Transport of radon through materials is a process strongly influenced by several parameters characterizing the materials themselves, such as porosity, permeability, grain size, content of ...radionuclides and diffusion coefficient of this gas through the interstitial pores and/or fractures of material. In order to enlighten more on the radon transport mechanisms, we are carrying out a systematic study on both in-soil radon measurements and laboratory analysis. Laboratory measurements are carried out on different types of samples from geologically different sites in the East Sicily (Italy), to measure the exhalation rate of radon at different controlled physical conditions, varying the parameters of porosity and grain size, content of radio, in order to characterize the dependence of the process of radon transport by these parameters.
We report in particular preliminary results of our study on radionuclide content and on the radon exhalation rate from building materials used in Mt. Etna and in the Hyblean Plateau villages.
This study is important from the radioprotection point of view and could represent a contribution to better define the transport process of radon through fractured media to clarify on correlation between radon concentration and geodynamical, volcanic and tectonic, events.
► Measurements of radium content in building materials. ► Measurements of radon exhalation rate. ► Dependence on grain size.
The MEV project is running for a long-term muography measurement at the North-East crater of the Etna Volcano, after the successful conclusion of the test phase in July 2017. Two sets of data were ...already acquired during 2017, during the last months of the summer, and 2018. Data analysis is currently ongoing in order to extract a two-dimensional density map of the target from the measured muon flux. But before, a major improvement on data pre-processing was required. It regards in particular the algorithm for event reconstruction and filtering and the introduction of a method to extract the telescope efficiency from data themselves. The main steps of this pre-analysis and their application to the test data set is described in this paper.
Three different methodologies were used to measure Radon (
222Rn) in soil, based on both passive and active detection system. The first technique consisted of solid-state nuclear track detectors ...(SSNTD), CR-39 type, and allowed integrated measurements. The second one consisted of a portable device for short time measurements. The last consisted of a continuous measurement device for extended monitoring, placed in selected sites. Soil
222Rn activity was measured together with soil Thoron (
220Rn) and soil carbon dioxide (CO
2) efflux, and it was compared with the content of radionuclides in the rocks. Two different soil–gas horizontal transects were investigated across the Pernicana fault system (NE flank of Mount Etna), from November 2006 to April 2007. The results obtained with the three methodologies are in a general agreement with each other and reflect the tectonic settings of the investigated study area. The lowest
222Rn values were recorded just on the fault plane, and relatively higher values were recorded a few tens of meters from the fault axis on both of its sides. This pattern could be explained as a dilution effect resulting from high rates of soil CO
2 efflux. Time variations of
222Rn activity were mostly linked to atmospheric influences, whereas no significant correlation with the volcanic activity was observed. In order to further investigate regional radon distributions, spot measurements were made to identify sites having high Rn emissions that could subsequently be monitored for temporal radon variations. SSNTD measurements allow for extended-duration monitoring of a relatively large number of sites, although with some loss of temporal resolution due to their long integration time. Continuous monitoring probes are optimal for detailed time monitoring, but because of their expense, they can best be used to complement the information acquired with SSNTD in a network of monitored sites.
Solid State Nuclear Track Detectors (SSNTDs), CR-39™ type, are usually adopted in many applications in which it could be necessary to select tracks according to the incident alpha-particle energy; so ...several authors have argued that track parameters such as the major/minor axis being the most often reported, can be used to determine the alpha-particle’s energy.
However, the use of these parameters only do an univocal result, for example the same axis length can be obtained for different combinations of incident angles and energies.
We report on a track analysis performed by a semiautomatic system that classifies tracks according to two parameters, diameter length and mean grey level. This kind of analysis can give information about the track depth, that increases monotonically with the incident energy and angle of the alpha particle. Combining the information on the two parameters it is possible to determine univocally the incident alpha-particle energy values.
In order to characterize CR-39 detectors according to the physical track parameters, detectors were irradiated, inside a vacuum chamber, by alpha particles at thirteen energy values, obtained by different mylar layers in front of a 241Am source. After the exposure the detectors were chemically etched to enlarge the tracks and then analyzed by means of a semiautomatic system, consisting on an optical microscope equipped with a CCD camera connected to a personal computer for image storage. A suitable routine analyzed the track parameters: diameter and mean grey level, allowing us to differentiate tracks according to the incident alpha-particle energy and then to individuate the discrimination factors for radon alpha tracks, when nuclear track detectors are applied in radon surveys.
► CR-39. ► Geometric and optical parameter. ► α spectrometry. ► Calibration.
In general people associate environmental radioactivity with the artificial radioactivity and knows very little about natural radioactivity. Thus there is a critical need to improve nuclear physics ...public education. From 2005 in Italy two programs were promoted from Ministry of Education and University and National Institute of Nuclear Physics (INFN) for scientific dissemination in the field of environmental radioactivity. High school students in many Italian regions were involved in particular in indoor radon measurements. With this program students acquired awareness about the risks of inhalation of radon and its progeny and at the same time contributed to carry out radon monitoring, participating to all the experimental phases, from detectors set-up to data analysis. In particular we report about the activities carried out at Catania University and INFN division regarding a survey in the eastern Sicily. The overall monitoring, spanned over a period of 5 years, was carried out using passive nuclear track detection technique, through CR-39 dosimeters. In total about 500 detectors were placed in dwellings and schools in 57 locations. The investigated area have shown medium–high indoor radon concentrations, higher than the Italian average (70 Bq/m
3
). From the evaluation of the participating teachers and students, this kind of activities represents a successful strategy to enhance dissemination of physics, in particular in radioactivity topics.
Tritium is a naturally occurring radionuclide, due to interactions of cosmic-rays with the upper layers of the atmosphere; but its presence in the environment is mainly due to residual fallout from ...nuclear weapons atmosphere tests, carried out from 1952 till 1980. Tritium reaches the Earth’s surface mainly in the form of precipitation, becoming part of the hydrological cycle, then the interest of tritium content analysis in drinking water is both for dosimetry and health-risk and for using tritium as a natural tracer in the groundwater circulation system. This paper presents results from a survey carried out in the Mt. Etna area (east and west flanks) and in the southern side of Nebrodi in Sicily (Italy), in order to determine tritium activity concentrations in water samples by using liquid scintillation counter. The investigated areas show quite low tritium concentrations, much below the Italian limit of 100 Bq L
−1
for drinking water and even comparable with the minimum detectable activity value. The effective dose due to tritium for public drinking water consumption was also evaluated.
One of the main contributions to indoor radon levels is given by the exhalation from building materials. For this reason we performed measurements of radon exhalation rate in materials commonly used ...in buildings of the eastern Sicily. The measurements were carried out by using solid state nuclear track detectors in diffusion chambers. We report the results obtained for samples of materials used both for building and for decorating dwellings. The obtained values have shown that building materials commonly used in the eastern Sicily have surface exhalation rates ranging between 1.9 and 43.1 mBq m
−2
h
−1
showing higher values for volcanic materials.
Natural radioactivity measurements represent an interesting tool to study geodynamical events or soil geophysical characteristics. In this direction we carried out, in the last years, several ...radionuclide monitoring both in the volcanic and tectonic areas of the oriental Sicily. In particular we report in-soil Radon investigations, in a tectonic area, including both laboratory and in-site measurements, applying three different methodologies, based on both active and passive detection systems. The active detection devices consisted of solid-state silicon detectors equipped in portable systems for short-time measurements and for long-time monitoring. The passive technique consisted of solid-state nuclear track detectors (SSNTD), CR-39 type, and allowed integrated measurements. The performances of the three methodologies were compared according to different kinds of monitoring. In general the results obtained with the three methodologies seem in agreement with each other and reflect the tectonic settings of the investigated area.
Radioactivity in underground waters from Mt. Etna was investigated on the basis of 13 samples. The samples were collected from springs, wells and galleries around the volcano. Water from nine out of ...thirteen intakes is used for consumption. Activity concentration of uranium isotopes
234,238U, radium isotopes
226,228Ra and radon
222Rn were determined with the use different nuclear spectrometry techniques. The measurements of radium and radon activity concentration were performed with the use of a liquid scintillation counter. The determination of uranium isotopes was carried out with the use of alpha spectrometry. All samples show uranium concentration above Minimum Detectable Activity (MDA), with the highest total uranium (
234U
+
238U) activity concentration equal to 130
mBq/l. For radium isotopes, all samples except one showed the activity concentration below MDA. Radon activity concentration was within the range from 1 to 13
Bq/l, hence these waters can be classified as low-radon waters.
Soil radon has been monitored at a fixed location on the northeastern flank of Mt. Etna, a high-risk volcano in Sicily. The aim of this study was to evaluate the effects of the recent volcanic ...activity on soil radon concentration. Continuous radon measurements have been performed since July 2001. While comparison between the trend in in-soil radon concentration and the acquired meteorological series (temperature, humidity and pressure) appear to confirm a general seasonal correlation, nevertheless particular anomalies suggest a possible dependence of the radon concentration on volcanic dynamics.
