Thorium Accelerator Driven Nuclear Power - Why not ?

Darryl

I had heard about a nulcear reactor, that did not require a critical mass, and therefore did not have the possibility of Loss of coolant or meltdown.

a reactor that required power to run, so if you want you can "Switch it off".

seems the present day reactors create a critcal mass, and all the control systems, (control rods, whatever) are inplace to stop meltdown from occuring. if the control system fail the "reactor will react more" and meltdown.
a standard nuclear power generator design is not "failsafe" but rather, its "FAILUNSAFE".

and accelerator driven power generation system will stop, if you turn off the accelerator.

when i googled ADR nuclear power, the first site i found was by none other Green Peace.

from there i was directed to a paper giving real values of the availabilty of thorium, and how thorium is much safer to mine, and more energy than uranium. and the reactor design produces a very small amount of waste.

low waste and a fairly short half life, the reactore itself can actually treat the waste and with low volume waste, ( and accountable waste), its possible to easily manage it. safely.

Thorum is very common, and from what ive read it is plentiful enough to supple 10 times the worlds present electricity requirements, for the next 1200 centuries !!.

so:

are there problems i have not read about.

why are these system not promoted, (is it because they dont make weapons grade stuff ?

why is this technology being heavily promoted as a viable option. ??

i guess they split the atom all the time at CERN, but NO ONE thinks that there will be a meltdown, there is just not enough stuff.

this looks like the same thing,, mabey its got a name problem, and take away the words "Nuclear reactor".

http://members.greenpeace.org/phpBB2...asc&highlight=

http://www.uic.com.au/nip67.htm


comments ???

Azael

I asked a similar question in this thread and got very good replies :)
http://www.physicsforums.com/showthread.php?t=132739

Azael

Thorium fuel cycle is beeing developed in India btw, they have plenty of thorium but not much uranium. I guess the rest of the world hasnt realy bothered with it yet because we have plenty of uranium aswell

http://www.world-nuclear.org/info/inf62.htm

ZapperZ

No, they don't "split the atom" at CERN. Particle colliders don't do that.

The one thing you haven't accounted for is the "wall plug efficiency". If you are using CERN as your reference point, then maybe you also need to figure out how much power is being used up JUST to make those few meager collisions, i.e. what is known as the "luminosity" of the interaction. Think of how much it is required to run such an accelerator, and then factor that out on how much power you get suck out of any nuclear reaction that is produced from such a collision.

This is, of course, way before we even consider the feasibility of generating any kind of nuclear fusion in terms of the physics from such a scenario. I mean, just look at RHIC (which would have been a closer comparision than CERN). Do you see them creating fusion interaction and able to extract any useable power out of such a nuclear-nuclear (such as Au-Au) collision?

On a separate note, I am utterly puzzled why people think that an accelerator is a viable alternative to generate nuclear power. This issue seems to be coming up rather often on here. I mean, I know what goes into an accelerator (I work at one), and the amount of effort and energy that is needed just to accelerate electrons alone, much less heavier nuclei (see RHIC). Did people simply not look at all those giant Klystrons that gobbled up megawatts and megawatts of power just to be able to deliver sufficent energies needed by these accelerators? I mean, forget about breakeven, I don't think you can even get 1% efficiency, assuming that you CAN in fact generate fusion reaction in the first place (something I highly doubt from a particle collider).

Zz.

Darryl

i certainly dont think an accelerator is a vaible alternative to nuclear power, and i was mistaken about CERN, my point was calling something a "Nuclear Reator" creates a fear about meltdowns etc.

and accelerator driven nuclear reaction does not (i believe) use very high energy particles from the accelerator, but low energy neutrons, (or something).

"In an ADS system, high-energy neutrons are produced through the spallation reaction of high-energy protons from an accelerator striking heavy target nuclei (lead, lead-bismuth or other material). These neutrons can be directed to a subcritical reactor containing thorium, where the neutrons breed U-233 and promote the fission of it. There is therefore the possibility of sustaining a fission reaction which can readily be turned off, and used either for power generation or destruction of actinides resulting from the U/Pu fuel cycle. The use of thorium instead of uranium means that less actinides are produced in the ADS itself."

whereas supercolliders type accelerators accelate particles to almost light speed, requireing vast amounts of energy.

ADS requires a stream of protons to liberate neutrons, and energy. as i read it. Im from Australia we apparently also have alot of thorium. and uranium.

Darryl

Thanks Azael for pointing me to your other thread, i missed it in my wanderings.

THe main point of that thread seems to be that it required a very high energy neutron steam to get any energy out.

but my quick seach tells me, its a 1 GeV proton stream that is required.

I did not know if that is alot or not, but for comparisong CERN is a 300GeV
ADS system only require 1/300th of that value, 1 GeV, medical image proton accelerators are being developed or allready in use, that generate 250 MeV, the paper also talked about building in think 1500 MW "modules", each powered by 1 accelerator.

i think the "Fail Unsafe" aspect of modern nuclear power generators is that you require a critical mass, and and self sustaining reaction, and your control systems have to function and work to control the reaction, if the control system fails the reaction still occures.

ADS if the control system fails, the proton beam fails, and the system shuts down.

ZapperZ

I work right next to a spallation source called the Intense Pulse Neutron Source. The ONLY reason why this is needed here (and at the Spallation Neutron Source being built at Oak Ridge) is the high flux and "monochromatic" energy&momentum distribution of neutrons. It takes a lot of effort and energy for that to occur and they are still struggling with the neutron intensity.

Again, the issue of "wall plug efficiency" is being neglected here in every discussion I have seen on such a proposal for a fusion source. Ask anyone working at such a facility about using it to generate fusion energy and they'll look at you funny.

Zz.

theCandyman

Do you mean that it is not possible to off set the energy used in the accelerators by using the resulting neutrons to cause fission?

Morbius

Darrl,

You are VERY mistaken about what you characterize as the "Fail Unsafe"
nature of present nuclear reactors. Nuclear reactors ARE designed to be
"Fail Safe". However, in the Three Mile Island Unit 2 accident, the operators
OVERRODE the fail safe systems. The ability of the operators to override
the fail safe systems was mandated by law.

Also, please read my reply to Azael's thread.

Accelerator systems have EXACTLY the same problem with meltdowns
that a critical system has. When a critical system overheats; it naturally
shutsdown the fission power. That's NOT what melts the core. It's the
"decay power" of the fission products that will melt the core, if not cooled.

An accelerator-driven sub-critical system has the EXACT SAME PROBLEM!!
When you shut off the accelerator, you don't shutoff the decay power of
the radioactive fission products.

An accelerator-driven sub-critical system is every bit as susceptible to
meltdown as is a critical system.

If it produces power; you have a meltdown problem unless you provide for
its mitigation. Sub-critical systems are no panacea.

Dr. Gregory Greenman
Physicist

Morbius

Darryll,

Greepeace is just plain 100% WRONG!!!

Dr. Gregory Greenman
Physicist

theCandyman

I agree, Greenpeace is the last source for nuclear related information I would use. Those people have an agenda, so they would likely make the information support their cause. They had something about the IAEA planning to stop promoting nuclear power becuae it was too dangerous (that might have been for April Fool's Day though, it was near that time that I lasted ran across anything from them).

ZapperZ

Remember that in conventional fission reactor, the neutron has to be "thermalized", i.e. slowed down by water before it can cause fission in the fuel rods. So using an accelerator to produce neutrons that generally have a higher energy than the thermal neutrons defeats the whole purpose. A breeder reactor can operate at a larger neutron energy, but is this really in the range that you'd get out of a spallation source? I don't think so.

Still, the issue isn't just creating energy out of such a thing. The issue here is how much energy did you put in, and how much did you get out. If we don't care about that, then this isn't an engineering problem and so why are we talking about it? After all, there are no "physics issues" here. The efficiency of something like this is the whole reason why one would even want to consider building something like this in the first place. I haven't seen anything that come close to justifying using an accelerator to generate nuclear energy. I seriouly doubt that one would even get 1% efficiency. You'll end up sucking in MORE energy than you can produce. What kind of a power plant is that?

Zz.

Morbius

Candyman,

Yes - another example of the self-serving LIES told by Greenpeace.

The IAEA doesn't promote nuclear power and it has nothing to say about reactor
safety. The charter of the IAEA is to police the Non-Proliferation Treaty, the NPT.

That's the IAEA's ONLY mission!!!

Greenpeace, as you say, has an agenda; and they have no scrupples about LYING
in support of that agenda.

Dr. Gregory Greenman
Physicist

Morbius

ZapperZ,

Correct!!! Even in a breeder reactor, the median neutron energy is about 200-250 keV.

That puts the median energy right in the middle of the resolved resonance region.

When I was at Argonne National Laboratory, I worked on the design of an "inherently-
safe" or "passively-safe" breeder reactor called the Integral Fast Reactor or IFR.

The main prompt feedback mechanism for shutting down the reactor in the event of
overheating was Doppler broadening of absorption resonances. The fact that the
median energy is in the resonance region makes Doppler broadening of resonances
particularly strong.

If one wants to read about the characteristics of an "inherently safe" reactor, check
out this interview by PBS's Frontline of my former boss, Dr. Charles Till:

http://www.pbs.org/wgbh/pages/frontl...iews/till.html

Dr. Gregory Greenman
Physicist

Morbius

Darryl,

WRONG!!!

Modern reactors have feedbacks to shutdown the reactor INDEPENDENT of the
control system!!!

For light water reactors, the moderator temperature feedback is the main feedback.
As ZapperZ explained, the neutrons in an LWR have to be slowed down or
"thermalized" in order to maintain the fission process. The neutrons are slowed by
collisions with the water. If the water heats up and becomes less dense - then the
collision rate decreases, there is less "slowing down" or "moderation" of the neutrons.

A critical reactor means you have an exact balance of neutron production and
destruction. If there is less moderation due to the heating of the water coolant /
moderator - that reduces the fission production; and the reactivity of the reactor
decreases. This happens INDEPENDENT of the control rods.

In fact, contrary to popular belief, a Pressurized Water Reactor or PWR; naturally
"load follows". You control the reactor with the temperature of the water coolant;
NOT the control rods. The control rods are basically a backup shutdown mechanism
in a PWR!

Doppler broadening of absorption resonances also works as an independent prompt
feedback mechanism in Light Water Reactors too.

Dr. Gregory Greenman
Physicist

entropiax

Sorry guys, my english is poor.

In Hungary there is a new web site. Unfortunately it is hungarian. It contains brand new information about energy conversion. It is not publicated, because the theory bypasses the second law of thermodinamics. As I know, the guys afraid scientific scandal, this is the reason they has not been publicated it yet.

The GE has a US Patent, converting heat energy to electricity directly.
It is used by satellite nuclear power.
Patent number: 5,139,895, date of patent aug 18, 1992

This patent thermally regenerates lithiumhidride about 850 Celsius, cools back it and gets electric energy from electric cell.

regenaration:LiH = Li + 1/2 H2 and the cell: Li|LiH|1/2H2

Theoretically impossible the regeneration of a cell the same temperature the cell works, because in this way not necessary cooling, so possible converting heat energy to electricity 100 percent.
This bypasses the second law of thermodinamics.

The pure Li|LiH|1/2H2 cell can works 688 celsius because it is the lithiumhidride melting point.
You can regenerate this cell on 850 celsius.
But they recognized potassium can react lithiumhidride.

K + LiH = KH + Li, but the KH is not stable and potassium and lithium do not compose alloy.
So the can regenerate LiH cell with potassium on the same temperature the cell works!
In this way possible high effiency conversion heat energy to electricity.
80-90 percent.
If you convert 1m3 LiH/sec you can convert 1.5 GW heat energy to electricity!
You can cool a nuclear reaktor with potassium.
The main problem of accelator driven nuclear reactor is, you have to put lot of electric energy to accelerator, you get heat energy and during the wrong conversion efficiency of steam turbine (30%) the energy balance is not so good.
Example japanese Omega project.
140 MW for the accelarator, the reactor produces 820 MW thermic energy, and the steam turbine generates only 240 MW electricity.
We get only 100 MW at all.
But we use this energy conversion, and calculate with 80 percent of efficiency, we get 500 MW.

The web site is http://secondlaw.acs.hu

entropiax

Sorry for lot of error