Cilt:03 Sayı:01 (2016)
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Item Elemental Analysis of Raw Materials of Nuclear Reactor Shielding to Develop Low Activation ConcreteISLAM, M.A.; MAHMUD, S.; HOSSAIN, S. M.; LATİF, SK. A.; AHSAN, M. H.In this study, elemental concentrations of Ce, Hf, Fe, Sb, Tb, Sc, Ta, Zn, Cs, Co and Eu in raw materials of reactor biological shielding (cement, sand and heavy minerals separated from beach sand) are determined by research reactor-based instrumental neutron activation analysis technique (INAA) so that a strategy can be made to develop low-activation concrete. These elements are mainly responsible of long-lived radionuclides induced in biological shielding of a reactor during its operation. The concentrations of the studied elements in white Portland cements are much lower in comparison with those in ordinary Portland cements. This study reveals that inland sands contain low concentrations of the studied elements than those of beach sands. Elemental compositional data of the shielding materials can be effectively used to choose ingredients necessary for constructing radiation shielding of a nuclear installation to reduce radiation hazard.Item Unexploited Information from Luminescence SpectraTOWNSEND, P.D.Luminescence is a highly sensitive technique to monitor the presence of impurities, imperfections and lattice distortions. To fully exploit it requires sensitive detection systems with high resolution spectral data and temperature control. This review notes both how detector technology has advanced, and mentions simple routes to generate more efficient use of existing photomultipliers. Modern detectors enable wavelength multiplexed spectrometer systems, which are prerequisites for both detailed thermoluminescence analyses and newer applications. These include recording the spectral changes from different crystalline phases, and capturing their characteristic intensity signatures at the phase transition temperature. Less expected is that the luminescence intensity is strongly influenced by the presence of impurities, even when they are not dispersed in the host lattice, but are grouped as nanoparticle inclusions. Spectacular host intensity changes can occur when the inclusions undergo phase transitions. Luminescence is also frequently used to monitor ion implanted materials, but for examples reported here, the spectra can be seriously distorted by absorption and reflectivity properties of the implant layer. Further, luminescence data have demonstrated that the underlying host material can be stressed and then relax into new structural phases. These aspects of spectral distortion and lattice relaxations may be far more common than has been noted in the previous literature. Finally, because the techniques are multi-disciplinary, brief mentions of systematic errors in signal analysis are noted.Item A Retrospective Study for Total Effective Doses of Nuclear Medicine Employees in Istanbul, TurkeyÇAVDAR, İ.; USLU, L.; YEYİN, N.; DEMİR, M.Thermoluminescence dosimeters (TLDs) are safely used to determine radiation doses. This study describes the radiation exposure doses of the radiation employees working at the Department of Nuclear Medicine, Cerrahpasa Medical Faculty in Turkey, where both radionuclide treatment and diagnostic imaging are done at a large scale. According to our results, the average effective dose value over five years belonging to an employee who works at radionuclide treatment service was found to have the highest value as 3.58±1.60 mSv. On the other hand, the average effective dose over a of total 29 employees is 1.53±0.59 mSv. A 5-year average effective dose was found as 1.29 mSv for technicians and 2.38 mSv for nurses. These results demonstrated that the radiation doses received by the employees working in different units are considerably different from each other. However, the doses received by all the workers in these units are under the regulatory limit. In conclusion, homogenized dose distribution between employees can be achieved in case of job rotations in-between.According to our results, the average effective dose value over five years belonging to an employee who works at radionuclide treatment service was found to have the highest value as 3.58±1.60 mSv. On the other hand, the average effective dose over a of total 29 employees is 1.53±0.59 mSv. A 5-year average effective dose was found as 1.29 mSv for technicians and 2.38 mSv for nurses. These results demonstrated that the radiation doses received by the employees working in different units are considerably different from each other. However, the doses received by all the workers in these units are under the regulatory limit. In conclusion, homogenized dose distribution between employees can be achieved in case of job rotations in-between.