Alkali activation of dif ferent type of ash as a production of combustion process

Presented study deals with the final struc ture and radiological properties of different fly-ash based geopolymers. Lig nite fly-ash (lignite Kolubara – Ser bia) and wood fly ash were obtained in combustion process together with commercial fly-ash. Synthesis of the geopolymers was con ducted by mixing fly-ash, sodium silicate solution, NaOH and water. The sam ples were strength ened 60 °C for 48 hours af ter stay ing at room temperature in covering mold for 24 hours. The X-ray dif frac tion, Fou rier trans form in fra red and SAM mea sure ments were conducted on the sam ples af ter 28 days of geopolymerization pro cess. The X-ray dif frac tion measurements of lignite fly-ash sam ples show anhydrite as the main constituent, while wood fly-ash samples consist of cal cite, albite and gypsum minerals. Besides determination of physicochemical properties, the aim of this study was radiological characterization of lignite fly-ash, wood fly-ash and the obtained geopolymer products. Ac tiv ity con cen tra tion of 40 K and radionuclides from the 238 U and 232 Th decay series, in ash sam ples and fly-ash based geopolymers, were determined by means of gamma-ray spectrometry, and the absorbed dose rate, D, and the annual effective dose rate, E, were calcu lated in accordance with the UNSCEAR 2000 report

Natural diatomite (Rudovci, Serbia) as adsorbent for removal Cs from radioactive waste liquids

The removal of Cs (I) ions from aqueous solution was studied using natural diatomite as adsorption materials originated from Rudovci, Serbia. The microstructure of natural diatomite has been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) while the degree of Cs adsorption was evaluated by atomic emission spectroscopy. The cation exchange capacity (CEC) values for natural diatomite was 50 meq/100g. Depending on whether the Cs adsorption occurred in the acidic and alkaline media at a temperature of 298.15 K in acidic media ΔG0 values was -12.674 kJ/mol, while in alkaline media ΔG0 was - 13.142 kJ/mol and a change of ΔS0 to 42.51 J/molK in acidic media and 44.08 J/molK in alkaline medium. [Projekat Ministarstva nauke Republike Srbije, br. 45012

Chemical, physical and radiological evaluation of raw materials and geopolymers for building applications

The main goal of this study was the evaluation of physical–chemical, as well as radiological properties of residual materials used for geopolymer synthesis and those final products as a possible application as new materials in a civil engineering industry. Concentration of 40K and radionuclides from the 238U and 232Th decay series in waste precursors, their metaphases and geopolymer samples synthetized by alkali activation were determined together with corresponding absorbed dose rate (D˙) and the annual effective dose rate. Natural activity concentrations in the alkali-activated material (geopolymer) were found to be lower than that of both residual materials and calcined ones

Systematic influences on the areas of peaks in gamma-ray spectra that have a large statistical uncertainty

A method is presented for calculating the expected number of counts in peaks that have a large relative peak area uncertainty and appear in measured gamma-ray spectra. The method was applied to calculations of the correction factors for peaks occurring in the spectra of radon daughters. It was shown that the factors used for correcting the calculated peak areas to their expected values decrease with an increasing relative peak-area uncertainty. The accuracy of taking the systematic influence inducing the correction factors into account is given by the dispersion of the correction factors corresponding to specific peaks. It was shown that the highest accuracy is obtained in the peak analyses with the GammaVision and Gamma-W software.21st International Conference on Radionuclide Metrology and itsApplications (ICRM), Argentinian Comis Nacl Energia Atomica, BuenosAires, ARGENTINA, MAY 15-19, 201