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Determination of cesium in aqueous extracts of cement samples
Straka, Marek ; Hraníček, Jakub (advisor) ; Nováková, Eliška (referee)
Cement is widely used as a solidification material of low and intermediate level radioactive waste containing caesium before shallow land burial. The aim of this thesis was to extract caesium out of seventeen cement samples with six different cement binder compositions, by extraction with deionized water, then determine the amount of caesium in the extracts and look for trends in the extract Cs concentrations with various extraction duration. Cement samples, with stable caesium nuclide, were used to simulate retention of caesium in immobilized radioactive waste. Ten extractions from each sample in total were made with time ranging from 2 to 1032 hours. Atomic absorption spectrometry with flame atomization, using acetylene as fuel and air as oxidant, was used for caesium determination. This method was optimized and the addition of KCl serving as ionization buffer for better results was explored and compared. Keywords Atomic absorption spectrometry, flame atomization, caesium, extraction,
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Examination of caesium concentration trends in extracts from cement blocks simulating radioactive waste
Straka, Marek ; Hraníček, Jakub (advisor) ; Nováková, Eliška (referee)
Cement is widely used as a solidification material of low and intermediate level radioactive waste containing caesium before shallow land burial. The aim of this thesis was to extract caesium out of 17 cement samples with 6 different cement binder compositions, by extraction with deionized water, then determine the amount of caesium in the extracts and look for trends in the extract Cs concentrations with various extraction duration. Cement samples, with stable caesium nuclide, were used to simulate retention of caesium in immobilized radioactive waste. Ten extractions from each sample in total were made with time ranging from 2 to 1032 hours. Atomic absorption spectrometry with flame atomization, using acetylene as fuel and air as oxidant, was used for caesium determination. This method was optimized and the addition of KCl serving as ionization buffer for better results was explored and compared. Keywords Atomic absorption spectrometry, flame atomization, caesium, extraction,
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Miniature plasma DBD atomizer for AAS and AFS
Straka, Marek ; Kratzer, Jan (advisor) ; Hrdlička, Aleš (referee)
Five designs of dielectric barrier discharge (DBD) atomizers have been constructed and optimized employing arsane as a model analyte. The individual DBD designs differed from each other in the style of electrode attachment, electrode shape and area. An externally heated quartz tube atomizer and another DBD atomizer design that have been studied before were used as reference. All the atomizer designs studied including the reference atomizers were found compatible with detection by atomic absorption spectrometry (AAS) giving comparable sensitivity of 0.44 s ng-1 As and detection limit around 0.2 ng ml-1 As under optimum atomization conditions. However, significant differences in optimum operation conditions were found among the DBD designs in terms of the applied voltage depending strongly on the style of electrode attachment. The design with metal strip electrodes glued to a quartz body requires more than 14 kV to be operated. The design with sputtered electrodes of the same shape can reach the same sensitivity with 8.5 kV. Selected DBD designs have been proven to be compatible also with other spectrometric detectors such as atomic fluorescence spectrometry (AFS) reaching detection limit 0.05 ng ml-1 As or atomic emission spectrometry (AES) with detection limit of 30 ng ml-1 As showing the...
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