Editing CANDU reactor (section)

===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>