Sunday, May 9, 2010

David LeBlanc: ORNL and Too Good to Leave on the Shelf

David LeBlanc of the Physics department of Carleton University, Ottawa, Canada and the Ottawa Valley Research Associates, Ltd., is a highly regarded participant in Energy from Thorium discussions and a reactor scientist of considerable note. David is notable because of a significant accomplishment. He has simplified the reactor core to a point beyond which further simplifications are likely to prove impossible. David's reactor core is nothing more than two metal shells, one inside the other. A fluid fuel carrier/moderator/coolant flow into the inner shell, and then out again. A fluid containing fertile thorium flows in a and out the second, outer shell. That is it. The entire core structure is composed of two sheets of shaped metal, one surrounding the other, with openings through which a very hot salt fluid is designed to flow. In the inner chamber, fissionable material that is chemically bonded to the carrier salt becomes critical.

No control rods are control rods are required to control David's reactor, because the inherent properties of the carrier/coolant salt automatically provide feedback that can control reactivity within the core and even shut the reactor down completely.

David is scheduled to give a talk titled, Molten Salt Reactors: An Exploration of Design Space

The abstract David's talk states:
This talk will first review past and current molten salt reactor design principles covering the main development period at Oak Ridge National Laboratory (ORNL) as well as more recent work such as the Thorium Molten Salt Reactor of France (now called the Molten Salt Fast Reactor) and the FUJI concepts of Japan. Two new proposed design routes will then be presented. First a novel but simple core geometry modification to solve the issues that led to the abandonment of ORNL's Two Fluid efforts of the mid-1960's. Two Fluid designs have separate salts to carry the fertile thorium and fissile 233U and which benefit from greatly simplifying fission product removal but previously called for unworkable core architecture. Secondly, the untapped potential of ORNL's late 1970's work on denatured converter reactors termed DMSRs and proposed improvements will be presented. This more conservative route will be shown to also have attractive resource sustainability and long-lived waste reduction while requiring the minimum of development work and maximizing proliferation resistance.

In addition to his pending ORNL talk, David is the author of a new article in the May 2010 issue of Mechanical Engineering, "Too Good to Leave on the Shelf.". The Article offers a brief history of the ORNL Molten Salt adventure, some fascinating pictures,

Too Good to Leave on the Shelf - Alvin Weinberg notes the 6,000 hour of full operation

Alvin Weinberg and the ORNL MSRE at 6000 hours of operation.

and David's own ingenious solution to a vexing problem that frustrated ORNL researchers in the 1960's. David also discusses the highly proliferation resistant DMSR, which has recently occupied his interest. He states

The amount of fissile material needed to start new reactors is also very important, especially in terms of a rapid fleet expansion. The 1 GWe DMSR was designed for 3.5 metric tons of U-235 (in easy-to-obtain low-enriched uranium) which can be lowered if uranium costs go up. A new PWR, by contrast, needs about 5 metric tons, whereas a sodium-cooled fast breeder such as the PRISM design requires as much as 18 tons of either U-235 or spent fuel plutonium. Any liquid fluoride reactor can be started on plutonium as well, but this turns out to be an expensive option, since removing plutonium from spent fuel costs around $100,000 per kilogram.

The DMSR features a larger, lower power density graphite core than other MSR breeder concepts. So while the graphite would last a full 30 years, the DMSR would still be only a fraction of the size of gas-cooled graphite reactors and would not require a pressure vessel. In fact, the simple thin-walled DMSR containment vessel would be wider but much shorter than those of PWRs and BWRs. The construction of the reactor containment building offers savings as it does not need the huge volume and ability to deal with steam pressure buildup needed for LWRs or CANDU reactors.


SteveK9 said...

Would it not be advantageous if advocates of Thorium reactors could arrange to give some presentations in India? Are there any appropriate conferences or meetings? Although India has it's own long-standing approach, it is the country that seems most determined to use Thorium as their primary energy source in the long-term. Are Indian scientists/engineers/politicians open to other concepts? Anyone in the Thorium 'community' know the answer?

Charles Barton said...

SteveK9, the indians are aware, but are committed to their 3 stage program, and I suspect far from ready to change. I do have readers in india.

Alex P. said...

I' ve noted a mistake when David claims in the article :
" The amount of uranium fuel needed—about 35 metric tons per GWe year—is only one-sixth of what is used by a pressurized water reactor. That means the price of uranium could rise an order of magnitude above its 2007 peak of $300 per kilogram before the fuel cost of a DMSR would reach even 1 cent per kWh "

Actually, it should be " reach 1 mill per kWh " (or 0,1 cent per kWh), maybe you can let know that to David

Alex P. said...

Just curious about DMSR, what's the uranium enrichment, if it' s used low enriched uranium ?

Charles Barton said...

It is actually a fairly high level of enrichment. Enough U-238 is added to prevent the weaponization of the U-233 used to fuel the reactor.

Bill Hannahan said...

Charles; thanks for the heads up. You and David have done an excellent job of laying out the facts. It is obvious that we should be moving ahead with this technology at maximum possible speed.

David said...

Charles, thanks for the very kind words.

Alex P. Perhaps you are misreading my statement. At 300$ per kg the fuel costs would be roughly 0.1 cents per kwh but my comment was that they could raise by an order of magnitude (i.e. 3000$ per kg) before you'd pass 1 cent per kwh. It is actually about 2400$ to be exact (or 84 million for U plus about 5 million for enrichment and conversion gives 1 cent per kwh).

Alex, the enrichment is variable. If we want the best uranium consumption we go up to the proliferation limit of 20% U235 for top ups (this allows the most thorium to be mixed in). At the other extreme we would use no thorium and enrichment would be about 4 or 5% (and uranium consumption might go up to 50 tonnes per GWe year).

David LeBlanc

Alex P. said...

Oopps, you' re right David, indeed I had misunderstood the point. Many thanks

Andreas said...

Hi thorium friends!

Regarding SteveK9 India questions:
Yes we are in contact with the managers of their thorium program. They agree that the MSR looks like the best long term solution for utilisation of thorium for energy production. And they have been knowing this ever since the ongoing research at ORNL.
IThEO will soon publish a "India Thorium Energy" report written by insiders and we hope it will be some interesting reading!
Andreas Norlin at
Thanks Charles for all the good reading!


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