There are no safe doses of radiation. Decades of research show clearly that the risk of harm increases with even small doses of radiation. Health risks include the risk of cancer, but also of other immune-related disorders, such as increasing allergies, asthma and even harmful effects on unborn children.
Radiation from nuclear materials is called “ionizing radiation”.
Ionizing radiation (radiation that can remove electrons from atoms/molecules) is powerful. In controlled amounts, it is used with care in medical diagnostics and therapies. Outside the medical arena, however, such radiation can be a deadly hazard to health. On acute exposure, ionizing radiation can cause “radiation sickness”, and lower exposures can have long-term detrimental health effects, including cancer.
Here’s an illustration showing non-ionizing and ionizing radiation in the context of radiation one is exposed to, day-to-day:
The radioactive elements (isotopes) present in nuclear waste emit ionizing radiation.
Over 200 radioactive isotopes are created in a nuclear reactor, and are present in nuclear fuel waste. Understanding how these radioactive materials behave involves two important factors: each isotope has a “half-life”, and each isotope “decays” into another radioactive isotope.
Half-life: in radioactivity, the half-life is the interval of time required for one-half of the atomic nuclei of a radioactive sample to decay (change spontaneously into other nuclear species by emitting particles and energy).
Decay: When a radionuclide decays, it transforms into a different atom – a decay product. The atoms keep transforming into new decay products until they reach a stable state and are no longer radioactive.
For example, one isotope present in nuclear fuel waste is water-soluble Cesium-137, which releases gamma radiation. If ingested, Cesium-137 travels to the internal organs – especially the reproductive organs. The elements in the waste that emit this radiation undergo “decay” over various periods, transforming into new elements. Cesium-137 has a half-life of 30 years, meaning that its radioactivity will wane considerably in the next 300 years.
Another example is Strontium-90, which has a similar half-life, and is known to move to the bones and soft tissue if it makes its way into the human body.
Other radioactive elements in used nuclear fuel waste, such as Plutonium-239, have half-lives of tens of thousands of years – some, hundreds of thousands. Plutonium-239 is one of the two fissile materials used for the production of nuclear weapons. If inhaled, even in microscopic quantities, Plutonium-239 can cause serious and even fatal damage to the lungs.
How dangerous is a CANDU nuclear fuel bundle?
The typical age of a used (irradiated) CANDU nuclear fuel bundle that would be shipped to a DGR by the NWMO is 40 years. Some bundles would be older, and possibly some would be newer.
Fuel bundles being transported would be contained in casks intended to shield people and the environment from most of the radiation, but we’ve been asked – what if such a cask were breached? How dangerous are the fuel bundles?
One hour a foot from a 40-year-old used CANDU fuel bundle can give you radiation sickness – possibly fatal
The radiation dose at 300mm (about one foot) from a 40-year-old irradiated CANDU fuel bundle is about one Sievert per hour. One Sievert is enough to cause radiation sickness – nausea, vomiting, hair loss, etc. Radiation sickness is a serious, often fatal medical condition.
Four hours a foot from a 40-year-old used CANDU fuel bundle will cause 50% of people to die painfully within 30 days
Four Sieverts (400 rems) of exposure will kill half of exposed people within the following 30 days, during which they will experience extreme radiation sickness.
For reference, the annual permissible dose (ref: CNSC, “Radiation Doses” webpage) for an atomic worker is 50 milliSieverts (0.05 Sieverts); that limit would be reached in 3 minutes at 300mm from a 40-year-old irradiated CANDU fuel bundle.
The average 5-year limit for an atomic worker is 20 milliSieverts per year; that annual limit would be reached in 72 seconds at a 300mm distance from the irradiated CANDU fuel bundle.
With info from this AECL report: https://www.osti.gov/etdeweb/servlets/purl/169800
– special attention to Figure 90.
How will residents of Northern Ontario be exposed to radiation by this project?
During the tens of thousands of shipments of radioactive waste, people along the route will be subject to “routine” levels of radiation. The doses are expected to be low, but there is no safe level of exposure to radiation. If a transportation accident caused releases from the containers, the levels of exposure could be very high.
At the project site, the wastes will be repackaged, resulting in additional “routine” exposures. Also, fans will bring air from the underground repository to the surface, and this air is expected also to include low levels of radiation.
To date, the NWMO has not provided communities under investigation with estimates of the level of exposure from these sources. In the longer term, if and when containers fail, it is expected that radioactive materials will eventually make their way to the surface. The timeline for these releases is uncertain, but the NWMO has no plans for very long-term monitoring and there are no known means of reversing the release of radioactive materials from a deep geological repository, if and when the release is detected.
Links to reliable sources for more information
Biological Effects of Ionization Radiation Report VII (commonly referred to as “BEIR VII”).
Related report: “Atomic Radiation is More Harmful to Women,” summarizing findings of the National Academy of Science’s landmark Biological Effects of Ionization Radiation Report VII, and was published by the Nuclear Information Resource Service in 2011. Very readable.
Radiation and Health page on Know Nuclear Waste website – contains a wealth of information and links to reliable data.
Medicine and Nuclear Power – a Sept. 2022 factsheet by Dr. Gordon Edwards of the Canadian Council for Nuclear Responsibility.