Urska Repinc

International Atomic Energy Agency (IAEA) | IAEA · Department of Safeguards

The activity of Ra-226 was determined using Alpha-spectrometry. The necessary relevant information was obtained from the method validation data, the quality control data and equitment calibration certificates. The activity concentration of Ra-226 in sample (Bq/L), is calculated by: Recovery obtained by gamma spectrometry und Alpha spectrometer effc...

In the frame of the accountancy measurements of the fissile materials, reliable determinations of the plutonium and uranium content in spent nuclear fuel are required to comply with international safeguards agreements. Large-sized dried (LSD) spikes of enriched ²³⁵U and ²³⁹Pu for isotope dilution mass spectrometry (IDMS) analysis are routinely appl...

Hair analysis is extensively used in forensic sciences, assessment of occupational or environmental exposure and in some cases for clinical and nutritional studies. The present study summarizes the analytical methodology and distribution of uranium and some selected trace metals e.g., Mn, Ni, Cu, Zn, Sr, Cd and Cs in human scalp hair samples using...

The International Atomic Energy Agency (IAEA) is responsible for independently verifying the nuclear material inventories in bulk handling facilities in States under safeguards. Part of the verification process includes the collection of representative nuclear material samples and the measurement of the key fissile isotopes in those samples at the...

Being aware of the importance to consider every step in the evaluation of the combined measurement uncertainty of the result, the purpose of this work was to evaluate the contribution of the radial thermal neutron flux gradient to the uncertainty budget for trace level uranium determination in biological materials by a radiochemical neutron activat...

In our present work 10 sports dietary supplements and 6 daily multivitamin/mineral supplements were analysed for vanadium content. Radiochemical neutron activation analysis was used to determine whether vanadium had been added to some popular dietary supplements used to increase muscle mass. After irradiation and rapid dissolution of the irradiated...

Radium-226 is one of the best known long-lived α-emitters abundantly present in the environment. The determination of radium isotopes in environmental samples usually requires a demanding chemical separation before measurement and quantification. Each step in the chemical separation process can involve losses of the analyte, therefore it is of vita...

Literature reports of the efficacy of para-sulfonatocalix[6]- and calix[8]-arenes as U(vi) complexants indicated that they might be useful for in vivo chelation of the novel therapeutic alpha-emitter (230)U. We have studied the complexation of U(vi) with para-sulfonatocalix[6]arene and para-sulfonatocalix[8]arene by time resolved laser induced fluo...

The quantitative description of the interactions of uranium with blood serum components is of high relevance for a rational design of molecules suitable for in vivo chelation of uranium. We have determined the stability constants for the complexation of U(VI) with human serum transferrin and albumin by time-resolved laser-induced fluorescence spect...

A procedure is described for the determination of cobalt in biological materials, based on post-irradiation separation radiochemical neutron activation analysis (RNAA) using the short-lived induced radionuclide 60mCo. 60mCo has been rarely used as an indicator radionuclide in NAA due to low concentrations usually found in biological materials and d...

Radiochemical neutron activation analysis (RNAA) for simultaneous determination of V, U and Mn at trace levels in biological materials is described. This method is based on short irradiation of the sample together with standards and se- quential separations of the induced nuclides based on selective solvent extractions. According to the very short...

Calibration of recently installed proportional counter at the Hot Cells Facility of the Jozef Stefan Institute was performed. Instrument was calibrated for determination of total beta activity, Sr-90 and Pb-210. Detection efficiencies for K-40, Sr-90, Y-90, Pb-210 and Bi-210 were determined, allowing for more accurate determination of the particula...

Calibration of recently installed proportional counter at the Hot Cells Facility of the Jozef Stefan Institute was performed. Instrument was calibrated for determination of total beta activity, Sr-90 and Pb-210. Detection efficiencies for K-40, Sr-90, Y-90, Pb-210 and Bi-210 were determined, allowing for more accurate determination of the particula...

Mercury tracers are powerful tools that can be used to study mercury transformations in environmental systems, particularly mercury methylation, demethylation and reduction in sediments and water. However, mercury transformation studies using tracers can be subject to error, especially when used to assess methylation potential. The organic mercury...

The paper addresses identification of industries and activities handling NORM and inventory of TENORM in Slovenia. The identification is based on survey of historical information available, results published in scientific papers, research reports made by research institutions within Slovenia, as well as original research aimed at obtaining more det...

A new RNAA procedure was developed for simultaneous determination of low levels of I and Mn in biological materials. The procedure is based on sample decomposition by alkaline-oxidative fusion in a mixture of Na2O2 + NaOH at 900°C followed by extraction of elementary iodine by chloroform. Subsequently, Mn is separated either by precipitation of hyd...

Summary In the present work an improvement of radiochemical neutron activation analysis for determination of nanogram levels of vanadium is described. The method is based on post-irradiation wet ashing and solvent extraction of vanadium with N-benzoyl-N-phenyl-hydroxylamine (BPHA) forming a violet chelate complex in strongly acidic medium. For qual...

Summary A radiochemical neutron activation analysis (RNAA) for simultaneous determination of uranium and vanadium in a single sample at trace levels is described. The method is based on post-irradiation wet-ashing and solvent extraction of vanadium with N-benzoyl-N-phenyl-hydroxylamine reagent. From the remaining aqueous phase, uranium is extracted...

The routine determination of the activity concentrations of uranium isotopes ($^{238}$U, $^{235}$U and $^{234}$U), thorium isotopes ($^{212}$Th, $^{230}$TI, and $^{228}$Th), $^{231}$Pa, $^{226}$Ra, $^{210}$Pb and $^{210}$Po in the environment is one of the most important tasks in uranium mining areas. Natural radionuclides contribute negligibly to...

Liquid scintillation counting has not been widely applied to a-particle detection because of its poor energy resolution and variable background. In the present work, a time saving and reasonably accurate method for determination of 226Ra in water has been developed, using liquid scintillation spectrometry and pulse-shape analysis. The effect of thr...

The uranium mine and mill at Žirovski vrh (RŽV), Slovenia stopped mining and milling in 1990. Mill tailings containing about 20 % moisture were transported to a disposal site called Boršt. The objective of this work was to study the migration of the radionuclides U-238, Ra-226, Pb-210 and Po-210 from the Boršt waste disposal site. For determination...

A proficiency test (PT) was carried out to investigate the quality of laboratory results measuring trace elements in sewage sludge. The scheme relied on reference values, established through flame atomic absorption spectroscopy and instrumental neutron activation analysis. Within the framework of the project, ”Proficiency testing in Central and Eas...

Optimization of measurements procedures for beta emitters with proportional counter recently installed at the Hot Cells Facility (HCF) of the Jozef Stefan Institute (JSI) is described. Specific detection efficiencies for 40 K, 90 Sr, 90 Y, 210 Pb and 210 Bi were determined that allows for more accurate determination of the particular radionuclides...