Is My Idea Valid? Nuclear Fusion Power

[the_wolfman]

I honestly don't know what metals they use for liners. It has to be highly conducting, but ideally you want it to be cheap. A guess is that they use copper. But there may reasons for using other metals too.

The biological shield is just what we call the shielding that surrounds the reactor protecting humans (and other biological organisms) from the radiation.

You can't heat a magnetically confined plasma with an ion beam because the magnetic field will deflect the ions.

We can heat the plasma using radio-frequency (rf) sources. However, we use frequencies that are absorbed by the plasma.
Most laser light and x-rays are the wrong frequency, and they will pass through the plasma. Instead we often use mircowave sources.

And I still don't understand why ion beams/lasers/xrays can't be used to heat the pellet to critical temperature and then magnetic fields to contain it

It sounds like you're thinking of a hybrid-method that uses inertia confinement to compress a pellet, and then magnetic fields to confined the compressed pellet? This won't work because the magnetic fields needed to keep the pellet compressed are huge. We simply don't have the technology necessary to create the necessary magnetic fields.

 

[dvp2015]

you are correct let me check back to revise my figures

google for ITER or JET, JET actually achieved positive output of energy. Is it "viable" depends on point of view. The profitable energy production looks possible, but we need years of hard work to achieve this. Anyway to ignite burning one need to provide the input power of gigawatt level (the production will gain dozens gigawatts). You can retrieve some energy from hot water sources, as from any other one, but for gigawatt level you need too many sources of that power density around.

 

[Mark Harder]

Okay, where mind I find resources to help me with this stuff, it would be pretty cool to solve energy problems and eliminate need for fossil fuels use

I'm not saying you're doing this, but I want to point out that people seem to have a tendency to look for 'the' solution to the energy problem. Don't get me wrong. Fusion is a fascinating topic and fusion may be such a powerful technology that it will take over the world, but it's probably a long way in the future. There are articles in Scientific American and American Scientist about fusion issues and developments. A lot of attention in the popular press focuses on the technological issues you mention, but some think solving the temperature + pressure problem may be easy compared to the challenges in engineering the materials used in a reactor (as we presently conceive of such) and obtaining and managing the fuel used. Then there are the folks who propose mining the Helium-3 isotope on the moon, since, they say, it's relatively plentiful there and it would be a better fuel than radioactive hydrogen-3. Another fascinating possibility is the Liquid Salt Thorium Reactor. India and China are sinking a lot of resources into engineering one of these. The idea has been kicked around since the '50s, and it may come to fruition a lot sooner than fusion and especially mining the moon. It has some important advantages over uranium-plutonium power, among them the difficulty of using it to create weapons-grade material, and a bountiful supply of thorium minerals around the world. India has the stuff lying around some of their beaches. Thorium reactors may become a way for poorer nations to supply themselves with electric power without creating fuel for bombs. There was an article about the thorium fuel cycle in American Scientist a few years ago. In the meanwhile, my guess is that we'll have to make do with several cleaner sources than fossil fuels, with no one of these dominating the field. And don't forget the best solution to energy problems is not using the energy in the first place! Conserving energy and reducing consumption of goods that require energy to make will go a long way toward reducing fuel use and greenhouse gas emissions. That's not a popular idea in some quarters. It may require some sacrifice on the part of consumers. If you're interested in solving energy problems technologically, you could research the efforts put into more efficient and less polluting technologies, and don't neglect the social and economic issues such solutions create.

 

[mfb]

google for ITER or JET, JET actually achieved positive output of energy.

Positive in the way that they got fusion power - yes. But no fusion without continuous heating, and fusion power was lower than this heating power. With more than 50% conversion of thermal power to electricity this could be used to generate electricity, but that is questionable (getting more than 50% conversion is tricky), and it is certainly not enough power for a power plant.

Anyway to ignite burning one need to provide the input power of gigawatt level (the production will gain dozens gigawatts).

No current or planned reactor is designed for dozens of gigawatts. The plan is always to get a few GW thermal power, for something like 1 GW electric power - similar to fission power plants.

 

[Teen4Ideas]

We can heat the plasma using radio-frequency (rf) sources. However, we use frequencies that are absorbed by the plasma.
Most laser light and x-rays are the wrong frequency, and they will pass through the plasma. Instead we often use microwave sources.It sounds like you're thinking of a hybrid-method that uses inertia confinement to compress a pellet, and then magnetic fields to confined the compressed pellet? This won't work because the magnetic fields needed to keep the pellet compressed are huge. We simply don't have the technology necessary to create the necessary magnetic fields.

Instead of containing all that force, why can't you just redirect it? Like in a torus? Have an inflow valve from the initial reaction chamber into the torus, then just loop the plasma right? Are you getting tired of this conversation yet?

 

[mfb]

You have to contain it in all three dimensions. One is easy in a torus (along the ring), the other two are not.
Note: that has nothing to do with pellets.

 

[Astronuc]

The first wall in a fusion reactor has to resist an aggressive environment including high temperature, high heat flux, and neutron/gamma radiation, as well chemical interaction. Ideally, it has high temperature and low atomic number (Z), since there is a change that the atoms on the surface can be knock off into the plasma, and high Z atoms result in energy losses due to recombination and brehmsstrahlung radiation.

The neutron irradiation has several effects: 1) radiation damage, i.e., atomic displacements in the lattice structure, 2) spallation reactions (e.g., (n,p), (n,d), (n,α)), and 3) activation. Neutrons knock atoms out of lattice sites, and in some metals, create voids. We measure displacements per atom. Neutrons knock out nucleons (spallation) or otherwise breakup small nuclei, and neutrons are absorbed and the nucleus transmutes by beta decay to a new element (Z+1).

Chemical effects involve hydrogen diffusion into the first wall, which can result in the formation of hydrides and blistering, where hydrides occupy greater volume than the bulk material. Blistering can produce flaking of the first wall, which finds it's way into the vacuum chamber causing impurities in the plasma, which increases the energy loss.

Austenitic stainless steel was an early candidate for Tokamak structural material, but austenitic alloys are subject swelling. Ferritic and martensitic steels resist swelling.

High temperature alloys and graphite are considered as well. Ceramics are also a possibilities.

http://en.wikipedia.org/wiki/Plasma-facing_material is a reasonably accurate article.

The challenge for materials increases with power density.

http://en.wikipedia.org/wiki/Alcator_C-Mod

 

[Mark Harder]

Another fascinating possibility is the Liquid Salt Thorium Reactor. India and China are sinking a lot of resources into engineering one of these. The idea has been kicked around since the '50s

That's not quite accurate. I checked with Wikipedia under Molten Salt Reactor Experiment (My underline.). People may have been thinking along this direction in the '50s. Alvin Weinberg might be called the father of the MSRE. He directed experimental molten salt reactor experiments in Oakridge, TN from 1964-1969. The original model used U-235 fluorides as fuel, and it did generate some plutonium. However, the fuel was later changed to Uranium-233. U-233 was generated in quantity in a separate reactor, and transferred to the MSRE. So it wasn't really a thorium reactor, since it didn't use Th as the primary fuel.

However, modern concepts still include breeding the initial charge of U-233 from Th-232 in a U-235 reactor. I don't know if U-233 can be made in an LFTR. LFTR designs make it easy to remove spent fuel and replenish with fresh fuel. Molten spent fuel is drained off and new molten fuel is pumped in. They also include a vital safety feature in the form of a solid plug in the liquid fuel line that melts if fuel temperatures get too high, draining the fuel into a separate containment vessel that passively quenches the nuclear reaction. There are disadvantages as well, and the projects are still controversial. Another information source is the Wikipedia article covering the 'Thorium Fuel Cycle', which covers these better than I can.

 

[Teen4Ideas]

High temperature alloys and graphite are considered as well. Ceramics are also a possibilities.

http://en.wikipedia.org/wiki/Plasma-facing_material is a reasonably accurate article.

The challenge for materials increases with power density.

http://en.wikipedia.org/wiki/Alcator_C-Mod

Is carbon fiber a viable candidate? Or carbon fiber layered on top of tungsten?

 

[Zackary Miller]

That's not quite accurate. I checked with Wikipedia under Molten Salt Reactor Experiment (My underline.). People may have been thinking along this direction in the '50s. Alvin Weinberg might be called the father of the MSRE. He directed experimental molten salt reactor experiments in Oakridge, TN from 1964-1969. The original model used U-235 fluorides as fuel, and it did generate some plutonium. However, the fuel was later changed to Uranium-233. U-233 was generated in quantity in a separate reactor, and transferred to the MSRE. So it wasn't really a thorium reactor, since it didn't use Th as the primary fuel.

However, modern concepts still include breeding the initial charge of U-233 from Th-232 in a U-235 reactor. I don't know if U-233 can be made in an LFTR. LFTR designs make it easy to remove spent fuel and replenish with fresh fuel. Molten spent fuel is drained off and new molten fuel is pumped in. They also include a vital safety feature in the form of a solid plug in the liquid fuel line that melts if fuel temperatures get too high, draining the fuel into a separate containment vessel that passively quenches the nuclear reaction. There are disadvantages as well, and the projects are still controversial. Another information source is the Wikipedia article covering the 'Thorium Fuel Cycle', which covers these better than I can.

You can make U-233 from Th-232 in a MSR, however that will produce Pa-233, which has a half life of 27 days and a neutron capture cross section > 1 for thermal neutrons, which necessitates constant reprocessing and thus increases the cost of operation as a reactor operator you have to both run a chemical plant and a reactor. Needless to say that could be quite expensive to do.

 

[DEvens]

It may require some sacrifice on the part of consumers. If you're interested in solving energy problems technologically, you could research the efforts put into more efficient and less polluting technologies, and don't neglect the social and economic issues such solutions create.

I am highly in favor of you making sacrifices. Especially economic and social sacrifices. It would be so nice if you would go first and show us what it's like.

The rest of us will go ahead and create the future.