Radon Daughter Measurements Research Articles

Measurement of radon daughters in water and in air using the detection unit “YAPMARE” with a YAP:Ce scintillation detector

With a focus on the detection of the Rn concentration in water in extreme conditions, the detection unit YAPMARE was developed by the company CRYTUR. The main part of the detection unit is a detection probe based on the Ø25×100 mm YAP:Ce detector. The measured water covers approximately 95% of the crystal surface (the detection volume is 12 ml). Measurements of 222Rn and 220Rn standards for determination of individual peaks in the spectra were conducted, including an observation of the 222Rn (and its daughters) behavior. For YAPMARE calibration, fresh water was taken from a drilled well in the Lounovice area (biotitic granodiorite–adamellite). The calibration was carried out with the assistance of radon in water monitor RADIM 4. The results of the water measurements in Lounovice were as follows: detection limit was about 50 Bq/l, and calibration coefficient was 0.0011 imp/s per 1 Bq/l. The results of the fresh water and air sample measurements have demonstrated the main advantages (spectrometric results of the measurement, possibility for water or air samples evaluation) and disadvantages (large size of scintillation crystal increases gamma ray background, calibration for each water with particular composition, and detector cleaning using HCl acid).

Aerosol climatology at the high‐alpine site Jungfraujoch, Switzerland

Continuous aerosol measurements have been performed at the high‐alpine site Jungfraujoch (3450 m above sea level) since 1988 by means of an epiphaniometer. The instrument, which determines the Fuchs surface area of the aerosol particles, was operated with a time resolution of 30 min. High correlation coefficients (r>0.8) were found between the epiphaniometer signal and other aerosol parameters, which could be attributed to a rather constant size distribution of the Jungfraujoch aerosol in the accumulation range (0.1<d<1 μm). Well‐defined diurnal variations with a peak in the late afternoon were observed on many days during summer, which was not the case during winter. Comparison with black carbon and radon daughter measurements revealed that these diurnal variations are due to vertical transport processes. A statistical analysis showed that the fraction of days with a well‐defined diurnal pattern increased with decreasing stability of the atmosphere; however, late afternoon peaks also occurred during days when the potential temperature profile indicated a stable atmosphere. First simulations with ALPTHERM, a new convection model which takes topography into account, were able to explain the observed aerosol patterns. This indicates that slope winds over a certain catchment area are responsible for the transport to this high‐elevation site. The distinct seasonal variation with summer values, which are about a factor of 10 higher than winter values, could therefore be attributed to seasonally varying transport processes, due to the seasonal variation of radiation. The data show that even sites at very high elevation cannot be assumed to be in the free troposphere all the time.

25 Years of TL Dosimetry at the Institute of Nuclear Physics, Krak w

The first TL materials (LiF:Cu,Ag and CaF 2 :Mn) and a simple reader were developed at the INP in 1966 and used for dose measurements in radiation protection and radiotherapy. Further developments of a reproducible doping method of LiF with Mg and Ti ions, and of a method of sintering pellets (MTS-N or MTS-7) allowed several investigations to be performed and the application of these TL detectors in environmental and individual monitoring. The properties of MTS- and MCP-type materials were systematically investigated. Particular attention was paid to the non-typical response of this last phosphor to radiations of different LET which was investigated experimentally and theoretically. A broad programme of investigations of the MCP phosphor with various activator contents allows its dosimetry properties to be optimised. For measurements of doses of weakly penetrating radiation and of neutrons thin dosemeters of different construction were developed. Since 1968 MTS dosemeters have replaced films in routine monitoring of individual doses of the INP workers. Levels of natural gamma radation throughout Poland outdoors and indoors and, in more detail, around several smaller area were investigated for several years using an automated TL system developed at the INP. Systematic long-term monitoring of the dose rate of gamma radiation at one site at the INP allowed us to observe seasonal dose rate fluctuations and to register coarse and subtle changes in the background dose rates after the Chernobyl catastrophe. A method of measurement of radon daughters with the use of thin CaSO 4 :Dy pellets was developed and is now routinely used in Polish coal mines. Thin dosemeters with enhanced 6 Li and 7 Li content were developed and are now used in an Albedo neutron dosimetry system which completes the comprehensive system of individual monitoring of INP workers.

Comparison of Radon Daughter Measurement Techniques Used in European Animal Exposure Facilities

Comparison of Radon Daughter Measurement Techniques Used in European Animal Exposure Facilities

Comparison of Radon Daughter Measurement Techniques Used in European Animal Exposure Facilities

Abstract The effects of radon daughter inhalation by animals is being studied by three organisations in Europe. The individual exposure facilities used are described. For meaningful comparisons of the results from these studies, the radiological character of the exposure atmospheres must be compared, therefore a series of comparison exercises has been initiated. It is planned to make measurements of radon daughter concentrations and 'unattached' fractions by the three groups side by side at each facility. The exposure atmospheres at two facilities have been studied to date; CEA/COGEMA, Razes, France and TNO, Rijswijk, The Netherlands. Sampling flow rate and reference standards were also intercompared by the groups. The paper discusses the measurement methods employed, and the reasons for discrepancies in results between the groups, thus ensuring that future work by all three groups will be directly comparable.

On the Accuracy of Grab-Sampling Methods for Radon Daughters

There are several methods to evaluate the potential alpha energy concentration due to radon daughters. Owing to the short-lived nuclides present in the decay chain of radon and the complexity of environmental parameters, the behaviour of radon daughters in the environment is rather complicated. Therefore, errors are easily induced in the measurements of radon daughters. In this investigation 10 methods developed by several investigators compiled as a software package were reviewed and tested one by one in a radon environment with known concentrations. The Alpha Smart 770 of Alpha Nuclear Canada was used to evaluate and make comparisons among these ten methods. Consistent results within an error of 6% were obtained for six methods. However, inconsistent results within an error of from 24% up to a factor of 4 were obtained for the other four methods. It is concluded that the method to be used should be evaluated before routine or large-scale sampling is planned.

On the Accuracy of Grab-Sampling Methods for Radon Daughters

There are several methods to evaluate the potential alpha energy concentration due to radon daughters. Owing to the short-lived nuclides present in the decay chain of radon and the complexity of environmental parameters, the behaviour of radon daughters in the environment is rather complicated. Therefore, errors are easily induced in the measurements of radon daughters. In this investigation 10 methods developed by several investigators compiled as a software package were reviewed and tested one by one in a radon environment with known concentrations. The Alpha Smart 770 of Alpha Nuclear Canada was used to evaluate and make comparisons among these ten methods. Consistent results within an error of 6% were obtained for six methods. However, inconsistent results within an error of from 24% up to a factor of 4 were obtained for the other four methods. It is concluded that the method to be used should be evaluated before routine or large-scale sampling is planned.

Theory of passive measurements of radon daughters in the tube type dosimeters

Abstract This paper deals with the method of calculating Working Levels Ratios (WLR) due to radon daughters. The formulation is restricted to ‘Tube Type Dosimeters’, containing Solid State Nuclear Track Detectors, covered with different thickness of thin absorbers such as plastic films or aluminium foils. The contributions of radon and its daughters present both in the volume of the Dosimeter as well as those plated out on the walls of the Dosimeter and on the detector surface are taken into account. The calculations are useful for passive measurements of radon daughters present in the environment and for personnel dosimetry.

Search for Buildings with High Radon Levels in Sweden: Measurements Carried out by Local Authorities in Both Older and Newly Built Homes

Local authorities in Sweden have made about 58,000 radon daughter measurements with the following aims: (1) to search for houses with high radon daughter levels, (2) to determine the level above which the house would be regarded as an insanitary dwelling, and (3) to check that the radon daughter concentrations in newly built houses are below the established limit. The sampling of dwellings is therefore not representative for Swedish homes. 5300 homes were found to have levels above the limit 400 Bq.m-3 EER. The highest level found was 28,000 Bq.m-3. In about one third of the homes found to have levels exceeding the limit, measures had been carried out to decrease the radon daughter concentration. About half of the homes in which the levels were decreased had levels below the limit for rebuilding, e.g. 200 Bq.m-3. Measurements in order to ascertain levels in newly built houses were made in about 1100 homes out of 200,000 built since 1981 which was the year in which requirements for newly built houses came into force. Of those built with radon-safe or radon-protective foundations, 94% had concentrations below the 70 Bq.m-3 EER limit, compared to 80% for traditional building techniques.

Search for Buildings with High Radon Levels in Sweden: Measurements Carried out by Local Authorities in Both Older and Newly Built Homes

Abstract Local authorities in Sweden have made about 58,000 radon daughter measurements with the following aims: (1) to search for houses with high radon daughter levels, (2) to determine the level above which the house would be regarded as an insanitary dwelling, and (3) to check that the radon daughter concentrations in newly built houses are below the established limit. The sampling of dwellings is therefore not representative for Swedish homes. 5300 homes were found to have levels above the limit 400 Bq.m-3 EER. The highest level found was 28,000 Bq.m-3. In about one third of the homes found to have levels exceeding the limit, measures had been carried out to decrease the radon daughter concentration. About half of the homes in which the levels were decreased had levels below the limit for rebuilding, e.g. 200 Bq.m-3. Measurements in order to ascertain levels in newly built houses were made in about 1100 homes out of 200,000 built since 1981 which was the year in which requirements for newly built houses came into force. Of those built with radon-safe or radon-protective foundations, 94% had concentrations below the 70 Bq.m-3 EER limit, compared to 80% for traditional building techniques.

Uncertainties in Radon Daughter Measurement Arising from Fluctuations in Room Parameters

Abstract A Monte Carlo simulation model is described to evaluate the uncertainties induced, on the one hand, by assuming constant daughter concentrations and a constant flow rate during sampling and, on the other hand, in calculating the different physical parameters of the radon decay products, using the room model. It is found that, in general the uncertainties due to counting statistics and due to the fluctuations in the pump flow rate are small compared to the uncertainties induced by the fluctuations of the parameters of the room model. With the model a number of realistic situations, such as smoking cigarettes, opening or closing a window, etc. are simulated. Sampling half an hour after smoking a cigarette, for instance, under-estimates the steady state value of the 214Bi concentration by 35%. The uncertainties in the determination of the deposition rate of the unattached daughters are also evaluated. It is shown that, without special precautions to keep a steady state situation in the room, the error easily exceeds 50%.

Uncertainties in Radon Daughter Measurement Arising from Fluctuations in Room Parameters

Uncertainties in Radon Daughter Measurement Arising from Fluctuations in Room Parameters

Radon in the environment—Opportunities and hazards

One of the many subjects that particle track etching has been applied to is radon, and radon in turn is of interest in many contexts. It is ubiquitous hazard to human health, concentrated in certain geological settings and further intensified by certain home-construction practices. Radon also acts usefully as a tracer for minerals, underground fluid flow, and stresses within the earth. Track methods of radon and radon-daughter measurements are surveyed. Applications are given to measurements of both indoor and outdoor radon for health physics, and an approach is noted to the knotty problems of retrospective studies of individual exposures. Numerous results show evidence of fluid flow through pore spaces in the ground. This flow transports radon and leads to other applications, such as locating subsurface uranium ore, and oil and natural gas deposits. Examples of premonitory radon signals from seismic events are also given.

Radon emanometry in soil gases and activity in ashes from El Chichon Volcano

Radon (222Em) emanation measurements in soil gases are reported in connection with the 1982 eruptions of El Chichon Volcano.222Em detection is performed with LR-115 cellulose nitrate track detectors. Results show a general decreasing pattern of222Em concentration in soil with time after the eruptions. Activity measurements of radon daughters in ashes show that a large amount of222Em and220Em was released from magma degassing during the eruptions, and that only a fraction of the degassed magma was erupted. An important fluid interaction between the magma chamber and the surrounding sedimentary rock is also suggested.

Field Validation Study of the MDA® Instant Working Level Meter in a High Gamma Background Mine Environment

Accurate and reproducible radon daughter measurements are essential to protect workers in the mining industry and assure compliance with federal regulations. The precision and accuracy of the MDA® Model 811 Instant Working Level Meter (IWLM) has been questioned when it is used in a high gamma environment of an underground uranium mine due to the increased statistical uncertainty associated with the background radiations. Comparative side by side sampling at a single underground mine station exhibiting a 3.0 mR/h “gamma background” was conducted utilizing the IWLM, the Kusnetz and the Tsivoglou methods. A total of fifty sets of samples were taken, with half using an unshielded IWLM and the other half using a lead shield to reduce the effect of the high gamma background radiation. IWLM, Kusnetz and “baseline” Tsivoglou measurements were then analyzed. A significantly large error was associated with the IWLM in both the shielded and unshielded data groups.

Field validation study of the MDA Instant Working Level Meter in a high gamma background mine environment.

Accurate and reproducible radon daughter measurements are essential to protect workers in the mining industry and assure compliance with federal regulations. The precision and accuracy of the MDA Model 811 Instant Working Level Meter (IWLM) has been questioned when it is used in a high gamma environment of an underground uranium mine due to the increased statistical uncertainty associated with the background radiations. Comparative side by side sampling at a single underground mine station exhibiting a 3.0 mR/h "gamma background" was conducted utilizing the IWLM, the Kusnetz and the Tsivoglou methods. A total of fifty sets of samples were taken, with half using an unshielded IWLM and the other half using a lead shield to reduce the effect of the high gamma background radiation. IWLM, Kusnetz and "baseline" Tsivoglou measurements were then analyzed. A significantly large error was associated with the IWLM in both the shielded and unshielded data groups.

Theory of passive measurement of radon daughters and working levels by the nuclear track technique.

A theoretical basis is described for long-term measurement of the activities of the alpha emitters in air by the track-etching technique. Inference of the other activities allows working levels to be derived. A set of absorber foils allows the differing response to alpha particles of different energies to be used to identify the relative abundance of the alpha emitters and the importance of diffusion to surfaces. The method is appropriate to measuring long-term exposures to radon atmospheres in homes or mines.

The equilibrium factor F.

Consideration of the equilibrium factor F between the concentration of the radon daughters and the concentration of radon is a part of the evaluation of the measurements of radon daughter concentrations in dwellings when applying limits. Measurements of radon, radon daughters and air exchange rates have been carried out in 225 dwellings in Sweden. The F-factors have been compared with the theoretical model described by Wicke, taking into account the wall effect. The parameters of the model are discussed. The situation of the dwelling and the habits of the occupants can be expected to have the greatest importance for the F-factors although the ventilation rate is usually the most important modifying factor. For low air exchange rates (l less than 0.30 hr-1) the probability that the F-factors were between 0.28 and 0.74 was 95% calculated according to the t-distribution. The arithmetical mean was found to be 0.51. For air exchange rates close to the average rate (0.30 less than l less than 0.60 hr-1), the F-factors were between 0.21 and 0.66 with a mean of 0.43, and for high air exchange rates (l greater than 0.60 hr-1) the F-factors were between 0.21 and 0.47 with a mean value of 0.33.

Radon and radon daughter measurements in solar buildings.

Measurements of radon and radon daughters in 11 buildings in five states, using active or passive solar heating, showed no significant excess in concentrations over the levels measured in buildings with conventional heating systems. Radon levels in two buildings using rock storage in their active solar systems exceeded the U.S. Nuclear Regulatory Commission's limit of 3 pCi/l. for continuous exposure in uncontrolled areas. In the remainder of the buildings, radon concentrations were found to be at levels considered to be normal. It appears that the slightly elevated indoor radon concentrations result from the local geological formations and from the tightening of the buildings rather than as a result of the solar heating technology.

Neutron response of Geiger-Müller photon dosemeters for neutron energies between 100 keV and 19 MeV.

Quantification of the precision of the many methods for measuring RaA, RaB and RaC concentrations has not heretofore included the effects of concentration and flowrate uncertainties. These uncertainties are here taken into account in the modified Tsivoglou method, resulting in better optimized counting intervals. The optimized modified Tsivoglou method which is developed is demonstrated experimentally to have a 37% better precision than the original modified Tsivoglou method. The optimization approach developed may also be applied to other radon daughter measurement methods.