Radon concentrations and absorbed dose measurements in a Pleistocenic cave

Radon concentration measurements were carried out using solid-state nuclear track-etch detectors (SSNTDs) type CA 80-15 cellulose nitrate films, in a Pleistocenic cave at Petralona, in Halkidiki, Northern Greece, at 55 km from the city of Thessaloniki. Radon levels as high as 88 kBq^.m^-3 (2.38 nCi^.l^-1) have been recorded inside the cave equivalent to 11.90 WL in terms of occupational exposure to radon and its decay products. Absorbed dose rates were performed using TL dosimeters, type TLD-200 (CaF₂-Dy) in a continuous monitoring program (integrated measurements). Dose rate levels as high as 110 nGy^.h^-1 were recorded inside the cave. In interpreting the high levels of radiation doses, radioactivity measurements regarding the naturally occurring ²³⁸U, ²³²Th and ⁴⁰K radionuclides were carried out in various speleothems found at different sites in the cave.     

Neutron yields from massive lead and uranium targets irradiated with relativistic protons

Long-lived isotopes can be transmuted into stable or short-lived elements either by neutron captures or neutron induced fission. The need of a large excess of neutrons has led to the use of accelerator driven sources (ADS). A series of experiments were carried out at the Synchrophasotron/Nuclotron of the Joint Institute for Nuclear Research (JINR) Dubna, using protons of 1.0 GeV. Solid Lead and Uranium targets surrounded by paraffin moderator were irradiated. On the outer surface of the moderator a number of Solid State Track Detectors were placed to monitor neutron spatial distribution. The results showed that the maximum neutron production was reached within the range of one to two proton mean free paths in the target. Then decreasing neutron production follows the proton beam attenuation along the target. Moreover, the results showed both targets neutron production evolution along the target, to be the same. However, neutron flux per incident proton is depended on the target mass, which was found to be higher for the heavier target.     

Spatial and seasonal variation of radionuclides in soils and waters near a coal-fired power plant of Northern Greece: environmental dose assessment

Journal of Radioanalytical and Nuclear Chemistry - The determination of the radionuclides of U- and Th-series as well as of 40K and 137Cs in soils and waters in a lignite mining area was performed....     

Radiation measurements and radioecological aspects of fallout from the Fukushima nuclear accident

Fallout from the Fukushima Nuclear Accident has been monitored for about 1 month in Thessaloniki, Northern Greece. Three different radionuclides, one short-lived, one relatively long-lived and one long-lived fission product were identified in air, precipitation, soil, grass and milk samples. The ¹³¹I, ¹³⁷Cs and ¹³⁴Cs activity concentrations in air reached 497, 145 and 126 μBq m⁻³, respectively on 4 April, 2011. The external exposure dose rate to humans of the order of 14.4 pSv per day due to ¹³⁷Cs deposited on the ground was very small compared to the normal background level. The accumulated dose equivalent to the adult thyroid from inhaled ¹³¹I varied from 0.4 to 3.5 nSv per day was insignificant and there was not any problem for the Greek population and no preventive measures were needed to be provided against the nuclear accident according to the Greek Atomic Energy Commission, the official agent of the Greek Government. Some special radioecological aspects in the air-grass-cow-milk-man pathway for ¹³¹I were particularly studied.     

Application of zeolitic rocks in the environment: assessment of radiation due to natural radioactivity

Journal of Radioanalytical and Nuclear Chemistry - The 238U, 226Ra, 210Pb, 228Ra, 228Th and 40K concentrations have been measured beside to radon emanation factor due to sample granulometric using...     

Radiological status in sea-sediments and sand near an oil shale power plant in North-Western Greece

Journal of Radioanalytical and Nuclear Chemistry - Oil and oil products belong to the naturally occurring radioactive materials-ΝΟRΜs. In the present study, the radiological status...     

Radionuclides from Fukushima accident in Thessaloniki, Greece (40°N) and Milano, Italy (45°)

¹³¹I, ¹³⁷Cs and ¹³⁴Cs were observed in environmental samples in Milano (40°N), Italy and Thessaloniki (45°N), Greece, soon after the nuclear accident in Fukushima, Japan. The radionuclide concentrations were determined and studied as a function of time. In Thessaloniki the ¹³¹I in air was observed for the first time on March 24, 2011. In Milano, the first evidence of Fukushima fallout has been confirmed with ¹³¹I and ¹³⁷Cs measured in wet precipitation collected 2 days later. The maximum ¹³¹I activity concentration in air of 467 ± 25 μBq m^?3, observed in Milano on April 3–4, 2011, was almost similar to the highest value of 497 ± 53 μBq m^?3 observed in Thessaloniki. The ¹³⁴Cs/¹³⁷Cs activity ratio values in air were around 1 in both regions. Soil, grass and milk samples were contaminated with ¹³¹I and ¹³⁷Cs at a low level. Finally, a dose assessment for these two areas showed clearly that the detected activities in all environmental samples were far below levels of concern.     

Cesium-137 in air late after the Chernobyl reactor accident

Summary Cesium-137 in air as high as 88.1 μBq ^. m^-3 was recorded in Thessaloniki, Northern Greece (40°38’N, 22°58’E) on June 3, 1998 very late after the Chernobyl reactor accident following a radiological incident occurred in a steel factory at Acerinox, Spain.     

Application of passive methods for electron flux measurements regarding to <Superscript>238</Superscript>U electron-disintegration studies

The electron flux is measured using ²³⁸U targets detecting the (e, n) and (e, f) reactions for which the data are currently available only for low energies. The photon and photoneutrons contamination of the primary electron beam are estimated through Monte Carlo simulations using MCNP code. A mean flux 4.40 (±?0.95)?×?10⁹ e cm^?2 s^?1 uniformly spreading over the irradiation filed is assessed. There is an acceptable agreement between the results corresponding to different nuclear reactions used. Therefore, the application of ²³⁸U (e, n) and (e, f) reactions as monitor-reference proves to be an improvement for further electron-disintegration studies.