Optimization of multilayer fuel assemblies for supercritical water-cooled reactors with mixed neutron spectrum

Highlights: ► The multilayer assembly in a mixed neutron spectrum core of SCWR is studied. ► We evaluate the thermal-hydraulic and neutronic performance of the assembly. ► We study the effect of number of layers, rod diameter, p/d and duct wall clearance. ► A optimized range of parameters is recommended and five design options are proposed. - Abstract: This article presents an optimized design of fuel assembly for the fast zone of a mixed-spectrum supercritical water-cooled reactor (SCWR-M) which is proposed by the Shanghai Jiao Tong University. The fuel assembly has multilayer structure and is axially divided into several seed and blanket layers. Both sub-channel and MCNP analysis are performed to assess thermal-hydraulic and neutronic performance of the fuel assemblies aiming at improving safety and sustainability. The effects of some design parameters, i.e., axial configuration, fuel rod diameter, pitch to diameter ratio and duct wall clearance on the thermal-hydraulic and neutronic performance of assemblies are investigated. Reference ranges of some parameters of the multilayer fuel assembly are proposed for future analysis.