(June 21, 2007) All nuclear reactors emit tritium, a radioactive form of hydrogen that is created in nuclear reactors. Like all radioactive substances, tritium causes cancer and birth defects. Ontario's Candu nuclear reactors emit much higher levels of tritium into the air and water than other reactor types. Greenpeace Canada released a report on the hazards of tritium releases, and recommends that pregnant women and children under the age of four should not live within 10 kilometers of a Candu reactor.
(657.5808) WISE Amsterdam - Radioactive tritium is being released into the environment at the highest rates in the world by Canada's nuclear reactors - at rates 10 times higher than those allowed in the United States and 100 times higher than the level allowed in Europe. A report released by Greenpeace Canada ("Tritium Hazard Report: Pollution and Radiation Risk from Canadian Nuclear Facilities") recommends that pregnant women and children under the age of four should not live within 10 kilometers of a Candu nuclear reactor in light of the latest scientific concerns about this particular nuclear waste.
Greenpeace believes that the risk posed by tritium has been underestimated by the Canadian government, and are calling for a review of the latest scientific evidence on the harmful effects of tritium: "We are not alone in asking questions about tritium. In 2006 the City of Toronto Medical Officer of Health called on the Ontario government to review the health implications of allowing such high levels of tritium in drinking water. And back in 1994, Ontario's Advisory Committee on Environmental Standards (ACES) recommended that allowable tritium levels be drastically reduced. The government rejected this request and sided with Ontario Hydro, which claimed it would cost Can$1 billion (US$735 million or 549 million Euro) to reduce tritium by the amount requested.
The Canadian government currently allows radiation levels of up to 7000 Bequerels, or Bq per liters of water (a measure of radiation). The 1994 ACES report recommended that allowable levels be reduced immediately to 100Bq per liters and down to 20Bq/l by the end of the nineties.
With the province of Ontario set to build and refurbish Can$46 billion worth of nuclear reactors over the next few years, it is essential that the government set safety levels for nuclear waste that are truly safe.
"By European protection standards, tritium emissions from Ontario's nuclear reactors would be considered hazardous and unacceptable" said Dr. Fairlie, an independent consultant on radiation who authored the report. "Recent scientific evidence shows tritium to be more hazardous than previously thought. Ontario should adopt a precautionary approach and act to reduce public exposures to tritium." Dr. Fairlie has degrees in chemistry and radiation biology and completed his doctoral studies at the Imperial College in London, England. He has worked with the World Health Organization, the European Parliament, and acted as advisor to several United Kingdom regulatory agencies and committees.
The June 2007 Greenpeace Canada report concludes that official attitudes on tritium are unscientific and incorrect, that tritium's hazardous nature should be fully acknowledged by radiation protection agencies in Canada, and that tritium's dose coefficient should be increased substantially.
This report on tritium releases in Canada is in two parts. Part 1 discusses tritium discharges from nuclear facilities in Canada and compares them with those from reactors in other countries. It examines the resulting tritium concentrations in drinking water, air and in food near Canadian nuclear stations. Although tritium releases from Candu facilities are very large, radiation protection regulators continue to maintain that these releases are of little concern because tritium's radiation doses and its resulting hazards are small.
Part 2 examines these contentions in considerable detail. It shows that tritium's radiation "doses" are, questionably, estimated to be several hundreds of times lower than most other radioactive elements. Radiation and radioactivity (including risks, doses, biology and epidemiology) are complex matters which are often difficult to grasp.
Therefore Part 2 is designed to be read primarily by health physicists and radiation protection scientists. However, efforts have been made to make this report more accessible to the wider public. In particular, technical terms have been explained and scientific jargon has been avoided. The report concludes that official attitudes on tritium are unscientific and incorrect, that tritium's hazardous nature should be fully acknowledged by radiation protection agencies in Canada, and that tritium's dose coefficient should be increased substantially.
Source: the report: Tritium Hazard Report: Pollution and Radiation Risk from Canadian Nuclear Facilities, released by Greenpeace Canada on 12 June 2007 can be found at:http://www.greenpeace.org/canada/en/documents-and-links/publications/tritium-hazard-report-polluContact: Greenpeace Canada, 250 Dundas St. W, Suite 605, Toronto, Ontario M5T 2Z5 Canada.
Most of the tritium is released into the air as steam (radioactive water vapour) and also as liquid (radioactive water). Although there is tritium in the irradiated fuel, the bulk of the tritium that is released from CANDU reactors comes from the use of heavy water moderator. CANDU means CANadian Deuterium Uranium reactor.
Water is H2O - two hydrogen atoms and one oxygen. Heavy water is D2O - two heavy hydrogen and 1 oxygen.
Heavy hydrogen is just like ordinary hydrogen but twice as heavy. The nucleus of an ordinary hydrogen atom is a single proton. (It is orbitted by a single electron.) But the nucleus of a heavy hydrogen atom (called "deuterium") has a proton and a neutron, so it's twice as heavy.
Now deuterium is not radioactive, but if another neutron is added to the nucleus we get tritium, or super-heavy hydrogen, which is 3 times as heavy as normal hydrogen and is radioactive with a half-life of 13 years. Thus D2O turns into DTO also called "tritiated water". That's one atom of deuterium, one atom of tritium, and one atom of oxygen, all compounded into a molecule of tritiated water.
Because the moderator of a CANDU reactor is being bombarded with trillions of neutrons all the time, the heavy water gradually becomes more and more tritiated. Because tritiated water is chemically almost identical to ordinary water, it cannot be separated from non-radioactive water or steam and so gets released to the environment.
Tabel: Tritium (HTO) releases (gaseous + liquid) from various reactor types (TBq/a) per GW year of electricity produced)
Heavy water reactors like CANDU release tremendously more tritium into the environment than any other reactor type, and the releases generally get worse year by year because the moderator gradually becomes more and more tritiated as time goes by.
Because of the enormous amounts tritium is generally seen as one of the (many) problems of nuclear fusion. Tritium is also used in nuclear weapons, so it's proliferation prone.