Further improving LBLOCA resistance of CANDU cooled by light water

Highlights: ► Improving LBLOCA resistance for CANDU cooled by light water. ► Ensuring negative coolant-void reactivity in CANDU cooled by light water. ► Very onset of LBLOCA passively shuts down CANDU cooled by light water. -- Abstract: CANDU and similar designs have higher resistance to large-break loss-of-coolant accident (LBLOCA). This is due to lower power density of the core, its cool, unpressurised moderator, completely separate from coolant, etc. A disadvantage, however, is that coolant voiding in any pattern, uniform or checkerboard, causes a power pulse in traditional core designs moderated and cooled by heavy water. In cores cooled by light, moderated by heavy water, such pulse is temporary, disappearing passively by itself and restricted to the case of checkerboard voiding. A small reactor remodelling is proposed here to ensure no power pulse in LBLOCA. Such result has been a historic goal for designers of reactors moderated by heavy water.