Methodology for experimental study of a stand-emulator of a passive cooling system for a research nuclear reactor pool

The safety of nuclear installations is largely determined by the tightness of the fuel element shells. As shown by the accident at the Fukushima-1 nuclear power plant, the main task in case of loss of power supply is to ensure reliable removal of residual heat from the holding pool with irradiated fuel assemblies. It is possible to increase the reliability of the heat sink in case of loss of power supply using passive heat removal systems.

In accordance with NP-033-11 «General provisions for ensuring the safety of research nuclear installations», the purpose of ensuring the safety of nuclear power plants is to limit the radiation effects of nuclear power plants on workers (personnel), the public and the environment during normal operation and violations of normal operation, including accidents.

The paper describes an experimental passive heat removal system developed based on the design features of the storage shaft of the IVV-2M research nuclear reactor. Its complete design is given, as well as its constituent elements.

The system consists of three parts, an evaporative, a condensing and a lifting and lowering path. The operation of the system is described in two modes:

1. Liquid-liquid – corresponds to the normal operation mode of the holding pool, in which the temperature of the coolant does not exceed the boiling point of alcohol 78,3 °C;
2. Liquid-two-phase – corresponds to the mode of heat dissipation in case of violation of normal operating conditions, in which ethyl alcohol boils in the circulation circuit.

Theoretical formulas for determining the heat output from the installation and the dependence of the expansion of a low-boiling coolant (alcohol) in the circuit during heating are presented.

To remove the parameters of the system circuit, thermocouples of the THA, evaporative module, heater and tank were used, the values of which were transmitted via ADAM 4014 converters to a computer. ADAMView and GenieDAQ software were used to output the readings.

In the course of the work, the results obtained on changes in temperatures in the circulation circuit of the system and the dynamics of changes in heat sink power, temperatures in the circuit, and the flow rate of the working fluid in the cooling mode are presented.

The introduction of passive heat sink systems for use in research facilities not only increases the safety of the installation itself, but also competitiveness in the market (when analyzing the literature, no analogues were found). At the moment, a significant number of nuclear research centers are being built not only in Russia, but also abroad. The proposed system of passive removal of residual heat emissions increases the competitiveness of new nuclear power plants, and can also be implemented in already operating installations.

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