Nuclear researchers knew long ago that reactor designs now in wide use had already been bested in safety by another design. Why did the industry turn its back on that design?
Imagine a nuclear reactor that runs on fuel that could power civilisation for millennia; cannot melt down; resists weapons proliferation; can be built on a relatively small parcel of land; and produces little hazardous waste. It sounds like a good idea, and it was a well-tested reality in 1970 when it was abandoned for the current crop of reactors that subject society to the kinds of catastrophes now on display in Japan.
This rather remarkable design is called the molten salt reactor (MSR), and it lost out for two reasons: 1) It wasn’t compatible with the U.S. government’s desire to have a civilian nuclear program that would have dual use, that is, that could supply the military with nuclear bomb-making materials. 2) Uranium-fuelled light water reactors, which are in wide use today, already had a large, expensive infrastructure supporting them back in 1970. To build MSRs would have required the entire industry to retool or at least create another expensive parallel infrastructure. And, that’s how MSRs became the victim of lock-in.
One familiar example will show how lock-in works. Anyone who types on a standard English keyboard may already know that the arrangement of the letters was designed to slow down typists so that the typebars–the things which strike the paper in a typewriter to make the letters–would not get jammed together. Other keyboards have since been designed to allow much faster, less error-prone typing, but few people have adopted them–even with the advent of computers which, of course, have no typebars to worry about.
Decisions made early on in the history of keyboard technology locked in a path for nearly all subsequent adopters. Everyone learned to use the so-called QWERTY keyboard, and so manufacturers only made this configuration, which then obliged all those new to typing to learn it, and so on. So strong was the lock-in for QWERTY that it’s been that way since the 1870s regardless of changes in typing technology.
Lock-in has worked in much the same way for the nuclear industry. The decision within U.S. government circles to focus on light water reactors and abandon MSRs relegated the latter to a footnote in the history of civilian nuclear power. And, because the United States was the leader in civilian nuclear technology at the time, every nation followed us. So, should the world look again at this “old” technology as a way forward for nuclear power after Fukushima?
My sympathies are with the MSR advocates. If the world had adopted MSR technology early on, there would have been no partial meltdown at Three Mile Island, no explosion at Chernobyl, and no meltdown and subsequent dispersion of radioactive byproducts into the air and water at Fukushima. It’s true that MSR technology is not foolproof. But its very design prevents known catastrophic problems from developing. The nuclear fuel is dissolved in molten salt which, counterintuitively, is the coolant. If the reactor overheats, a plug at the base melts away draining the molten salt into holding tanks that allow it to cool down. Only gravity is required, so power outages don’t matter.
As for leaks, a coolant leak (that is a water leak) in a light water reactor, can quickly become dangerous. If there is a leak from an MSR, the fuel, which is dissolved in the molten salt, leaks out with it, thereby withdrawing the source of the heat. You end up with a radioactive mess inside the containment building, but that’s about it.
If the world had adopted MSRs at the beginning of the development of civilian nuclear power, electricity production might now be dominated by them. And, we might be busily constructing wind generators and solar panels to replace the remaining coal- and natural gas-fired power plants. Would there have been accidents at MSRs? Certainly. Would these accidents have been large enough and scary enough to end new orders for nuclear power plants as happened after the 1979 Three Mile Island accident in the United States? I doubt it.
Having said all this, I believe that MSR technology will never be widely adopted. The same problem that derailed it early in the history of civilian nuclear power is still with us. We still have lock-in for light water reactors. Yes, the new designs are admittedly quite a bit safer. But these designs still don’t solve as many problems as MSRs do, and they continue to rely on uranium for their fuel. MSRs have shown themselves capable of running on thorium, a metal that is three times more abundant than uranium, and 400 times more abundant than the only isotope of uranium that can be used for fuel, U-235. This is the basis for the claim that MSRs fuelled with thorium could power civilisation for millennia.
Attempts have been made to run current uranium-fuelled reactors using thorium. But all the dangers remain because the reactors are still subject to catastrophic meltdowns. Only in the MSR, where the fuel is dissolved in molten salt, is this danger avoided altogether.
The Chinese have announced that they are interested in pursuing MSRs and the use of thorium to fuel them. Perhaps in China–where the nuclear industry is synonymous with the government and therefore does what the government tells it to–MSRs might actually be deployed. I have my doubts. Even China suffers from the lock-in problem. Back in the United States it is easier to predict that we’ll see little progress. In the U.S. it is the industry that tells the government what new nuclear technologies will be developed rather than the other way around. And, the American nuclear industry is committed to light water reactors.
I believe that even if the Fukushima accident had not occurred, nuclear power generation would probably have done no more than maintain its share of the total energy pie in the coming decades. Now, I am convinced that that share will shrink as people in democratic societies reject new nuclear plants. This could, in turn, free up funds to pursue energy sources that could serve us well and permanently. The cheapest is conservation. We desperately need to reduce our energy use significantly so that we can come into balance with the amount of power that renewable energy can realistically provide us. And, we need to build that renewable energy infrastructure, primarily wind and solar, while solving the problem of electricity storage that currently plagues it.
The nuclear future we were promised in the 1950s and 1960s never arrived. Fukushima tells us that it probably never will. We need to get on with the business of constructing an energy infrastructure that provides all of us a decent, healthy and dignified life while accepting the limits suggested by wisdom and ultimately imposed upon us by nature.