Compact Fusion Reactor

[John Fedup]

Aviation Week has a story today about Lockheed-Martin's compact fusion reactor research. Although fusion reactors are the holy grail for clean energy independence, nothing real ever seems to develop. This L-M design is interesting because of its size and relative safe operation and should be applicable to both surface and sub surface ships. Even the dream of the atomic jet might be a possibility. Hope it turns out to be better than "cold fusion"

 

[My2Cents]

The size they are quoting must be for just the core and blanket. These things will still require heavy radiation shielding and a lot of auxiliary machinery for things like tritium extraction/recovery.

 

[John Fedup]

The size they are quoting must be for just the core and blanket. These things will still require heavy radiation shielding and a lot of auxiliary machinery for things like tritium extraction/recovery.

The research team envisions a container sized reactor that would fit on a semi flatbed and would be about 100 Mw. The article implies tritium deuterium fusion resulting in He-4. The fuel amounts are small and the tritium is being fused so no extraction is necessary. As for shielding, I am not sure. The neutrons are to transfer their high kinetic energy to the reactor chamber which would than be the heat source for steam I assume. Not sure what material the chamber would need to be made of. Likely this fusion reaction would produce some gamma photons so shielding is required.

 

[protoplasm]

The research team envisions a container sized reactor that would fit on a semi flatbed and would be about 100 Mw. The article implies tritium deuterium fusion resulting in He-4. The fuel amounts are small and the tritium is being fused so no extraction is necessary. As for shielding, I am not sure. The neutrons are to transfer their high kinetic energy to the reactor chamber which would than be the heat source for steam I assume. Not sure what material the chamber would need to be made of. Likely this fusion reaction would produce some gamma photons so shielding is required.

Remembering back to uni days, you're correct, the tritium is fused, so no extraction. Lithium is present to capture the neutrons, producing tritium (which again is then fused) and more helium. I'm unsure about how much gamma radiation is actually being produced, but I seem to remember from the dim dark past that it is significantly less than from fission. The shielding shouldn't need to be as great as that for fission reactor

 

[My2Cents]

The research team envisions a container sized reactor that would fit on a semi flatbed and would be about 100 Mw.

The article implies tritium deuterium fusion resulting in He-4.

Actually D2 + T3 => He4 + n + gamma. That is a fast neutron and the rest of the energy is in the gamma.

The fuel amounts are small and the tritium is being fused so no extraction is necessary.

The tritium is produced by fast neutron absorption in the Li-6 {Li-6 + n => He4 + T3 + gamma} blanket and needs to be extracted from that and fed into reactor to fuse. Unfortunately the lithium-neutron absorption process is inefficient, so a layer of U-238 is usually added between the reactor and the blanket as a fast fission neutron multiplier to produce the required tritium production.

As for shielding, I am not sure. The neutrons are to transfer their high kinetic energy to the reactor chamber which would than be the heat source for steam I assume. Not sure what material the chamber would need to be made of. Likely this fusion reaction would produce some gamma photons so shielding is required.

The neutrons from the fusion reaction react with the neutron multiplier then the blanket where some are absorbed to create tritium to sustain the process. The rest of the neutrons are absorbed by various structures and shielding. The gammas, a byproduct of almost every nuclear reaction, are likewise absorbed in the blanket, structure, or shielding. Heat energy extracted from the blanket (molten lithium) is used to produce power.

It is interesting to note that they are proposing to use an open Brayton cycle turbine engine rather than a conventional closed cycle steam loop. This is likely to be controversial due to the single containment between the tritium and atmosphere rather that the double containment in the steam cycle designs.

 

[John Fedup]

If this design works out and the cost is hopefully less than current navy fission reactors, then CFRs would be viable for smaller navy warships as they would pose much less risk if they are hit by enemy fire. The CFR could supply extra power for energy hungry future weapons systems like rail guns and lasers. For future submarine acquisitions by current diesel electric sub operators, this could be a huge game changer, again, assuming the costs are viable. As the CFR is a much safer design than any fission reactor the cilivian market hopefully can further reduce costs. It's green too, the environmentalists will be pacified.

 

[cdxbow]

Actually D2 + T3 => He4 + n + gamma. That is a fast neutron and the rest of the energy is in the gamma.

The tritium is produced by fast neutron absorption in the Li-6 {Li-6 + n => He4 + T3 + gamma} blanket and needs to be extracted from that and fed into reactor to fuse. Unfortunately the lithium-neutron absorption process is inefficient, so a layer of U-238 is usually added between the reactor and the blanket as a fast fission neutron multiplier to produce the required tritium production.

The neutrons from the fusion reaction react with the neutron multiplier then the blanket where some are absorbed to create tritium to sustain the process. The rest of the neutrons are absorbed by various structures and shielding. The gammas, a byproduct of almost every nuclear reaction, are likewise absorbed in the blanket, structure, or shielding. Heat energy extracted from the blanket (molten lithium) is used to produce power.

It is interesting to note that they are proposing to use an open Brayton cycle turbine engine rather than a conventional closed cycle steam loop. This is likely to be controversial due to the single containment between the tritium and atmosphere rather that the double containment in the steam cycle designs.

That's great additional information. I hope it's correct because I have used it to explain it to my kids. I noticed this device is 'T4', anyone know if there has been T1-3? If so how much did they 'work'? Lockheed Martin must be reasonably confident of success if they are mapping out publicly a ten year plan as presented in the article.

 

[ngatimozart]

I read the article which is interesting. Yes, I remember the Fleischmann and Ps controversy of 1989 - 90 and its subsequent deleterious impact upon the research field. Recently there has been reports of claims by the Italian scientist Andrea Rossi who has unexplained "massive" amounts of cheap energy in a cold fusion reaction. The energy obtained is claimed to be in amounts far greater than those that can be explained by chemical reactions. There is verification by independent researchers but nothing published in independent reputable scientific journals yet. Cold fusion reactor verified by third-party researchers, seems to have 1 million times the energy density of gasoline | ExtremeTech.

NASA also appears to be following this research path NASA’s cold fusion tech could put a nuclear reactor in every home, car, and plane | ExtremeTech. This article also gives a basic explanation of the process they and Rossi use. It involves using hydrogen fuel and a nickel lattice.

From the article about Rossis E-Cat device, it appears that this device is far smaller than the 40ft box (ISO 40ft container) that the Skunk Works have come up with. However all that means is that there are different approaches to the research problem, which is good. The biggy is that for this too work power output must exceed power input. The potential of cold fusion is that fusion reaction may be achieved without the requirement of extremely high temperature and high pressure that is present in the centre of a sun or at the ignition of the 2nd stage of a thermonuclear explosion. However, it remains to be seen if it works. The LM approach is to use magnetic containment of the heat created. Wonder if they have to deal with pressure issues?

Mind you the potential of this technology is awesome. The mind boggles. If the technology becomes the size of the device in the Rossi article then potential for it on aircraft is unlimited. Be very light, no need to carry fuel etc. As the LM video states potential for ships too is unlimited. Unlimited range. This is only the beginning.

 

[StobieWan]

I'm not so sure Rossi is on the up and up:

Andrea Rossi Energy Catalyzer - E-Cat Hoax

On LockMarts announcement, I'm less surprised by the proposed size as by the way the article simply bypasses the fact that the longest sustained fusion reaction yet recorded is measured in very small units of time - is there a reason to think this is a relatively trivial issue? I'm not up on the science unfortunately

 

[cdxbow]

Rossi is a fraud. Period. Hoping Lockheed isn't.

 

[kato]

Rossi isn't all that recent too, he's been at it since the mid-90s.

 

[StobieWan]

and convicted too

 

[cdxbow]

and convicted too

I think Lockheed have been convicted of a few things over the years.

 

[John Fedup]

Well, nothing has happened with cold fusion for 25 years and after 70 years there are some promising developments with magnetically confined fusion so maybe cold fusion needs another 50 years of research! Bottom line, no fast neutrons means no fusion (from what I understand anyway).

 

[StobieWan]

Cold Fusion has no theoretical basis underpinning it - there's nothing there to work on. When the results were first seen, the researchers didn't know what they were seeing and began to put together some theoretical constructs to explain what they were seeing.

Nuclear fusion is relatively well understood and is now an engineering problem - we're past the "how does it work" part and into the "how can we practically apply this understanding.

Cold fusion is not on the same footing.

 

[StobieWan]

I think Lockheed have been convicted of a few things over the years.

Not delivering fraudulent goods however - bribery and corruption, surely yes, they have a whole chapter of law devoted to them But in the main, if they offer to flog you an aircraft or a missile or whatever, it'll be to spec and work.

 

[StingrayOZ]

Nuclear fusion is relatively well understood and is now an engineering problem - we're past the "how does it work" part and into the "how can we practically apply this understanding.

We have been able to use fusion in thermonuclear devices for half a century. Also the Fusor, is a fusion reactor, just not a very efficient one, but one that is easily built. Again for nearly 50 years. We are well into how can we do this with efficiently so that it is commercially useful. While they aren't commercially used to produce energy, Fusors are sold as a neutron source and have been used for transmutation of elements. ITER want commercially viable fusion.

Cold fusion is not on the same footing.

Cold fusion is like filling your regular car up with water and saying its going to do 10,000 km on a tank. There are deep and serious reasons why this can't happen and why its all wrong. No one is measuring neutrons, with no neutrons its not fusion. The energy output looks a lot more like a chemical reaction. (AFAIK - I haven't been looking at any "new" stuff because its so dodgy).

We can sustain Fusion for 6 min 30 in a tokamak. There is progress being made on fusion. ITER has high hopes. Interestingly various green parties/antinuclear groups and movements oppose the the ITER.

The US Navy invested quite a bit into something called a Polywell. However, they haven't exactly been pouring money into it. They see it more as a curious project than a viable source of energy. However its a very curious design, and has had surprisingly promising results. Yet no one knows about the research in Polywells but everyone knows about Cold Fusion.

 

[StobieWan]

Six minutes and thirty seconds? That's way better than I thought - hopefully more progress will be made in that direction but I am gratified we're into minutes not microseconds.

 

[ngatimozart]

I'm not so sure Rossi is on the up and up:

Andrea Rossi Energy Catalyzer - E-Cat Hoax

On LockMarts announcement, I'm less surprised by the proposed size as by the way the article simply bypasses the fact that the longest sustained fusion reaction yet recorded is measured in very small units of time - is there a reason to think this is a relatively trivial issue? I'm not up on the science unfortunately

Cool thanks for that. I hadn't dug into the background taking it on face value. I did a 100 level physics paper at uni many years back and understand that based on present knowledge, fusion needs very high temperatures and very high pressures. We are talking in the millions of degrees and pounds per square inch, something we can only achieve at present inside a thermo nuke. I do find the LM approach intriguing and being able to contain the temp by a magnetic force field is ground breaking. Wonder if it's possible to do the same or similar for the pressure.

 

[StobieWan]

I think electromagnetic containment has been the standard for a while now - keep the stuff spinning in a loop - it's a neat solution that avoids any seriously challenging materials science. The trick is still in getting more energy out of the damn thing than went in, and that relies on keeping the mill spinning for a lengthy period - which we're still measuring in minutes I'm afraid.

I'm intrigued to know what the reasoning is behind the idea that Lockmart can get by those hurdles in ten years or less. The compactness of the design is exciting of course- presumably they're looking to market it as a swap out replacement for a GT power station - it could just plug right in where the GT's were and it'd be a relatively simple operation re-commission as such.

Really intriguing, but we've all been stung with fusion several times over