Thursday, December 18, 2008

End Game: Answering the World's Energy Needs from Nuclear Waste

Lars Jorgensen is an Electrical Engineer who is Chief Technologist for Radio Products for Texas Instruments. In his spar time Lars has an unusual hobby. He is doing unpaid work on the development of the Liquid Fluoride Thorium Reactor, in a project that Rod Adams describes as the Nuclear equivalent of the Open Source movement in computing. The goal of the project, is to develop viable LFTR designs including the design tools that would be useful for Nuclear Engineers. In addition Lars is doing research on the use of LFTRs to solve the problem of the nuclear waste from other reactors. At the same time, Jorgensen's concept will cause produce vast amounts of electricity from the waste destroying process through the use of the LFTRs involved in the electrical generation process.

The idea of "burning" transuranium elements, the principle toxic wastes in nuclear waste, in molten salt type reactors is not new. During the 1950's my father verified that plutonium was compatible with a molten salt fuel carrier, and thus was suitable for use as a nuclear fuel in molten salt reactors. The idea of Using LFTRs to destroy nuclear weapons was pioneered by a group of nuclear scientists and Engineers at ORNL. In 1991, Uri Gat, and J. R. Engel of ORNL, and C. H. Dodds, of the University of Tennessee, proposed burning fissile fuel from dismantled nuclear weapons in LFTRs, as a means of nuclear deproliferation. That is the process of destroying the raw materials of nuclear weapons.

V. V. Ignatiev, S. A. Konakov, S. A. Subbotine, and R. Y. Zakirov of the Kurchatov Institute in Moscow, and K. Grebenkine proposed the use of Molten Salt Reactors as a means of disposing of nuclear waste. They noted that LFTRs had advantages over Liquid Metal reactors for nuclear waste disposal. The Russian research has lead to the development of the MOSART reactor design. The MOSART is a liquid salt fuel reactor concept intended to burn nuclear waste.
A similar proposal has come from Charles W. Forsberg of ORNL.

Forsberg noted that the development of
Brayton power cycles (rather than steam
cycles) that eliminate many of the historical challenges in building MSRs and (2) the conceptual development of several fast-spectrum MSRs that have large negative temperature and void coefficients, a unique safety characteristic not found in solid-fuel fast reactors.
Forsberg pointed to the potential of LFTRs to both produce electricity and destroy the dangerous components of nuclear waste.

In a draft paper titled. "An Improved End Game for the Non-Moderated Thorium Molten Salt Reactor", Lars Jorgensen has determined that by combining the disposal of nuclear waste and the generation of electricity in LFTRs vast amounts of electricity can be generated. Jogensen foresees a world wide demand for 7,500 GWe, nearly 20 times the current electrical consumption in the United States. With the use of electricity for water desalinization, Jorgensen further foresees electrical demand increasing to as much as 20,000 GWe.

Jorgensen, drawing on work by French nuclear scientists, H. Nifenecker, D. Heuer, J.M. Loiseaux, O. Meplan, A. Nuttin, S. David, and J.M. Martin, offers plans
to simultaneously reduce the current TRU wastes 15-fold (with onsite recycling) to 15,000 fold reduction (with the best offsite recycling), while also supplying 9000 GWe electricity for an energy-hungry world.
This is surely an ambitious undertaking.

Despite his ambition, Jorgenson's plan is simple. He reference the French Non Moderated Thorium Molten Salt Reactor, a Liquid Fluoride Thorium Reactor, as the his waste burning power generation reactor. By 2046 enough fissionable transuranium elements will be present in American Light Water Reactor Waste to start enough TMSRs to produce 125 billion watts of electricity. The TMSR is a breeder, that is it will produce more fuel than it burns. Other reactors will be started with U-233 from original TMSR fleet.

Jorgensen believes that his concept would work world wide to get rid of nuclear waste. As many as 1000 large TMSR could be built to use the word wide supply of 8842 tons LWR TRU waste as nuclear fuel. Each reactor would produce 1 billion watts of electricity. From that initial fleet enough U-233 would be produced to start another 8000 reactors. Enough to supply the entire wolds electrical demands 100 years from now.

Jorgensen plans for the TRUs from light water reactors to remain in TMSR cores until they are used up, a process that would take several hundred years. After 200 years more that 56% of the original LWR TRU inventory will have been used up. If there is a desire to shut down the TMSR fleet, as the amount of TRU drops inside the TMSRs, the TRUs can be withdrawn from the core by batch chemical processing of the fuel, Fission products and U-233 would of course be processed out of the fuel salts at the same time. The withdrawn TRUs would be transfered to the cores of other reactors, and the reactor whose TRUs are processed out can be shut down.

According to Jorgensen:
We can virtually eliminate the inventory TRUs in the reactor cores by gradually shutting down the reactors and fissioning the residual inventory off. The optimization goals of the shutdown procedure are:
1) minimize the final inventory of TRUs disposed as waste;
2) shut down the vast majority of reactors, as quickly as possible, consistent with the first goal.
Eventually the TRU's and U-233 involved in the process can be "burned down" to a tiny amount of waste. as much as an 11,000 fold reduction in the amount of waste. The final waste will come from two sources: a very small leak of TRU and U-233 into the fission product stream, and the TRU and U-233 inventory left over when the final, very small TMSR no longer contains enough fissionable material to maintain a chain reactor.

Jorgensen concludes:
The deployment not only provides 1,800,000 GW-yr (1.8 PW-yr) of electricity, but eliminates 90 to 99.99% of the world’s predicted transuranic waste inventory. The NM-TMSR’s fuel flexibility allows virtual elimination of the waste inventory arising from shutting down the reactor fleet. This sort of flexibility is much more difficult to achieve with any proposed solid fuel reactor. The Th-U233 cycle operates with TRU inventories only 5% of those for U238-Pu239 based breeder reactors. While much R&D needs to be funded and completed to bring this reactor to fruition, it is far less than the projected costs for Yucca Mountain, and solves both the TRU waste and energy generation challenges facing our society today.
For those concerned about nuclear proliferation, the TMSR and similar LFTRs are wonderful deproliferation tools. Uranium and plutonium from nuclear weapons and weapons available stockpiles can be used as starter charges for LFTRs and burned up by the nuclear process. LFTR can be designed to produce no more U-233 than is burned up in its chain reaction. Thus far from being a nuclear proliferation menace, the LFTR can becomes a prime tool for lowering the possibility of nuclear war.


Bill Hannahan said...

85-90% of all mined uranium is sitting at enrichment facilities ready for use in advanced reactors. An 80 year U.S. lifetime supply of electricity from fission in second and third generation reactors using a once through fuel cycle leaves less than 10 pounds of heavy metal in spent fuel. The heavy metal in existing spent fuel is a tiny spoonful compared to the amount humans will use if nothing better than fission is discovered.

The time, man-hours, money and political capital required is far too high a price to warrant saving this material. Let it go, bury it under the deep seabed.

We should focus all our energy on two things.

1 Mass production of third generation plants.

2 R&D, including construction of demo plants for advanced designs for which recycling makes sense.

Charles Barton said...

Bill, I am not sure that mass production of LWRs is possible.

ab said...

Damn, that's funky - seeing passages I've edited while helping Lars with his paper, even quoted on a blog, let alone something peer reviewed.

Still looking for Holly Mackerel, Charles?

Charles Barton said...

Peer reviewed? As you are aware fish with fins and scales are kosher. Hopefullly Lars will get his paper published in a peer reviewed journal.

DW said...

And ONLY fish with fins and scales are kosher. Which is why the rabbis debate that this is actually punishment, or a reminder of punishment, while seeing people chow down on lobster!


Charles Barton said...

I recently learned the reason for Gefilte fish. It is against rabbinic Law to pick the bones out of fish on the Shabbot, and other Jewish holidays. Gefilte fish comes with the bones prepicked. Eating Lobster won't get you to hell according to Jewish Law, but it plays hell with the scheduled return of the Messiah.


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