Thorium Power – Working Since 1992 To Develop An Improved Fuel For Light Water Reactors

In the Sunday news magazine section of The Washington Post dated August 2, 2009 (it is still funny the way that magazines are often post dated) there is a lengthy and detail rich article about Thorium Power’s leader, Seth Grae, and his epic journey towards introducing an improved fuel design based on the unique characteristics of thorium for existing and future light water cooled nuclear power plants. The article, written by Leslie Allen, is titled If Nuclear Power Has a More Promising Future … Seth Grae Wants to Be the One Leading the Charge.

The article begins in a setting familiar to me – one in which a group of people excited about a great idea try to explain to investors why they should care, why the idea is better than those of others who are asking for money, and how the investors will eventually get their money back – with a substantial return on investment. Not surprisingly, this particular investor pitch ended with some skeptical head shaking, even though the people from Thorium Power had been able to deftly answer almost every question posed. One investor in particular has a reaction that I have experienced on a number of occasions while trying to pitch Adams Atomic Engines, Inc.:

One banker says flatly that many investors believe nuclear power, any nuclear power, is an “outdated technology.”

Thorium Power grew out of the work of Alvin Radkowsky, a man who made a huge impact on the world, even though few people have ever heard of him. He was Admiral Rickover’s primary nuclear reactor designer for many decades and oversaw the initial designs for the reactors for nuclear submarines, aircraft carriers, cruisers, and even the land based Shippingport reactor that became the basis for commercial light water reactors. Towards the end of his time with the Naval Reactors program, Radkowsky had the opportunity to develop an idea that he had been working on since studying under Edward Teller. He had determined that thorium had properties that could prove useful for future reactors and had invented ways to prove it.

The vehicle for pursuing thorium fuel designs was a program initiated by a December 1965 Atomic Energy Commission decision to pursue reactor designs that would result in breeding fissile material from fertile material in a light water reactor. In a phased research, development and testing program, Radkowsky and his team worked their way to a demonstration of a uranium-233/thorium-232 core that began operating in the Shippingport reactor in August 1977 and continued operating without refueling until October 1982. During that five year period, the Light Water Breeder Reactor achieved an average capacity factor of 62% (slightly lower than most light water reactors in that time period due to periodic shutdowns for sample testing of the fuel). It could have kept going, but the General Accounting Office (GAO) thought it would be a better use of taxpayer dollars to stop the test run and evaluate the results before the people knowledgeable about the program retired or died off.

Unfortunately for Radkowsky and for Seth Grae, who is still in the business of explaining why thorium has such high potential as an improved light water reactor fuel, it took another five years of painstaking testing of the fuel removed from Shippingport to determine that it contained approximately 3-5% MORE fissile material after that five year run than it did when the fuel was freshly loaded into the core. That might not sound so impressive, but just think about the implications of a material that can slowly and steadily be converted from something that does not readily fission into something that does and then into heat to keep a steam plant generating electricity. Then think about the implications of the fact that the fuel can be configured to work inside existing and near future nuclear power plants.

That is what drove Radkowsky to work on improvements and to infect Seth Grae and his family with excitement about the prospects for the technology. Unfortunately, Radkowsky died in 2002 and Grae is still running into resistance from skeptics in the investment community, at licensing agencies, and at nuclear power plant operating companies. Thorium based fuel does not fit comfortably into the current infrastructure of uranium enrichment, fabrication and installation that keeps operating reactors supplied with reliable heat.

As Radkowsky and his team found when they built the last core of the Shippingport reactor, achieving a configuration that produces a fertile to fissile conversion ratio greater than 1.0 in a light water reactor is a bit tricky. It requires a number of different isotope concentrations in carefully positioned fuel assemblies, and it requires fuel assemblies that can be moved during power operation to eliminate the need for neutron poisons in the form of control rods or dissolved boron. Much of the core that achieved a conversion ratio greater than 1.0 in the period from 1977-1982 required essentially hand labor that was not suitable for the mass production techniques available in the mid 1970s. Of course, computer controlled manufacturing has progressed rather significantly in the 35 years since those elements were assembled.

From my point of view, thorium fuel for light water reactors is also disadvantaged by the fact that it is a good solution to a minor problem. It is touted as a way to produce fuel that is resistant to diversion for clandestine nuclear weapons programs, but that is true of current fuel designs where there has NEVER been a case of diverting commercial nuclear fuel to use it as the raw material for weapons. Thorium fuel does provide the breeding potential mentioned above and offers the opportunity for long residence times between refueling events, but fuel is currently a minor component of the overall cost of owning and operating a large nuclear power plant. According to the Nuclear Energy Institute, the average cost of fuel for an American commercial nuclear power plant is less than 0.5 cents per kilowatt hour. Most of the cost is associated with non-fuel operations and maintenance (20%) and paying back the initial capital cost of the plant (70%).

Not surprisingly, my friend from Energy from Thorium, Kirk Sorensen, had added a comment on Leslie Allen’s article about Seth Grae and Thorium Power suggesting that using thorium in a solid fuel for light water reactors is probably not the best way to make use of its unique physical properties. As many of you know, Kirk is a strong advocate for using thorium dissolved in molten salts to overcome some of the challenges faced by Radkowsky. The molten core thorium-based reactors first developed at Oak Ridge as part of the Aircraft Nuclear Propulsion program do not need the same kind of careful placement and hand manufacturing as solid cores do in order to achieve breeding in a thermal spectrum light water reactor. Molten cores will also be able achieve recycling in a continuous chemical process during operation, rather than as a batch after a long core residence.

Isn’t it wonderful that there are so many options from which to choose! Some consider that confusing and frustrating; I think it is delightful to know that fission can move down so many paths simultaneously in order to overcome fossil fuel dominance in the energy market.