Editing CANDU reactor (section)

==Tritium production==
[[Tritium]], <sup>3</sup>H, is a radioactive isotope of [[hydrogen]], with a [[half-life]] of 12.3 years. 
It is produced in small amounts in nature (about 4&nbsp;kg per year globally) by [[cosmic ray]] interactions in the upper atmosphere. Tritium is considered a weak [[radionuclide]] because of its low-energy radioactive emissions ([[beta particle]] energy up to 18.6&nbsp;keV).<ref name="tritium">{{cite web |url=http://www.ehso.emory.edu/content-forms/3anuclidedatasafetysheets.pdf |title=Nuclide Safety Data Sheet: Hydrogen-3 [Tritium] |page=1 |access-date=22 July 2015 |archive-url=https://web.archive.org/web/20130520184942/http://www.ehso.emory.edu/content-forms/3anuclidedatasafetysheets.pdf |archive-date=20 May 2013 |url-status=dead }}</ref> The beta particles travel 6&nbsp;mm in air and only penetrate skin up to 6 micrometers.  The biological half-life of inhaled, ingested, or absorbed tritium is 10–12 days.<ref name="tritium" />

Tritium is generated in the fuel of all reactors; CANDU reactors generate tritium also in their coolant and moderator, due to [[neutron capture]] in heavy hydrogen. 
Some of this tritium escapes into containment and is generally recovered; a small percentage (about 1%) escapes containment and is considered a routine radioactive emission (also higher than from an LWR of comparable size). Responsible operation of a CANDU plant therefore includes monitoring tritium in the surrounding environment (and publishing the results).

In some CANDU reactors the tritium is periodically extracted. Typical emissions from CANDU plants in Canada are less than 1% of the national regulatory limit, which is based on [[International Commission on Radiological Protection]] (ICRP) guidelines<ref>{{cite web |url=http://www.opg.com/safety/nsafe/nuclear/faq.asp |title=Ontario Power Generation: Safety |publisher=Ontario Power Generation |access-date=December 1, 2008 |archive-url=https://web.archive.org/web/20090105031455/http://www.opg.com:80/safety/nsafe/nuclear/faq.asp |archive-date=January 5, 2009 |url-status=dead}}</ref> (for example, the maximal permitted drinking-water concentration for tritium in Canada, 7,000&nbsp;[[Becquerel|Bq]]/L,<ref>{{cite web |url=https://www.canada.ca/en/health-canada/services/environmental-workplace-health/reports-publications/water-quality/guidelines-canadian-drinking-water-quality-summary-table.html#t3 |title=Guidelines for Canadian Drinking Water Quality: Summary Tables |date=October 2024 |publisher=Health Canada |access-date=30 January 2025}}</ref> corresponds to 1/10 of the ICRP's dose limit for members of the public). Tritium emissions from other CANDU plants are similarly low.<ref name="green">{{cite web |url=http://www.greenpeace.org/canada/Global/canada/report/2007/6/tritium-hazard-report-pollu.pdf |title=Tritium Hazard Report: Pollution and Radiation Risk from Canadian Nuclear Facilities |last1=Fairlie |first1=Ian |date=June 2007 |publisher=Greenpeace |archive-url=https://web.archive.org/web/20120803195853/http://www.greenpeace.org/canada/Global/canada/report/2007/6/tritium-hazard-report-pollu.pdf |archive-date=3 August 2012 |url-status=dead}}</ref><ref>{{cite conference |url=https://arhiv.djs.si/proc/port2001/pdf/508.pdf |title=Overview of the Tritium-in-air Monitoring System of Cernadova NPP U1 Romania: Modernization and Improvement Project |last1=Murgoci |first1=S. |last2=Popescu |first2=I. |last3=Ibadula |first3=R. |date=10–13 September 2001 |conference=International Conference Nuclear Energy in Central Europe |location=Portorož, Slovenia |access-date=January 30, 2025}}</ref>

In general, there is significant public controversy about radioactive emissions from nuclear power plants, and for CANDU plants one of the main concerns is tritium. In 2007 [[Greenpeace]] published a critique of tritium emissions from Canadian nuclear power plants by [[Ian Fairlie]].<ref name="green"/> This report was criticized<ref>Dr. Richard Osborne, [http://www.nuclearfaq.ca/ReviewofGreenpeacereport_Final.pdf "Review of the Greenpeace report: 'Tritium Hazard Report: Pollution and Radiation Risk from Canadian Nuclear Facilities'"], Canadian Nuclear Association, 13 August 2007.</ref> by Richard Osborne.<ref>[http://www.cna.ca/english/pdf/Studies/BioDr-Richard_Osborne.pdf "Biography: Dr. Richard V. Osborne"] {{Webarchive|url=https://web.archive.org/web/20110706173702/http://www.cna.ca/english/pdf/studies/BioDr-Richard_Osborne.pdf |date=6 July 2011 }}, Canadian Nuclear Association.</ref>