How Long Until We Have Working Nuclear Fusion Reactor?

Well? Eni's working on one with MIT scientists and apparently there are nuclear fusion startups (whatever will they think of next on planet Startup) but most people seem to be sceptical. What does the forum think?

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Haven't kept up to date for a couple of years, but the place to look as the most likely place that someone has a smallish usefully working reactor is the US navy. If they don't have it first then some heads should roll.

I should ask one of my cousin inlaws as he works at Cadarache, although that project has been screwed up by the politicians getting involved.

The MIT one (again should ask another family member as she works there) does seem to be interesting especially if memory serves right with the way they control the neutron radiation degrading the reactor. Some good work also seems to have been done on instabilities with in the plasma. But seems to me another break through on increasing magnet strengths is required to control the plasma.

But lets hope it works out, although there is the possibility it'll not be cost effective against renewables in most markets. Would be very useful in space flight and colonising other places.  

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I guess it depends on how you define "working nuclear fusion reactor"

 

 

 

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Um, one that generates energy continuously and can be used on a commercial scale?

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On 10/11/2018 at 5:44 AM, Marina Schwarz said:

Well? Eni's working on one with MIT scientists and apparently there are nuclear fusion startups (whatever will they think of next on planet Startup) but most people seem to be sceptical. What does the forum think?

The startups' appearances were closely timed and recent.  This suggests to me that an enabling technology appeared, a critical market condition changed, or the potential of older technologies is being exhausted.  Whatever the case, competent efforts are now being invested in fusion.  If it can happen, it will.  When?  Dunno.  They haven't yet broken even - much less built a prototype, electricity-producing reactor.  We can't speculate on timelines when there are so many unknowns.

Answer: "When" is, as yet, an unproductive question.  "How can we support the effort?", on the other hand, may bear fruit. 

 

On 10/14/2018 at 3:27 AM, JunoTen said:

Something like 15 years if you're optimistic, but as stated it might not be cost-competitive with renewables (especially solar-on-the-roof) because I suppose there is a big investment for the reactor and also the cost of transmission.

https://www.nbcnews.com/mach/science/long-wait-fusion-power-may-be-coming-end-ncna833251

Transmission costs are enormous for renewables; a fusion reactor that produced no waste and was safer in operation than current-gen fission reactors would dramatically reduce transmission costs over  renewables and possibly reduce them over other generation options. 

Some of these fusion concepts are pulsed power that require an active input to function.  Otherwise, they lie inert.  This provides them a level of inherent safety.  If the physics allow them to be small, they'll be factory built and located close enough to loads for heat/power cogeneration.  At that point, you have low manufacturing costs, low fuel costs, low transmission costs, and low safety costs - all in a load-following package.  Drop it in, turn it on, and leave it alone for years/decades at a time.  In other words, once fusion's generation cost is in the same ballpark as other technologies, it renders everything else obsolete through reduced non-generation costs and versatility.  

If we can make it generate at reasonable cost.  That's a big if. 

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2 hours ago, mthebold said:

Drop it in, turn it on, and leave it alone for years/decades at a time

How would the reactor be shielded from neutron radiation for this time scale without active maintenance of some sorts? 

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1 hour ago, DA? said:

How would the reactor be shielded from neutron radiation for this time scale without active maintenance of some sorts

If you're basing your question in the ITER attempt, that thing is a case study in how not to advance a technology. 

I see three things we can work with: 

1)  Lower the quantity & energy of neutrons.  Fission is necessarily neutronic, that being what sustains the reaction.  Some forms of fusion are, conveniently, aneutronic.  More precisely, each nuclear fuel produces a different quantity of neutrons at a different average energy.  Neutron radiation damage depends on both quantity & energy of the neutrons, so one might be able to design a reaction with less neutron damage.

2)  Design radiation-resistant materials.  First, let's talk about neutron damage.  Fission reactors operate at high power for 40-60 years.  At this point, they anneal the reactor pressure vessel, effectively removing the damage.  The vessel can then go another 40-60 years.  They don't, however,  I believe nuclear reactor operation licenses can only be renewed twice, for a total of 80 years.  More recently, Russia has developed alloys specifically resistant to neutron damage.  I don't know if they commercialized it, but I believe the target life was 100 years.  The point is, materials can be designed to withstand radiation for decades. 

3)  Design a more robust reactor core. Fission reactors get 40-60 years out of a high pressure vessel.  These vessels are designed to contain 160 Bar of steam, and failure means a complete meltdown.  For that reason, 40-60 years is an incredibly conservative service life.  Will fusion reactors require the same pressures?  Doubtful; fusion only works in a fully evacuated chamber.  Will they require such high safety margins?  Also doubtful; if a fusion reactor core fails, the reaction immediately stops with little/no release of radiation.  With the mechanical requirements relaxed, we might be able to throw on extra shielding to reach the desired lifespan. 

So we have some advantages to work with: newer materials, tailor-made fusion reactions, and lower pressures.  We also have more flexibility in our safety systems.  Current fission reactors have those enormous concrete domes not only to protect from external threats, but also to contain a reactor failure.  They're made from an inch of steel and four feet of concrete so that, in the event of a reactor failure, the radioactive, high-temperature, high pressure steam can't escape.  You don't need all that for a fusion reactor, freeing up resources to improve the fusion core itself. 

Maybe you end up with a fusion reactor core body that lasts for decades, but you replace nozzles, electrodes, and other incidentals every few months.  Maybe you leave it all in place for 5-10 years before swapping in a new module.  I don't know how it will play out exactly, but we have options. 

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On 10/14/2018 at 7:05 AM, Marina Schwarz said:

Um, one that generates energy continuously and can be used on a commercial scale?

It always seems to be 30 years away😉

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I know, right? It's kind of frustrating for a casual observer such as myself so I can't imagine how frustrating it must be for those involved in crossing that 30-year bridge. 

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On 10/23/2018 at 4:53 PM, NickW said:

It always seems to be 30 years away😉

On 10/23/2018 at 10:32 PM, Marina Schwarz said:

I know, right? It's kind of frustrating for a casual observer such as myself so I can't imagine how frustrating it must be for those involved in crossing that 30-year bridge. 

My observation from rubbing shoulders with academia: 

1)  There are always people with pet projects in need of funding.  These people will say whatever necessary to get that funding. 

2)  There are always politicians looking to put their name on grand ideas and distribute money to buy votes.  These politicians fund the pet projects.

3)  I've never heard a private company say "It's 30 years out".  

4)  Great ideas tend to wait decades for Enabling Technologies to make them possible. 

I suspect government hyped fusion without any hope - much less plan - for success.  The politicians and academics got what they needed out of the hype though.  Today, however, we have private capital taking an honest swing at it.  That gives me hope that fusion is within reach.  

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I know Eni's put money in it. This must mean something.

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6 hours ago, Marina Schwarz said:

I know Eni's put money in it. This must mean something.

They put a lot of money into 'Cash All Gone' (Kashagan - Kazakstan)

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Wait, isn't it producing? I thought it was.

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1 hour ago, Marina Schwarz said:

Wait, isn't it producing? I thought it was.

Eventually

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On 10/24/2018 at 5:32 AM, Marina Schwarz said:

I know, right? It's kind of frustrating for a casual observer such as myself so I can't imagine how frustrating it must be for those involved in crossing that 30-year bridge. 

I once met a scientist working on the ITER project. He told me they would all be retired before fusion could be operated on a commercial scale.

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Oh, that's disheartening.

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I have been following the nuclear fusion project in France since the early 1990s. In 1993, specifically, I predicted that the world would undergo a technological lag for about 20-30 years before we could start to see the displacement of internal combustion engine vehicles by electric ones and nuclear fusion operating on a commercial scale to demand significant quantities of lithium. We are now approaching the upper limit of my forecast and can ascertain that only one half of my prediction was met. What happened? My first guess is that despite many billions of dollars spent by major powers in the ITER project, a lack of political will characterized most of these years of slow technological development mainly because of the existence of vested interests working within the different sponsor governments that prevented the consolidation of scientific breakthroughs. What I am saying now is that just as it occurred with EVs the time has come for some private entrepreneur such as Elon Musk to turn nuclear fusion feasible.     

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(edited)

Fusion faces very serious engineering issues of a fundamental nature, and this has been known for decades.   These issues will be there even if the plasma physics barriers are overcome.

The basic problem is that fusion reactors will have very low volumetric power density.

ITER, for example, is designed to produce about 0.05 MW per cubic meter of reactor volume (including the volume of the magnets but not the building enclosing the reactor).   The power density of its fusion plasma will be 0.5 MW/m^3.  MIT's ARC or Lockheed Martin's cusp reactor do a bit better, with overall power density of around 0.5 MW/m^3.

In contrast, the power density of the reactor vessel of a PWR is around 20 MW/m^3 (and the core itself inside that vessel, 100 MW/m^3).

Fusion reactors will be more than an order of magnitude larger than fission reactors, at a given thermal power output, and also much more complex.   So how can they possibly be economically competitive with fission, never mind the power sources that are killing fission?  Note that the cost of fuel for fission reactors (both making it and disposing of it) is minor, compared to capital and non-fuel operating costs.

The fundamental problem that causes this bad power density is one of heat transfer.  All the energy in a fusion reactor has to radiate through the wall of the reactor.   The ratio of wall surface area/volume (which is inversely proportional to the linear dimensions of the reactor) is lousy.  Compare this to a fission reactor, where the ratio of the surface area of fuel rods to the volume of the core (which is inversely proportional to the diameter of the fuel rods, which is about 1 centimeter) is much higher.

It is simply easier to get heat out of a fission core (or a fossil fuel boiler) than out of a fusion reactor.

Edited by paulfdietz
correct phrasing error
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