This study presents the radiological characterization of 15 solid radioactive waste samples originating from the BN-350 sodium-cooled fast reactor (Kazakhstan) during its decommissioning phase. The studied materials include components of ventilation and wastewater treatment systems, pipeline elements and various operational tools. The objective of the study was to determine the activity levels of the samples and to assess appropriate pathways for their subsequent management and processing. The results indicate that all studied materials fall within the category of low-level radioactive waste. Gamma spectrometric analysis shows that Cs-137 is the dominant and only identified gamma-emitting radionuclide contributing to the activity of the studied samples.

The research involved conducting resource tests on two experimental water-cooled technological channels (WCTCs) utilizing low-enriched uranium (LEU) fuel within the IVG1.M research reactor. This testing was a crucial step in the reactor's conversion from highly enriched uranium (HEU) fuel to LEU. The research focused on two key parameters, namely the specific activity and the relative release of fission products (FPs) into the coolant, to evaluate the tightness of the fuel element cladding. A gamma-spectrometric sampling method was proposed to determine the relative release of FPs, which involved assessing the specific activity of the coolant, calculating the release rate (Release), the born rate (Born), and the R/B ratio of FPs. Comparative gamma-spectrometric measurements were conducted to analyze the content of FPs and activation products (AP) in the coolant of WCTCs utilizing both LEU and HEU during the tests. From the comprehensive list of detected radionuclides in the IVG.1M reactor coolant, well-identified reference radionuclides recommended for monitoring fuel element cladding tightness were carefully selected. The results of the study provided insights into the specific activity and relative release of FPs, demonstrating that quantitative values for the relative release of FPs from WCTCs using LEU and HEU fuel were comparable.