The heavy ion radiation performance of NCringFET with single and dual-k spacers using both the inner and outer drain arrangements are investigated using 3D TCAD simulations. DC performance parameters, including ON current (Ion), OFF current (Ioff), and Ion/Ioffratio, are obtained for all NCringFET structures. The behavior of NCringFET to heavy ion irradiation is analyzed, and the device’s susceptible area is identified via single-event transient analysis. It was discovered that the most susceptible area for an inner drain arrangement is the centre of the drain, whereas the most susceptible area for an outer drain arrangement is the spacer near the drain. The source region is the least susceptible area for both outer and inner drain arrangements. Also, the single-event transient performance of NCringFET-based Inverters using both outer and inner drain arrangements are examined. NCringFET with an inner drain arrangement exhibits improved performance in radiation-prone areas due to its reduced collected charge, making it a more suitable choice for applications requiring high reliability and radiation tolerance at both the device level and circuit level.