SPARK-LS: A novel design of a compact liquid chloride salt cooled fast reactor based on tube-in-duct fuel concept

Abstract A novel design of a compact liquid chloride salt cooled fast reactor (SPARK-LS) was proposed in the present study as a distributed energy resource for easy transportation and convenient deployment in diverse applications, such as electricity generation and district heating. The SPARK-LS reactor with rated power of 40 MWth can operate for 10 effective full power years without refueling. An innovative tube-in-duct fuel concept with coolant inside the tubes and fuel outside was adopted to achieve higher fuel volume fraction and lower pressure drop when compared with traditional pin-type fuel. Neutronics and thermal-hydraulics design and preliminary safety analysis were accomplished to obtain an optimized core design by using the advanced reactor design and analysis code system SARAX. Titanium was adopted as the reflector material due to its low density, good corrosion resistance, large strength-to-density ratio and decreased albedo with the neutron spectrum hardening. The optimized core design featured with compact volume and light weight was proved to satisfy the design constraints of peak coolant temperature, peak fuel centerline temperature and coolant pressure drop. The negative coolant density reactivity coefficient in the full core was ensured during the whole core lifetime thanks to the compact core design and the adoption of the titanium reflector. Based on the quasi-static reactivity balance method, five anticipated transients without scram were analyzed to confirm the inherent safety feature of SPARK-LS. It was shown that passive shutdown could be achieved safely for all the transients and the residual decay heat after the shutdown could be removed automatically by the natural circulation of coolant.