Much ado about scripting, Linux & Eclipse: card subject to change


Reacting Badly

I live not far from Pickering Nuclear -- in fact, about 5 blocks from where the nuclear fallout from an explosion would apparently reach. Yes, the cloud is supposed to stop at Morningside Ave. Riiight. Luckily, the reactors which had a bad rep in the 90s were cleaned up and are back in service, though Greenpeace has its doubts.

Anyway, with the summer in full swing and my A/C working hard to keep my house habitable, I'm reminded of the past few years of outages, brownouts, and full-blown blackouts we've had here over the years. This morning I did a little reading into where things are at in the world of nuclear energy, and I have to say I'm disappointed.

Back in the 40s, the West led fission technology and it unfortunately led to a rather effective (if deadly) end of WWII. There's been much speculation about the reasons Germany never built the bomb before the US did, but I digress. Since then, we've enjoyed nuclear energy in a number of forms, but they've all mostly been water-cooled systems which are now, in retrospect, highly inefficient and expensive. In Canada, we're pretty much stuck with CANDU-style reactors because they're of a Canadian design, and at least are safer than the infamous design used at Chernobyl. I'm all for 'support locally-developed tech' but when there's the potential for a better, cheaper, and safer solution, it's time to look past our own backyard and toward what the neighbours are doing. (Why can't the AECL license the new tech? They'll happily build CANDU 6 reactors for other countries -- why not these new ones?) In the world of nuclear energy, we're not keeping up with the Joneses.

So what's the alternative? Well, there are several, but there's one that I've been tracking for a while now, since I was clued into it via this WIRED article, "Let a Thousand Reactors Bloom". China is moving along nicely in their plan to surpass Canada with their use and consumption of nuclear energy, but they're not doing it with the old, expensive designs. They're pioneering a new design, developed in South America by PBMR, which instead of fuel rods and water cooling, uses graphite-covered uranium "pebbles" and some inert gas (eg., helium).

The design of the of PBMR fuel makes it easy to store the spent fuel, because the silicon carbide coating on the fuel spheres will keep the radioactive decay particles isolated for approximately a million years, which is longer that the activity even of plutonium. [T]he PBMR fuel can be stored on site for at least 80 years, [and] has a greater "burn-up" [...] which makes it less valuable to recycle. [...] The spent coated particle fuel can be disposed of in a deep under-ground repository. (Coated particle fuel will maintain its integrity for up to ~ 1 million years in a repository, ensuring that spent fuel radionuclides are contained for extremely long periods of time. The plutonium will have decayed away completely in 250 000 years).

The PBMR is walk-away safe. [T]he reactor will cool down naturally on its own in a very short time. This is because the increase in temperature makes the chain reaction less efficient and it therefore ceases to generate power. The size of the core is such that it has a high surface area to volume ratio. This means that the heat it loses through its surface (via the same process that allows a standing cup of tea to cool down) is more than the heat generated by the decay fission products in the core. Hence the reactor can never (due to its thermal inertia) reach the temperature at which a meltdown would occur. The plant can never be hot enough for long enough to cause damage to the fuel.

Radiation Leakage
The helium itself, which is used to cool the reaction, is chemically and radiologically inert: it cannot combine with other chemicals, it is non-combustible, and non-radioactive. Because oxygen cannot penetrate the helium, oxygen in the air cannot get into the high temperature core to corrode the graphite used in the reaction or to start a fire. If, through some accident, the helium gas duct (inlet and outlet lines) is ruptured, it would take some nine hours for natural air to circulate through the core. Even if this could happen, it would only lead to less than 10-6 (one millionth) of the radioactivity in the core being released per day. That means that the amount of activity released in 24 hours under this very severe (and recoverable) situation would be some 10 000 times less than that requiring any off-site emergency actions. To avoid such a total failure of the main gas ducting it is designed to leak before it breaks, so that the depressurisation will be gradual and cannot lead to such a rupture. The helium pressure inside the closed cycle gas turbine is higher than the air pressure outside it, so nothing can get inside the nuclear circuit to contaminate it. [1]

As of 2004, China has one of these reactors in use, with another planned for 2010 and at least 30 more old-school water-cooled reactors coming online in the next 15 years. It seems they want to do more research on the new tech before leaping forward with it [2], but if all goes well the plan is to "spread this technology both at home and to the whole world" [3].

Meanwhile, back in North America... nothing much is happening. Well, that's not entirely true. A couple CANDUs in Ontario are being fixed up for re-use [4]. There's talk of building new CANDUs in Alberta to support the oil industry there. The US is watching what China is doing and predicting the world's nuclear outlook, suggesting China will be among the top five nuclear countries by 2025 (along with the US, France, Japan, and South Korea). Oddly, Canada, Germany, and Russia are predicted to decline in nuclear output. I wonder why, considering the AECL is developing a new CANDU design, the ACR-1000 for service by 2016. Maybe we'll be switching to wind and solar? Yeah, right.