Sunday, February 24, 2013

Small Nuclear Power and Nuclear Scalability

One of the myths which we have to contend with as we create the post carbon era is the myth that no single energy source will be so scalable as to be extremely helpful in solving the post carbon energy problem. The post carbon energy problem is the replacement of fossil fuels as energy sources with carbon free environmentally safe energy technology.

I first came across this myth in 2007 at a time when I was evaluating several advanced nuclear technologies that had potential for offering a major contribution in solving the global post carbon energy problem. I looked at the system being developed in India and noted that it was quite complex. Although the end product would be small reactors that would breed Thorium producing U-233 a very attractive reactor fuel. Along the way the Indian system sought to utilize liquid metal reactors in order to breed both Plutonium and U-233 also to be used in more nuclear power plants. I felt the Indian system was too complex and likely to have problems.

Another technology that attracted my attention was the Pebble Bed Reactor. The Pebble Bed Reactor was another Thorium breeding technology. It was first researched in Oak Ridge, TN  just after WWII. Later Pebble Bed prototype research was conducted in Germany. The Germans abandoned this technology in the wake of the Chernobyl nuclear accident, but South Africa and China continued to research it. Eventually South Africa also abandoned this technology, but China, as far as I know, continues their Pebble Bed Reactor research. In addition to the Pebble Bed Reactor and the two major reactor designs contemplated by the Indians, an Oak Ridge technology, the Molten Salt Reactor, attracted my interest.

By the late 1960s, Molten Salt research technology had reached the point at which commercial Molten Salt Reactors were feasible although their full usefulness was not apparent at the time. Government bureaucrats reviewed potential nuclear technologies and mistakenly came to the conclusion that two technologies, Liquid Sodium Fast Breeder Reactors and Pressurized Light Water Reactors, represented mature technologies while the Molten Salt Reactor did not. These conclusions were erroneous because the safety of light water reactors had not been properly attended to during the Nixon administration and a huge uproar pitting bureaucrats and scientists had taken place in Congress. The bureaucrats insisted that light water reactor technology of the early 70s was safe enough. The government scientists insisted that it was not. The Nixon administration had selected liquid metal breeder technology for a new generation of reactors, however, this choice turned out to be a major mistake because billions of dollars were spent on it during the 1970s and 80s without a single successful commercial prototype being built.
The Molten Salt Reactor which appeared very promising was not given an opportunity to demonstrate that it had unique capacities which would move the nuclear age forward.

We  have, at present, many useful nuclear technological ideas that could help with carbon technology replacement. The best of them would use advanced forms of nuclear power. Small reactors can be constructed in factories. By increasing the number of reactors manufactured in the factory, costs can be lowered. Small reactors can be housed in caves or mines or in underground silos that can protect reactors from aircraft and other forms of terrorism. Power reactors can be built at old coal fired steam plant sites thus replacing dirty coal with clean nuclear power. All of these would tend to lower the cost of nuclear generated electricity.

Factory produced small reactors can be build in large numbers over relatively short periods of time. By increasing the number of factory built small reactors, we lower the cost of individual units and thus decreasing the amount of time it would take to replace carbon technology in electrical generation with nuclear generated electricity. There are a significant number of different nuclear technologies that can be build in large numbers quickly. Since we lack evidence that would help us to determine which of them is the best, we ought to pick out several as most promising and move forward with them quickly.
China has given us an example of this. The Chinese have built a prototype of a small Pebble Bed Reactor and are spending several hundred million dollars a year to develop Molten Salt Reactors as well as Liquid Sodium Breeder Reactors.

Alvin Weinberg, the godfather of the Molten Salt Reactor, is largely ignored in the United States, but his reputation is growing in China and in the United Kingdom. I personally believe that Molten Salt Reactors represent the most scalable nuclear technology for the future and that it has the potential to provide many of our needs including the need to fulfill global electrical demand. Of course I do not have anything like conclusive evidence to back this up and therefore we need alternative technologies in case I am mistaken. Fortunately, as I have pointed out, many alternatives are available. We should not to putting all of our eggs in a single basket. Even if we have a single basket that has a high probability of success, we should still think about our fall back positions. People who say no one technology can solve our energy problems ought to come forward and show, rather than repeat energy myths, how technologies such Molten Salt Reactors and Liquid Sodium Reactors cannot solve energy problems.


donb said...

Of course, this myth is just that. What the myth-makers don't understand is the incredible energy density of nuclear materials. With what other energy source do we have enough fuel for more than a century's worth of our energy consumption just sitting in storage? We have exactly this with thorium byproduct from rare earth mining, depleted uranium, and used nuclear fuel. This incredibly dense fuel is not terribly rare. We know that enough uranium flows into the world's oceans from erosion to continuously power the whole world. Thorium is more than twice as abundant as uranium.

There are two 'baskets' of fuel, thorium and uranium, either of which is more than enough to power civilization for as long as we might be around. Both together give us many more options. There are many potential 'baskets' of reactors to use these fuels. The computer simulations have been done, and they show that these reactors will work. The greater danger going forward is not that some reactor might fail, but rather that we are failing to try these reactors.

Rasmus Kiehl said...

Rudolf Schulten, a central figure in nuclear energy in Germany from the 1960s through the 1980s, called the molten salt reactor "an abomination like no other" (interview, 1989). He considered it an important achievement that he was able to prevent any development work on the MSR in Germany. Instead, work proceeded on the pebble bed reactor.

Nathan2go said...

I'm not sure what Schulten disliked about the MSR, perhaps all of the highly radioactive fluid inside, and the resulting contamination of the containment room. The TRISO pebble fuel form does a good job of locking up the radio-isotopes, but only until one tries to recycle them.

The only way to make a breeder (a reactor which produces inexhaustible energy without needing uranium enrichment) without reprocessing is the traveling wave reactor, which is still theoretical, and possibly not cost competitive.


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