Izvestiya vuzov. Yadernaya Energetika

The peer-reviewed scientific and technology journal. ISSN: 0204-3327

Experimental Research of the Properties of Concentrated Solutions of Boric Acid in Application to Cooling of VVER Reactors

6/05/2024 2024 - #02 Nuclear power plants

Lebezov A.A. Morozov A.V. Sahipgareev A.R. Soshkina A.S. Shlepkin A.S.

DOI: https://doi.org/10.26583/npe.2024.2.02

UDC: 621.039.58:532.77

The article presents the results of an experimental study of the thermophysical properties of aqueous solutions of boric acid with the addition of potassium hydroxide added to the VVER coolant as a corrective additive to maintain the required pH value of the primary circuit medium.

The parameters were measured at pressure P=0.1 MPa in the temperature range 25– 90°C in the following ranges of H3BO3 concentrations in solutions: density – 2.5 – 230 g/kg H2O, viscosity – 2.5 – 100 g/kg H2O, surface tension – 2.5 – 150 g/kg H2O. Such a high concentration of boric acid is achieved in the VVER core in the event of large break loss of coolant accident and simultaneous failure of emergency power supplies. At the same time, cooling of the core is ensured through the operation of passive safety systems, which must ensure the supply of a boric acid solution with a concentration of 16 – 20 g/kg into the core.

The main experimental equipment and research methodology are described. The dependencies of thermophysical properties of solutions on the concentration of boric acid in them based on the processing of experimental data were obtained. Peculiarities of changes in the surface tension of H3BO3 with changes in the concentration and increase in temperature of a solution of boric acid with a corrective addition of potassium hydroxide have been revealed.

The results of the conducted research make it possible to expand the range of known properties of aqueous solutions of boric acid and are of great practical importance for nuclear power plants with new generation VVER reactors. The experimental data obtained can be used to clarify the results of calculations of emergency processes in a VVER reactor plant during the operation of a complex of passive safety systems, including a passive core flooding system, a passive heat removal system from the steam generator, and a system of third-stage hydraulic accumulators.


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VVER boric acid emergency modes thermophysical properties passive safety systems

Link for citing the article: Lebezov A.A., Morozov A.V., Sahipgareev A.R., Soshkina A.S., Shlepkin A.S. Experimental Research of the Properties of Concentrated Solutions of Boric Acid in Application to Cooling of VVER Reactors. Izvestiya vuzov. Yadernaya Energetika. 2024, no. 2, pp. 19-29; DOI: https://doi.org/10.26583/npe.2024.2.02 (in Russian).