K. Stamoulis

Radon Activity Levels And Effective Doses In The Perama Cave, Greece

Abstract— An investigation of atmospheric radon levels in the Perama Cave, North-western Greece, has been carried out using CR-39 detectors. The detectors were placed at various locations along the guided cave pathway and exposed during different sampling periods. Mean concentrations amounting to 925 ± 418 and 1,311 ± 352 Bq m−3 were recorded in the summer and winter months, respectively. As the Perama Cave is one of the most popular in Greece, attracting more than 85,000 tourists per year, the quantification of effective doses to staff and visitors was an issue of importance. Doses less than 5.1 μSv per visit were calculated for tourists and around 1.8 mSv y−1 for seasonal guides, employed for periods of high visiting frequency. The annual exposure of permanent guides was estimated to fall between 3 and 10 mSv, which is the range of action levels recommended by the ICRP.

A survey of 222Rn concentrations in dwellings of the town of Metsovo in North-Western Greece

A radon survey has been carried out of indoor radon concentrations in dwellings located in the town of Metsovo, in north-western Greece. To measure indoor radon concentrations, CR-39 detectors were installed in randomly selected houses and were exposed for about 3 mo, during summer and winter. Gamma spectroscopy measurements of the soil’s radium content also were performed. The indoor radon concentration levels varied from 17.6 to 750.4 Bq m−3, while the radium concentration of soil varied from 4.9 to 97.1 Bq m−3. Seasonal variation of the radon levels and the influence of house features and soil are discussed.

Kinetics of radiocesium sorption in lake sediments

The sorption of radiocesium (137Cs) in sediments sampled from Lake Pamvotis of Ioannina was studied in a laboratory simulation. In a series of experiments, the kinetics of 137Cs sorption and 137Cs distribution profiles in sediment cores were investigated. The results have shown that a significant percentage of 137Cs (35%) is adsorbed in the sediments during the first 3 d, at a rate of 0.41 +/- 0.05 d-1. The rest of 137Cs is adsorbed with the slower rate of 0.024 +/- 0.004 d-1. 137Cs rapidly reaches (< 5 d) a depth that does not exceed 3.5 cm. The sorption of 137Cs was found to follow Freundlichs empirical law, which describes the adsorption of most substances in solution to solids.

Measurements of222Rn migration in soil

The concentration of radon (222Rn) was measured in the soil near the ground surface, using CR/39 solid state nuclear track detectors. The measurements were carried out in PVC tubes at 0.25 m intervals up to 1.25 m. The detectors were etched in 7N NaOH solutions at 80°C. The α-tracks from radons decay were counted using a microscope. A microscope-camera-computer system developed for automatic counting was also used. The results provide evidence for the non-diffusive transport of radon in soils. A transport length of (46.9±3.2) cm was estimated for radon transport near ground surface. Also the variation of soils radon concentration was correlate to humidity and atmospheric pressure.

Tritium Concentration in Rainwater Samples in Northwestern Greece

Tritium is an isotope of hydrogen, produced in the upper level of the atmosphere. It enters the water cycle after its oxidation and through the precipitation. The measurement of tritium concentration in rainwater is of great importance because it can be used for hydrology investigations such as the recharge mode or the vulnerability of aquifers. For this purpose, rainwater samples were collected for a period of 16 months from October 2002 to January 2004 from a sampling station at Ioannina, northwestern Greece. Each sample was filtered and measured without any further treatment for tritium activity, using a super low-level background, liquid scintillation analyzer. Five mL of the sample were mixed with 15 mL of scintillation cocktail, specially designed for low-level tritium measurements and its beta activity was measured for 500 min. Results show that during the sampling period, the tritium concentration varied up to two fold, increasing during the spring and summer months. The measured tritium concentrations in rainwater, which ranged from 9 ± 4 to 23 ± 5 TU, can be used for local hydrology studies.