Precise modelling and operation characteristics analysis of the small helium-xenon gas cooled reactor power system with the air heat sink

The helium-xenon cold nuclear reactor system has a good prospect in aviation power because of its simple system, small size and lightweight. In this paper, based on the Modelica language, we independently developed a Brayton cycle system analysis program for a small helium-xenon cooled nuclear reactor, and verified the key models. Firstly, a design analysis was conducted on the flow and heat transfer enhancement of the reactor coolant channel, and the factors limiting the system power and final parameters were analyzed through simulation calculations. Then, the transient operating conditions of the system under different reactivity introduction methods and controlling the constant inlet temperature of the compressor were simulated, and the dynamic operating characteristics of the system and the coupling effects of the main equipment were studied. The simulation results show that the main factor limiting the power increase and final parameter reduction of the system is that the low density of air at high altitude cannot provide sufficient low-temperature cooling air to take away a lot of waste heat. Increasing flight speed and reducing flight altitude can increase the cooling power of the air cooler and reduce the final system parameters. By introducing the same reactivity through different reactivity insertion ways, the ultimate steady-state operating state of the system is the same. By controlling the compressor inlet temperature to be constant, the system output power can be improved. The relevant system analysis results provide a reference for the design of aeronautic electric propulsion system of helium-xenon cooled nuclear reactor.