Dear Editor,
As many in our area are heading back to school, it’s occurred to me that many of my neighbours here in South Bruce are still unclear about some of the basics of the proposed Deep Geological Repository (DGR) for spent nuclear fuel. In the spirit of higher learning, I’d like to recap a few DGR basics, and share my informed opinion that the DGR design is extremely safe.
1. The primary reason for the DGR is to protect our water, especially
the Great Lakes, from any future exposure to nuclear waste. Most of the
waste is currently stored above ground, on the lakeshore. Nearly
everyone, including many opponents of the DGR, agree that moving it 40km inland and putting it 600m underground would make it much safer in the long term.
2. When fuel bundles come out of the reactor, they are lethally
radioactive, and give off a lot of heat. However, the radioactivity decreases logarithmically, which means really fast at first, and then slower later on. By the time fuel bundles go to the DGR, they will have been out of the reactor for at least 30 years, so they are producing a comparatively very low level of radiation and heat. After 200 years, you could safely hold one in your hands for a short period of time.
3. It’s pretty easy to shield people from radiation. I myself have stood over the spent fuel bay in Bruce A, looking into the crystal clear water at fresh fuel bundles, giving off their characteristic pretty purple glow. This was perfectly safe, and I didn’t even get enough radiation to show up on my ultra-sensitive thermo-luminescent dosimeter. Why? Because 10m of water is more than adequate to shield people from a very powerful radiation source. The nuclear industry is really good at shielding people from radiation. They’ve been doing it successfully here in Bruce County for over 50 years, and the methods and technology keeps getting better all the time.
4. The only real danger that old spent fuel would cause is if you eat it. That is, if it gets into your food or water. That’s what the DGR is designed to protect against. Since the waste lasts for a very long time (millennia), the DGR has layer upon layer of barriers to keep the waste from ever getting into any water, or reaching the surface.
5. First off, the waste is NOT liquid, and it is NOT water-soluble.
Spent fuel is hard ceramic pellets, encased inside a special metal alloy (zirconium), that resists any sort of corrosion.
The fuel bundles are placed inside heavy steel cylindrical containers, so strong they can resist the pressure of the next ice age. (They’ve actually tested them, with a pressure equal to the weight of 3km-deep ice). The containers are coated with copper, so they will never rust.
6. As if that’s not enough, the containers will be encased in bentonite clay, to prevent any water from ever hitting them. When bentonite clay gets wet, it expands to form an impermeable, waterproof barrier.
Finally, the placement rooms are built 600m underground, inside a layer of extremely dense bedrock that’s been there for 500 million years, give or take.
7. All of this is confirmed by robust engineering and computer modelling. For example, the engineers have ensured that any bit of residual heat being produced will safely dissipate into the surrounding bedrock, without causing any damage to the containers or the surrounding rock.
8. But what if the scientists were wrong? What if someone made a mistake, and one of the barriers fails? Well, just to be safe, the scientists have considered the wildest possible future scenarios, and produced “what if” scenarios.
For example, assume every barrier fails, and for some unfathomable reason the clay is gone, the containers break, the zirconium alloy corrodes, the whole thing gets flooded with water, and the fuel pellets are just sitting down there, 600m underground.
Then assume there’s a person living directly above the site that drills a well, (remember wells and ground water only go down 30m or so), and he grows all his own food right on the site. The scientists have modeled how much radiation that hypothetical person would get each year, and it’s about equivalent to eating 2 bananas. (Yes, all bananas are mildly radioactive, due to high potassium levels).
So, you may be for or against the DGR, for any number of reasons, but if you’re concerned about radiation, my suggestion is to consider the above, and worry about something else.
Tony Zettel,
Mildmay
