For the boiling light water cooled heavy water moderated reactor considered in the present report (the AHWR, incorporating pressure channels and calandria; see Annex VI), smaller capacity — in view of the designers — facilitates:

— The use of natural convection for heat removal in normal operation, eliminating, for example, main circulation pumps;

— Achievement of a slightly negative void coefficient of reactivity;

— Provision of a relatively large coolant inventory in the main coolant system to ensure its high thermal inertia and slow pace of transients;

— Provision of a relatively large inventory of water in a reasonably sized gravity driven water pool (GDWP), located inside the containment and intended for passive emergency injection of cooling water, passive containment cooling, and passive decay heat removal via the isolation condensers.