The Scientific and Technical Council of the State Scientific and Technical Center for Nuclear and Radiation Safety (SSTC NRS) considered results of research efforts undertaken by its staff to improve regulation for the safe use of nuclear energy at its regular meeting.
Yaroslav Belov, a researcher in the Radiation Protection Department, reported on potential use of the MACCS2 code to improve emergency planning for nuclear and radiation accidents at NPPs. The accident scenario involving power unit blackout with failure to isolate the containment was used as an example to compare the results obtained with the MACCS2 code with those received with the RODOS decision support system and HotSpot code. The comparative analysis revealed some disagreement between the results, which is due to differences in the methodological approaches to dose calculation and dose coefficients incorporated in these codes. The MACCS2 code may be used for emergency planning in Ukraine only provided that the input data are carefully prepared and structured in detail.
Semen Yanovskiy, a senior researcher in the NPP Thermohydraulic and Probabilistic Safety Analysis Department, presented thermal hydraulic models for VVER-1000/320 and VVER-440/213 developed for the TRACE code. The models include the main hydraulic components and thermal structures and simulate primary and secondary components, control systems, signals, and control variables. In his research work, the expert confirmed that the results obtained with the TRACE code were correct. They were used for comparative calculations of actual incidents and design-basis accidents at NPPs. They showed good agreement with the results obtained with a similar model for the RELAP5 code.