Editing Tritium (section)

== Environmental contamination ==
{{Globalize||United States|date=January 2022}}
Tritium has leaked from 48 of 65 nuclear sites in the US. In one case, leaking water contained {{convert|7.5|μCi}} of tritium per liter, which is 375 times the current EPA limit for drinking water, and 28 times the [[World Health Organization]]'s recommended limit.<ref>[https://www.nbcnews.com/id/wbna43475479 Radioactive tritium leaks found at 48 US nuke sites]. NBC News (21 June 2011). Retrieved on 16 October 2014.</ref> This is equivalent to {{convert|0.777|ng/L}} or roughly 0.8 [[parts per trillion]].

The US [[Nuclear Regulatory Commission]] states that in normal operation in 2003, 56 [[pressurized water reactor]]s released {{convert|40600|Ci}} of tritium (maximum: {{convert|2,080|Ci|abbr=on}}; minimum: {{convert|0.1|Ci|abbr=on}}; average: {{Convert|725|Ci|abbr=on}}) and 24 [[boiling water reactor]]s released {{convert|665|Ci|TBq|abbr=on}} (maximum: {{convert|174|Ci|abbr=on}}; minimum: 0&nbsp;Ci; average: {{convert|27.7|Ci|abbr=on}}), in liquid effluents.<ref>[https://www.nrc.gov/reactors/operating/ops-experience/tritium/faqs.html#normal NRC: Frequently Asked Questions About Liquid Radioactive Releases] "What are normal amounts of tritium released from nuclear power plants?"</ref> {{convert|40600|Ci|abbr=on}} of tritium weigh about {{convert|4.207|g}}.


=== Regulatory limits ===
The legal limits for tritium in [[drinking water]] vary widely from country to country. Some figures are given below:
: {| class="wikitable"
|+ Tritium drinking water limits by country<ref>
 {{cite web
 |url=http://nuclearsafety.gc.ca/eng/resources/health/tritium/tritium-in-drinking-water.cfm
 |title=Tritium in drinking water
 |publisher=[[Canadian Nuclear Safety Commission]]
 |date=3 February 2014
 |access-date=23 February 2017
 }}
</ref>
!valign="bottom"| Country
!valign="bottom"| Tritium limit<br/>(Bq/L)
!valign="bottom"| Equivalent dose<br />([[microsievert|μSv]]/year){{efn|Based on ICRP Report 30 calculation: {{val|1.8e-11|u=Sv/Bq}}, {{val|730|u=L/year}}, {{val|1e6|u=μSv/Sv}}; quoted in <ref>{{cite web |title=Standards and Guidelines for Tritium in Drinking Water (INFO-0766) |url=https://nuclearsafety.gc.ca/eng/resources/health/tritium/standards-and-guidelines-for-tritium-in-drinking-water.cfm |website=Canadian Nuclear Safety Commission |language=en |date=3 February 2014}}</ref> }}
|-
| Australia
|align="right"| 76,103{{efn|This figure is derived from the guideline dose of 1&nbsp;mSv per year from all sources of radiation in drinking water in The Australian Drinking Water Guidelines 6, assuming that tritium is the only radionuclide present in the water.<ref name="The Australian Drinking Water Guidelines 6">
 {{cite web
 |date=March 2015
 |title=Australian Drinking Water Guidelines 6
 |page=98  |language=en
 |publisher= National Health and Medical Research Council, National Resource Management Ministerial Council, Commonwealth of Australia, Canberra
 |url=https://www.nhmrc.gov.au/file/16934/download?token=gAKh3uQk
 }}</ref>}}
|1,000
|-
| Japan
|align="right"| 60,000
|{{#expr:60000 * 1.8 / 1e11 * 730 * 1e6 round 2}}
|-
| Finland
|align="right"| 30,000
|{{#expr:30000 * 1.8 / 1e11 * 730 * 1e6 round 2}}
|-
| World Health Organization
|align="right"| 10,000
|{{#expr:10000 * 1.8 / 1e11 * 730 * 1e6 round 2}}
|-
| Switzerland
|align="right"| 10,000
|{{#expr:10000 * 1.8 / 1e11 * 730 * 1e6 round 2}}
|-
| Russia
|align="right"| 7,700
|{{#expr:7700 * 1.8 / 1e11 * 730 * 1e6 round 2}}
|-
| Canada (Ontario)
|align="right"| 7,000
|{{#expr:7000 * 1.8 / 1e11 * 730 * 1e6 round 2}}
|-
| United States
|align="right"| 740
|{{#expr:740 * 1.8 / 1e11 * 730 * 1e6 round 2}}
|-
| Norway
|align="right"| 100<ref>
 {{cite web  |url=https://lovdata.no/dokument/SF/forskrift/2015-07-03-870
 |title=Forskrift om visse forurensende stoffer i næringsmidler
 |language=no
 |publisher=[[Lovdata]]
 |date=10 July 2015
 |access-date=7 January 2023
 }}</ref>
|{{#expr:100 * 1.8 / 1e11 * 730 * 1e6 round 2}}
|-
|}
The American limit results in a dose of 4.0&nbsp;[[Roentgen equivalent man|millirem]]s (or 40&nbsp;micro[[sievert]]s in [[SI units]]) per year per EPA regulation 40CFR141, and is based on outdated dose calculation standards of National Bureau of Standards Handbook 69 circa 1963. Four millirem per year is about 1.3% of the natural background radiation (~3&nbsp;mSv). For comparison, the [[banana equivalent dose]] (BED) is set at 0.1&nbsp;μSv, so the statutory limit in the US is set at 400 BED. Updated dose calculation standards based on International Commission on Radiological Protection Report 30 and used in the NRC Regulation 10CFR20 results in a dose of 0.9&nbsp;millirem (9&nbsp;μSv) per year at 740&nbsp;Bq/L (20&nbsp;nCi/L).<ref name=US-NRC-Trit-Bkg>
{{cite report
 | title = Backgrounder on Tritium, Radiation Protection Limits, and Drinking Water Standards
 | date = 15 March 2011
 | publisher = U.S. [[Nuclear Regulatory Commission]]
 | url = https://www.nrc.gov/reading-rm/doc-collections/fact-sheets/tritium-radiation-fs.html
 | access-date = 10 February 2012
}}
</ref>