Radon determination

Dyck, W., 1969. Radon determination apparatus for geochemical prospecting for uranium. Geol. Survey Canada, Paper 68-21, 13 pp. 

Dyck W. Field and laboratory methods used in the Geological Survey of Canada in geochemical surveys, no. 10 radon determination apparatus for geochemical prospecting for uranium. Pap. geol. Surv. Can. 68-21, 1969, 30 p. 

From radium called niton at first, L. nitens, shining) The element was discovered in 1900 by Dorn, who called it radium emanation. In 1908 Ramsay and Gray, who named it niton, isolated the element and determined its density, finding it to be the heaviest known gas. It is essentially inert and occupies the last place in the zero group of gases in the Periodic Table. Since 1923, it has been called radon. 

The key point to remember, in the merits of year-round radon removal, is that there is no guarantee that radon problems will not be present even in the summer months. The radon levels found in individual houses are a complex result of radon source strength, soil transport, the number, size, and location of entry points, weather, and the way the house is operated.2 To be certain of maintaining low radon levels in the house normally requires that an SSD mitigation system works properly 24 h per day, 365 days per year. It is for this reason that durability and system performance are very important considerations. The performance level goal for the system is 100% on-time operation for the life of the building. This requires excellent durability of system components and a reliable means for determining whether the system is fully operational at all times. 

The question most often asked by homebuilders is Can one determine whether radon-resistant construction techniques should be applied to a given site ... 

Polyethylene-based membranes are manufactured for use in hazardous waste landfills, lagoons, and similar applications. Two of these products have been tested to determine their effectiveness as barriers against radon diffusion. (In most cases, diffusive flow is considered of little or no significance as a mechanism of radon entry compared with convective flow). A 20-mil high-density polyethylene tested 99.9% effective in blocking radon diffusion under neutral pressure conditions. A 30-mil low-density polyethylene tested 98% effective in blocking radon diffusion under neutral pressure conditions. 

When siting new residential construction, builders would like to determine the potential for radon problems associated with each building site. Unfortunately, at present there are no reliable, easily... 

Several papers present reviews of measurement methods or improvements in existing methods. Yamashita et al. (1987) present the description of a portable liquid scintillation system that can be used for thoron (Rn-220) as well as radon (Rn-222) in water samples. Thoron measurements have not been made for houses where radon in water may be a significant source. Such an instrument could be useful in making such determinations as well as in studying geochemical problems as described in this report. A review of measurement methods by Shimo et al. (1987) and of development and calibration of track-etch detectors (Yonehara et al., 1987) are also included. Samuelsson... 

This inverse relationship between equilibrium factor and "unattached" fraction and their relationship to the resulting dose is important in considering how to most efficiently and effectively monitor for exposure. This inverse relationship suggests that it is sufficient to determine the radon concentration. However, it is not clear how precisely this relationship holds and if the dose models are sufficiently accurate to fully support the use of only radon measurements to estimate population exposure and dose. 

Cohen, B.S., Deposition of Ultrafine Particles in the Human Tracheobronchial Tree A Determinant of the Dose from Radon Daughters, this volume (1987). 

DSMA Atcon, Ltd., Review of Existing Instrumentation and Evaluation of Possibilities for Research and Development of Instrumentation to Determine Future Levels of Radon at a Proposed Building Site, Report INF0-0096, Atomic Energy Control Board, Ottawa, Canada (1983). 

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. 

Determination of the frequency distribution of radon levels in residential structures on a nationwide basis through a national survey. 

The objectives of this study are to determine the frequency distribution of radon levels in residential structures on a nationwide basis and to investigate factors which affect these levels. This study is needed to obtain a more accurate estimate of the average radon level in homes and to provide reliable data on the number of homes exceeding various radon levels. Such information will provide a better understanding of the magnitude of the public health problem associated with indoor radon levels. In addition this information will establish the base line level against which results of other surveys and indoor radon measurements can be compared. 

For example, the sample size needed to determine the radon level exceeded by 1% of the housing units in the U.S. with a relative standard error (RSE) of 10% is about 20,000 units. 

In the studies performed by Hultqvist during the 1950s instantaneous sampling techniques were used. Equipment was designed by Rolf Sievert for determining radon concentration in housing and was described by Hultqvist (Hultqvist, 1956). 

The selection of the 1980-82 measurements (Swedjemark and MjOnes, 1984) was made on dwellings built before 1976 and with the aim of determining dose distributions and the collective dose to the Swedish population from the exposure of the short-lived radon decay products. This was done by using the statistical selection made by the National Institute for Building Research intended for an energy study of the Swedish stock of houses. From a selection of 3 100 houses in 103 municipalities, 2 900 were inspected. The data was found to be in substantial conformity with data from the land register and the population census of 1975. For the study of the radon concentration 752 dwellings were selected at random. 

The main parameters determining the indoor radon concentration in detached houses are the effective radium concentration (product of the radium concentration and the emanation factor) and the permeability of the ground. The effects of other factors are not so easy to ascertain from the existing data. 

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