Radon detection

Alter, H.W. and P.B. Price, Radon Detection Using Track Registration Material, U.S. Pat. 3665 194 (1972). 

Some might argue that the radon example illustrates certain market flaws because many low-income families have not purchased radon detection and remediation systems. Such reasoning is incorrect. The radon detection and removal markets work well, but the distribution of income is such that some choose not to purchase these commodities. 

Upward penetration distance (in metres) of radon from a buried source in terms of bulk diffusion coefficient (D ), fraction of radon detectable (N/Nq) and thickness of inactive cover above the source (from Novikov and Kapkov, 1965)... 

Allen, J.W., 1976. Development of a portable radon detection system. US Dept of Energy, Open File Report, GJBX-50, pp. 1-32. 

Morrison, W.A., Pollock, H.C. and Scarth, R.F., 1969. Radon detection as a method for uranium prospecting. General Electric Research and Development Center, 69-C-085,29 pp. 

Smith, R.C., 1978. Radon detection using thermoluminescent calorimeters in uranium exploration. In Uranium Exploration Techniques. Saskatchewan Geol. Survey, Spec. Publ. 4, pp. 85-108. 

Your teacher will supply the class with several commercial radon-detection kits—one for each group of students. The four-day exposure canisters will probably be the most practical to use however, the 30-day emits win usually give more accurate results. 

Radon Detecting buried U Instruments differentiating radon and thoron... 

Static sampling systems are defined as those that do not have an active air-moving component, such as the pump, to pull a sample to the collection medium. This type of sampling system has been used for over 100 years. Examples include the lead peroxide candle used to detect the presence of SO2 in the atmosphere and the dust-fall bucket and trays or slides coated with a viscous material used to detect particulate matter. This type of system suffers from inability to quantify the amount of pollutant present over a short period of time, i.e., less than 1 week. The potentially desirable characteristics of a static sampling system have led to further developments in this type of technology to provide quantitative information on pollutant concentrations over a fked period of time. Static sampling systems have been developed for use in the occupational environment and are also used to measure the exposure levels in the general community, e.g., radon gas in residences. 

The test kit is used to detect radon in home basements. 

Radon is a radioactive gas that can cause hmg cancer. It has been detected in the basements of some homes. How many protons are there in a Rn-220 atom How many neutrons ... 

Radon-222 is an unstable nuclide that has been detected in the air of some homes. Its presence is a concern because of high health hazards associated with exposure to its radioactivity. Gaseous radon easily enters the lungs, and once it decays, the products are solids that remain embedded in lung tissue. Radon-222 transmutes to a stable nuclide by emitting a and P particles. The first four steps are a, a, P, p. Write this sequence of nuclear reactions and identify each product. 

Since radon is a colorless, odorless, and tasteless gas, the only way to detect its presence is to sample and analyze an area s air using a conventional radon measurement test. If the test reveals elevated radon levels, the homeowner will have to decide what steps to take to reduce the levels.7 The higher the level of radon present in a home, the more likely an active radon reduction system such as subslab depressurization (SSD)8 may be required. Lower radon levels may require only a passive reduction system, such as simple sealing. 

In 1900 Ernest Rutherford (1871-1937) detected the radon-220 isotope as a decay product of thorium. In the same year, Dorn showed the radon-222 isotope to be a decay product of radium. 

After the end of the 4-day exposure, the detectors were returned to EML for analysis. The amount of radon adsorbed on the carbon device was determined by counting the gamma rays of radon progeny in equilibrium with radon. The concentrations of radon in the buildings were determined from the radioactivity in the device and the calibration factor, obtained in a radon chamber, that takes into consideration the length of exposure and a correction for the amount of water vapor adsorbed during the exposure. The lower limit of detection with this technique is 0.2 pCi/1 for a measurement period of 4 days when the test sample is counted for 10 min, 4 days after the end of exposure. More than 90% of the radon monitoring devices were analyzed successfully. Most of the unsuccessful measurements were due to delays or losses caused by the participants. 

Flow-Type Ionization Chamber (PFC). The Flow -Type Ionization Chamber Method (PFC) has been developed for continuously measuring radon gas in the atmospheric air. The detail of the device has been described elsewhere (Shimo, 1985). Briefly, measurements are continuously carried out by drawing air through the detector at 1.0 2.0 /min. The ionization currentdue to alpha particles from radon and its daughters is detected with a vibrating reed electrometer (VRE) in the same manner as the DSC. The sensitivity... 

Detection Limits of Instruments. The measuring range of those six instruments are shown in Figure 1. All of the instruments except for the DSC are able to detect the minimum radon concentration at 1 3... 

Bq/m (e.g. Shimo and Ikebe, 1979), five out of six techniques (excluding the DSC) are comparable of detecting radon in the outdoor air. The DSC can only be used when the radon concentration is 3... 

Figure 1. The detection range of various instruments, NL Natural radon concentration level.

Ikebe et al., 1984) are useful for precise measurements of low level radon, they are too expensive to make long-term measurements at numerous locations. The bare track detectors had been studied before the two other types of detectors were developed (Rock et al., 1969 Alter and Fleischer, 1981). The devices are suitable for measurements in a large number of dwellings, because the detectors are very inexpensive and can be sent and set up easily. The materials used for alpha particle detection are an allyl diglycol... 

As there are few data on the ratio of thoron concentration to radon, we have assumed that the value is constant and is equal to 0.14, Error(4) and Error(5) are assumed to be negligible for the error calculation. The error due to ambiguities in classification and discrimination of tracks according to the shape or the size was assessed by experiment and the relative error (1 S.D.) was less than 10%. The relative error due to the variations of F, f, and (V a) is less than 13% as described in the previous section. The combined error due to these factors is estimated to be 16%. The total error can be obtained by combining this error and Error(l). If we use the definition that the lowest detectable limit is the radon concentration at 50 % relative S.D., the lowest detectable... 

Fleischer, R. L. and A. Mogro-Campero, Mapping of Integrated Radon Emanation for Detection of Long-Distance Migration of Gases Within the Earth Techniques and Principles,. 1. Geophvs. Res. 83(B7) 3539-3549 (1977). 

The radon in the air i/as measured continuously by electroprecipitation of the positively charged Po-218 ions in an electric field (10 kV) on a surface barrier detector (Porstendorfer, et al., 1980). For this purpose the air i/as dried, filtered and sucked into an aluminium sphere ( 2 1) with a flowrate of 0.5 lmin-1. The counts due to Po-218 and Po-214 were proportional to the radon activity concentration. Their disintegrations were directly detected by alpha spectroscopy with an energy resolution of about 80 keV. The monitor could detect down to 5 Bq m 3 with a two hour counting time and 30 % statistical accuracy. 

Figure 2. Ratio of the unattached Po-218 concentration to the radon concentration for different flow rates during sampling. The daughters are alternately sampled with ( ) and without (O) the detection head.

Vanmarcke, H., Calibration of a radon daughter detection system, Report Nucl. Phys. Lab. (1984)... 

The amount of particles determine the quantity of decay products that stay in the air (equilibrium fraction, F) and the fraction of activity associated with the "unattached or ultrafine mode of the size distribution (fDot) These decay products are certainly harmful at high concentrations but we cannot yet detect the effects at normal levels because the vast majority of lung cancer death are due to smoking. Models predict that potentially 9000 lung cancer deaths per year in the United States are due to indoor radon. Methods are currently available and new methods are being developed and tested for lowering the levels of radon in indoor air. 

Safety and security Temperature Toxic gases like CO, CO2, exhaust gases, smoke,. .. Combustible gases like CH4, C2H6 (gas detection via flame detection (Europe), fire detectors, caravans with gas detectors) UV sensors Radon sensing... 

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