Izvestiya vuzov. Yadernaya Energetika

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

Study on the kinetics of bismuth oxide reduction by hydrogen as applied to the technology of removing hydrogen from circulation circuits with heavy liquid metal coolants

9/30/2019 2019 - #03 Chemistry, physics and technology of reactor coolants

Ivanov I.I. Shelemetyev V.M. Askhadullin R.Sh.

DOI: https://doi.org/10.26583/npe.2019.3.10

UDC: 621.039.58

As part of the project of developing methods for removing hydrogen and tritium from the circulation circuits of reactor plants with heavy liquid-metal coolants, the kinetics of bismuth oxide reduction by hydrogen in the temperature range 425–500°C and hydrogen concentration 25–100 vol.% has been investigated. The kinetic characteristics of the reaction under study were determined by continuously measuring the concentration of water vapor (reaction product) in mixtures of hydrogen and helium that passed through a heated reaction vessel with a sample of bismuth oxide. The concentration of water vapor was measured using a thermoconductometric detector. The obtained time dependences of the bismuth oxide reduction degree (with varying reaction conditions) were processed by the method of affine time transformation. Thermodynamic analysis showed that reduction process proceeds without any intermediate products, i.e., directly with metallic bismuth. It was also found that the reduction process ran in kinetic mode. All kinetic curves were combined successfully by the affine time transformation method; therefore, it can be assumed that the reduction mechanism is the same in the entire temperature range and hydrogen concentration range studied. The limiting stage of the reaction is the adsorption of hydrogen on the surface of the bismuth oxide sample. The time dependence of the reduction degree is in good agreement with Yerofeev’s equation of «nucleation and growth model» with n = 1. The reaction activation energy is 92.8 ± 1.9 kJ/mol. The rate of the reduction reaction is directly proportional to the concentration of hydrogen in its mixture with an inert gas.


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heavy liquid metal coolants nuclear safety hydrogen tritium hydrogen purification of HLMC hydrogen afterburner bismuth oxide reaction kinetics thermoconductometric analysis affine time transformation method equation of nucleation and growth model Yerofeev’s equation