What is striking about the CANDU reactor design is that there are so many tubes. In the CANDU 6 reactor, you have 380 horizontal tubes that carry the fuel, the energy producer, and the problem with having tubes in a nuclear reactor is that neutrons are constantly bombarding every material. Neutrons can transmute elements, so the composition of the tubes is changing with time. All kinds of mechanisms occur on the atomic scale, leading to an unpredictable behaviour for these tubes, as is recognized by the nuclear industry and in particular is well-documented by the Canadian Nuclear Safety Commission, the CNSC.
These are two major weaknesses in the CANDU design. The fact that it has a positive void coefficient of nuclear reactivity—I assume that some of you have been reading Ontario newspapers where this has been discussed quite a bit over the last year—simply means that if a pipe breaks and water is missing, the reactor design is such that nuclear reactions are accelerated. So at the time when you're missing water to take away the heat produced by the nuclear reactions, the neutrons go dancing a little faster.
You can have a power pulse that goes up a factor of ten over its normal output in one second, and then the computer that's in control of the reactor will drive down these neutron-absorbing rods. But it will take another second for these rods to come down. So you have a power pulse that lasts for about two seconds. According to the CNSC--I highly recommend that those interested read this document, INFO-0790, published in June of this year by the CNSC, where everything I'm saying is detailed. In that two-second power pulse, enough energy can be deposited in the core to melt the uranium as well as the tubes holding it. The molten metal can enter the moderator, which is heavy water, and cause a steam explosion.
The CNSC advises us that physical containment, the one metre of reinforced concrete, will probably hold in the explosion. Good! I'm very willing to believe that. But as an investor, do I want a multi-billion dollar investment to depend on the bursting of a single tube out of 380 tubes? There are six kilometres of high-pressure tubing in CANDU reactors. The pressure is not small. It is 100 atmospheres, a pressure you find at a depth of one kilometre. Very few submarines can stand that depth of one kilometre in the ocean. Those tubes have to stand it every day, at a very high temperature besides.
This positive void coefficient of nuclear reactivity is not the only trouble, although it is the major trouble of the CANDU reactor, and it is well-recognized by the industry. I'll have you notice that my colleagues on my left promoting the nuclear power industry have failed to mention the problem of the positive void.
The top guy in the French nuclear establishment, Bernard Bigot, was interviewed recently in a French film that came out only about two weeks ago. He talked about public distrust of nuclear power, and he said that our whole business has to be based on trust. The top guy, Bernard Bigot, said that. I agree with him 100%. If you consult your dictionaries or history books, or any linguist, trust has to be based on transparency.
People who have the knowledge, like you people sitting on the left here, have to tell things the way they are. There was no mention on your part of this power pulse problem, a major problem, and it was published in a June 29 article in the Globe and Mail.
The second major weakness of these pressure tubes, as I mentioned before, is the constant neutron bombardment and the flow-assisted corrosion that thins out the tubes, making them weaker, and it can lead to bursting.
Have a look at my third slide. You have to have sympathy for the designers and operators of the CANDU nuclear reactors, because nuclear power is a very, very ticklish business. This whole thing is driven by a neutron cloud. There is nothing more complex in the world, as far as I know, than the neutron cloud in a nuclear reactor, and in particular in the CANDU reactor. It's still the object of much uncertainty, as is well-documented by the CNSC in this June 2009 document. These neutrons are moving around, and there are power excursions. The reactor is controlled by a computer program.
The Canadian nuclear industry only realized in 2000 that the old nuclear models were not accurate enough. New models were introduced, but not all companies are fully up-to-date with the new modelling of nuclear reactors, as is documented here. The point is that when you have something that complicated, it's very hard to control. The CNSC admits it's very hard to predict exactly what would happen if a pipe burst, except a lot of trouble.
The next slide shows some beautiful engineering, and I recognize it, but the trouble is with the thermal hydraulics--I happen to also work in the thermal sector; I work in several areas of physics and engineering. The trouble is that uranium generates a whole lot of power out of these 17 reactors in Ontario that power half the province. A hell of a lot of power is produced here, and it's carried away by water. If the temperature goes up and you start getting a fuel element meltdown, how is the water going to take away the heat, especially if there has been a pipe break? It's a very difficult problem. When you read the papers on that you realize the authors complain about the complexity of the problem.
A fundamentally vulnerable aspect of CANDU reactors stems from the possibility of a pressure tube rupture. It happened with the Pickering 2 reactor in August 1983. The tubes operate at high pressure, 100 atmospheres, 300 degrees Celsius, and, as I mentioned before, under intense neutron bombardment. The metals change and their behaviour becomes unpredictable.
The second point is the positive nuclear reactivity coefficient, about which Greenpeace has talked a lot. I talk here about the two-second power pulses I mentioned earlier. We'll skip to the next slide.
On significant events in Canada in 2008-09 regarding nuclear reactors designed by AECL, I find it interesting that I list about five significant events here and none of my colleagues on the left mentioned even one of them.
In April 2008, the CNSC did not approve the integrated safety review proposed by Ontario Power Generation, which has a lot of nuclear engineers who were found not to be up-to-date with the latest modelling of nuclear reactors. The weaknesses notably concerned the positive void coefficient.
In May 2008, AECL announced its abandonment of the MAPLE reactor development. What's even more serious is that it reveals to this very committee its inability to explain the unexpected behaviour of the coefficient of nuclear reactivity.
This positive coefficient of nuclear reactivity has been well known to AECL. They talked about it in their 2002 and 2003 annual reports. They proposed then that you could have a new uranium fuel with dysprosium that would take away this power pulse problem. Bruce Power of Kincardine believed that. They worked for years trying it out, but they announced to the CNSC in the spring of this year that they're discarding this avenue as non-functional. Instead they're going to have to try to lower the rods a little faster instead of taking a whole second.
In June 2009, the CNSC published this document that I highly recommend to you, especially appendix F. It's only four pages. In these four pages you will learn more about the core business of AECL reactors than if you heard a whole day of talks such as the ones you just gave. You give PR talks. You don't tell the truth.