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Nuclear Fusion Reactor  (Source: The Institute of Telecommunications Professionals)
Could lead to an endless supply of clean energy

Researchers from Purdue University have found mechanisms that are vital to interactions between surfaces inside a thermonuclear fusion reactor and hot plasma, which could lead to the development of coatings capable of tolerating radiation damage and ultimately, fusion power plants. 

The inner lining of a fusion reactor often faces horrific conditions leading to radiation damage due to the hot plasma. With the use of nanotechnology, nuclear engineers are looking to "define" small features in the coating as a way to understand and develop a new material that can come in contact with plasma and not be harmed. Finding a material durable enough to withstand such harsh conditions has been difficult, until now. 

Along with researchers at Princeton University in the Princeton Plasma Physics Laboratory, Purdue researchers are using the National Spherical Torus Experiment to test materials, which is the country's only spherical tokamak reactor. They will also study materials in a special "plasma-materials interface probe," then transfer these materials to an "in situ surface analysis facility laboratory."

"We will bring the samples in and study them right there, and will be able to do the characterization in real time to see what happens to the surfaces," said Jean Paul Allain, an assistant professor of nuclear engineering at Purdue University. "We're also going to use computational modeling to connect the fundamental physics learned in our experiments and what we observe inside the tokamak."

One of the tested linings is lithiated graphite, which consists of lithium being added to the inner graphite wall, and when it diffuses into the reactor wall. Then deuterium atoms and the lithiated graphite bind together in the fuel inside these tokamaks, which are what the fusion reactors are called. A magnetic field inside the tokamaks encloses a circular-shaped plasma of deuterium, which is an isotope of hydrogen. 

When a fusion reaction occurs, deuterium atoms hit the inner lining of the fusion reactor and can be sent back to the core and recycled back to the plasma, or they're "pumped," which causes them to bind with the lithiated graphite. 

"We now have an understanding of how the lithiated graphite controls the recycling of hydrogen," said Allain. "This is the first time anyone has looked systematically at the chemistry and physics of pumping by the lithiated graphite. We are learning, at the atomic level, exactly how it is pumped and what dictates the binding of deuterium in this lithiated graphite. So we now have improved insight on how to recondition the surfaces of the tokamak."

The use of a fusion power plant could cut exhaust completely because the deuterium fuel is in seawater. Also, it could produce 10 times more energy than a nuclear fission reactor. Plants like these would be an endless supply of clean energy.

This study was led by Chase Taylor, a doctoral student, Bryan Heim, a graduate student, and Allain. Two papers have been written on the topic, and one will be presented at the Fusion Nuclear Science and Technology/Plasma Facing Components meeting in August.



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RE: Fusion Power - Is it really that clean?
By sleepeeg3 on 7/29/2010 2:45:23 AM , Rating: 1
We only have enough estimated fissile material for 80-200 years. That is why fusion is imperative to our future.

From this article, I am not sure what the advantage is of the lithiated graphite. Does it extend the life of the coating? From what I recall, graphite has the advantage of being cheap, but also requires the highest rate of replacement, creating the most low level radioactive waste.


By Fritzr on 7/31/2010 1:53:31 AM , Rating: 2
That limit assumes that only high grade naturally occurring fuel is used.

Breeder reactors convert nuclear "waste" into new fuel that can be used to fuel other reactors. The benefit of breeders is that the waste product of the reaction is a greater amount of usable fuel than is needed to charge the reactor. The "Great Evil" is that the common designs are meant to produce weapons grade plutonium. The designs that produce "poisoned" plutonium unsuitable for weapons were shelved as they could not be used for weapons production, but they do exist and have been tested.

The Traveling Wave reactor mentioned & linked in an earlier post is fueled with "spent" nuclear fuel.

There is also research into recycling nuclear waste to extract the remaining fuel usable for current generation reactors.

Fast Flux Breeder Reactors burn the nuclear waste from other reactor designs and convert long lived isotopes into short lived isotopes. The waste product is then processed to remove the residual usable fuel and the remaining mid grade nuclear waste only needs to be stored for a century or two. This reactor class could be used to burn the high level waste created by the effects of the fusion reaction on the reactor vessel and it's containment.

The difference between fusion and these alternate fission designs is that the alternative fission reactors exist and operate today whereas the fusion reactors for at least the last 40yrs will be producing power "within the next 10yrs".

That is 40 years ago researchers promised fusion power as early as 30yrs ago. 40 years later they are making the same promise..."We're almost there, only 10yrs more!"


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