Vincenzo Roca

The ALTCRISS project on board the International Space Station.

The Alteriss project aims to perform a long term survey of the radiation environment on board the International Space Station. Measurements are being performed with active and passive devices in different locations and orientations of the Russian segment of the station. The goal is to perform a detailed evaluation of the differences in particle fluence and nuclear composition due to different shielding material and attitude of the station. The Sileye-3/Alteino detector is used to identify nuclei up to Iron in the energy range above similar or equal to 60 MeV/n. Several passive dosimeters (TLDs, CR39) are also placed in the same location of Sileye-3 detector. Polyethylene shielding is periodically interposed in front of the detectors to evaluate the effectiveness of shielding on the nuclear component of the cosmic radiation. The project was submitted to ESA in reply to the AO in the Life and Physical Science of 2004 and data taking began in December 2005. Dosimeters and data cards are rotated every 6 months: up to now three launches of dosimeters and data cards have been performed and have been returned with the end of expedition 12 and 13

A radon facility at Naples University: Features and first tests

A radon calibration facility was developed at Naples University (Italy). It consists of an exposure chamber, a radon reference monitor and an apparatus suitable for radon circulation and air climatic control. The parameters that are possible to change and control are carrier gas, radon activity, gas pressure, temperature, and humidity. The characterization of the facility is actually underway to verify its reliability and stability with respect to various parameters of interest.

Radon Exposure Assessment and Relative Effective Dose Estimation to Inhabitants of Puglia Region, South Italy

Indoor radon concentrations were measured in dwellings of the Puglia region in Southern Italy using LR-115 passive detectors. The results show that the radon concentrations varied from 15 ± 2 to 2166 ± 133 Bq/m3 with a geometric mean of 114 Bq/m3 and a geometric standard deviation of 2.3. An analysis on the factors affecting radon concentration such as age of the dwellings, floors, and stories, was performed. The mean effective dose to inhabitants has been calculated and found to be 8.2 mSv/y. Finally, for estimation of cancer risks, the lifetime risk and lung cancer cases per years per million have been calculated.

Tests of shielding effectiveness of Kevlar and Nextel onboard the International Space Station and the Foton-M3 capsule

Radiation assessment and protection in space is the first step in planning future missions to the Moon and Mars, where mission and number of space travelers will increase and the protection of the geomagnetic shielding against the cosmic radiation will be absent. In this framework, the shielding effectiveness of two flexible materials, Kevlar and Nextel, were tested, which are largely used in the construction of spacecrafts. Accelerator-based tests clearly demonstrated that Kevlar is an excellent shield for heavy ions, close to polyethylene, whereas Nextel shows poor shielding characteristics. Measurements on flight performed onboard of the International Space Station and of the Foton-M3 capsule have been carried out with special attention to the neutron component; shielded and unshielded detectors (thermoluminescence dosemeters, bubble detectors) were exposed to a real radiation environment to test the shielding properties of the materials under study. The results indicate no significant effects of shielding, suggesting that thin shields in low-Earth Orbit have little effect on absorbed dose.

Radon Exposure Assessment for Sewerage System’s Workers in Naples, South Italy

An indoor radon survey has been carried out in 17 workplaces of sewerage system of Naples city using E-Perm detectors in long-term configuration. The main objective was to assess the mean effective dose for workers. The measured indoor radon concentration ranged from 1714 to 3789 Bq m−3 in the rooms located on second level underground, from 138 to 5772 Bq m−3 in the rooms on first level underground and from 53 to 913 Bq m−3 in the ground floor. The mean annual effective doses in the ground floor, first and second level underground were found to be 0.85 mSv, 0.29 mSv and 0.43 mSv, respectively. These values are less than the lower limit of International Commission on Radiological Protection (ICRP) recommended action levels of 3–10 mSv y−1.

INDOOR RADON CONCENTRATION MEASUREMENTS IN SOME DWELLINGS OF THE PENISOLA SORRENTINA, SOUTH ITALY

In this study, the indoor radon concentrations have been measured in 93 dwellings of the Penisola Sorrentina, using LR115 detectors. The detectors were placed in the bedrooms and living rooms for two consecutive semesters starting from December 2010 to December 2011. The annual average indoor radon concentrations vary from 25 to 722 Bq m(-3), with a mean value of 132 ± 114 Bq m(-3). Correlation between indoor radon measurements and same building characteristics was also studied. Based on the obtained results, the mean annual effective dose of 2.4 mSv y(-1) received by inhabitants was estimated.

222Rn + 220Rn monitoring by alpha spectrometry

Controlled 222Rn+220Rn mixed atmospheres have been realised introducing calibrated sources in a stainless steel chamber. An electrostatic alpha monitor internal to the chamber has been used for an accurate discrimination of alpha peaks due to the products of the two isotopes. In the chamber, different specific activities are achieved in order to test the response of the internal reference instrument and to evaluate the possible interferences due to contemporary presence of both radon isotopes. Results show that: (i) the atmospheres are very stable, (ii) the monitor is adequate for their control because the various alpha lines are well evaluated and (iii) using Tyvek® filter, the efficiency of monitor is stable and constant vs. activity.

Gamma dose rate measurements in dwellings of Campania region, South Italy

A survey of gamma exposure in dwellings of Campania region, southern Italy has been performed using Thermo Luminescent Dosimeters (TLD). In each dwelling TLDs were exposed for six months in the room where the inhabitant spent most of their time, generally the bedroom or living room. The arithmetic mean was found to be 264 ± 111 nGy/h, after the subtraction of the cosmic contribution. The effects of building materials and geographic location were also examined. Using UNSCEAR model, the annual effective dose due to indoor gamma radiation was evaluated and it was found to be 1.3 mSv/y, that is higher than Italian national average of 0.4 mSv/y.

Indoor radon activity concentration measurements in the great historical museums of University of Naples, Italy.

Indoor radon activity concentrations were measured in seven Museums of University of Naples, very old buildings of great historical value. The measurements were performed using a time-integrated technique based on LR-115 solid-state nuclear track detectors. The annual average concentrations were found to range from 40 up to 1935 Bq m(-3) and in 26 % of measurement sites, the values were higher than 500 Bq m(-3) which is the limit value of Italian legislation for workplace. Moreover, we analysed the seasonal variations of radon concentrations observing the highest average in cold weather than in warm.

RADON MEASUREMENTS AND EFFECTIVE DOSE FROM RADON INHALATION ESTIMATION IN THE NEAPOLITAN CATACOMBS

In this study, the indoor radon activity concentrations have been measured in the Neapolitan catacombs using LR115 detectors. The detectors were exposed for two quarters, one in the warm season and the other in the cold. This has allowed one to evaluate the seasonal variations of concentrations, while the diurnal variations were evaluated performing continuous measurements by a Radim 5 monitor. The authors found that radon concentrations were lower in winter than in summer. Based on their values, taking into consideration the working hours in the catacombs and the equilibrium factor of 0.4, the effective dose to workers was estimated.