Editing CANDU reactor (section)

==History==

The CANDU development effort has gone through four major stages over time. The first systems were experimental and prototype machines of limited power. These were replaced by a second generation of machines of 500 to 600&nbsp;MW<sub>e</sub> (the CANDU&nbsp;6), a series of larger machines of 900&nbsp;MW<sub>e</sub>, and finally developing into the CANDU&nbsp;9 and ACR-1000 effort.<ref name=slides>V. G. Snell, [http://canteach.candu.org/library/19990101.pdf "CANDU Safety, #1 – CANDU Nuclear Power Plant Design"] {{Webarchive|url=https://web.archive.org/web/20110723232020/http://canteach.candu.org/library/19990101.pdf |date=23 July 2011 }}, AECL, 24 May 2001.</ref><ref name="CANDU Evolution">[http://www.aecl.ca/Assets/Publications/Posters/CANDU-Evolution.pdf "CANDU Evolution"] {{Webarchive|url=https://web.archive.org/web/20110606063052/http://www.aecl.ca/Assets/Publications/Posters/CANDU-Evolution.pdf |date=6 June 2011 }}, AECL.</ref>

===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>

{{anchor|CANDU-6}}

===600 MW<sub>e</sub> designs ===
The successes at NPD and Douglas Point led to the decision to construct the first multi-unit station in Pickering, Ontario.  Pickering A, consisting of Units 1 to 4, went into service in 1971.  Pickering B with units 5 to 8 came online in 1983, giving a full-station capacity of 4,120&nbsp;MW<sub>e</sub>.  The station is very close to the city of [[Toronto]], in order to reduce [[electric power transmission|transmission]] costs.

A series of improvements to the basic Pickering design led to the CANDU&nbsp;6 design, which first went into operation in the early 1980s. CANDU&nbsp;6 was essentially a version of the Pickering power plant that was redesigned to be able to be built in single-reactor units. CANDU&nbsp;6 was used in several installations outside Ontario, including the [[Gentilly Nuclear Generating Station|Gentilly-2]] in Quebec, and [[Point Lepreau Nuclear Generating Station]] in New Brunswick. CANDU&nbsp;6 forms the majority of foreign CANDU systems, including the designs exported to Argentina, Romania, China and South Korea. Only India operates a CANDU system that is not based on the CANDU&nbsp;6 design.

===900 MW<sub>e</sub> designs===
The [[economics of nuclear power plants]] generally scale well with size. This improvement at larger sizes is offset by the sudden appearance of large quantities of power on the grid, which leads to a lowering of electricity prices through supply and demand effects. Predictions in the late 1960s suggested that growth in electricity demand would overwhelm these downward pricing pressures, leading most designers to introduce plants in the 1000&nbsp;MW<sub>e</sub> range.

Pickering&nbsp;A was quickly followed by such an upscaling effort for the [[Bruce Nuclear Generating Station]], constructed in stages between 1970 and 1987. It is the largest nuclear facility in North America and second largest in the world (after [[Kashiwazaki-Kariwa Nuclear Power Plant|Kashiwazaki-Kariwa]] in Japan), with eight [[nuclear reactor|reactors]] at around 800&nbsp;MW<sub>e</sub> each, in total 6,232&nbsp;MW (net) and 7,276&nbsp;MW (gross).  Another, smaller, upscaling led to the [[Darlington Nuclear Generating Station]] design, similar to the Bruce plant, but delivering about 880&nbsp;MW<sub>e</sub> per reactor in a four-reactor station.

As was the case for the development of the Pickering design into the CANDU&nbsp;6, the Bruce design was also developed into the similar CANDU&nbsp;9.<ref>[http://www.iasmirt.org/SMiRT15/S01-4 "CANDU 9 Evolution and Future Heavy Water Reactors"] {{Webarchive|url=https://web.archive.org/web/20111008232452/http://www.iasmirt.org/SMiRT15/S01-4 |date=8 October 2011 }}, AECL, 15–20 August 1999.</ref> Like the CANDU&nbsp;6, the CANDU&nbsp;9 is essentially a repackaging of the Bruce design, so that it can be built as a single-reactor unit. No CANDU&nbsp;9 reactors have been built.

===Generation III+ designs===
{{Main|Advanced CANDU reactor}}
Through the 1980s and 1990s the nuclear power market suffered a major crash, with few new plants being constructed in North America or Europe. Design work continued throughout, and new design concepts were introduced that dramatically improved safety, capital costs, economics and overall performance. These [[Generation III reactor|generation III+]] and [[Generation IV reactor|generation IV]] machines became a topic of considerable interest in the early 2000s, as it appeared that a [[nuclear renaissance]] was underway and large numbers of new reactors would be built over the next decade.<ref>[http://www.world-nuclear.org/info/inf104.html "The Nuclear Renaissance"], World Nuclear Association.</ref>

AECL had been working on a design known as the ACR-700, using elements of the latest versions of the CANDU&nbsp;6 and CANDU&nbsp;9, with a design power of 700&nbsp;MW<sub>e</sub>.<ref name="CANDU Evolution"/> During the nuclear renaissance, the upscaling seen in the earlier years re-expressed itself, and the ACR-700 was developed into the 1200&nbsp;MW<sub>e</sub> ACR-1000. ACR-1000 is the next-generation (officially, "generation III+") CANDU technology, which makes some significant modifications to the existing CANDU design.<ref name=acr1000/>

The main change, and the most radical among the CANDU generations, is the use of pressurized light water as the coolant. This significantly reduces the cost of implementing the primary cooling loop, which no longer has to be filled with expensive heavy water. The ACR-1000 uses about 1/3rd the heavy water needed in earlier-generation designs. It also eliminates tritium production in the coolant loop, the major source of tritium leaks in operational CANDU designs. The redesign also allows a slightly negative [[void coefficient|void reactivity]], a major design goal of all Gen III+ machines.<ref name=acr1000>[http://www.aecl.ca/Assets/Publications/ACR1000-Tech-Summary.pdf "ACR-1000 Technical Summary"] {{Webarchive|url=https://web.archive.org/web/20110606062512/http://www.aecl.ca/Assets/Publications/ACR1000-Tech-Summary.pdf |date=6 June 2011 }}, AECL.</ref>

The design also requires the use of [[enriched uranium#slightly enriched uranium|slightly enriched uranium]], enriched by about 1 or 2%. The main reason for this is to increase the burn-up ratio, allowing bundles to remain in the reactor longer, so that only a third as much spent fuel is produced. This also has effects on operational costs and timetables, as the refuelling frequency is reduced. As is the case with earlier CANDU designs, the ACR-1000 also offers online refuelling.<ref name=acr1000/>

Outside of the reactor, the ACR-1000 has a number of design changes that are expected to dramatically lower capital and operational costs. Primary among these changes is the design lifetime of 60 years, which dramatically lowers the price of the electricity generated over the lifetime of the plant. The design also has an expected capacity factor of 90%. Higher-pressure steam generators and turbines improve efficiency downstream of the reactor.<ref name=acr1000/>

Many of the operational design changes were also applied to the existing CANDU&nbsp;6 to produce the Enhanced CANDU&nbsp;6. Also known as CANDU&nbsp;6e or EC&nbsp;6, this was an evolutionary upgrade of the CANDU&nbsp;6 design with a gross output of 740&nbsp;MW<sub>e</sub> per unit. The reactors are designed with a lifetime of over 50 years, with a mid-life program to replace some of the key components e.g. the fuel channels. The projected average annual [[capacity factor]] is more than 90%. Improvements to construction techniques (including modular, open-top assembly) decrease construction costs. The CANDU&nbsp;6e is designed to operate at power settings as low as 50%, allowing them to adjust to load demand much better than the previous designs.<ref>[http://www.aecl.ca/Reactors/EC6.htm "Enhanced CANDU 6"] {{Webarchive|url=https://web.archive.org/web/20110606053133/http://www.aecl.ca/Reactors/EC6.htm |date=6 June 2011 }}, AECL.</ref>

===Sales efforts in Canada===
By most measures, the CANDU is "the Ontario reactor". The system was developed almost entirely in Ontario, and only two experimental designs were built in other provinces. Of the 29 commercial CANDU reactors built, 22 are in Ontario. Of these 22, a number of reactors have been removed from service. Two new CANDU reactors have been proposed for Darlington with Canadian government help with financing,<ref>{{cite news | first = David | last = Ljunggren | title = Canada nuclear firms seek Ottawa financing | work = Reuters | date = 7 August 2008 | url = https://www.reuters.com/article/marketsNews/idUSN0743618220080807?sp=true | access-date = 10 August 2008}}</ref> but these plans ended in 2009 due to high costs.<ref>{{cite news |url=https://www.thestar.com/business/2009/07/14/26b_cost_killed_nuclear_bid.html |title=$26B cost killed nuclear bid |newspaper=Toronto Star |date=14 July 2009 |first=Tyler | last= Hamilton}}</ref>

AECL has heavily marketed CANDU within Canada, but has found a limited reception. To date, only two non-experimental reactors have been built in other provinces, one each in Quebec and New Brunswick, other provinces have concentrated on hydro and coal-fired plants. Several Canadian provinces have developed large amounts of hydro power. Alberta and Saskatchewan do not have extensive hydro resources, and use mainly fossil fuels to generate electric power.

Interest has been expressed in [[Western Canada]], where CANDU reactors are being considered as heat and electricity sources for the energy-intensive [[tar sands|oil sands]] extraction process, which currently uses [[natural gas]]. [[Energy Alberta Corporation]] announced 27 August 2007 that they had applied for a licence to build a new nuclear plant at Lac Cardinal (30&nbsp;km west of the town of [[Peace River, Alberta]]), with two ACR-1000 reactors going online in 2017 producing 2.2 [[gigawatt]]s (electric).<ref>[https://www.cbc.ca/news/business/company-begins-process-to-build-alberta-s-1st-nuclear-plant-1.642324 "Company begins process to build Alberta's 1st nuclear plant"], CBC News, 28 August 2007.</ref> A 2007 parliamentary review suggested placing the development efforts on hold.<ref>[https://web.archive.org/web/20170110162426/http://uk.reuters.com/article/oilsands-nuclear-idUKN2838636320070328 "Canada wary of nuclear power for oil sands"], Reuters, 28 May 2007.</ref> The company was later purchased by Bruce Power,<ref>[http://www.energyquest4nanticoke.ca/intent.htm "Bruce Power Signs Letter of Intent With Energy Alberta Corporation"] {{webarchive|url=https://web.archive.org/web/20110827032951/http://www.energyquest4nanticoke.ca/intent.htm |date=27 August 2011 }}, Marketwire, 29 November 2007.</ref> who proposed expanding the plant to four units of a total 4.4 gigawatts.<ref>[http://www.world-nuclear-news.org/IT-Bruce_Power_to_make_important_announcement_130308.html "Bruce Power to prepare Alberta site"], ''World Nuclear News'', 14 March 2008.</ref> These plans were upset and Bruce later withdrew its application for the Lac Cardinal, proposing instead a new site about 60&nbsp;km away.<ref>[http://www.world-nuclear-news.org/newsarticle.aspx?id=24286 "Bruce thinks again on Alberta site"] {{Webarchive|url=https://web.archive.org/web/20111214220257/http://www.world-nuclear-news.org/newsarticle.aspx?id=24286 |date=14 December 2011 }}, ''World Nuclear News'', 9 January 2009.</ref> The plans are currently moribund after a wide consultation with the public demonstrated that while about {{frac|5}} of the population were open to reactors, {{frac|4}} were opposed.<ref>{{cite news |url=https://www.alberta.ca/release.cfm?xID=275218E7F1F68-B25C-81BE-9AF25F7ADE436D8A |title=Province releases results of nuclear consultation |date=14 December 2009}}</ref><ref>{{cite news |url=http://www.edmontonexaminer.com/2016/04/13/though-there-is-potential-for-nuclear-power-in-alberta-theres-more-than-just-public-opinion-holding-it-back |title=Though there is potential for nuclear power in Alberta, there's more than just public opinion holding it back |first=Doug |last=Johnson |date=13 April 2016 |newspaper=Edmonton Examiner |access-date=24 November 2016 |archive-url=https://web.archive.org/web/20161125110315/http://www.edmontonexaminer.com/2016/04/13/though-there-is-potential-for-nuclear-power-in-alberta-theres-more-than-just-public-opinion-holding-it-back |archive-date=25 November 2016 |url-status=dead }}</ref>

===Foreign sales===
During the 1970s, the international nuclear sales market was extremely competitive, with many national nuclear companies being supported by their governments' foreign embassies. In addition, the pace of construction in the United States had meant that cost overruns and delayed completion was generally over, and subsequent reactors would be cheaper. Canada, a relatively new player on the international market, had numerous disadvantages in these efforts. The CANDU was deliberately designed to reduce the need for very large machined parts, making it suitable for construction by countries without a major industrial base. Sales efforts have had their most success in countries that could not locally build designs from other firms.

In the late 1970s, AECL noted that each reactor sale would employ 3,600 Canadians and result in $300 million in balance-of-payments income.<ref>[http://archives.cbc.ca/science_technology/energy_production/clips/906/ "The push to sell Candus abroad"], CBC, 7 December 1978.</ref> These sales efforts were aimed primarily at countries being run by dictatorships or similar, a fact that led to serious concerns in parliament.<ref>[http://archives.cbc.ca/science_technology/energy_production/clips/900/ "Selling Candus to 'the wrong people, at the wrong time'"], CBC, 1976.</ref> These efforts also led to a scandal when it was discovered millions of dollars had been given to foreign sales agents, with little or no record of who they were, or what they did to earn the money.<ref>[http://archives.cbc.ca/science_technology/energy_production/clips/904/ "Mysterious millions spent on Candu sales commissions"], CBC, 14 October 1976.</ref> This led to a [[Royal Canadian Mounted Police]] investigation after questions were raised about sales efforts in Argentina, and new regulations on full disclosure of fees for future sales.<ref>"$4 million bribe given on Candu Argentina says", ''Toronto Star'', 13 June 1985.</ref>

CANDU's first success was the sale of early CANDU designs to India. In 1963, an agreement was signed for export of a 200 MWe power reactor based on the Douglas Point reactor. The success of the deal led to the 1966 sale of a second reactor of the same design. The first reactor, then known as [[Rajasthan Atomic Power Station|RAPP-1]] for "Rajasthan Atomic Power Project", began operation in 1972. A serious problem with cracking of the reactor's end shield led to the reactor being shut down for long periods, and the reactor was finally downrated to 100&nbsp;MW.<ref>"Datafile: India", Nuclear Engineering International, February 1995, p. 22.</ref> Construction of the RAPP-2 reactor was still underway when India detonated its first [[atomic bomb]] in 1974, leading to Canada ending nuclear dealings with the country. Part of the sales agreement was a technology transfer process. When Canada withdrew from development, India continued construction of CANDU-like plants across the country.<ref>David Martin, [http://www.ccnr.org/exports_3.html#3.2 "Exporting Disaster: CANDUs for India"], Canadian Coalition for Nuclear Responsibility, November 1996.</ref> By 2010, CANDU-based reactors were operational at the following sites: Kaiga (3), Kakrapar (2), Madras (2), Narora (2), Rajasthan (6), and Tarapur (2).

In Pakistan, the [[Karachi Nuclear Power Complex|Karachi Nuclear Power Plant]] with a gross capacity of 137&nbsp;MW<sub>e</sub> was built between 1966 and 1971.

In 1972, AECL submitted a design based on the Pickering plant to Argentina's Comision Nacional de Energia Atomica process, in partnership with the Italian company Italimpianti. High inflation during construction led to massive losses, and efforts to re-negotiate the deal were interrupted by the March 1976 coup led by General Videla. The [[Embalse Nuclear Power Station]] began commercial operation in January 1984.<ref>David Martin, [http://www.ccnr.org/exports_3.html#3.1 "Exporting Disaster: The Cordoba CANDU"], Canadian Coalition for Nuclear Responsibility, November 1996.</ref> There have been ongoing negotiations to open more CANDU&nbsp;6 reactors in the country, including a 2007 deal between Canada, China and Argentina, but to date no firm plans have been announced.<ref>[http://www.world-nuclear-news.org/newsarticle.aspx?id=13990 "Canada, Argentina and China to cooperate on Candu projects"] {{Webarchive|url=https://web.archive.org/web/20110609044738/http://www.world-nuclear-news.org/newsarticle.aspx?id=13990 |date=9 June 2011 }}, ''World Nuclear News'', 5 September 2007.</ref>

A licensing agreement with Romania was signed in 1977, selling the CANDU&nbsp;6 design for $5 million per reactor for the first four reactors, and then $2 million each for the next twelve. In addition, Canadian companies would supply a varying amount of equipment for the reactors, about $100 million of the first reactor's $800 million price tag, and then falling over time. In 1980, [[Nicolae Ceaușescu]] asked for a modification to provide goods instead of cash, in exchange the amount of Canadian content was increased and a second reactor would be built with Canadian help. Economic troubles in the country worsened throughout the construction phase. The first reactor of the [[Cernavodă Nuclear Power Plant]] only came online in April 1996, a decade after its December 1985 predicted startup.<ref>David Martin, [http://www.ccnr.org/exports_2.html#2.3 "Exporting Disaster: Romania"], Canadian Coalition for Nuclear Responsibility, November 1996.</ref> Further loans were arranged for completion of the second reactor, which went online in November 2007.<ref>[http://www.aecl.ca/Reactors/CANDU6/CANDU6-Units/Cernavoda.htm "Cernavoda"] {{Webarchive|url=https://web.archive.org/web/20110606085131/http://www.aecl.ca/Reactors/CANDU6/CANDU6-Units/Cernavoda.htm |date=6 June 2011 }}, AECL.</ref>

In January 1975, a deal was announced for a single CANDU&nbsp;6 reactor to be built in South Korea, now known as the [[Wolseong Nuclear Power Plant|Wolsong-1 Power Reactor]]. Construction started in 1977 and commercial operation began in April 1983. In December 1990 a further deal was announced for three additional units at the same site, which began operation in the period 1997–1999.<ref>David Martin, [http://www.ccnr.org/exports_2.html#2.4 "Exporting Disaster: South Korea"], Canadian Coalition for Nuclear Responsibility, November 1996.</ref> South Korea also negotiated development and technology transfer deals with Westinghouse for their advanced System-80 reactor design, and all future development is based on locally built versions of this reactor.<ref>[http://www.world-nuclear-news.org/C_South_Koreas_nuclear_power_independence_2805082.html "South Korea's nuclear power independence"], ''World Nuclear News'', 28 May 2008.</ref>

In June 1998, construction started on a CANDU&nbsp;6 reactor in Qinshan China [[Qinshan Nuclear Power Plant]], as Phase III (units 4 and 5) of the planned 11 unit facility.  Commercial operation began in December 2002 and July 2003, respectively.  These are the first heavy water reactors in China.  Qinshan is the first CANDU-6 project to use open-top reactor building construction, and the first project where commercial operation began earlier than the projected date.<ref>[https://www.iaea.org/NuclearPower/Downloads/Technology/meetings/2011-Dec-12-16-WS-Paris/2.11-A.KHAN-CanduEnergy.pdf Khan, Azhar, ''Challenges & Successes of Candu Energy (former AECL) in Nuclear Construction: Case Study of China and Romania''], presentation at IAEA Workshop on Construction Technologies for Nuclear Power Plants: A Comprehensive Approach, Paris, December 12–16, 2011.</ref>

CANDU Energy is continuing marketing efforts in China.<ref>url=http://www.newswire.ca/en/story/1441373/candu-energy-inc-welcomes-positive-review-of-afcr-technology-in-china {{Webarchive|url=https://web.archive.org/web/20141110223443/http://www.newswire.ca/en/story/1441373/candu-energy-inc-welcomes-positive-review-of-afcr-technology-in-china |date=10 November 2014 }}</ref> In addition, China and Argentina have agreed a contract to build a 700 MWe CANDU-6 derived reactor. Construction is planned to start in 2018 at [[Atucha Nuclear Power Plant|Atucha]].<ref name=wnn-20150508>{{cite news |url=http://www.world-nuclear-news.org/NN-Argentina-China-talks-on-new-nuclear-plants-08051501.html |title=Argentina-China talks on new nuclear plants |publisher=World Nuclear News |date=8 May 2015 |access-date=19 May 2017}}</ref><ref name=wnn-20170518>{{cite news |url=http://www.world-nuclear-news.org/NN-Argentina-and-China-sign-contract-for-two-reactors-1805175.html |title=Argentina and China sign contract for two reactors |publisher=World Nuclear News |date=18 May 2017 |access-date=19 May 2017}}</ref>

===Economic performance===
The cost of electricity from any power plant can be calculated by roughly the same selection of factors: capital costs for construction or the payments on loans made to secure that capital, the cost of fuel on a per-watt-hour basis, and fixed and variable maintenance fees. In the case of nuclear power, one normally includes two additional costs, the cost of permanent waste disposal, and the cost of decommissioning the plant when its useful lifetime is over. Generally, the capital costs dominate the price of nuclear power, as the amount of power produced is so large that it overwhelms the cost of fuel and maintenance.<ref>[http://nuclearinfo.net/Nuclearpower/WebHomeCostOfNuclearPower "Cost of Nuclear Power"] {{Webarchive|url=https://web.archive.org/web/20110610172522/http://nuclearinfo.net/Nuclearpower/WebHomeCostOfNuclearPower |date=10 June 2011 }}, nuclearinfo.net.</ref> The [[World Nuclear Association]] calculates that the cost of fuel, including all processing, accounts for less than one cent (US$0.01) per kWh.<ref name=econ>{{cite web|url=http://www.world-nuclear.org/info/inf02.html|title=The Economics of Nuclear Power|publisher=[[World Nuclear Association]]|access-date=14 June 2011|archive-date=4 June 2010|archive-url=https://web.archive.org/web/20100604000308/http://www.world-nuclear.org/info/inf02.html|url-status=dead}}</ref>

Information on economic performance on CANDU is somewhat lopsided; the majority of reactors are in Ontario, which is also the "most public" among the major CANDU operators. Several anti-nuclear organizations like the Ontario Clean Air Alliance (OCAA) and Pembina have claimed that every CANDU design in Ontario went over budget by at least 25%, and average over 150% higher than estimated.<ref name=apexa>Jack Gibbons, "Darlington Re-Build Consumer Protection Plan", Ontario Clear Air Alliance, 23 September 2010, Appendix A, p. 7–8.</ref> However, this is predicated on using "dollar of the day" figures that are not adjusted for inflation. With inflation accounted for, all plants were on or under budget with the exception of Darlington.{{cn|date=May 2023}} Even accounting for inflation, Darlington went far over budget, at almost double the original estimate, but this project was stopped in-progress thereby incurring additional interest charges during a period of high interest rates, which is a special situation that was not expected to repeat itself.{{cn|date=May 2023}}

In the 1980s, the pressure tubes in the Pickering&nbsp;A reactors were replaced ahead of design life due to unexpected deterioration caused by [[hydrogen embrittlement]]. Extensive inspection and maintenance has avoided this problem in later reactors.

All the Pickering&nbsp;A and Bruce&nbsp;A reactors were shut down in 1999 in order to focus on restoring operational performance in the later generations at Pickering, Bruce, and Darlington. Before restarting the Pickering&nbsp;A reactors, OPG undertook a limited refurbishment program. The original cost and time estimates based on inadequate project scope development were greatly below the actual time and cost and it was determined that Pickering units 2 and 3 would not be restarted for commercial reasons.

These overruns were repeated at Bruce, with Units 3 and 4 running 90% over budget.<ref name=apexa/> Similar overruns were experienced at Point Lepreau,<ref>[https://www.cbc.ca/news/canada/new-brunswick/point-lepreau-overruns-to-cost-1-6b-1.830293 "Point Lepreau overruns to cost $1.6B"], CBC News, 20 October 2009.</ref> and Gentilly-2 plant was shut down on 28 December 2012.<ref>CBC News, [http://www.cbc.ca/news/canada/montreal/quebec-s-gentilly-2-nuclear-plant-shuts-down-after-29-years-1.1159855 "Quebec's Gentilly-2 nuclear plant shuts down after 29 years"], ''CBC'', 28 December 2012.</ref>

Based on the projected capital costs, and the low cost of fuel and in-service maintenance, in 1994 power from CANDU was predicted to be well under 5&nbsp;cents/kWh.<ref>[http://www.nuclearfaq.ca/cnf_sectionC.htm#SectionC "How do the economic benefits of nuclear power compare to other sources in Canada?"], CANDU FAQ, Section C.1.</ref>

In 1999, Ontario Hydro was broken up and its generation facilities re-formed into [[Ontario Power Generation]] (OPG). In order to make the successor companies more attractive for private investors, $19.4&nbsp;billion in "stranded debt" was placed in the control of the Ontario Electricity Financial Corporation. This debt is slowly paid down through a variety of sources, including a 0.7-cent/kWh tariff on all power, all income taxes paid by all operating companies, and all dividends paid by the OPG and [[Hydro One]].

As of October 2022, Darlington is into the final half of the 10-year major refurbishment project of all four units, having reached their design mid-life. The budget is set at $12.5 billion, and planned to produce power at 6 to 8 cents/kWh. The project is currently on-time and on-budget.<ref>{{Cite web|url=https://www.opg.com/strengthening-the-economy/our-projects/darlington-refurbishment/|title=Ontario Power Generation - Darlington Refurbishment|date=5 October 2022|website=Ontario Power Generation|language=en|access-date=5 October 2022}}</ref>

Darlington Units 1, 3 and 4 have operated with an average lifetime annual capacity factor of 85% and Unit 2 with a capacity factor of 78%,<ref>[http://media.cns-snc.ca/nuclear_info/candu_performance.html  "CANDU Lifetime Performance"] {{Webarchive|url=https://web.archive.org/web/20120117215048/http://media.cns-snc.ca/nuclear_info/candu_performance.html |date=17 January 2012 }}, Canadian Nuclear Society.</ref> As of 2010, refurbished units at Pickering and Bruce had lifetime capacity factors between 59 and 69%.<ref name=g5>Jack Gibbons, "Darlington Re-Build Consumer Protection Plan", Ontario Clear Air Alliance, 23 September 2010, p. 5.</ref> This includes periods of several years while the units were shut down for the retubing and refurbishing. Post-refurbishment capacity factors are much higher with Bruce A1 at 90.78%, Bruce A2 at 90.38% (2013+),<ref name="pris_iaea_org" /> Pickering A1 at 71.18% and Pickering A4 at 70.38%.<ref>{{Cite web|url=https://pris.iaea.org/PRIS/CountryStatistics/ReactorDetails.aspx?current=49|title=IAEA Power Reactor Data|date=4 October 2022|website=IAEA Power Reactor Data|language=en|access-date=5 October 2022}}</ref> In 2009, Bruce&nbsp;A units 3 and 4 had capacity factors of 80.5% and 76.7% respectively, in a year when they had a major Vacuum Building outage.<ref>[http://www.brucepower.com/wp-content/uploads/2011/05/20092.pdf Bruce Power ''Focus – 2009 Year in Review''] {{Webarchive|url=https://web.archive.org/web/20110928103412/http://www.brucepower.com/wp-content/uploads/2011/05/20092.pdf |date=28 September 2011 }}, 2010.</ref>