Evaluation of Natural Radioactivity and Radiological Hazards in Some Building Materials Used in Kars

Bu çalışmada, Kars ilinde kullanılan bazı yapı malzemelerinin radyoaktivite seviyeleri ve bu malzemelerinin kullanılmasından kaynaklanabilecek radyolojik riskler belirlendi. Kars'ın değişik bölgelerinden 10 farklı yapı malzemesini (kireçtaşı, kil, tras, alçıtaşı, demir cevheri ve dört farklı çimento numunesi) temsil eden toplam 60 numune toplanmıştır. Bu numunelerdeki 226Ra, 232Th ve 40K radyoizotoplarının radyoaktivite konsantrasyonları HPGe gama ışını spektrometre sistemi ile ölçüldü. 226Ra, 232Th ve 40K radyoizotoplarının ortalama radyoaktivite konsantrasyonları sırasıyla 22,87 Bq kg-1 , 19,49 Bq kg-1 , 265,29 Bq kg-1 ve 1,7 Bq kg-1 olarak bulundu. Elde edilen değerler kullanılarak yapı malzemeleri için radyolojik tehlike indisleri (radyum eşdeğer aktivitesi, yapı içi soğurulmuş doz hızı, yapı içi etkin doz hızı, I indisi ve I indisi) hesaplandı. Bu sonuçlar Türkiye’de ve dünyadaki çeşitli ülkelerde benzer malzemeler için bildirilen sonuçlarla kıyaslandı. Bu araştırmanın sonucunda incelenen yapı malzemelerinin radyolojik bir risk oluşturmadığı ve binaların inşasında güvenle kullanılabileceği görülmüştür.In this study, radioactivity levels of some building materials used in Kars province and radiological risks that could arise from these building materials were determined. A total of 60 samples representing 10 different building materials (limestone, clay, tras, gypsum, iron core and four different cement samples) from various regions of Kars were collected. The radioactivity concentrations of 226Ra, 232Th and 40K radioisotopes in these samples were measured using an HPGe gamma-ray spectrometry system. The mean radioactivity concentrations of 226Ra, 232Th and 40K were found to be 22.87 Bq kg-1 , 19.49 Bq kg-1 , 265.29 Bq kg-1 and 1.74 Bq kg-1 , respectively. Radiation hazard indices (radium equivalent activity, absorbed dose rate indoors, annual effective dose rate indoors, I index and I index) were calculated for the building materials using these obtained values. These results were compared with the results reported for similar materials in Turkey and in several countries around the world. As a result of this research, it was observed that the building materials examined did not constitute a radiological risk and could be used safely in the construction of buildings

Neodymium and Erbium Coordination Environments in Phosphate Glasses

The local structures of Nd3+ and Er3+ ions in two series of rare-earth (RE) phosphate glasses with nominal compositions xR203-(1-x)P2O5, where R=Nd and Er and 0.05≤x≤0.28, have been characterized by LIII-edge extended x-ray-absorption fine-structure spectroscopy (EXAFS). The RE coordination number depends on the R2O3 content, decreasing from 9.0 (10) oxygen nearest neighbors in ultraphosphate compositions (x\u3c0.15) to 6.4 (9) oxygen nearest neighbors for the metaphosphate (x∼0.25) compositions. The average Er-O bond distance decreases from 2.29 (1) to 2.23 (1) Å, and the average Nd-O bond distance decreases from 2.40 (1) to 2.37 (1) Å over the same compositional range. The changes in coordination environments are consistent with the conversion of isolated RE polyhedra to clustered RE polyhedra sharing common oxygens as the number of available terminal oxygens per RE ion decreases with increasing x

A High Energy X-Ray and Neutron Scattering Study of Iron Phosphate Glasses Containing Uranium

The atomic structure of iron phosphate glasses containing uranium has been studied by complementary neutron and x-ray scattering techniques. by combining x-ray and neutron structure factors, detailed information about different pair interactions has been obtained. Most of the basic structural features such as coordination numbers and O-O and P-O distances in uranium containing glasses are the same as those in the base glass of batch composition 40Fe2O3-60P2O5 (mol %). However, the Fe-O distances change slightly with the addition of uranium. The observed structural parameters support a structural model in which the waste elements occupy voids in the Fe-O-P network, hence, not altering the basic structure of the parent iron phosphate glass

Oxygen and Phosphorus Coordination Around Iron in Crystalline Ferric Ferrous Pyrophosphate and Iron-phosphate Glasses with UO₂ or Na₂O

Fe K-edge x-ray absorption fine-structure (XAFS) measurements were performed on glass samples of (Fe3O4)0.3(P2O5)0.7 with various amounts of Na2O or UO2. Near-edge and extended-XAFS regions are studied and comparisons are made to several reference compounds. We find that iron in the base glass is ~25% divalent and that the Fe2+ coordination is predominantly octahedral, while Fe3+ sites are roughly split between tetrahedral and octahedral coordinations. Also, we measure roughly one FeñOñP link per iron. Substitution of Na2O or UO2 up to 15 mo1% primarily affects the first FeñO shell. The results are compared to data from the related material Fe3(P2O7)2

Structure and properties of iron phosphate glasses: A novel host matrix for the vitrification of high-level nuclear wastes

The atomic structure, glass forming and crystallization characteristics, and the chemical durability of vitreous binary iron phosphates of approximate batch composition 40Fe2O3-60P2O5 (mol%) and those containing up to 40 wt% of one or more common nuclear waste components such as Na2O, CS2O, SrO, UO2, or Bi2O3 have been investigated. The analytical tools used are Fe-57 Mössbauer, x-ray absorption, x-ray photoelectron, and Raman spectroscopies, high energy x-ray and neutron diffraction techniques, differential thermal analysis (DTA), and the product consistancy test (ASTM C-1285-94). The excellent chemical durability of iron phosphate glasses containing nuclear waste components is indicated by dissolution rates (at 90 °C in distilled water) as low as 10-10 to 10-11 g/cm2/min. When melted in air at 1100 to 1200°C, these iron phosphate melts reach a redox equilibria corresponding to a Fe(II)/Fe(III) ratio less than 0.51. The Fe(II) content increases with increasing melting temperature and when melted in reducing atmospheres. However, the glass forming ability of the melts decreases when the Fe(II)/Fe(III) ratio exceeds ca. 0.67. Both species of iron ions are coordinated with 5 to 5.5 near neighbor oxygen ions. The phosphorous-oxygen network is dominated by (P2O7 )4- dimer units. The iron-oxygen coordination and the phosphorous-oxygen network do not appreciably depend on the type or the concentration of the waste elements. The waste ions, which are situated outside the second shell coordination environment of iron and phosphorus ions, are not a major influence on the chemistry of the iron-oxygen-phosphorus host matrix. Therefore the addition of waste components does not cause major changes in properties such as the chemical durability of the iron phosphate host matrix. Vitreous iron phosphate host matrices appear to be a low cost and effective alternative to borosilicate glasses for vitrifying selected nuclear wastes --Abstract, page iv

Structure and Properties of Lanthanum-Aluminum-Phosphate Glasses

Glass-forming characteristics, properties and structural features of glasses in the La2O3-Al2O3-P2 O5 system have been investigated. The glass-forming region is small compared to the Na2O-Al2O3-P2O5 system. Glass transition temperature increases and thermal expansion coefficient, refractive index, and density all decrease as the alumina content of the glass is increased. Infrared (IR) spectroscopy indicates that the glass network is dominated by bridging P-tetrahedra with terminal tetrahedra present in glasses with O/P ratios \u3e 3. 27Al magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy indicates that Al ions are incorporated in these glasses in 4-, 5-, and 6-coordinated sites. The average Al-coordination number (CN) increases with an increase in the Al/La ratio and decreases with an increase in the O/P ratio. Both trends can be explained by the avoidance of Al-O-Al bonds in the glass structure. © 2001 Elsevier Science B.V

Effects of different feed and temperature conditions on growth, meat yield, Survival Rate, feed conversion ratio and condition factor in Rainbow trout (Oncorhynchus mykiss) fingerlings

In this study, we investigated effects of different feeds (live food (Artemia+Drosophila sp.), wet feed (Spleen+Liver) and commercial feed) and different water temperatures (9.10±0.85 and 15.00±0.50°C) on meat yield, Survival Rate (SR), Feed Conversion Ratio (FCR), Condition Factor (CF) and growth in Rainbow trout, Oncorhynchus mykiss (Walbaum) fingerlings. The fingerlings had 0.23±0.04 g mean initial weight. The study lasted a total of 16 weeks and carried out according to completely randomized factorial experimental design (3X3X2). At the end of the experimental period, final weights of fish having about the same initial weights showed big differences. The highest final weight was 13.05±0.21 g from the higher temperature and commercial feed group. The differences between the groups were found statistically significant (p<0.05). In terms of feed conversion ratio, very different values were observed among the groups and their differences were also statistically significant (p<0.01). At the end of research, carcass weights differences between the results of the commercial feed, wet feed and live food groups were statistically significant (p<0.05). In terms of condition factor values, the differences between the groups were insignificant. In terms of Hepatosomatic (HSI) and Viscerasomatic (VSI) indices the differences between the results of the groups were found statistically significant (p<0.05). © Medwell Journals, 2010

Structural Features and Properties of Lead-iron-phosphate Nuclear Wasteforms

The structure and properties of vitreous and crystalline lead-iron-phosphate glasses containing up to 21 wt% of a simulated high level waste have been investigated using Fe-57 Mössbauer, X-ray diffraction and Raman spectroscopies. The Mössbauer spectra indicated that both Fe(II) and Fe(III) ions were present in all the samples. The Raman spectra for the glasses contained two dominant bands, which were characteristic of pyrophosphate groups, (P-O) stretching mode of P-O nonbridging oxygen at 1074 cm−1 and sym stretching mode of bridging oxygen at 760 cm−1, respectively. The chemical durability of glassy and crystallized samples was investigated by measuring their weight loss in distilled water at 90 °C for up to 32 days. The weight loss of the lead-iron-pyrophosphate wasteforms was up to 100 times less than that for window glass. X-ray diffraction patterns showed that FeSiO3 and SiP2O7 phases are present in samples containing more than 14 wt% of the simulated nuclear waste

Chemical Durability and Structure of Zinc-iron Phosphate Glasses

The chemical durability of zinc-iron phosphate glasses with the general composition (40−x)ZnO-xFe2O3-60P2O5 has been measured. The chemical durability and density of these glasses increase with increasing Fe2O3 content. Glasses containing more than 30 mol% Fe2O3 had an excellent chemical durability. The dissolution rate (DR), calculated from the weight loss in distilled water at 90 °C for up to 32 days, was not, vert, similar10−9 g/cm2/min which is 100 times lower than that of window glass and 300 times lower than that of a barium ferro, aluminoborate glass. The structure and valence states of the iron ions in these glasses were investigated using Mössbauer spectroscopy, X-ray diffraction, infrared spectroscopy and differential thermal analysis. X-ray diffraction indicates that the local structure of the zinc-iron phosphate is related to the short range structures of crystalline Zn2P2O7, Fe3(P2O7)2 and Fe(PO3)3. Both Fe(II) and Fe(III) ions are present in all of these glasses. The presence of an Fe-O-P related band in the infrared (IR) spectra of the glasses containing more than 30 mol% Fe2O3 is consistent with their excellent chemical durability