Editing Nuclear meltdown (section)

===CANDU reactors===
[[CANDU]] reactors, Canadian-invented deuterium-uranium design, are designed with at least one, and generally two, large low-temperature and low-pressure water reservoirs around their fuel/coolant channels. The first is the bulk heavy-water moderator (a separate system from the coolant), and the second is the light-water-filled shield tank (or [[CANDU Reactor#Basic design and operation|calandria]] vault). These backup heat sinks are sufficient to prevent either the fuel meltdown in the first place (using the moderator heat sink), or the breaching of the core vessel should the moderator eventually boil off (using the shield tank heat sink).<ref name=Allen>{{cite journal|first=P.J.|last=Allen |author2=J.Q. Howieson |author3=H.S. Shapiro |author4=J.T. Rogers |author5=P. Mostert |author6=R.W. van Otterloo |title=Summary of CANDU 6 Probabilistic Safety Assessment Study Results|journal=Nuclear Safety|volume=31|issue=2|date=April–June 1990|pages=202–214}}</ref> Other failure modes aside from fuel melt will probably occur in a CANDU rather than a meltdown, such as deformation of the calandria into a non-critical configuration. All CANDU reactors are located within standard Western containments as well.