Science - Sealed, Delivered.

Tritium in the Environment

Fri Jan 30 2009

Not sure if this of particular interest to anyone other than myself, but it’s been in the news quite a bit these days:

MP raps Tories over leak at Chalk River nuclear plant

A spokesman for Atomic Energy of Canada Ltd., Dale Coffin, said that on Dec. 5 a seal failed in the reactor and about 50 litres of heavy water spilled and was contained in stainless steel barrels of water.

Coffin said four litres evaporated up the stack, carrying what he called a minute amount of radioactive tritium. He said the amount was less than what AECL is required to report..

A few years ago I was actually hired on contract by a small Ottawa company to adapt some software and then subsequently setup an analysis of potential environmental impacts of Tritium in the environment. Though the approach I devised is generally applicable, the particular interest for this project was an analysis of the Chalk River NRU my client was conducting for yet another client (the wonderful world of consulting!). Tritium (which is simply a heavy isotope of Hydrogen) is a tricky thing, because it associates readily with oxygen to form tritiated water. So tracking releases in a model can be quite difficult when compared to more typical isotopes, and requires specialized models, with consideration of several ‘compartments’, including at least soil, water and air.

Tritium is usually released in tiny amounts, and is primarily a beta emittter. This is relatively good news, as beta particles usually have a hard time penetrating thicknesses comparable to skin. The chemistry side of things bears both good news and bad: while tritium, being chemically identical to hydrogen, is not toxic chemically (unlike many other radioisotopes), it is comparably mobile and can be ingested by inhalation or food or even potentially skin pathways.

Tritium releases have an interesting history. Tritium is often used for lighting-type applications, and there was a notable release many years back during an airfield fire when one shack full of runway lights was destroyed. Tritium also caused considerable concern in the aftermath of 9/11 as responders, still unsure what they were dealing with, scoured the area and detected beta emissions emanating from ground zero. The source of these emissions was ultimately traced to the substantial concentration of destroyed equipment (e.g. scopes, watches) of first responders who perished during the attack.

It’ll be interesting to see how this progresses.

Update: The Daily Observer posted an extended story, with substantially more details and viewpoints, today