Radioactive emissions from TRIUMF can be categorized into several distinct types, with the largest component being “air activation products”: short-lived, gaseous substances created when neutrons produced by accelerated beams of particles inside the accelerator enclosures interact with ambient air. These are produced and exhausted by the ventilation system while accelerators are operating, and vanish via decay shortly after accelerators are switched off. All emissions are monitored continuously and are within regulatory limits.
Real time detectors (“air monitors”) sample the air flowing out of the exhaust stacks to measure the quantity released. Another detector, in the direction of our nearest neighbours, measures air activation. The amount of radiation measured at this location is consistent with the modeled quantity derived from stack emissions. The table below shows the results of both measurements and the model for the last five years, in units of microsieverts (µSv) – a unit of “dose” to measure the exposure to radiation. The last column (“Ratio”) suggests that the environmental transport model is conservative by about a factor of 3.
|Year||Measured Dose (µSv)||Modeled Dose (µSv)||Ratio|
Based on this data the dose to our nearest neighbor is 25 times less than the federal regulatory limit.
To place this into context, natural radiation is present at all times in all places. There are several different sources of natural background radiation, including radon from rocks, cosmic radiation from outer space, and radioactivity naturally occurring in food, such as milk (~0.2 µSv/litre) and bananas (~0.1 µSv/banana). In Vancouver, a typical resident receives 1300 µSv of natural radiation in one year.
The maximum amount of radiation that any member of the public receives in one year due to our operations is 1/500 of the amount they receive annually from nature, or approximately equivalent to eating 20 bananas or drinking 10 litres of milk.