The dissertation is dedicated to the research and solution of problems of metrological support of measurements of the characteristics of ionizing radiation and modernization of the reference base of Ukraine according to the requirements of the European Union.
In the first section, the current aspects of the development of methods and means of metrological support of means of measuring ionizing radiation are considered. In particular, the main concepts and dosimetric values of radiometry, which include the half-life and activity of a radioactive substance, are considered. The passage of X-ray (γ) rays and (α, β -particles through a substance is accompanied by ionization of the atoms of this substance. During ionization, the radiation loses part of its energy, that is, the substance absorbs radiation energy. These phenomena are the basis of the work of ionizing radiation counters, and also the basis of the work of radiation standards, which are used in the scheme of transferring the size of the radiation unit from the mentioned standard through the working standard to the FTA. Since this is a tried-and-tested methodology, the methodology of metrological support of ionizing radiation measuring devices is considered further in the section, namely the current regulatory documentation, such as of Ukraine and the EU. At the same time, the most widely used dosimetric measuring equipment in Ukraine is analyzed and evaluated according to metrological characteristics.
In the second chapter, the methodology of measuring the characteristics of dosimetric values, methods and means of their creation are studied. The standard characteristics of X-ray and gamma radiation are considered in detail, which significantly depend upon transferring the size of the unit - from the standard to a specific HRT (to a specific batch of HRT) - on the design features of the calibration equipment, on the location of the calibrated HRT in the irradiation zone and on a number of operating parameters and factors impact Therefore, in this section, the methods of creating (forming) standard characteristics of X-ray and gamma radiation are consistently considered, because the accuracy of transmitting the size of a radiation unit depends on them. Based on the results of previous studies, existing calibration procedures for X-ray and gamma radiation measuring equipment are analyzed in detail. The results of the analysis contribute to their improvement and improvement of the metrological parameters of the calibration of the FTA. On this basis, the method of calibrating dosimeters and dose power meters of gamma and X-ray radiation is considered.
The third chapter focuses on research issues of standards of dosimetric units of ionizing radiation: they guarantee the metrological reliability of transmitting the size of the radiation unit. At the same time, reference equipment of collimated and non-collimated geometry is evaluated separately. First, the peculiarities of transmitting the size of gamma radiation units for reference equipment of collimated geometry are discussed. Here, the location of calibrated HRTs in the irradiation space is particularly important. The zone within which the spatial impact factor is minimal is highlighted. Similarly, the presence and value of influencing factors when transmitting the size of gamma radiation units for reference equipment with lead attenuators, which refer to equipment of non-collimated geometry, were evaluated. Such technically and organizationally complex work, based on the optimization of the radiation dose of operators, was practically carried out in Ukraine for the first time. At the same time, the ability of the specified equipment to ensure the reproduction of the special requirements of the EU standards during the calibration of special FTAs was simultaneously evaluated. As a result, their suitability is confirmed by the results of tests and reconciliation.
In the fourth chapter, the aspects of the applied implementation of methods and means of metrological support of dosimetric measurements of the characteristics of ionizing radiation are considered. Based on the experience of previous operations and modernization of X-ray and gamma radiation reference equipment, the peculiarities of using the above-mentioned equipment are studied. Methods of calibration of ionizing radiation dosimeters and radiation dose meters are being developed and improved, as the last stage of unit size transfer. The processing of measurement results, which has been carried out for a long time in the EU in accordance with GUM, and in Ukraine - in accordance with DSTU ISO/IEC Guide 98-4: 2018 and DSTU ISO/IEC Guide 60: 2007, is important for the work of the latter. Conformity assessment. Code of established practice, 2008. It was successfully implemented in item 4.4 - Optimization of the uncertainty calculation procedure during the calibration of dosimetric measuring equipment and reference equipment.
