Rick Has A Word or two for sceptics.

[Chuck Connors]

Forgive me folks, but what are we talking about here? Polywell...or general DOE funding and politics? I'm completely with you that the DOE's agenda is politically motivated, but is there proof that it (or Chu) is withholding funding from Polywell?

I'm not defending the DOE, but I am calling into question them pressuring the Navy not to fund Polywell in the new adminstration.

[Helius]

Forgive me folks, but what are we talking about here? Polywell...or general DOE funding and politics? I'm completely with you that the DOE's agenda is politically motivated, but is there proof that it (or Chu) is withholding funding from Polywell?

I'm not defending the DOE, but I am calling into question them pressuring the Navy not to fund Polywell in the new adminstration.

There can be no proof; All we can look at is the evidence. I think at this time, Polywell will be ignored by the DOE, and will continue to be ignored so long as it does not appear to compromise the status quo, the current Energy supply paradigm.
We hear Steven Chu's benefactors say such things as: "everything must be part of the mix"... And there is no evidence that Chu's DOE will compromise that with any newfangled or even guaranteed oldfangled technology.

The greatest evidence is that IFR research, cancelled in 1994 by the 104th congress, was never restarted, and the researchers hushed by the Clinton administration (or risk retribution). The IFR would have changed the whole dynamic of energy production in this country. Those researchers were poised to really shake up the whole energy paradigm. That is the greatest Evidence.

In a more general sense, we see that there is No real research taking place that has a Higher power density than existing fossil fuel energy production. Physics & economics tells us that there are things that we can do to even exceed the IFR. There are extremely disruptive potentialities that could be initiated and rolled out before the end of the next decade.

It is absolutely safe to be assured that the current state of Energy production and consumption will NOT be dynamically changed by research and development of lesser power density methods. A public view and pursuit of windmills and Insulation as a solution to energy shortfalls guarantee current and expanding revenue flows in existing fossil fuel industries.

That's the plan: Everything stays as "part of the mix".

[Helius]

ZOW! http://www.sandia.gov/news/resources/re ... plant.html
Do I eat crow now or later?

[Aero]

Do I eat crow now or later?

I would say, "Later," perhaps much later.

It seems like a good idea but their are other similar ideas out there. This concept is still in the laboratory, in the design phase. It's a long way, with many technological and political hurdles between the laboratory and the field.

[Professor Science]

Can someone give me an explanation how breeder reactors work? I'm floating somewhere between magic and neutron bombardment, and neither is a terribly satisfying explanation.

[D Tibbets]

Do I eat crow now or later?

I would say, "Later," perhaps much later.

It seems like a good idea but their are other similar ideas out there. This concept is still in the laboratory, in the design phase. It's a long way, with many technological and political hurdles between the laboratory and the field.

The link looks like a straight forward application of mass production. The cost advantages would be due to standardization and serial production of fission reactors. The smaller size would mean a higher cost per megawatt produced, so presumeably the mass production savings and longevity offsets this. The design is a liquid sodium breeder reactor which reportably increases the usefull core lifetime. Has anyone ever produced a commercial liqiud soduim reactor?

As for nonproliferation concerns, I would think that a breeder reactor would be a much greater concern. If a nation wishes to extract plutonium from thier reactor, they will. I'm sure the powers that be already know very well when a client nation uses a transferred reactor for weapons production- eg. N. Korea. The proposed reactor would not change this. The powers would still need to intimidate the offending nation or actively destroy or remove the reactor (would still need the willingness to use military intervention to enforce the rules). The only real benifit would be that fewer plutonium bombs could be made from any single reactor. This would be counterbalanced by the presence of more reactors in more nations. Threatening a nation with no more new reactors would impede the development of large stockpiles of atomic bombs, but it would not impede the developement of a few bombs with the perhaps several reactors already in the nation.

Also, the more numerous dispersed reactors would be more challenging to protect from terrorists that wish to get some material for dirty bombs.


Dan Tibbets

[TallDave]

Can someone give me an explanation how breeder reactors work? I'm floating somewhere between magic and neutron bombardment, and neither is a terribly satisfying explanation.

The banal oracle of our age, Wikipedia.

http://en.wikipedia.org/wiki/Breeder_reactor

A breeder reactor is a nuclear reactor that generates new fissile or fissionable material at a greater rate than it consumes such material. These reactors were initially (1940s and 1960s) considered appealing due to their superior fuel economy; a normal reactor is able to consume less than 1% of the natural uranium that begins the fuel cycle, whereas a breeder can utilize a much greater percentage of the initial fissionable material, and with re-processing, can use almost all of the initial fissionable material.

Production of fissile material in a reactor occurs by neutron irradiation of fertile material, particularly uranium-238 and thorium-232.

Breeders will be important when (if) we have to start using thorium because cheap uranium is exhausted.

Breeders can be designed to utilize thorium, which is more abundant than uranium.

Thorium will last 1,000 -100,000 years, after which ITER may have a market.

[TallDave]

Helius,

I remember being initially excited by, and then mildly disappointed in the IFR.

http://en.wikipedia.org/wiki/Integral_Fast_Reactor

I think critics may be right about the capital costs.

[KitemanSA]

Don't let the issues with IFR dishearten you. The Thorium fueled Molten Salt Reactor can refuel itself while allowing about a 9% growth rate in fuel supply. Also, the fuel created is much more proliferation resistant.

[Professor Science]

Can someone give me an explanation how breeder reactors work? I'm floating somewhere between magic and neutron bombardment, and neither is a terribly satisfying explanation.

The banal oracle of our age, Wikipedia.

http://en.wikipedia.org/wiki/Breeder_reactor

Breeders will be important when (if) we have to start using thorium because cheap uranium is exhausted.

Breeders can be designed to utilize thorium, which is more abundant than uranium.

Thorium will last 1,000 -100,000 years, after which ITER may have a market.

I've read that, it's the "more fuel out than in" thing the boggles me, how are you getting power out as well as fuel, perpetual motion machines can only be built by a bored lisa simpson.

[blaisepascal]

I've read that, it's the "more fuel out than in" thing the boggles me, how are you getting power out as well as fuel, perpetual motion machines can only be built by a bored lisa simpson.

It's not really "more fuel out than in", it's really converting a non-fuel into a fuel faster than it's using up the fuel.

In order for nuclear fission chain reactions to work, you want isotopes which are "fissible", meaning that they can be triggered to undergo fission by neutron capture relatively easily.

U-238 is the most abundant isotope of Uranium. It is not fissible. Pu-239 is fissible, and U-238 will convert to Pu-239 by capturing a neutron then rapidly undergoing beta decay twice. So if you put U-238 in the presence of a good neutron source (like, say, a running nuclear reactor) you'll get lots of Pu-239, which is a much better nuclear fuel than U-238.

Th-232 is the most abundant isotope of Thorium. It is not fissible. U-233 is fissible, and Th-232 will convert to U-233 by capturing a neutron then undergoing beta decay twice. So if you put Th-232 in the presence of a good neutron source (like, say, a running nuclear reactor) you'll get lots of U-233, which is a much better nuclear fuel than Th-232.

In a breeder reactor, the system is designed so that the fission of Pu-239 (or U-233) is able to convert more U-238 (or Th-232) into Pu-239 (or U-233) than is consumed the process.

It isn't perpetual motion because the energy stored in U-238 or Th-232 is still very high compared to the eventual fission products. But the U-238/Th-232 isn't very usable as-is.

[MSimon]

Can someone give me an explanation how breeder reactors work? I'm floating somewhere between magic and neutron bombardment, and neither is a terribly satisfying explanation.

The banal oracle of our age, Wikipedia.

http://en.wikipedia.org/wiki/Breeder_reactor

Breeders will be important when (if) we have to start using thorium because cheap uranium is exhausted.

Breeders can be designed to utilize thorium, which is more abundant than uranium.

Thorium will last 1,000 -100,000 years, after which ITER may have a market.

I've read that, it's the "more fuel out than in" thing the boggles me, how are you getting power out as well as fuel, perpetual motion machines can only be built by a bored lisa simpson.

Professor Science? You seem rather weak in nuclear technology.

1. There are non fuel atoms
2. There are fuel atoms

If while burning fuel atoms you also convert non-fuel atoms to fuel atoms you can get energy out and fuel out as long as there are a lot more non-fuel atoms than fuel atoms and you convert non-fuel to fuel faster than you burn it. It all depends on your neutron economy.

[chrismb]

An article I've linked to before, and worth it again;

http://www.spectrum.ieee.org/energy/nuc ... asteland/0

there is text in the middle which does a succinct job of explaining it simply, within the context of reprocessing:

"All reactors get their heat from bundles of rods filled with a fissile fuel. The rods are inserted into a core in close proximity to each other, enabling neutrons radiating from the fuel in each rod to split heavy atoms of uranium or plutonium in neighboring rods, thereby generating more neutrons, which split more atoms, and so on. In most conventional power reactors, water or graphite is employed as a moderator to slow down the neutrons, thus rendering them more likely to be absorbed by U-235 atoms, knocking out more neutrons. That is necessary because the concentration of fissionable material in the fuel is low, just a few percent. In contrast, breeder reactor fuel contains a high fraction of fissionable material, so that a moderator is not required.

There is an additional potential advantage to the breeder reactor. By surrounding the fuel rods in its core with a jacket of U238, which is not fissionable by slow neutrons, the reactor can produce power and simultaneously ”breed” new plutonium faster than the plutonium in the fuel rods is consumed. The U238 atoms capture neutrons to form fissile plutonium 239."

My understanding is that the key to this being that U238 (which isn't used in conventional reactors as 'fuel') doesn't absorb slow neutrons to then fission, but does produce plutonium when fused with a neutron which in turn is then a fissionable fuel. So it effectively 'burns' U238 rather than U235.

[Helius]

More simply, you can consider a reactor as a black box: Thorium-232 or Uranium-238 goes in; and the same mass in the form of fission resultant (split atoms), and a huge amount of process heat comes out. Forget for now that Th-232 or U-238 is only fertile (can be converted in a reactor to fissile material) and is not fissile directly. It still contains extremely high potential energy.

The Fission product will actually only weigh 99.9% of the original to be burned mass Th232 or U238, due to mass conversion to energy: E=MC**2.
OK, maybe 4 9's. I'm not going to do the math.

The problem with our current generation of Nuclear reactors is that Fission product stays within the fuel elements and eats too many neutrons spoiling the reaction, causing a bad neutron economy, as Simon points out. A fuel element lasts only about 3 years, then it must come out of the reactor. I'd be like your car if the result of combustion stayed in your gasoline: You'd have to take out and replace your gasoline in your fuel tank long before you consumed it.

There are far better designs for Nuclear reactors, but due to ignorance, FUD and political inertia, we're far to slow in pursuing them.

[Professor Science]

Ok, neutron's from fissioned materials hit poor fissioning nuclei turning them into now more productive compounds, this is more or less what my intuition had, but it's good having an outside source corroborate. And the transmutation probably uses energy that wouldn't have been harnessed anyway, so it's more like closing up a loss loop.