Preliminary analysis of the in-orbit operation characteristic of the inherent safety space reactor power system

The inherent safety space reactor power system with a coupled thermoelectric conversion in a liquid metal lithium-cooled reactor represents a highly reliable space power. Compared with the ground reactor, the SNRPS has its own characteristics in safety considerations, mainly manifested in the SNRPS before launch, during launch and during the ascent into orbit will be affected by the launch vehicle. Which can be analyzed by the common methodology of probabilistic risk management. To investigate the response characteristics during in-orbit operation accidents, a transient analysis model of the liquid metal-cooled space reactor power system is established. The system response characteristics of the inherent safety space reactor power system conceptual designs are preliminarily analyzed under four potential typical in-orbit operating conditions, including (1) rated operating condition, (2) control drum misoperation events, (3) partial loss of coolant flow accident, and (4) partial failure of the radiator area accident. The results show that the power system has inherent safety in-orbit operation characteristics due to the system design operating parameters, which the coolant temperature below 1200 K at the rated operating condition. Even under typical operating accidents, the system coolant remains highly supercooled (more than 200 K), preventing boiling from occurring. The maximum temperature of the core fuel pin and cladding materials remains lower than their safety limits, ensuring that no core melting phenomenon occurs.