Heavy water (D2O) is the most feasible moderator and coolant in nuclear-fission reactors while deuterium (D) will be the nuclear fuel for thermonuclear fusion in the distant future.

• 摘要重水(D2O)乃核分离反应器中最适用之缓冲剂及冷剂，而重氢(D)则为不久将来将发展出之核融合反应的燃料。