Specialists from the All-Russian Thermal Engineering Institute (VTI – Vserossiiskii Teplotekhnicheskii Institut) have completed a set of studies monitoring the condition of the inner surface of the heat exchange tubes (TOT – TeploObmennikh Trubok) of the steam generator of the BN-800 power unit at the Beloyarsk NPP. The research results are of practical importance for increasing the reliability of equipment operation and predicting their specific contamination.
The BN-800 sodium-cooled fast reactor at unit 4 of the Beloyarsk NPP is a unique facility where closed nuclear fuel cycle technologies are tested. Unit 4, along with unit 3 (a BN-600), are the world’s only commercially operating sodium-cooled fast reactors. One of the main elements of unit 4 are its steam generators, which are shell-and-tube heat exchangers, in the shell of which liquid sodium flows, while the tubes contain desalted water. This type of equipment is extremely important, and requires special control of the condition of the heating systems, on which the efficiency of heat transfer and operational safety directly depend.
Previously, there were no methods for determining the condition of the inner surface of the steam generator tubes. Specialists from the VTI Physics and Technology Department have now developed and tested three methods to solve the problem. The first involves producing transverse sections of TOT fragments. The second technique makes it possible to determine the specific contamination of individual sections of the tubes. The third technique involves visual assessment of the surface of working samples before and after removal of deposits and oxide film.
As a result of the research, the scientists determined the rate of formation of deposits, their distribution among heat exchange zones and the state of the protective film, which prevents metal corrosion. The resulting set of data has become the basis for forecasting changes in the state of heating systems and improving approaches to equipment operation.
“VTI confirmed the high level of engineering competencies by developing control techniques for complex and unique equipment – fast neutron reactor,” said VTI Director General Ivan Boltenkov. “Such developments strengthen the scientific and technical potential of the Institute and make a significant contribution to increasing the reliability and safety of domestic nuclear energy.”
These methods can now be used to improve operational regulations and are an important component of increasing the service life of equipment at nuclear energy facilities.
