Editing CANDU reactor (section)

===Early efforts===
The first heavy-water-moderated design in Canada was the [[ZEEP]], which started operation just after the end of [[World War II]]. ZEEP was joined by several other experimental machines, including the [[NRX]] in 1947 and [[National Research Universal reactor|NRU]] in 1957. These efforts led to the first CANDU-type reactor, the [[Nuclear Power Demonstration]] (NPD), in Rolphton, Ontario. It was intended as a proof-of-concept and rated for only 22&nbsp;[[MWe|MW<sub>e</sub>]], a very low power for a commercial power reactor. NPD produced the first nuclear-generated electricity in Canada and ran successfully from 1962 to 1987.<ref>Jeremy Whitlock, [http://mailman.mcmaster.ca/mailman/private/cdn-nucl-l/0202.gz/msg00127.html "NPD Historical Plaque"], Canadian Nuclear Society, 22 February 2002.</ref><ref>[http://archives.cbc.ca/science_technology/energy_production/topics/104-896/ "First Candu reactor powers Canadian homes"], CBC News, 4 June 1962.</ref>

The second CANDU was the [[Douglas Point]] reactor, a more powerful version rated at roughly 200&nbsp;MW<sub>e</sub> and located near [[Kincardine, Ontario|Kincardine]], Ontario.  It went into service in 1968 and ran until 1984. Uniquely among CANDU stations, Douglas Point had an oil-filled window with a view of the east reactor face, even when the reactor was operating.  Douglas Point was originally planned to be a two-unit station, but the second unit was cancelled because of the success of the larger 515&nbsp;MW<sub>e</sub> units at [[Pickering Nuclear Generating Station|Pickering]].<ref>{{cite web | url = http://www.cns-snc.ca/history/DouglasPoint/DouglasPoint.html | author = Canadian Nuclear Society | title = The Douglas Point Story | archive-url = https://web.archive.org/web/20080517095721/http://www.cns-snc.ca/history/DouglasPoint/DouglasPoint.html | archive-date = 17 May 2008 | url-status = dead}}</ref><ref>{{cite web | url = http://www.cns-snc.ca/history/DouglasPoint/AECL-2400/AECL2400-1.html | author = Canadian Nuclear Society | title = Douglas Point Nuclear Power Station | archive-url = https://web.archive.org/web/20080319113419/http://www.cns-snc.ca/history/DouglasPoint/AECL-2400/AECL2400-1.html | archive-date = 19 March 2008 | url-status = dead}}</ref>

[[File:Centrale nucléaire Gentilly.jpg|thumb|left| Gentilly-1 (right) and Gentilly-2 (left)]]
[[Gentilly Nuclear Generating Station|Gentilly-1]], in [[Bécancour, Quebec]], near [[Trois-Rivières]], Quebec, was also an experimental version of CANDU, using a boiling light-water coolant and vertical pressure tubes, but was not considered successful and closed after seven years of fitful operation.<ref>Gordon Edwards, [http://www.ccnr.org/Nuke_Quebec.html "Nuclear Power in Quebec"], Canadian Coalition for Nuclear Responsibility, 1995.</ref> Gentilly-2, a CANDU-6 reactor, began operating in 1983. Following statements from the in-coming [[Parti Québécois]] government in September 2012 that Gentilly would close, the operator, [[Hydro-Québec]], decided to cancel a previously announced refurbishment of the plant and announced its shutdown at the end of 2012, citing economic reasons for the decision. The company has started a 50-year [[nuclear decommissioning|decommissioning]] process estimated to cost $1.8 billion.<ref>{{cite news |author=CBC News |author-link=CBC News |title=Quebec nuclear reactor shutdown will cost $1.8 billion |date=3 October 2012 |work=[[Canadian Broadcasting Corporation]] |url=https://www.cbc.ca/news/canada/montreal/quebec-nuclear-reactor-shutdown-will-cost-1-8-billion-1.1159201 |access-date=4 October 2012}}</ref>

In parallel with the classic CANDU design, experimental variants were being developed. [[WR-1]], located at the [[Atomic Energy of Canada Limited|AECL]]'s [[Whiteshell Laboratories]] in [[Pinawa, Manitoba]], used vertical pressure tubes and organic [[Petroleum|oil]] as the primary coolant. The oil used has a higher boiling point than water, allowing the reactor to operate at higher temperatures and lower pressures than a conventional reactor. WR-1's outlet temperature was about 490&nbsp;°C compared to the CANDU&nbsp;6's nominal 310&nbsp;°C; the higher temperature and thus thermodynamic efficiency offsets to some degree the fact that oils have about half the heat capacity of water. The higher temperatures also result in more efficient conversion to steam, and ultimately, electricity. WR-1 operated successfully for many years and promised a significantly higher efficiency than water-cooled versions.<ref>[http://media.cns-snc.ca/history/wr-1/wr-1_5.html "Fact Sheet: WR-1 Reactor"] {{Webarchive|url=https://web.archive.org/web/20120501120012/http://media.cns-snc.ca/history/wr-1/wr-1_5.html |date=1 May 2012 }}, Canadian Nuclear Society.</ref><ref>[http://media.cns-snc.ca/history/wr-1/wr-1_1.html "Whiteshell Reactor no. 1"] {{Webarchive|url=https://web.archive.org/web/20101219034549/http://media.cns-snc.ca/history/wr-1/wr-1_1.html |date=19 December 2010 }}, Canadian Nuclear Society.</ref>

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