A new modification of the flow channel insert (FCI) called "double-layer" or "nested" FCI (nFCI) is assessed numerically for the poloidal duct flows in the dual-coolant lead-lithium (DCLL) blanket under the US DEMO outboard (OB) blanket conditions. The proposed nFCI mitigates the thermal stress while providing sufficient thermal insulation and reducing the MHD pressure drop.