[en] A commercially-available radionuclide calibrator is used to maintain the unit of activity in the Slovak Institute of Metrology (SMU) and to check and verify activity meters in the field of nuclear medicine. The calibration of the instrument is described. The long-term stability is checked at regular intervals by means of ¹³⁷Cs and ²²⁶Ra reference sources. A slow decrease of efficiency of about 2% per year has been observed, which has to be corrected for. An energy-dependent efficiency curve of the ionization chamber is established by transfer of calibration factors from a similar instrument at the Physikalisch-Technische Bundesanstalt (PTB). The curve has been checked by measurements with activity standards of ⁶⁰Co, ⁵⁴Mn, ²²Na, ⁸⁵Sr, ⁶⁵Zn, ⁸⁸Y, ⁵⁷Co, ¹³⁹Ce, ¹³⁷Cs, ¹²⁵I, ²⁴¹Am, ²¹⁰Pb and ¹⁰⁹Cd. The established curve permits one to calculate calibration factors for additional short-lived radionuclides used in nuclear medicine. An overall uncertainty was obtained for activity measurements with calculated calibration factors under standard measurement conditions of better than 1.8%

[en] Charges for waste water treatment by radiation using ⁶⁰Co and ¹³⁷Cs are calculated. The calculations consider doses necessary for treatment, the frequency of radiation source replenishment and the price of radionuclides. (author)

[en] The calibration of ionization chamber measuring systems in terms of activity is described. The energy-dependent efficiency curves of three chambers at the Bureau International des Poids et Mesures, the National Physical Laboratory and the Physikalisch-Technische Bundesanstalt are determined and compared using a fitting procedure for the experimental radionuclide efficiencies by the Microsoft (MS) EXCEL Solver program. An estimation of the uncertainty of the efficiency curves and the deviations of experimental and calculated radionuclide efficiencies are given. By this fitting method, discrepancies in the efficiency determination can be detected at a level of about one percent. Systematic deviations entering into the calculations either from emission probabilities per decay or from absolute activity standardization are discussed

[en] The paper explains relationships between various forms of efficiency curves and derives a new option for the ionization chamber efficiency representation. First, the ionization chamber efficiency term is analysed, being expressed in various units depending on experimental conditions. Then, the efficiency curve concept is explained and discussed. The next section introduces the quantities necessary for a calculation of photon energy conversion efficiency and derives its relationship to the customary form of efficiency curve. The considerations are demonstrated for the example of SIR ionization chambers whose characteristics are essential for activity determination worldwide as they serve as a pointer for international comparisons in the area of activity measurements. (author)

[en] An ionization chamber without and with an iron liner (absorber) was calibrated by a set of radionuclide activity standards of the Physikalisch-Technische Bundesanstalt (PTB). The ionization chamber is used as a secondary standard measuring system for activity at the Slovak Institute of Metrology (SMU). Energy-dependent photon-efficiency curves were established for the ionization chamber in defined measurement geometry without and with the liner, and radionuclide efficiencies were calculated. Programmed calculation with an analytical efficiency function and a nonlinear regression algorithm of Microsoft (MS) Excel for fitting was used. Efficiencies from bremsstrahlung of pure beta-particle emitters were calibrated achieving a 10% accuracy level. Such efficiency components are added to obtain the total radionuclide efficiency of photon emitters after beta decay. The method yields differences of experimental and calculated radionuclide efficiencies for most of the photon-emitting radionuclides in the order of a few percent

[en] A criterion for selection from three types of irradiation reactors is derived based on the mathematical model of radiolysis kinetics of phenol in aqueous solutions in the presence of auxiliary and retarding additions. (author)

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No abstract available

[en] The mixture of ionogenic substances is separated and concentrated into zones with equal mobility using the isotachophoretic technique. A radioactive compound or mixture of radioactive and non-active compounds is analyzed in one or two conjugate steps either separately or from one sample feed. Qualitative and quantitative evaluation is made by measuring the response of one or two parameters of which one is the measurement of activity and the other, e.g., the measurement of conductivity. The equipment for the implementation of the method consists of a voltage supply, a unit for leading and trailing electrolyte with a sampler, a capillary or groove, radiometric or other detectors and evaluation electronics and recording equipment and a fractionation cock. The equipment may be completed with a similar unit for pre-separation. (Ha)

[en] A method of preliminary concentration of metals on a liquid emulsion membrane is described. Chemical equilibria in three-phase systems are considered and the process parameters are determined. Results on the concentration of uranium, cerium, cobalt, manganese, strontium, calcium, pertechnetate by the method mentioned are presented. For uranium concentration factor is above 350 at the extraction degree up to 98 %; for cerium - 100 %. Separation of Co-Mn and Sr-Ca is considered in case of their joint presence. 18 refs.; 9 figs