Authors:Yang Ya-xin, Liu Qing-cheng, Wu Xin-min, Huang Yan-jun, Lin Jun, Wu Ya-mei, Li Shu-zhen, and Hsia Yuan-fu
A new air radon monitor is proposed based on the combination of an aluminum disk and an electric multilevel clearance system
(EMCS). The positively charged, small aluminum disk has a high collection ability to radon with a collection efficiency of
about 60%. The old radon progenies were eliminated by the EMCS in the air entrance of the monitor with an efficiency of about
99%. The monitor was calibrated in the national standard radon chamber in Hengyang, China. Compared to the radon double-filter
equipment, the results, gained by both apparatus, coincide with each other.
This paper presents a method for measuring indoor radon concentrations using a commercially available air-purifying respirator
filter as a component of the radon monitor. The filter used was Survivair’s NIOSH (National Institute for Occupational Health
and Safety)-approved 100800 model. The method is based on the diffusion of radon gas into the activated carbon of the filter
and the measurement of the radioactive daughters resulting from the radon decay. The photopeaks of the 214Bi daughter gamma rays (0.609 MeV) were analyzed with a Hyper-Pure Germanium (HPGe) detector and a multichannel system. A
monotonically increasing and very close to linear response relation between the integrated area under the 214Bi photopeak and the radon concentration of the activated carbon was found. A well-defined relation held for radon levels
ranging from 15 to 4,700 Bq/m3. This procedure results in highly reproducible and reliable measurements of indoor radon levels. Interesting applications
include the investigation of radiological accidents involving radon and the retrospective measuring of indoor radon concentrations
by analyzing the filters of the respirators worn by personnel working during the relevant period.
An effort to define and characterize the environmental effects that control the release and mobility of radon in the environment is presented. The results of our preliminary field experiments on the long-term study of our radon activity measurements are reported.
Authors:O. Baykara, M. İnceöz, M. Doğru, E. Aksoy, and F. Külahcı
On-line monitoring of soil radon (222Rn) concentration system was constructed on one of the main active fault zone of East Anatolian Fault System (EAFS) in Turkey.
The preliminary results, observed during the second part of 2004 and first part of 2005 is presented. During the monitoring
of soil radon concentration, numerous anomalies that equal or twice standard deviation were observed. In addition, the variation
of the radon concentration was examined between the mean values and plus/minus two standard deviations and any increase in
radon concentration above this limit was assumed to be 222Rn anomalies. These anomalies usually appeared between a few days or weeks before the earthquakes occurrence. The obtained
data were also compared as considered respect to the earthquakes occurred in a 100 km radius of the fault system.
The uranium mining was stopped in the Mecsek Mountains in 1997. Most of the dwelling houses, located close to a mine-tunnel, show a yearly average of indoor radon activity concentration higher than the EU recommendation for existing buildings (300 Bq/m3). To reduce the high radon concentration, new radon mitigation was completed in a selected house and the mitigation effect has been studied. Indoor radon concentration was monitored continuously for one month once before and three times after the mitigation technique was applied. Due to the mitigation, the initial radon concentration was decreased by 71% (average radon concentration before the mitigation: 1480±74 Bq/m3, after the mitigation: 420±33 Bq/m3). In the paper these results are interpreted from the point of view of functioning of the applied mitigation technique and dependence of the mitigation efficiency on the meteorological conditions.
Authors:Tadeusz Przylibski, Jakub Bartak, Elżbieta Kochowska, Lidia Fijałkowska-Lichwa, Krzysztof Kozak, and Jadwiga Mazur
The article presents new Polish probes SRDN-3, developed at the Institute of Nuclear Chemistry and Technology in Warsaw, equipped
with a semi-conductor detector used for continuous measurements of 222Rn activity concentration. Due to a relatively high lower detection limit, the device is dedicated for use in underground
spaces—caves, adits, mines, tourist routes in strongholds, pyramids, etc. Its structure allows for difficult conditions in
which the device is transported to the measurement site, as well as hard operating conditions caused chiefly by large ambient
relative humidity, reaching up to 100%. The authors present calibration results of these appliances, as well as the results
of their work in a cave and an adit in the Sudetes (SW Poland). After almost 2 years of working in difficult conditions, the
probes displayed high reliability. No defects of the semi-conductor detectors or the electronics were observed, which ensured
problem-free communication of the probe-programmer-PC set. Thanks to this, the authors have a 2 year stock of data, recorded
hourly by five probes, at their disposal. The only element that did not withstand the test of extreme operating conditions
was one of the combined relative humidity and temperature sensors. No powering problems were observed either, and the batteries
were replaced once a year, before the winter season. Also the programmer functioned faultlessly, enabling data transmission
to a PC, which, being much more sensitive to operating conditions, had been placed away from the site of probe exposure. After
using more sensitive temperature, relative humidity and pressure sensors, SRDN-3 probes will certainly prove an excellent
tool for microclimate measurements (including measurement of air-atmosphere exchange) in caves and other underground sites.
Even nowadays they are already a satisfactory tool for monitoring 222Rn concentration in underground spaces.
Experiments were designed to evaluate, in a controlled way, some of the variations that can be expected in radon concentration in soil due mainly to meteorological factors and to close spacing monitoring in the field. Electronic continuous radon monitoring and the track-etch method were used to record the radon -decay. The radon emanation in daily measurements and in long term surveys showed a general effect modulated by temperature and pressure variations. Radon monitoring in soil for nearby stations showed that a 10% range of variation can be expected with the track-etch method and as a result of non-homogeneous emanation pattern of the soil.
In order to calibrate vials containing charcoal for measurement of radon, emanation sources of radon were produced in-house using 226Ra salts. Calibrated emanation standards containing solution of 226Ra(NO3)2 absorbed into inorganic compounds were prepared. The emanation coefficient of 222Rn for these standards vary from 0.23-0.25. The emanation sources were found to be suitable for calibrating radon monitors.
This paper presents radon and thoron concentrations measured in the prehispanic tunnel of the Sun Pyramid and in the archeological tunnel 1 in the Moon Pyramid. Radon and thoron concentrations were measured using several electret passive environmental radon monitor (E-PERM) configurations and detection systems. Results were in good agreement with no significant difference (P<0.01). Radon concentration in both pyramids was 1ower than the action levels proposed by the ICRP 65. Therefore, the equivalent effective dose (HE) calculated for the highest concentration was much lower than the action level (3-10 mSv . y-1). A quality assurance program was improved.
Authors:T. Martinez, L. Cabrera, M. Navarrete, J. Garcia, P. Gonzalez, A. Ramirez, and U. Martinez
Gamma exposure rate and radon levels were measured in 75 single-family dwellings in Mexico City in order to correlate them with local environment. Radon monitoring was performed both indoors and outdoors using a continuous working level monitor for short-lived radon decay products; the gamma exposure rate was measured using CaSO4: Dy+PTFE. The results obtained show a log-normal distribution. The mean indoor radon concentration is lower than 45 Bq/m3 and the mean indoor gamma exposure rate was 11.29 R/h.