Editing CANDU reactor (section)

== Fuel cycle ==
[[File:CANDU fuel cycles.jpg|thumb|right|upright=1.5|Range of possible CANDU fuel cycles: CANDU reactors can accept a variety of fuel types, including the used fuel from light-water reactors.]]

A heavy-water design can sustain a chain reaction with a lower concentration of fissile atoms than light-water reactors, allowing it to use some alternative fuels; for example, "[[reprocessed uranium|recovered uranium]]" (RU) from used LWR fuel. CANDU was designed for natural uranium with only 0.7%&nbsp;<sup>235</sup>U, so reprocessed uranium with 0.9%&nbsp;<sup>235</sup>U is a comparatively rich fuel. This extracts a further 30–40% energy from the uranium. The Qinshan CANDU reactor in China has used recovered uranium.<ref>{{cite web |title=CANDU Reactor in China first to directly use recovered uranium fuel |url=https://www.newswire.ca/news-releases/candu-reactor-in-china-first-to-directly-use-recovered-uranium-fuel-539599062.html |publisher=Atomic Energy of Canada Ltd |access-date=4 March 2021}}</ref> The DUPIC (''Direct Use of spent PWR fuel in CANDU'') process under development can recycle it even without reprocessing. The fuel is sintered in air (oxidized), then in hydrogen (reduced) to break it into a powder, which is then formed into CANDU fuel pellets.

CANDU reactors can also [[thorium fuel cycle|breed fuel]] from the more abundant [[thorium]]. This is being [[thorium fuel cycle|investigated]] by India to take advantage of its natural thorium reserves.<ref name=":0">[http://nextbigfuture.com/2012/08/canada-and-china-work-on-thorium-candu.html "Canada and China work on Thorium Candu Fuel and India May Start Mining 1 million tons of Thorium"] {{Webarchive|url=https://web.archive.org/web/20120806041625/http://nextbigfuture.com/2012/08/canada-and-china-work-on-thorium-candu.html|date=6 August 2012}}, [[Next Big Future]], 2 August 2012.</ref>

Even [[MOX fuel#Overview|better than LWRs]], CANDU can utilize a mix of uranium and plutonium oxides ([[MOX fuel]]), the plutonium either from dismantled [[nuclear weapon]]s or reprocessed reactor fuel. The mix of isotopes in reprocessed plutonium is not attractive for weapons, but can be used as fuel (instead of being simply nuclear waste), while consuming [[weapons-grade plutonium]] eliminates a proliferation hazard. If the aim is explicitly to utilize plutonium or other [[actinide]]s from spent fuel, then special inert-matrix fuels are proposed to do this more efficiently than MOX. Since they contain no uranium, these fuels do not breed any extra plutonium.