nuclear fusion anyone?

[ik9000]

while the BBC is busy reporting on BS stories about Drag Race and whether young lovers should dump their partner before university other sites bother to report on things that are vaguely interesting and important:

https://uk.reuters.com/article/uk-br...-idUKKBN1WI13F

It would be nice if we can make it happen. I didn't think the Oxford research project had found a sustainable lasing source for industrial scale-up yet though. Has there been a breakthrough or are we just doing it because the Chinese are? I hope this isn't dependent on their funding/involvement...

[scaryjim]

Obligatory XKCD:



2040 is still 21 years out, so...

[Ttaskmaster]

Why worry about something that isn't going to happen......

[Smudger]

Already been done...

[g8ina]

JET at Culham Labs has been doing this since at LEAST the mid 70s.

In fact, I just picked up an info leaflet just last night at my camera club, havent read it yet, will report back shortly.

[g8ina]

and apparently they achieved 16MW back in 1997 !!!

[g8ina]

and ITER is our best bet. Googling that shouold bring u up to speed.

[ik9000]

Yes, proof of concept has been nailed for some time, but the issue has always been finding a sustainable lasing material that is abundant enough and economical enough to make the process viable on an industrial scale. When I last checked a few years ago that was still not resolved.

[AETAaAS]

2040 is still 21 years out, so...

Don't worry, its a government project. 21 year target means 28 years and 400% over budget.

[ik9000]

or else potentially world-beating only to be cancelled part-way after a change of government. cough *TSR2* cough.

[[GSV]Trig]

Mmmm TSR2, Born to Bomb..

[watercooled]

Still, $220M is quite a lot of money to invest? Seems like more than a speculative/token amount.

[Xlucine]

The issue with fission isn't the spent fuel (the quantities in involved is tiny), it's the rest of the reactor. Bombarding any material with neutrons will form strange and exciting radionuclides, so the vast quantities of stuff that makes up the reactor structure becomes low-grade nuclear waste - not hot enough to where it needs cooling, but radioactive enough that no-one wants it near them. Most fusions reactions (including the deuterium-tritium one used in ITER) release neutrons as part of the reaction, and as these can't be contained by magnetic fields they bombard the walls of the tokamak.

So fusion is not clean (probably about the same amount of nuclear waste as a fission plant), we aren't running out of fissionable material yet, and fusion costs orders of magnitude more than fission (infinitely more, going by the investment against energy delivered to the grid). Why are we doing this again?

[philehidiot]

The issue with fission isn't the spent fuel (the quantities in involved is tiny), it's the rest of the reactor. Bombarding any material with neutrons will form strange and exciting radionuclides, so the vast quantities of stuff that makes up the reactor structure becomes low-grade nuclear waste - not hot enough to where it needs cooling, but radioactive enough that no-one wants it near them. Most fusions reactions (including the deuterium-tritium one used in ITER) release neutrons as part of the reaction, and as these can't be contained by magnetic fields they bombard the walls of the tokamak.

So fusion is not clean (probably about the same amount of nuclear waste as a fission plant), we aren't running out of fissionable material yet, and fusion costs orders of magnitude more than fission (infinitely more, going by the investment against energy delivered to the grid). Why are we doing this again?

Indeed, are there any Gen 3 Type II reactors online yet? Gen 4 should fission everything. As you say, the issue is the decomissioning of the plant. Where there's not a massive amount of waste from the production of energy in new designs, the amount of low level waste is huge when it has had its day.

This is one of the reasons Fukushima was such a stupid set up. If you look at the history, you can say that the level of quake they had was a 1 in 1000 year event (very roughly). From that you can say that a 7.0 quake will be around a 1 in 100 year event. The sea wall is not the only factor here, the elevation is also a factor and not just the elevation of the reactors (sufficient) but the elevation of the emergency systems to stop a plant blakc out (much lower). Look at how hard it is to decomission nuclear sites. We have 50 year old nuclear subs sat rotting as it's easier and safer to let them sit, contained for now. It's the same with reactor buildings. Robots fry in the dosey environment very quickly and even now we're limited as to how long they'll be operable for. So it's sensible to let reactors sit and for the nasty stuff to decay before you start tearing it apart. Look at the new containment around Chernobyl and you'll see how long a process this can be. And it's quite probable you'll need active cooling for those reactors / fuel rods even when they are shut down.

So a nuclear site is probably a risk for ~150 years, assuming you don't just cordon it off and maintain the building. And Fukishima is at risk of 1.5 tsunamis which would flood their emergency generators for that time. Oh and they didn't protect the generators because hey, nothing is gonna happen to take out external power AND our backups, right? RIGHT?

As I said, stoopid. So the issue as far as I'm concerned is not the reactor and its waste but the legacy it leaves and how that's managed. At the moment, it really isn't very well.

And as stated above, fusion provides the same issue. So why are we doing this? Simples:

Without fusion, we can't create enough antimatter for the matter-antimatter reactor that's gonna take us off this planet when we've screwed it completely.

That and the world's energy demands are going up and up and transitioning the poor off wood and coal and oil is very hard to do when their governments don't have enough poke to stop everyone murdering each other. If you have enough chooch from a central, properly managed fusion station then you can interconnect it and sell it to these countries. Maybe drive up the standard of living enough so they aren't killing each other or, if they are, at least they can use ray guns.

Also remember in first world countries, hydrocarbons are currently being directly burned to make things go and, whilst it may be utterly stupid at the moment, the future is electric. That's a whole lotta energy that needs to be supplied by the grid and not by tankers full of happy boom boom juice.

According to my little red dot of judgement, there are 15 spelling mistakes in this. I careth not.

[watercooled]

So fusion is not clean (probably about the same amount of nuclear waste as a fission plant),

That's not even remotely true. As far as actually concerning high-level waste is concerned, you're dealing with pretty much just reactor components, not thousands of tons of spent fuel to reprocess and store on top of reactor components. The high-level waste also doesn't remain high-level for nearly as long as fission waste products so realistic storage and disposal is far more straightforward.

Why are we doing this again?

Because uranium is relatively scarce, thorium less so but less proven as a fuel, but either way they're quite finite. Given the timescale needed for fusion R&D it's sensible to start before the need becomes critical. Also there's effectively no proliferation risk with fusion, far less waste, very little accident potential, and so on. It's not just a school science project to keep people busy.

[watercooled]

And as stated above, fusion provides the same issue.

It really doesn't. There is no risk of decay heat for a fusion reactor, so no requirement for external power should the reactor trip. The same can be said of more advanced fission designs but we're still waiting on walk-away safe reactors to get built, and they're safe because of thermal design, not because of inherent safety of the fuel/process.

With fusion reactors, the reaction is difficult to sustain so a failure leads to the reactor pretty much just stopping. There's no massive lump of fission products to meltdown without sufficient cooling, no graphite moderators to catch fire, no control rods to get stuck. Even in a deliberate, catastrophic containment breach you have a worst-case of a tritium leak, which is still of no substantial concern to health.

There is great incentive to develop fusion power reactors for the above reasons and more, it's not just a sideways step from fission in terms of safety, etc.