How Long Until We Have Working Nuclear Fusion Reactor?

[Marina Schwarz + 1,576]

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?

[DA? + 301]

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.  

[Refman + 207]

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

 

 

 

[Marina Schwarz + 1,576]

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

[JunoTen + 118]

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

[DA? + 301]

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? 

[NickW + 2,714]

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😉

[Marina Schwarz + 1,576]

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. 

[Marina Schwarz + 1,576]

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

[NickW + 2,714]

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)

[Marina Schwarz + 1,576]

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

[NickW + 2,714]

1 hour ago, Marina Schwarz said:

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

Eventually

[Guillaume Albasini + 851]

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.

[Marina Schwarz + 1,576]

Oh, that's disheartening.

[Juan Carlos Zuleta + 2]

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.     

[paulfdietz + 1]

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 November 22, 2018 by paulfdietz
correct phrasing error