[en] A radioactive decay series such as that of U-238 is said to be in a state of secular equilibrium when the number of atoms of each daughter being produced in the series is equal to the number of atoms of that daughter being lost be radioactive decay. When this condition exists, it is possible to determine the amount of the parent of the decay series by measuring the radiation from daughter element. Radioactive disequilibrium is quite a common occurrence in roll-front or sandstone-type uranium deposits. The reason is that uranium may be mobile when oxidized and daughter products formation lags behind. This leads to a distribution of radioelements wherein the daughter products (e.g. Bi - 214) are left behind, creating a daughter excess or parent-deficiency state, with strong gamma ray activity. Miners should receive from geologists a precise and sufficiently detailed geological report, including all the informations about disequilibrium problems of the uranium, deposits. (author)

[en] Radon gas is becoming a major concern in North America. This paper describes a hand-held monitor, called a 'Radon Sniffer', which has been developed recently by Thomson and Nielsen Electronics Limited in Kanata, Ontario to monitor radon daughter products inside buildings. Unlike former monitors which required users to send samples away to be analyzed, the Radon Sniffer displays the count immediately on a digital readout. The monitor can be powered by a line adapter or an optional high-capacity rechargeable battery pack

[en] The Technical Measurements Center is evaluating the reliability of using short-term exposures of alpha-track radon detectors to estimate annual average radon-daughter concentrations (RDC) in residences in the Grand Junction, Colorado, area. This Prompt Alpha-Track Study was initiated in the summer of 1985 and will be completed in the summer of 1986. Two sets of data are being collected, each consisting of two-, three-, four-, five-, and six-month-long exposures of alpha-track radon detectors. October 2 was selected as the midpoint of the Fall set of exposures and April 2 as the midpoint of the Spring set of exposures. These dates were selected after analyzing the RDC data collected by the Colorado Department of Health during the Grand Junction Remedial Action Program. This interim report on the Prompt Alpha-Track Study discusses the preliminary results of the Fall measurements. Terradex Type SF Track Etch detectors were exposed at 50 stations in 34 structures where previous annual average RDC and/or radon data have been collected. Two detectors were deployed at each station for each short-term exposure. Three additional annual detectors were deployed at each station concurrently with the six-month Fall detectors. The detectors were processed at a sensitivity level of 0.2 picocurie-month per liter. Preliminary results indicate that all of the short-term Fall measurements using October 2 as the midpoint of the exposure can reliably estimate the annual average indoor radon concentration in structures. The precision of both the short-term measurements and the methods is acceptable at 4 picocuries per liter (pCi/l). Results of a paired t-test indicate no difference in the measured radon concentration between a short-term measurement and an annual measurement, at the 0.01 level of significance. These conclusions are provisional since only the Fall data have been analyzed. A final report will integrate the Fall, Spring, and annual data

[en] Significant progress has been made recently in developing a completely passive, integrating radon daughter dosimeter suitable for personnel monitoring in uranium and other mines. This dosimeter concept is based on the Track Etch method for alpha particle detection. Tests in radon test chambers and uranium mines with these types of dosimeters have shown that they can produce results comparable with the currently used grab-sample radon daughter detection methods. In most instances the Track Etch dosimeters provide radon daughter exposures that are accurate to within +-20%. The encouraging results from these tests suggest that this dosimeter design offers significant advantages over the current methods for determining personnel radon daughter exposures of uranium and other mine and mill workers

[en] Published in summary form only

[en] The estimation of the radiation exposure of the public in living rooms requires long-term measurements of the potential alpha energy concentration of radon daughters during periods of some months. Because such measurements are quite difficult to perform, in most cases the radon concentration is therefore measured, from which the potential alpha energy concentration can be calculated assuming an appropriate equilibrium factor. Equilibrium factors resulting from short-term measurements of the radon daughter concentrations are not representative for longer periods of time. Long-term measurements by means of the difference method, using, for instance, bare and filtered solid state etched track detectors, are characterised by an unsatisfactory uncertainty in the measurement of the derived equilibrium factor. Therefore, a new approach is proposed to estimate the equilibrium factor based on the calculated relationship between the equilibrium factor and the activity concentrations of the different radon decay products. In comparison with the common difference method, this concept indicates an improvement, provided the activity concentration of ²¹⁴Po is detected separately. (Author)

[en] Radon and its decay products (Rn-d) have been part of man's natural environment through every stage of his evolution; they are inhaled by every breathing species and represent the component of the natural radiation dose to the general public. Lately this issue has become very controversial because of its potential impact on society on a wide range of topics, such as energy conservation and occupational safety of miners

[en] Abstract only

[en] In the following, it is suggested that in spite of the irrefuteable radiological role of the radon progeny, the radon gas level serves, practically, as a better indicator to the radiological respiratory health hazards, then does the measured radon progeny level itself. This suggestion is based on the evaluation of the information produced by commercially available Rn progeny meters, and of the radiological significance of the unattached fraction of the Rn progeny. (author)

[en] A plurality of spaced apart gas collection shelters are positioned on the earth's surface in an area of interest. Each such shelter consists of a low profile, smoothly curved, dome-shaped tent anchored to the ground and provided with an effective air seal around its periphery. The covering material of the shelter is selected so that it is highly permeable to infrared radiation. Means may be provided for continuous recirculation of the trapped air over highly adsorbent surfaces which filter out and collect radioactive decay products or other gases of interest for subsequent quantitative and qualitative analysis