1,721,003 research outputs found
Study of ageing and fading in CR-39 detectors for different storage conditions
No full textThe aim of this study was to investigate the effect of ageing and fading on PADC detector response, as a function of the storage time and temperature. Several groups of CR-39 detectors provided by Radosys, Ltd. were exposed at the reference radon chamber of the Istituto Nazionale di Metrologia delle Radiazioni Ionizzanti, at the ENEA centre in Casaccia. The results indicate that low-temperature storage inhibits the effect of both ageing and fading. Finally, the overall reduction in CR-39 sensitivity due to the combined ageing/fading effect was estimated. In particular, the sensitivity of the detectors continuously exposed in air at room temperature over 6 and 3 months was reduced, respectively, by 7.5 and 4 %. © The Author 2014
Metrological aspects of international intercomparison of passive radon detectors under field conditions in Marie Curie's tunnel in Lurisia
No full textIn 2014, an intercomparison exercise of passive radon detectors under field conditions in the Marie Curie's tunnel belonging to the Lurisia spas complex (Lurisia, Piedmont, Italy) has been held. Radon activity concentration in the tunnel was measured with six radon active monitors, previously calibrated at ENEA-INMRI facilities. In the present paper, a synthesis of the metrological aspects of the intercomparison is given. Indeed particular attention was paid to metrological characterization of radon monitors and their response upon ambient conditions. Correction factors have been defined to be applied when measurements are performed in severe environmental conditions. In particular, it has been found that monitors are particularly sensitive to the effect of air density: the AlphaGUARD (AG-SAPHYMO, GmbH) efficiency decreases with the air density, while for the MR1 PLUS (Tesys, Italy), the opposite applies. When the reference monitors were placed into the Marie Curie's tunnel, to the recorded average radon concentrations correction factors were applied. After the correction the difference between data coming from AG and MR1 PLUS is within the 1.7%
Experimental tests on the reduction of radon decay products’ unattached fraction in indoor environment and its influence on effective dose
No full textThe work studies the influence of how the unattached fraction of radon daughters can influence effective dose. An experimental work was carried out for measuring the unattached fraction in presence of different size aerosols, and for each test an estimate of the effective dose was given. Tests were carried out at fixed radon concentrations and with different size aerosols. Potential alpha energy concentrations of both total and free fractions were measured, together with radon and aerosols air concentrations. Results showed increments of the equilibrium factor, reduction of the unattached fraction, and decrease of the effective dose. © 2017, Akadémiai Kiadó, Budapest, Hungary
A step towards accreditation: A robustness test of etching process
No full textIn the present study the robustness of the etching process used by our laboratory was assessed. The strategy followed was based on the procedure suggested by Youden. Critical factors for the process were estimated using both Lenth's method and Dong's algorithm. The robustness test evidences that particular attention needs to be paid to the control of the etching solution's temperature. © 2015 Elsevier Ltd
Acomparison of radon and its decay products' behaviour in indoor air
No full textThe inhalation of short-lived radon decay products (RDP) yields the greatest contribution to the natural radiation exposure. This paper deals with a study carried out to improve the knowledge of the behaviour of RDPs, their interaction with particulates and the plateout during the time. The tests confirmed that a high aerosol particle concentration increases the probability that an ion sticks to aerosol and remains long in the air, leading to both an increase of F and a decrease of fp, as reported in the literature. The same experimental protocol applied in a small radon chamber showed a strong reduction of the equilibrium factor (an average of -10 %), because in a small environment the plateout phenomenon prevails on the attachment to particulate
Effect of indoor-generated airborne particles on radon progeny dynamics
No full textIn order to investigate the interaction between radon progeny and particles, an experimental campaign was carried out in a radon chamber at the Italian National Institute of Ionizing Radiation Metrology, quantifying the amount of attached and unattached radon daughters present in air, as well as the equilibrium factor in the presence of particles generated through indoor sources. A fixed radon concentration was maintained, while particles were generated using incense sticks, mosquito coils and gas combustion. Aerosols were characterized in terms of particle concentrations and size distributions. Simultaneously, radon concentration and attached/unattached potential alpha energy concentration in the air were continuously monitored by two different devices, based on alpha spectroscopy techniques. The presence of particles was found to affect the attached fraction of radon decay products, in such a way that the particles acted as a sink for radionuclides. In terms of sources which emit large particles (e.g. incense, mosquito coils), which greatly increase particle surface area concentrations, the Equilibrium Factor was found to double with respect to the background level before particle generation sessions. On the contrary, the radon decay product dynamics were not influenced by gas combustion processes, mainly due to the small surface area of the particles emitted. © 2016 Elsevier B.V
Main results of the international intercomparison of passive radon detectors under field conditions in Marie Curie's tunnel in Lurisia (Italy)
No full textIn recent years a large number of radon intercomparison exercises has been organized; most of them took place in radon chambers, in reference atmosphere of the parameter to control (i.e. radon gas) under temperature, humidity and atmospheric pressure stable conditions. In 2014, in the tunnel belonging to the Lurisia spas complex (Lurisia, Piedmont, Italy), with natural high concentrations of uranium and radon gas, an intercomparison exercise has been held to give to radon measurement services and laboratories the possibility to test their passive systems under field conditions, which are less controlled and much more challenging. The response of laboratories was very positive: 46 participants from 10 European countries and 3 non-European countries. Generally about 80% of results of participants were considered acceptable even if it was observed a global trend of a substantial underestimation of the actual radon concentration
An international cooperation by using an all-encompassing passive radon monitor
No full textThe recently developed radon film-badge makes it possible to measure radon indoors, in soil, in water and/or in aqueous media (e.g. mud). As a result of its wide response linearity, this monitor has been successfully used to measure radon in-water with concentrations from 10 to ~10 000 Bq/L. By exploiting the unique characteristics of this badge, a mini-survey has been carried out by Health Canada in which radon in water was measured from 12 private wells, as well as in tap water originating from the Ottawa River. Due to the widespread interest of different laboratories in using these passive monitors, laboratories were provided with plastic films to construct their own badges by using in-house CR-39 detectors. Monitors were then irradiated by a known radon concentration at the National Institute of Radiation Metrology (ENEA)'s radon chamber and sent back to each laboratory for processing and counting. Even though these laboratories have been using different etching- and counting-procedures, the film-badge responses varied only within ~12%. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: [email protected]
On the interaction between radon progeny and particles generated by electronic and traditional cigarettes
No full textDuring their entire lives, people are exposed to the pollutants present in indoor air. Recently, Electronic Nicotine Delivery Systems, mainly known as electronic cigarettes, have been widely commercialized: they deliver particles into the lungs of the users but a "second-hand smoke" has yet to be associated to this indoor source. On the other hand, the naturally-occurring radioactive gas, i.e. radon, represents a significant risk for lung cancer, and the cumulative action of these two agents could be worse than the agents separately would. In order to deepen the interaction between radon progeny and second-hand aerosol from different types of cigarettes, a designed experimental study was carried out by generating aerosol from e-cigarette vaping as well as from second-hand traditional smoke inside a walk-in radon chamber at the National Institute of Ionizing Radiation Metrology (INMRI) of Italy. In this chamber, the radon present in air comes naturally from the floor and ambient conditions are controlled. To characterize the sidestream smoke emitted by cigarettes, condensation particle counters and scanning mobility particle sizer were used. Radon concentration in the air was measured through an Alphaguard ionization chamber, whereas the measurement of radon decay product in the air was performed with the Tracelab BWLM Plus-2S Radon daughter Monitor. It was found an increase of the Potential Alpha-Energy Concentration (PAEC) due to the radon decay products attached to aerosol for higher particle number concentrations. This varied from 7.47±0.34MeVL-1 to 12.6±0.26MeVL-1 (69%) for the e-cigarette. In the case of traditional cigarette and at the same radon concentration, the increase was from 14.1±0.43MeVL-1 to 18.6±0.19MeVL-1 (31%). The equilibrium factor increases, varying from 23.4%±1.11% to 29.5%±0.26% and from 30.9%±1.0% to 38.1±0.88 for the e-cigarette and traditional cigarette, respectively. These growths still continue for long time after the combustion, by increasing the exposure risk. © 2014 Elsevier Ltd
Determination of blank indication of active radon monitors
No full textThe importance of determination of the blank indication for active radon monitors is discussed. Two new blank chambers were developed at ENEA-INMRI that allows such determination with an uncertainty lower than a few Bq/m3. Results are reported and that show the large blank variability between radon active monitors and its growth with time when such monitors are used at high radon concentrations. © 2013 Elsevier Ltd
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