Özlem Karadeniz

Vertical distributions and gamma dose rates of 40K, 232Th, 238U and 137Cs in the selected forest soils in Izmir, Turkey.

This paper presents the results obtained from a radioecological study carried out in the selected forest sites of Izmir, Turkey. The levels of gamma-emitting radionuclides, 40K, 232Th, 238U and 137Cs, in soils were determined using gamma spectroscopy. The activity profile for 40K, 232Th and 238U exhibits a uniform distribution with respect to depth. The depth distribution of 137Cs activity was established by fitting the experimental points to an exponential or a Gaussian function. About 42-97% of the 137Cs deposition was found in the first 10 cm of soil even after 18 y from Chernobyl accident. The dose-rate and annual-effective dose received from external irradiation were quantified. It is indicated that 137Cs from the fallout plays a less role in external radiation exposures in forest sites of Izmir than in potential exposures from naturally occurring radionuclides accounted for by soil.

Radiological mapping in the granodiorite area of Bergama (Pergamon)-Kozak, Turkey

As higher radiation levels are associated with granodiorite area and the maps are more practical to interpret the results of radiological survey, the distributions of the specific activities of 226Ra, 232Th, 40K in soil-granite samples and indoor 222Rn activities throughout the granodiorite area of Bergama (Pergamon) were mapped in detail. Samples from the granites and soils underlying Kozak-Bergama (Pergamon) granodiorite area were collected and analyzed by HPGe gamma spectrometry system, while indoor radon levels in 20 dwellings of rural areas at this area were measured by the alpha track etch integrated method. This paper represents the baseline maps of natural radioactivity levels (226Ra, 232Th, 40K and 222Rn) and corresponding absorbed dose rates from outdoors terrestrial gamma radiation.

Indoor radon measurements in the granodiorite area of Bergama (Pergamon)-Kozak, Turkey

Indoor radon levels in 20 dwellings of rural areas at the Kozak-Bergama (Pergamon) granodiorite area in Turkey were measured by the alpha track etch integrated method. These dwellings were monitored for eight successive months. Results show that the radon levels varied widely in the area ranging from 11±1 to 727±11 Bq m(-3) and the geometric mean was found to be 63 Bq m(-3) with a geometric standard deviation of 2 Bq m(-3). A log-normal distribution of the radon concentration was obtained for the studied area. Estimated annual effective doses due to the indoor radon ranged from 0.27 to 18.34 mSv y(-1) with a mean value of 1.95 mSv y(-1), which is lower than the effective dose values 3-10 mSv given as the range of action levels recommended by International Commission on Radiation Protection. All dosimetric calculations were performed based on the guidance of the UNSCEAR 2000 report.

Indoor 222Rn levels and effective dose estimation of academic staff in Izmir-Turkey.

OBJECTIVE To investigate the annual effective doses from indoor radon received by academic staff in the Faculty building. METHODS Measurements of indoor radon concentrations were performed in the Arts and Sciences Faculty of Dokuz Eylül University for two surveys of about 1 month duration respectively using the SSNTD (Solid State Nuclear Track Detectors) method with LR115 detectors. Time integrated measurements comprised different locations inside the faculty building: classrooms, toilets, canteen and offices. Homes of academic staff were also tested for radon. RESULTS The arithmetic mean radon concentration is 161 Bq m-3 with a range between 40 and 335 Bq m-3 in the Faculty. Six offices and three classrooms have a radon concentration above 200 Bq m-3. The results show that the radon concentration in classrooms is generally higher than in offices. Based on the measured indoor radon data, the annual effective doses received by staff in the Faculty were estimated to range from 0.79 to 4.27 mSv, according to UNSCEAR methodology. The annual effective doses received by staff ranged from 0.78 to 4.20 mSv in homes. On average, the Faculty contributed 56% to the annual effective dose. CONCLUSION Reported values for radon concentrations and corresponding doses are within the ICRP recommended limits for workplaces.

Radiological maps for fallout 7Be in forest soil horizons in a mountainous area of Turkey

ABSTRACT Due to the paucity of data on separate spatial distribution of cosmogenic 7Be radionuclide activities in forest soil layers, a spatial study was performed in Mount Ida (Kazdagi)/Edremit, Turkey. In this study, it was aimed to examine the 7Be spatial variability and depth distribution in the surface soil layers. The 7Be activity concentrations were determined by HPGe gamma spectrometry system and the distributions of 7Be activities in the OL and OF + OH horizons throughout the region were mapped separately. Activity concentrations of 7Be in OL horizons and OF+OH horizons varied as 35 ± 23–701 ± 40 Bq kg−1 and 0.96 ± 0.63–197 ± 11 Bq kg−1, respectively. 7Be inventories (0.20 ± 0.06–5.69 ± 0.75 kBq m−2) in the study area were relatively higher when compared with the other regions of the world. 7Be inventories increased with altitude, slope and the thickness of the humus layer in some of the investigated area. Average 7Be activity level in deciduous forest stand type was significantly higher than that for coniferous and mixed stand types. Our limited data could not provide a latitudinal distribution pattern of 7Be soil inventory or precipitation dependence and further investigation is needed.

A study on the extrinsic sensitivity and counting efficiency of a gamma camera for a cylindrical source and a rectangular detector

In this work, the extrinsic counting efficiency and extrinsic sensitivity of a cylindrical source and a gamma camera with a rectangular detector were determined using homogeneous Tc-99m. Scattered radiation effects were evaluated by both analyzing the energy spectrum of 99mTc for the scatter fraction and plotting the extrinsic counting efficiency and sensitivity. It is found that the scattered fraction values increased with increasing source thickness. Calculated extrinsic sensitivity shows a gradually decreasing trend with increasing source thickness. The extrinsic efficiency decreases with increasing source thickness. It is concluded that increasing source to detector distances results with increasing extrinsic counting efficiency but decreasing extrinsic sensitivity.

Indoor radon measurement in Izmir Province, Turkey

ABSTRACT In 2013, an extensive study was performed in a total of 117 locations in Izmir province and indoor radon levels were measured using the alpha track etch integrated method with LR-115 detectors. As the maps are more practical to interpret the results of radiological survey, the distributions of indoor 222Rn activities in four most densely populated districts of Izmir were mapped in detail. It is seen that the estimated average radon concentration level (210 Bq m−3) determined in Izmir province was almost three times higher than the mean value for Turkey (81 Bq m−3). Exposed annual effective dose equivalents for Izmir province were estimated in the range of 0.7 to 12.3 mSv year−1 with a mean of 5.3 mSv year−1. In this study, it is pointed out that indoor radon concentration was affected by the age of the building and height above the ground.

Preliminary dose estimation from indoor radon for the medical staff of Radiation Oncology and Nuclear Medicine

ABSTRACT The aim of this preliminary study was to measure the indoor radon activity concentration in the houses and offices of Radiation Oncology and Nuclear Medicine staff at Dokuz Eylül University and to assess the results from a radiological perspective. LR-115 type II solid-state nuclear track detectors were installed in the homes and hospital and were exposed for 2 months. LR-115 type II detectors were etched for 90 min in 10% (2.5 M) NaOH solution at 60°C and radon activity concentration was determined from observed microscopic track densities. It was observed that measured indoor radon concentration ranged between 18 and 624 Bq/m3 with a geometric mean of 95 Bq/m3 in hospital, and between 22 and 560 Bq/m3 with a geometric mean of 129 Bq/m3 in homes. Estimates of the annual effective dose received by medical staff who participated in the study ranged between 0.76 and 8.79 mSv. On average, the hospital building contributed 41% to the annual effective dose. The reported values for radon concentrations and the corresponding estimated annual effective equivalent doses were within the limits recommended by the International Commission on Radiological Protection as well as the Turkish Atomic Energy Commission recommended limits for workplaces and houses.