Studies of corium properties

As part of the scientific and technical program “Development of Nuclear Energy in the Republic of Kazakhstan”, studies are being carried out of the physicochemical and thermophysical properties of the corium resulted from model experiments.

Data on the corium properties and the processes associated with core melting and the fuel behavior, materials and structures of nuclear reactors in transient and emergency conditions are extremely necessary when designing new nuclear plants with increased safety, as well as for planning and implementing measures for handling corium in emergency NPP.

Experiments to simulate the processes that occur with corium in a nuclear reactor during a severe accident are carried out on the high-temperature simulation bench VCG-135, which is a unique research tool that allows heating samples up to 3000 °C. Tungsten-rhenium thermocouples are used as the main means of measuring temperature in experiments, and pyrometers are used for non-contact temperature measurement. Studying of samples after heating at the VCG-135 test bench are carried out using the latest equipment (Enpyrean X-ray diffractometer, optical and scanning electron microscopes, and UTFI-2device for determining the thermophysical properties)

In 2018, within the work on the scientific and technical program, the composition and properties of corium were classified, the factors determining the main characteristics required to solve the problems of ensuring safety systems were identified. Based on the classification, a method has been tested for obtaining the corium of the required composition. During testing the method, solidified melts and data on the corium melting points of two different compositions were obtained.

In 2019, a method for studying the characteristics of solidified corium was developed and tested. Computer simulation of the residual energy release in the corium obtained by the induction method was carried out.

This year, work to obtain data on the thermophysical, physicochemical and structural properties of corium will be completed.