 

Radon A naturally occurring radioactive inert gas that cannot be seen, smelled, or tasted, formed by radioactive decay of radium atoms in soil and rocks RDA Recommended daily allowance the National Academy of Sciences sets the required nutrient values for healthy people in the United States. The values take into consideration the needs of all individuals RDI Recommended daily intake... 

The high sensitivity of DSA to the chemical interactions between a solid surface labeled with the radioactive inert gas and aggressive agents made it possible to reveal the very beginning of corrosion reactions. The durability of... 

General mention should be made of the a-emitters radium 226, polonium 210, radon (radioactive inert gas) 220 and 222, uranium isotopes and thorium isotopes. 

A relatively simple method, which is based on the CV-radioactivity of the radioactive inert gas radon 222 and enables radon 222 to be determined... 

An instrument for counting radioactive particles based on their ability to ionize an inert gas such as Ar. 

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. 

Krypton is expensive to produce, which limits its use as an inert gas. It is used in a mixture with argon to fill incandescent light bulbs, fluorescent lamps, lasers, and high-speed photography lamps. Radioactive Kr-85 is used as a source of radiation to measure the thickness of industrial materials. It is also used to test for leakage of scientific instruments. 

Radon gas fits the criteria to be classed as a noble element located in group 18(V11IA) or group 0. It is the only noble inert gas that is naturally radioactive. It is the heaviest of the gases in group 18. 

An Electron Capture Detector operates as follows a CECD is essentially a tube thru which a stream of inert gas flows. A weak radioactive source on the walls of the tube irradiates the gas and generates within it a population of free electrons. These electrons are extracted from the gas stream by a positive electrode. The number extracted per second is measured as a current flowing thru this electrode... 

A radioactive tracer technique was ultimately chosen as a mapping tool. The isotope Kr-85 was selected because it can represent the gaseous, vaporous and solid materials in the reactor. Being an inert gas it does not interact chemically with any of the species present. It is readily dispersible... 

Radon ( Rn or Rn) is a radioactive noble gas, which is chemically relatively inert. The gas originates from traces of uranium or U) in various materials, e.g. granites. The Rn atom is formed in the mineral grains of the material. A certain fraction of atoms formed escapes into the material pore space and diffuses to the material surface to be released in to the surrounding air. 

The metastable atoms that must be produced in the argon and helium detectors need not necessarily be generated from electrons induced by radioactive decay. Electrons can be generated by electric discharge or photometrically, which can then be accelerated in an inert gas atmosphere under an appropriate electrical potential to produce metastable atoms. This procedure is the basis of a highly sensitive helium detector that is depicted on the left-hand side of Fig. 1. The detector does not depend solely on metastable helium atoms for ionization and, for this reason, is called the helium discharge ionization detector (HDID). 

The two other decay processes in Table 5.4 are less common in nature. In K-capture, any orbiting electron (usually in an inner shell) combines with a proton in the nucleus to form a neutron. This relatively rare nuclear transformation process (e + p+ —> n°) is just the opposite of that for P decay, meaning that the formed nucleus also has the same mass but is displaced one element to the left on the periodic table. Conversion of to °Ar by K-capture is an example of the chemical conversion that can attend radioactive decay, in this case leading to transformation of a non-volatile alkali metal into the inert gas Ar, the third most abundant gas in the atmosphere. Although no nuclear particle is emitted by K-capture, the attending cascade of electrons into lower orbitals leads to X-ray emission of characteristic energy that can be measured by the appropriate detectors. The last decay process (also rare) involves emission of a positron (p+), a positively charged electron. The nuclear process (p+ n° + p+) has the same net effect as K-capture and is also characterized by X-ray emission. 

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