Measuring metal samples of the equipment being currently dismantled in the turbine hall of SSE ChNPP Delivery Stage 1; with further calculation of the proportionality factors for difficult-to-measure radionuclides

The Customer: SSE ChNPP, Ukraine

 The Objective: Development of mathematical models for the distribution of radioactive contamination in the equipment.

The research activities included measurements of metal samples; processing, classification and analysis of the results; development of mathematical models for the distribution of radioactive contamination and performance of the calculations.

Due to the fact that the stock of radioactive isotopes that could contaminate equipment includes the ones, which activity determination requires use of elaborate and expensive methods of radiochemical analysis, it was decided to carry out a series of works to find simplified and fairly reliable assessment methods basing on correlation relationship between the activities of certain isotopes. The proportionality factors between the activities of easily measurable radionuclides (key radionuclides) and those requiring elaborate methods were calculated. Based on the research data, we identified the radionuclides that can be used as key ones and application of the direct gamma spectrometry methods would be enough to measure them. Values of the proportionality factors were calculated for the period from 2016 to 2045.

Due to the fact that most direct measurement methods and the outdated procedures of radiochemical analysis do not allow estimation of low activities of some radionuclides in metal, thus making impossible estimation of isotope fractionations and calculation of the scaling coefficients, the most advanced methods of radiochemical analysis were applied. This allowed getting the value of radionuclides specific activity in metal at very low levels, close to the background values. Within the framework of this research, some values were obtained for the first time in Ukraine.

The scale coefficients, which were obtained within the framework of this research, allow significant reduction of negative effects in the natural environment by way of replacing radiochemical methods of radionuclide measurements requiring a significant quantity of chemical agents with the direct spectrometry methods.

The research results were handled to the Customer.