Heavy water (D2O) is one of several commonly-used moderators found in nuclear reactors (others include graphite, beryllium and light–i.e., ordinary–water). A moderator slows down fast-moving neutrons released by nuclear fission so they have more time to react with the nuclear fuel. That permits a sustained, controlled chain reaction using unenriched uranium. Reactors using enriched uranium … Continue reading Is “heavy water” dangerous?