N. Altinsoy

Natural radioactivity levels of granites used in Turkey

Thirty granite samples commonly used in Turkey were surveyed for natural radioactivity. Concentrations of natural radionuclides in all samples were determined by gamma-ray spectroscopy with hyper-pure germanium detector. The activity concentrations measured for (226)Ra and (232)Th ranged from 0.7±0.1 to 186±1 Bq kg(-1), and from 0.5±0.1 to 249±2 Bq kg(-1), respectively. The activity concentrations obtained for (40)K varied from minimum detectable activity (0.4 Bq kg(-1)) to 1935±11 Bq kg(-1). The radium equivalent activity (Ra(eq)), the absorbed dose rate (D), the external hazard index (H(ex)) and the annual effective dose equivalent were also calculated and compared with the international recommended values. Granite samples were also analysed mineralogically. It was observed that the presence of large amount orthoclase and radiogenic accessory minerals are the sources of high activity concentration levels.

Determination of the health hazards due to background radiation sources in the city of Adapazari, Northwestern Turkey

Human body is exposed to ionising radiations both internally and externally by mainly high-energy cosmic ray particles incident on the earths atmosphere and radioactive nuclides that originated in the earths crust. The main objective of this study is to assess the health hazards due to environmental radiation sources in the city of Adapazari, one of the most important industrial cities of the country, Northwestern Turkey. For this purpose, natural radiation sources, external terrestrial radiations, cosmic radiations, and inhalation exposures have been investigated. The annual average external terrestrial radiation doses were determined as 0.08 and 0.35 mSv at outdoor and indoor atmospheres, respectively. The annual average cosmic radiation doses were found to be 0.08 and 0.05 mSv for directly ionising photon components and neutron components, respectively. The annual average inhalation exposure doses due to radon and thoron were obtained as 1.42 and 0.19 mSv, respectively, in the region. The annual average effective dose due to natural radiation sources was determined as a total of 2.35 mSv with the predetermined ingestion radiation dose. The lifetime cancer risk due to the background ionising radiations has been determined as 0.9×10−2 for the residents of the Adapazari city, with the average lifespan of 70 years. The results of the effective doses due to background radiation sources in the region and the worldwide averages were discussed.

A study of indoor radon levels in rural dwellings of Ezine (Çanakkale, Turkey) using solid-state nuclear track detectors

Indoor radon activity level and radon effective dose (ED) rate have been carried out in the rural dwellings of Ezine (Canakkale) during the summer season using Radosys-2000, a complete set suitable to radon concentration measurements with CR-39 plastic alpha track detectors. The range of radon concentration varied between 9 and 300 Bq m(-3), with an average of 67.9 (39.9 SD) Bq m(-3). Assuming an indoor occupancy factor of 0.8 and 0.4 for the equilibrium factor of radon indoors, it has been found that the 222Rn ED rate in the dwellings studied ranges from 0.4 to 5.2 mSv y(-1), with an average value of 1.7 (1.0) mSv y(-1). There is a possibility that low radon concentrations exist indoors during the summer season in the study area because of relatively high ventilation rates in the dwellings. A winter survey will be needed for future estimation of the annual ED.

A radiotracer application for the turbulent dispersion of fluids

Abstract The concentration profiles for turbulent flow were determined using a radiotracer technique. An experimental test device was constructed and sodium-24 was used as the tracer. Methylene-blue was also used for a comparison of the results. Samples were taken from different radial planes. The mean squared displacement was calculated and compared with the data of Taylor and Middleman [Taylor, A.R., Middleman, S., 1974. Turbulent dispersion in drag-reducing fluids. AIChE Journal, 20(3), 454-461]. It was shown that the radiotracer technique could be applied successfully to turbulent flow in vertical pipes.

Selenium Adsorption on Activated Carbon by Using Radiotracer Technique

Selenium (Se) is an essential trace element for human beings and plays important roles in human health but it is also toxic at concentrations above 1 mg of selenium per kg of body weight. Therefore, elimination of selenium ions from aqueous solutions is important. Se can be eliminated by using activated carbon as an adsorbent. Radiotracer concept is applicable for observation of elimination mechanism. For this reason, selenium radioisotope can be used as tracer. Selenium dioxide is irradiated in the central thimble of ITU TRIGA Mark II Training and Research Reactor for radiotracer production. Radioactivity measurements are carried out by the gamma-ray spectroscopy system to determine the effect of different experimental parameters. The relative importance of test parameters like concentration of adsorbate, pH of the solution, and contact time on adsorption performance of activated carbon for selenium ion is examined. Typical adsorption isotherms (Langmuir, Freundlich, Dubinin–Radushkevich, and Temkin) are determined for the mechanism of sorption process. Evaluation of experiments for different parameters shows possibility of elimination of selenium from aqueous media by using activated carbon.

Radon concentrations in three underground lignite mines in Turkey.

Monitoring of radon in underground mines is important in order to assess the radiological hazards to occupational workers. Radon concentration levels in three underground lignite mines (Tunçbilek, Omerler and Eynez) of Turkey were obtained in this study. For this reason, atmospheric radon level measurements were carried out in mines using CR-39 track detectors. Chemical etching of the detector tracks and subsequent counting were performed at Cekmece Nuclear Research and Training Center. The obtained results were evaluated according to the International Commission of Radiation Protection and the Turkish Atomic Energy Authority whose radon action levels for workplaces are 500-1500 and 1000 Bq(-3), respectively. The radon gas concentrations in the lignite mines were determined to be between 50 +/- 7 and 587 +/- 16 Bq m(-3). The results obtained in these experiments are far under the action levels. The computed radon doses for the mine workers of Tunçbilek, Omerler and Eynez lignite mines are 1.23, 2.44 and 1.47 mSv y(-1), respectively.

Evaluation of Rubidium and Potassium Diffusion in Soil by Radiotracer Technique

In this study, diffusion of rubidium and potassium in soil was observed representing two alkaline elements. Generally, these elements are found as salt compounds in the earth. Soil columns were prepared in the laboratory conditions. Rubidium chlorite and potassium nitrate compounds were irradiated at ITU TRIGA Mark II nuclear research reactor at the Energy Institute of ITU to produce the radiotracer 86Rb and 42K. The irradiated compounds were sprinkled to the surface of different soil columns and were watered with realistic amounts. Radioactivity measurements were carried out by using a scintillation detector at the outside of the column for different soil depths in different diffusion times. As the results of the study, the behavior of two alkaline elements was observed appropriately similar in the soil.

Investigation of Salt Diffusion in Soil by Using Radiotracing Technique

In this study, it is aimed to observe diffusion of sodium in soil samples by using radiotracing technique. To produce the radiotracer 24Na, sodium-carbonate compound was irradiated at ITU TRIGA Mark II Research reactor at Energy Institute of Istanbul Technical University. The irradiated sodium-carbonate samples were sprinkled to the surface of soil columns. Then soil was watered with representative amounts of water according to selected rain regimes in Istanbul. Radioactivity measurements were carried out by using high efficiency gamma-ray measurement system at the outside of the column for different soil depths in different times.

ESTIMATION OF ADULT PATIENT DOSES FOR CHEST X-RAY EXAMINATIONS AND COMPARISON WITH DIAGNOSTIC REFERENCE LEVELS (DRLs)

The aim of this study was to evaluate the radiation doses to patient during chest (posterior anterior/and lateral) examinations. The study was performed in three public hospitals of İstanbul province with a total of 300 adult patients. Entrance surface dose (ESD) measurements were conducted on computed radiography, digital radiography and screen film system. ESD was estimated by using International Atomic Energy Agency (IAEA) model and Davies model which are the common indirect models. Results were compared with diagnostic reference levels from the European Commission, IAEA and National Radiological Protection Board. Although the results are compatible with the international diagnostic reference levels, they present variations between the hospitals. Dose variations for the same type of X-ray examination support the idea that further optimization is possible.

Evaluation for elimination of methylene-orange from aqueous media by using membrane

Elimination of the methylene orange which are the main sources of environmental pollution from aqueous media were investigated experimentally by using 0.45 µm hydrophilic nylon membran. Removal of the methylene orange were performed with successfully. Furthermore, repetition effect also was examined rationally. With this study, membrane usage for elimination of the methylene orange are convenient for elimination of them from the aqueous media.