Performance optimization of fuel assembly based on two-way helical editing method

Conventional One-Way Helical (OWH) arrangements in Helical Cruciform Fuel (HCF) assemblies inherently restrict cross-flow, limiting lateral heat transfer and increasing local overheating risks. This study proposes a novel Two-Way Helical (TWH) design to overcome this critical limitation. Computational Fluid Dynamics (CFD) analysis of a 5 × 5 HCF assembly demonstrates that the TWH arrangement can effectively generate specific large-scale cross-flow through its design, dramatically increasing lateral mass flow rate by a factor of 39 compared to OWH and reducing peak fuel surface temperature to 88.6 % of the OWH value under identical conditions. Critically, at half the mass flow rate (a postulated Loss-of-Flow Accident (LOFA) scenario), TWH further lowers the peak temperature to just 80.5 % of that in OWH. This breakthrough in flow field control achieves substantial thermal-hydraulic optimization. The TWH design provides a novel approach for actively tailoring internal cross-flow to enhance heat transfer and mitigate hotspots as needed, offering significant potential to improve safety margins and economic competitiveness concurrently in HCF-based nuclear reactors.