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The Canadian Nuclear FAQ  

by Dr. Jeremy Whitlock

www.nuclearfaq.ca

The following letter is in response to a story carried by several newspapers, including The Ottawa Citizen, during the final week of May, 1997. The story, by science writer Tom Spears, discusses an historic radioactive leak from a fuel-storage bay at Chalk River Laboratories' (now decommissioned) NRX reactor, monitored continuously by AECL and reported regularly in public documents to the government regulator, the Canadian Nuclear Safety Commission (CNSC). The leak contains small amounts of radioactive contaminants, but the amount released to the Ottawa River nearby is much less than 1% of the drinking water health standard. This is simply due to dilution, which in this case is equivalent to adding about 10 microlitres (1/100 of one mL) of radioactive (tritiated) water to 6 trillion litres of river water, on a monthly basis. That's a dilution factor of over 1017.

As the following letter indicates, published in the June 4, 1997 edition of The Ottawa Citizen, the effect on the environment is insignificant, and much less than the natural radioactivity of the river itself. Specifically, in that same monthly flow of "6 trillion litres" of the Ottawa River mentioned above, there can also be found about half a mL of tritiated water (50 times the Chalk River amount quoted above), from background sources alone.
May 29, 1997

The Ottawa Citizen
1101 Baxter Rd.
Box 5020, Ottawa, Ont.
K2C 3M4
email: letters@thecitizen.southam.ca

To the Editor:

In your article "Chalk River's Dirty Secret" (front page, May 28), several citizens of the Pembroke area express doubt as to whether the Ottawa River could dilute the historic radioactive leak from Chalk River's NRX fuel storage bay. I thought I would do a quick calculation that might aid their deliberations on this issue: The article states that in 1994, 4000 litres per day leaked from the fuel bay, with a contained radioactivity of 18 billion Becquerels per day. Let's assume that the entire 4000 litres per day made it into the river without retention in the soil, natural decay over time, etc. The flow of the Ottawa River past Pembroke is roughly 200 billion litres per day, which would therefore have diluted the radioactivity of the Chalk River water to 1/10 of a Becquerel per litre - an unmeasurably small quantity, and much less than the drinking water quality standard.

In contrast, the natural radioactivity of the Ottawa River is something like 5 Becquerels per litre, 50 times the activity of the diluted Chalk River water. Furthermore, there are 50 Becquerels in every litre of milk, and 40 Becquerels in every case of beer - both of which are openly available in Pembroke. These are all utterly small amounts of radiation which can be made to sound important simply because the unit of measurement, the Becquerel, is minuscule. It is analogous to quoting the speed of your car in inches per hour, rather than miles per hour.

Here is another way to look at it: approximately one trillion Becquerels of radioactivity flow past Pembroke on a daily basis, from all natural sources combined, which the Chalk River leak increased by about 2% (by my calculations, with the above conservative assumptions made). Dilution is clearly an effective and widely-used strategy for dealing with moderate amounts of pollution: Pembroke citizens employ this strategy every time they flush their toilets, drive their cars, or exhale a breath of air.

Radiation demands respect, but more importantly, it demands common sense. I urge the concerned citizens of the Pembroke area to visit Chalk River Laboratories and learn more about the natural and man-made sources of radiation around them. In particular, the measurements of radioactivity in the Ottawa River, above and below Chalk River Laboratories, have been available for years in public reports.

Jeremy Whitlock

Responses to the Ottawa Citizen:

Dave Taylor (Concerned Citizens of Manitoba), June 9/97

Kelly O'Grady (Concerned Citizens of Renfrew County), June 9/97

Norman Rubin (Energy Probe), June 9/97

My response to the above three letters:

Jeremy Whitlock, June 16/97

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