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<compact fusion>

We were very excited to have Lockheed Martin's moonshot factory, the Advanced Development Program (better known as the original "Skunkworks"), represented at Solve for X this year. When we began talking to folks at the ADP about Solve for X, they literally gave us five moonshot ideas they've been working on ... all of which blew us away. Of the five, we agreed that compact fusion was the most audacious and had the greatest potential for radical, beneficial impact of the world. 

Problem: Energy access & climate change

Solution: A 100MW compact fusion reactor that runs on plentiful and cheap deuterium and tritium (isotopes of hydrogen). 

Breakthrough technology: Charles Chase and his team at Lockheed have developed a high beta configuration, which allows a compact reactor design and speedier development timeline (5 years instead of 30).
Peter Niermann's profile photoLarry Weinheimer's profile photoStephen Bowlin's profile photoDave DeWitt's profile photo
Compact fusion would certainly be a game changer.
Whenever I hear nuclear, I think waste. I watched the video but not too sure what and how to dispose of the waste. Also what about safety implications?
+Richard Tan  Fusion is much cleaner than fission.  From what I understand there are no direct radioactive by-products of fusion, although I think I may have read that the containment vessel can become somewhat radioactive over time.

Anyone with more knowledge of the subject ready to way in?
Fusion has no direct waste. There is neutron activation of the vessel. However this is orders of magnitude easier to deal with. With proper material choice, that is also easier since neutron economy is not important, it would be safe in decades. Also after just hours it will be many times less "hot" that anything out of a Fission reactor.  

There is also the possibility of using these high energy neutron to get rid of the waste from fission reactors. Since you can have a subcritical assembly, you can burn actinides safely... or rather in a  safer way. 
Ok so now i have watched it... and what.. there are Zero details. Just the standard "Our approach is X times better and more awesome". Yea? Really? Then show me the data. Or at the very least, some details. Like say what magnetic configuration you are using? 

Everyone like to rag on things like JET and ITER. Yet nothing else has come closer to fusion on any relevant metric.  
+Greg Ewing yeah, but it was an X talk. I could see him struggling to stay away from "boring" detail. That he wasn't charismatic was -- to me -- a good sign. He's a researcher not a salesman. He'd flop at Ted. Good. We don't need Teddy. Most of the world is suffering, and not just from boredom. But yeah, let's see some numbers.
This is clearly a Moonshot! A reactor roughly 300 cubic meters (This is really SMALL) producing 100 MW, it can be used in ships, submarines, miniaturized versions could be used in Trains, Planes and even large trucks.

Lets see if they can make it work.
Meanwhile Thorium MSR reactors will be developed, as thorium is more abundant than tritium and deuterium, operating thorium based nuclear reactors are less expensive to operate and gives energy at lower cost.
+sourabh bajirao Thorium MSR reactors are a great development, and they are cleaner than traditional fission, but still not as clean as a fusion reactor.   Also I'm not sure that thorium is more common than deuterium - there is a lot of ocean out there!  Thorium is a good fall back option, but compaction fusion if possible would be even better.
Deuterium plus tritium also creates neutrons.Those may activate up the vessel, though you can capture them with other methods, preferably water.
+Peter Kövesárki That was the activation i was talking about. It is many orders of magnitude easier to deal with than fission waste (ie the hard part of nuclear waste).  

+sourabh bajirao 
Thorium is not more common than Deuterium or the Lithium needed to bread Tritium. And lets not forget that Thorium is fertile not a fuel. You create 233U from it that is used as the fuel. It produces about the same waste as a normal Uranium fuel cycle with full reprocessing. There are however less Actinides that makes a bit easier... but then there is that pesky 234U, a strong gamma emitter than would make reprocessing very difficult. 

Reprocessing adds about a factor of 60 to the usefulness of a pound of Uranium  Note that you must reprocess for a Th cycle since its not a fission fuel. 

Finally the LFTR are totally safe/can't go wrong is really misleading. First nothing goes wrong as planed. Ever. Secondly its still a fission reactor with all the normal issues. ie decay heat. It can never just "turn off", cooling must be provided for quite some time. The salts used react with water and are corrosive. Core breaches are of course possible and just as bad as normal reactors (but better than that Russian rubbish). It is not a panacea of nuclear energy. 

Last but not least it would about about 10 years to build a full prototype and another 10-20 years of running before this would really be deployable in a wide scale. 

Currently MSR reactors are not being developed. 
+Greg Ewing MSR reactors not developed? Whether any current project has enough funding is an open question, but that they are not developed is a false statement. Of the more publicized are +Kirk Sorensen's Flibe Energy and the very recent (also presented on the Solve for X website)

Feel free to join the Thorium community over at

And the MSR (LFTR) is considered inherently safe for the simple reason that gravity is the only energy you need to solve a meltdown. There is no pressure, so you won't get atmospheric blowouts, and so on. Yes, there are challenges, but they are the right ones.
+Lars Ivar Igesund There have been only 3 very early prototypes are the largest was 10MW. They are a long way from developed. The last one, one that used 233U for fuel but left out any breading of 233U from Th for cost reasons was mostly ok. But no unity breading ratio was demonstrated and 10MW is a far cry from 1000MW.  For utility scale they are not developed. The time frames i gave are from proponents of MSR, and IAEA reports. 

The last design that could never have problems was pebble bed reactor. The only reason you didn't hear what a total disaster that was, was because it happened the same time as Chernobyl.

Soon as you say... "perfectly safe, nothing can go wrong" everyone knows your wrong. Miss management  cost cutting, operator mistakes or even a big bloody earth quake. Things never go wrong the way you plan. Ever. That is way its wrong in the first place.
+Greg Ewing They are not developed as in being in the market, but they are under development. China is even (going by their own words) putting real effort into it.
The freed neutron doesn't break down the containment walls as it does in the Tomamak? Do we still need to harvest Helium-3 from the Moon's surface?
Don't need helium-3, that's a different fusion reaction. The fuels for this one are deuterium (abundant in seawater) and tritium (which barely exists in nature, but can be made by exposing lithium to the neutrons from the fusion reaction).
+Greg Ewing Most of the liquid thorium designs feed thorium directly into the reactor vessel. The neutrons in the reactor convert it to U233 on the fly.

Decay heat is actually much less of a problem with MSRs, because with liquid fuel you can get rid of the fission products as you go. Some of them are gases and just bubble right out.

The salts do not react with water. (Some fast reactors, on the other hand, use sodium, which decidedly does.) Oak Ridge researchers felt they'd figured out an alloy that solved the corrosion problem.

MSRs are being developed in a number of countries, most notably China, which has a billion-dollar budget for it and several hundred researchers on the task. Cheap-enough fusion would make MSRs obsolete, but I'm glad to have them as a backup.
So will we also know if their design has failed within 5 years, or sooner than that?  The first five years are spent on the science and experiments, with a prototype in 2017.

That is aka research, just to know if it will even work, is going to continue until 2017.

Maybe this is why Lockheed Martin's SkunkWorks doesn't get to talk about its research projects so much.  The downside to moonshot projects is that everyone is interested in them, but few understand what the stakes actually are.
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