nuclear waste management

This comes to mind every time I hear debate about nuclear and toxic waste disposal. The general public is uninformed and politicians are lax to go near such a nasty issue.

There are currently forty thousand tons of used nuclear fuel sitting in shielding pools and concrete canisters in Canada (20 million rods weighing 20 kilos each). It is still emitting heat and dangerous radiation. While it is possible to reprocess this material by enrichment and reuse it in reactors, it is not currently cost effective to do so (and we’d still have waste in the end anyway). We have an obligation to make this material safe for future generations, and the safest way to do this is through Deep Geological Disposal. This involves finding a highly stable location underground with no interaction with groundwater systems. Batholiths (large bodies of magma that cooled deep in the crust) are the ideal setting, since they often have negligible porosity or permeability, and are inherently very tough rock.

The estimated cost of burying Canada’s nuclear waste in batholiths in the shield is between 9 and 13 billion dollars over the next century, for the waste currently awaiting disposal and the waste that will likely be generated in future.

We have in this country the most attractive setting imaginable for toxic and nuclear waste disposal. The Canadian Shield, centred around the Hudson Bay, is a thick volume of buoyant (relative to the mantle) crystalline (igneous and metamorphic, i.e. tough) old crustal rock, rife with batholiths.

It is well understood how to sequester material in deep facilities. You line the walls with sheet metal, then concrete, then bentonite or another clay to ensure an impermeable boundary even in the unlikely event that one of the rare but powerful intra-cratonic earthquakes causes a shift or breach in the facility.

It would be an expensive but relatively simple matter to tunnel a kilometre down into a huge intrusive, build a large containment facility, and stuff our waste down there, at the aforementioned cost. But why stop there? We could drastically offset that cost, and even profit from the endeavour, if we were to dispose of the waste from other countries in our stable shield rocks as well. If we charged the US and Mexico to dispose of their wastes we would soon cover the construction of the storage facilities and then begin earning a profit. There’s also the added benefits of our much more stable rock being used for North American waste disposal, reducing the risk of environmental damage across the continent.

There is controversy in the US regarding Yucca Mountain, their Department of Energy’s favoured disposal site. While the geology may be sound, there is little doubt in my mind that deep storage in shield rocks is inherently safer over the extreme long term. We don’t have to gauge the US over waste storage; they would be responsible for transportation, but if we charged, say, $350,000 CAD a ton, we would cover the expense of burying our own waste when we buried about the same amount of theirs.

It’s not a matter of raking in cash, in my mind it’s a matter of human safety over the next few thousand years. Toxic waste management should be borderless, not an “us or them” issue, as in “why should we deal with the US’s waste?”, since the answer is “because we have the more stable rock”.

I don’t think that the concept of safety over the next million years is particularly relevant. If humans are still around even in a thousand years, it would be surprising; we’re getting very good at developing ways of killing ourselves, or we will have raped the planet and escaped to somewhere else. If we are around, think of the technologies we’d have for dealing with the material. The only case I can envision in which safety for ten thousand years is important is if there’s some apocalypse and we’re thrown back to the stone age, with no knowledge of the waste’s existence or dangers.

I would suggest that we take the whole world’s waste, but I think the environmental risk associated with shipping millions of tons of nuclear waste across the ocean is unacceptable. Each continent has one or more ancient cratons, so to avoid trans-oceanic shipping humanity should probably just construct similar sites in stable cratonic rocks on each continent.

http://www.nwmo.ca/Default.aspx?DN=1487,20,1,Documents
http://www.nuclearfaq.ca/cnf_sectionE.htm
http://en.wikipedia.org/wiki/Craton
http://en.wikipedia.org/wiki/List_of_Platforms%2C_Shields_and_Cratons