Search

Aim of a low radon cleanroom technology is to minimize at the same time radon, radon decay products concentration and aerosol concentration and to minimize deposition of radon decay products on the surfaces. The technology placed in a deep underground laboratory such as LSM Modane with suppressed muon flux and shielded against external gamma radiation and neutrons provides "Zero dose" space for basic research in radiobiology (validity of the LNT hypothesis for very low doses) and for the fabrication of nanoelectronic circuits to avoid undesirable "single event effects." Two prototypes of a low radon cleanroom were built with the aim to achieve radon concentration lower than 100 mBq·m 3 in an interior space where only radon-free air is delivered into the cleanroom technology from a radon trapping facility. The first prototype, built in the laboratory of SÚRO Prague, is equipped with a standard filter-ventilation system on the top of the cleanroom with improved leakproofness. In an experiment, radon concentration of some 50 mBq·m -3 was achieved with the filter-ventilation system switched out. However, it was not possible to seal the system of pipes and fans against negative-pressure air leakage into the cleanroom during a high volume ventilation with the rate of 3,500 m 3 ·h -1 . From that reason more sophisticated second prototype of the cleanroom designed in the LSM Modane uses the filter-ventilation system which is completely covered in a further improved leakproof sealed metal box placed on the top of the cleanroom. Preliminary experiments carried out in the SÚRO cleanroom with a high radon activity injection and intensive filter-ventilation (corresponding to room filtration rate every 13 s) showed extremely low radon decay products equilibrium factor of 0.002, the majority of activity being in the form of an "unattached fraction" (nanoparticles) of 218 Po and a surface deposition rate of some 0.05 mBq·m -2 ·s -1 per Bq·m -3 . Radon exhalation from persons may affect the radon concentration in a low radon interior space. Balance and time course of the radon exhalation from the human body is therefore discussed for persons that are about to enter the cleanroom., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Štekl, Hůlka, Mamedov, Fojtík, Čermáková, Jílek, Havelka, Hodák and Hýža.)

High-volume aerosol samplers combined with laboratory analysis using high-resolution gamma ray spectrometry allow determining artificial radionuclides in the atmosphere at sub μBq/m3 levels. A major drawback of this procedure is a significant delay of the analysis result after any potential radioactive contamination deposition on the aerosol filter. Within the scope of the HAMRAD project, an autonomous device was developed in order to increase the sampling and measuring frequency. This approach yields higher detection limits (minimum detectable activity concentration [MDAC]) due to the deposited activity of radon decay products on the filter. In order to quantify the radon effect, a simple mathematical model was developed to predict MDAC for the particular radionuclide of interest for the given background conditions. It was found that MDAC can vary by a factor of ~2 for typical 'radon' conditions (~10 Bq/m3) at SÚRO Prague and by a factor up to 5 for high radon concentration (100 Bq/m3)., (© The Author(s) 2019. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

This paper reports on the structure of the autonomous station for monitoring artificial gamma activity in surface water bodies for the purposes of emergency preparedness of the Czech Republic. A simple design based on the NaI(Tl) submersible detector powered by a combined solar and wind source has been employed. Data transfer is provided by a satellite connection. The detection capabilities of the device have been tested for various unfavourable conditions, and the detection limits have been lowered by using the noise adjustment singular value decomposition (NASVD) method. The detection capabilities of the device fulfil the legal requirements for emergency monitoring, and are almost equal to the detection capabilities of other available devices with a more complicated and less versatile structure., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

In order to increase the early warning ability of the radiation monitoring network of the Czech republic, a high-volume aerosol sampler was upgraded with a NaI(Tl) probe placed directly above the aerosol filter. The paper demonstrates the possibility of using a method based on principal component regression to accurately subtract the complicated natural background caused by radon decay products. This approach yielded minimum detectable activities of 8mBq/m 3 , 3mBq/m 3 and 7mBq/m 3 for 131 I, 134 Cs and 137 Cs, respectively, after 24h of sampling., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

(210)Po was determined in 24-h urine of seven healthy males from Prague, Czech Republic, for ten consecutive days. The results show that for each volunteer, the urinary excretion of (210)Po changed only little from day to day in the studied time period. For two volunteers, the difference in the daily excreted (210)Po activity for two consecutive days was not significant, given the 95% confidence interval (two sigma) of the activity measurements. The same is valid for the excretion data of the other volunteers, except for some days where the differences were slightly higher. The range of daily urinary excretion of (210)Po of each volunteer in the studied time period was quite narrow. Among the volunteers, the maximum daily urinary excretion value of (210)Po was at most about a factor of 2.5 higher than the lowest excretion value. An attempt to explain the observed small inter-individual variability of (210)Po excretion in daily urine is made.

This paper presents the results of atmospheric radioactivity monitoring over the Czech Republic, as obtained by the Radiation Monitoring Network, following the Fukushima Dai-Ichi Nuclear Power Plant accident. Maximum values for (131)I were 5.6 mBq m(-3) in aerosol form and 13 mBq m(-3) in gaseous form. The maximum values for (134)Cs and (137)Cs were 0.64 and 0.72 mBq m(-3), respectively. The estimated effective half-time for removing the activity from the atmosphere was 6-7 d and 3.5 d for caesium and iodine, respectively. The gaseous-to-total activity ratios of (131)I ranged between 0.3 and 0.9, with an arithmetic mean value of 0.77. The mean value for the (134)Cs/(137)Cs ratios was close to 1.0. The effective inhalation dose due to the accident for an adult living in the Czech Republic was estimated at <4 × 10(-5) mSv, out of which the proportion of (131)I was 88%., (© The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

During the 7th European Conference on Protection Against Radon at Home and at Work held in the autumn of 2013 in Prague, the second intercomparison of measuring instruments for radon and its short-lived decay products and the first intercomparison of radon/thoron gas discriminative passive detectors in mix field of radon/thoron were organised by and held at the Natural Radiation Division of the National Radiation Protection Institute (NRPI) in Prague. In total, 14 laboratories from 11 different countries took part in the 2013 NRPI intercomparison. They submitted both continuous monitors for the measurement of radon gas and equivalent equilibrium radon concentration in a big NRPI chamber (48 m3) and sets of passive detectors including radon/thoron discriminative for the measurement of radon gas in the big chamber and thoron gas in a small thoron chamber (150 dm3)., (© The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)