The distribution of natural radionuclides 40K, 228Ac, and 226Ra on Romanian Territory: a radiometric study.

To estimate the radiation hazard due to the natural terrestrial radioactivity, 598 samples of soil covering the entire Romanian territory were collected and analyzed for the distribution of natural radionuclides 40K, 228Ac, and 226Ra. The ultra-low background Slanic-Prahova underground laboratory was used to determine the gamma-ray-specific activity of these radioactive isotopes with an uncertainty between 5 and 20%. All these data permitted to establishing a set of 2D maps illustrating the distribution of specific activity of each radionuclide as well as of the resulting air dose rate, all of them illustrating an heterogeneous distribution, increased values being displaced on the western and south-western territory. Mediated over 598 points, these determinations led to a value of annual effective dose of 0.7 ± 0.15 mSv/y and an external hazard index of 0.46 ± 0.1, both attesting to a radioecologically safe environment for human activity.

137Cs distribution on the territory of Romania 30 years after Chernobyl accident.

To estimate the contribution of Chernobyl 137Cs contamination, in 1993 and especially 2016, its total inventory was determined by gamma-ray high-resolution spectroscopy in 62 and respectively 747 soil samples covering the entire Romanian territory. This permitted to estimate the 137Cs inventory as varying between 0.4 and 187 as well as between 0.2 and 94.2 kBq/m2 for years 1993 and 2016, respectively. By representing the spatial distribution of 137Cs inventory in Voronoi polygons, it was possible to evidence a decrease of the total 137Cs inventory over entire Romanian territory with a factor of about 3 from about 3.6 TBq to less than 1.2 TBq, exceeding in this way the natural decay which suggests that a certain amount of 137Cs was washed out by precipitation and, at a lower extent, was incorporated into plants. At the same time, by evaluating the maximum contribution of 137Cs to the population exposure, in 1993 as well as in 2016, the supplementary annual effective dose did not exceed, in the majority of sampling points the value of 0.2 mSv/year.

Quality assurance for measurements of the radioactivity in the area of the"Horia Hulubei" National Institute for Physics and Nuclear Engineering, IFIN-HH.

This paper presents one part of the activities deployed by the Laboratory for Environment and Personnel Dosimetry (LDPM) of IFIN-HH, namely the radiological monitoring of the environment within the Institute's area and its surrounding influence zone, according to the program approved by the National Regulatory Body for Nuclear Activities, CNCAN. The representative reports regard the radioactive content of soil, surface and underground water, cultivated and spontaneous vegetation, aerosols and atmospheric fallout, sediments. The common requirement is that the measured quantities be precise and the reported values be reliable and credible. This goal is achieved by maintaining a Quality System, verified within the obtaining and maintaining of the laboratory accreditation, according to the international standard ISO/IEC 17025:2005.The LDPM is accredited by the Romanian accreditation body, RENAR, member of the European Accreditation, EA and is designed by CNCAN as a notified testing laboratory. Many measurements were performed in collaboration with the Radionuclide Metrology Laboratory (RML) from IFIN-HH, RENAR accredited and CNCAN notified for calibration and for testing in the field of radioactivity measurement. This paper proposes a short presentation of the important aspects in our activity: i. description of equipment, samplingmethods, processing and measurement of environmental samples; ii. validation of equipment and methods by participation in international and national proficiency tests; iii. a five year follow chart, containing the results in measurement of samples; iv. a recent application, with a wide impact in Romanian mass media: the credible daily report on the possible influence of Fukushima accident over the Romanian environmental radioactivity.

Ultra-low background measurements of decayed aerosol filters.

Aerosol samples collected on filter media were analyzed using HPGe detectors employing varying background-reduction techniques in order to experimentally evaluate the opportunity to apply ultra-low background measurement methods to samples collected, for instance, by the Comprehensive Test Ban Treaty International Monitoring System (IMS). In this way, realistic estimates of the impact of low-background methodology on the sensitivity obtained in systems such as the IMS were assessed. The current detectability requirement of stations in the IMS is 30 µBq/m3 of air for 140Ba, which would imply ~106 fissions per daily sample. Importantly, this is for a fresh aerosol filter. One week of decay reduces the intrinsic background from radon daughters in the sample allowing much higher sensitivity measurement of relevant isotopes, including 131I. An experiment was conducted in which decayed filter samples were measured at a variety of underground locations using Ultra-Low Background (ULB) gamma spectroscopy technology. The impacts of the decay and ULB are discussed.