ah, right so.
I'm still not in any way convinced it's a solution. There's not that much wrong with fission that will be solved by hot fusion, either
( the mighty badger Aphrodite, on a bar stool, by your side, Thu 18 Oct 2012, 13:36, 2 replies, latest was 13 years ago)

You mean apart from the hugely toxic side products that occur from fission and that simply don't exist with fusion?

(Bazongaloid, Thu 18 Oct 2012, 13:41, Reply)

yeah, but I'll take toxic products (which, despite the wailing of hippies, we are pretty adept at dealing with)
over the inherent instability and associated danger of fusion. Well, maybe not take it, but at least accept there are pros and cons.
( the mighty badger Aphrodite, on a bar stool, by your side, Thu 18 Oct 2012, 13:44, Reply)

*wails*

( tangledupinblue hairy badge with moving eyes, Thu 18 Oct 2012, 13:46, Reply)

A fusion reaction cannot accelerate out of control, you cut off the supply of fuel and the reactions cease
Unlike with a fission reactor, where if you aren't careful with the control rods, you'll wind up burning a radioactive hole through the Earth's crust if it all goes pears.
(Bicycle Repairman "you're also a bit of a wanker", Thu 18 Oct 2012, 13:47, Reply)

I'm pretty sure the "you just cut off the fuel supply and..."
was an argument used in development of fission reactors.
( the mighty badger Aphrodite, on a bar stool, by your side, Thu 18 Oct 2012, 13:50, Reply)

No it wasn't.
Or if it was, it was an argument made by people who don't understand how fission reactors work and therefore whose opinions are totally invalid.

I don't try and argue against complex brain surgery techniques for exactly the same reason.
(Bazongaloid, Thu 18 Oct 2012, 13:53, Reply)

fission stops if you no longer have enough material to sustain a chain decay reaction.

( the mighty badger Aphrodite, on a bar stool, by your side, Thu 18 Oct 2012, 13:54, Reply)

Why are you talking dirty to me?

(Bicycle Repairman "you're also a bit of a wanker", Thu 18 Oct 2012, 13:56, Reply)

because it's science chat and I fancy you.

( the mighty badger Aphrodite, on a bar stool, by your side, Thu 18 Oct 2012, 13:57, Reply)

But that happens a long time after you're dead and charcoally.
with fusion all that happens is it stops and you are left with a big pile of water.
(Bazongaloid, Thu 18 Oct 2012, 13:58, Reply)

I definitely don't know this, so it's just a straight-up question
given the "issue" with fission is that the reaction becomes a chain until it runs out of fuel, and the fusion could do the same, how is fusion safer? I get that you could control the fuel feed in a fusion system which you obviously can't in a fission one because of the whole critical mass thing, but theoretically anything smaller than iron can fuse and release energy. If we build a fucking big one, isn't there a risk assoicated with things other than the fuel fusing? and what if a fuel supply cutoff fails?
( the mighty badger Aphrodite, on a bar stool, by your side, Thu 18 Oct 2012, 14:02, Reply)

Fusion doesn't chain reaction in the same way.
You need to keep the pressure and temperature incredibly high to make teh reaction happen. When it does you end up with a net increase in energy, but if it goes tits up and say your reacion chamber broke, there would be an instantaneous drop in pressure. Now there might be a big fire, but the reaction would stop straight away and therfore not continue fusing.

Plus, the product of fusion is helium, so rather than blowing highly radioactive shit everywhere, you have a bit of a fire and everyone talking in squeaky voices. No harm no foul.
(Bazongaloid, Thu 18 Oct 2012, 14:07, Reply)

I totally get the by-products being safer.
assuming it's just and H to He fusion.

I'm still not convinced at large scale there isn't a serious risk - I guess it depends how interchangable temperature and pressure are as reaction conditions.
( the mighty badger Aphrodite, on a bar stool, by your side, Thu 18 Oct 2012, 14:10, Reply)

There is a risk, it could explode and kill all the people in the factory
but what it won't do, what it physically cannot do, is keep burning and reacting and melting the core so it sinks through the Earth's crust, all the while spewing out deadly toxins and irradiating a wide area around the plant, and some of Wales.

So from that point of view, it's immeasurably safer.
(Bazongaloid, Thu 18 Oct 2012, 14:12, Reply)

You have a similar level of risk...
...if you drop a freshly baked McDonald's apple pie onto the pavement.

They're the hottest substance known to science.
(Bicycle Repairman "you're also a bit of a wanker", Thu 18 Oct 2012, 14:17, Reply)

My labs are only class 2
we can't have McDonalds apple pies in them, the safety handling systems aren't up to it. So I am unable to confirm or deny this.
( the mighty badger Aphrodite, on a bar stool, by your side, Thu 18 Oct 2012, 14:22, Reply)

I see that.
I just wonder, for a large reactor, just how big a bang it would be. I mean the explosion might well wipe out a whole city rather than just the factory.

Still, I appreciate, better than a massive radiation leak. Unless, of course, it's in Wales.
( the mighty badger Aphrodite, on a bar stool, by your side, Thu 18 Oct 2012, 14:19, Reply)

The answer is therefore obvious!
We build the fucker in Runcorn.
(Bicycle Repairman "you're also a bit of a wanker", Thu 18 Oct 2012, 14:20, Reply)

Possibly as big as a fission reactor
You wouldn't build it in the city centre, that would be retarded.

You're such a retard.
(Bazongaloid, Thu 18 Oct 2012, 14:20, Reply)

yeah, well, it takes one to know one
and you know perfectly well what I meant.
( the mighty badger Aphrodite, on a bar stool, by your side, Thu 18 Oct 2012, 14:22, Reply)

That depends which city centre you have in mind.
I can think of a few which would be made more desirable with the addition of an explodey, hydrogen hot-hot thing.
(Bicycle Repairman "you're also a bit of a wanker", Thu 18 Oct 2012, 14:25, Reply)

Erm....you know how a fission reactor works don't you?
Just checking.

Worth reading up on how Chernobyl happened, the control rods became jammed in the atomic pile and thus couldn't moderate the reaction.
(Bicycle Repairman "you're also a bit of a wanker", Thu 18 Oct 2012, 13:53, Reply)

I'm not saying in reality it's physically possibly to stop a fission reaction.
just that theoretically if you remove fuel it'll stop.
( the mighty badger Aphrodite, on a bar stool, by your side, Thu 18 Oct 2012, 13:55, Reply)

Practically speaking, if you stop putting fuel pellets into a fusion reactor
It'll stop right away. A fission reactor remains hot for ages after, not to mention that the fuel itself can become flammable and thus cause further contamination - see Calder Hall for more details.
(Bicycle Repairman "you're also a bit of a wanker", Thu 18 Oct 2012, 13:58, Reply)

If fusion goes wrong it just stops
if fission goes wrong it explodes and you get hot flamy death everywhere.

And I'm not remotely convinced we are in any way "adept" at dealing with nuclear waste. Burying it in a big hole, a hole that they can't dig anywhere because nobody wants it, isn't really dealing with it, it's just pushing it under the carpet.

I'm totally in favour of building a fuck load of new fission plants though, it would make the UK pretty much self reliant. If we did what the french did and just build a standard design several times we'd be creating our own cottage industry too.
(Bazongaloid, Thu 18 Oct 2012, 13:47, Reply)

That instability is not a big issue from my understanding. There's not self sustaining part of a fusion reaction.
It has to be activly managed by magnetic (or laser) compression and removal of the fused products. If you let it carry on it just stops. Nothing like a meltdown.
(PsychoChomp, Thu 18 Oct 2012, 13:47, Reply)

fission curry
fusion not curry
( Naked Ape call me Caitlyn, Thu 18 Oct 2012, 13:45, Reply)

hahahaha!

( sporters I’m sincerely gratitude to you, Thu 18 Oct 2012, 13:52, Reply)

Thanks sporters

( Naked Ape call me Caitlyn, Thu 18 Oct 2012, 13:56, Reply)

Well, fission is really only feasible for a short period of time as we've only got 80 years of commercially viable Uranium in the ground
Fusion has the advantage of using an abundant source of fuel. From what I've read about it - and the gazzes I've exchanged with a b3tan involved in an experimental fusion reactor project - the main constraint is one of containment. It's more of an engineering problem than a theoretical physics problem.
(Bicycle Repairman "you're also a bit of a wanker", Thu 18 Oct 2012, 13:44, Reply)

what are you planning to fuel your fusion reactor with, out of interest?

( the mighty badger Aphrodite, on a bar stool, by your side, Thu 18 Oct 2012, 13:45, Reply)

Kittens :(
He's an awful awful man
( Naked Ape call me Caitlyn, Thu 18 Oct 2012, 13:47, Reply)

it's spelt Kityums.

( the mighty badger Aphrodite, on a bar stool, by your side, Thu 18 Oct 2012, 13:50, Reply)

Plastascine that you heat in the oven.
Hard as a fucking rock that stuff.
(Bazongaloid, Thu 18 Oct 2012, 13:48, Reply)

Fimo

( Naked Ape call me Caitlyn, Thu 18 Oct 2012, 13:48, Reply)

pricks who play hockey and have gay nicknames

(quintsy, Thu 18 Oct 2012, 13:49, Reply)

It's not my fusion reactor
I could build a model one out of lego if you'd like? I can fuel it with little bits of lego.

As I understand it, it comes down to sourcing Deuterium, which is very abundant in seawater.
(Bicycle Repairman "you're also a bit of a wanker", Thu 18 Oct 2012, 13:50, Reply)

which you'll need to extract from seawater.
which needs power. lots of it. it's the same argument as to why hydrogen fuelled cars are a gigantic fucking scam, ecologically and sustainably speaking.


Look, I'm being deliberately facetious here, I'm sure there's something in fusion, I'm just pointing out that there are massive flaws in it, which people somehow brush under the carpet with something that's seen as "the future"
( the mighty badger Aphrodite, on a bar stool, by your side, Thu 18 Oct 2012, 13:52, Reply)

Hydrogen fuelled cars would be great
but it's difficult to store and trasnport the hydrogen, and difficult to manufacture it in situ efficiently.

But solve eitehr of those problems and BAM free electricity.
(Bazongaloid, Thu 18 Oct 2012, 13:54, Reply)

erm, dude
you're made of hydrogen and so is the sea

you don't need to 'manufacture' it
(quintsy, Thu 18 Oct 2012, 13:56, Reply)

neither of those are the problems at all (well, they are, but not the really big one)
it's impossible to make hydrogen in any quantity without catalytically cracking hydrocarbons. Which a) uses hydrocarbons you could have just burnt in a petrol engine and b) takes place about 1300 centigrade, meaning it uses up just a tiny bit of energy to make it.
( the mighty badger Aphrodite, on a bar stool, by your side, Thu 18 Oct 2012, 13:57, Reply)

Turn the thermostat up a bit and BAM!

(Bicycle Repairman "you're also a bit of a wanker", Thu 18 Oct 2012, 13:59, Reply)

You can electrolyse water.
Only not very efficiently. Which is one of the points I made above.

Do keep up.
(Bazongaloid, Thu 18 Oct 2012, 13:59, Reply)

The sun also emits a lot of Deuterium
The surface of the moon is covered in the stuff apparently. Of course, we can't sweep all the shit off the streets of London at a reasonable cost, let alone the surface of the moon, so that may be a few decades off just yet.
(Bicycle Repairman "you're also a bit of a wanker", Thu 18 Oct 2012, 14:02, Reply)

you can't at scale.
using current tech you could probably electrolyse enough water annually to cover about 1% of the private vehicles in London, I think.

And it uses more energy to electrolyse water than you get by burning hydrogen and it always will do, that's not a problem that can be "solved" because it's a fundamental thermodynamic principle. So, it's not free anything. It's a higher cost both financially and in energy terms, it's just a load of smoke and mirrors to make it appear not to be.
( the mighty badger Aphrodite, on a bar stool, by your side, Thu 18 Oct 2012, 14:05, Reply)

That is rendered nearly moot if the energy conversion has been done already.
Those fossil fuels required energy input to get to their current state, it just took many millions of years.

If we sweep up solar deuterium from the surface of an asteroid, the sun has already done the hard bit for us.

In theory of course.
(Bicycle Repairman "you're also a bit of a wanker", Thu 18 Oct 2012, 14:22, Reply)

that might well be fine for a fusion reactor
it's not gonna power a hydrogen car though, which is what we're on about here.

Although, I'm prepared to take at least a small punt that the energy required to get a harvesting vehicle clear of the earth's gravitational pull might be more than you could ever recover from the deuterium it could collect.
( the mighty badger Aphrodite, on a bar stool, by your side, Thu 18 Oct 2012, 14:25, Reply)

Well, we already send vehicles with electrolyticly separated hydrogen and oxygen to the moon
Which is a far better use of it than simply cracking it to power millions of cars, wasting gigawatts of energy in the process merely as a sop to the big oil companies who are investing in hydrogen storage technology.
(Bicycle Repairman "you're also a bit of a wanker", Thu 18 Oct 2012, 14:39, Reply)

Cracking methane emitted from landfills.
This is another revenue stream that will make me a billionaire.
(PsychoChomp, Thu 18 Oct 2012, 14:04, Reply)

+ once I can persuade someone to invest several million pounds in my not-yet-started start-up company

( tangledupinblue hairy badge with moving eyes, Thu 18 Oct 2012, 14:05, Reply)

just run the cars on methane. it burns.

( the mighty badger Aphrodite, on a bar stool, by your side, Thu 18 Oct 2012, 14:06, Reply)

only the really hot ones

(quintsy, Thu 18 Oct 2012, 14:12, Reply)

It's not emmited consistantly
and a lot of it leaks away. It's not gonna work.
(Bazongaloid, Thu 18 Oct 2012, 14:14, Reply)

Tell me about it
Someone in my office is fucking leaking a lot of it right now

:-(
(Bicycle Repairman "you're also a bit of a wanker", Thu 18 Oct 2012, 14:18, Reply)

alright then anerobic digestors.

(PsychoChomp, Thu 18 Oct 2012, 14:24, Reply)

These are a great idea
and should be used everywhere. As should waste incinerators.
(Bazongaloid, Thu 18 Oct 2012, 14:33, Reply)

Fully agree
doing some stuff with the whisky industry up here associated with that. About the only downside of AD units is that they don't handle high protein levels very well so you have to be selective about the food waste you put it them. But otherwise they're a no-brainer.
( the mighty badger Aphrodite, on a bar stool, by your side, Thu 18 Oct 2012, 14:38, Reply)

I agree, they kick out a decent amount of heat as well.
I wonder if there's much study about the ideal size for them.
(PsychoChomp, Thu 18 Oct 2012, 14:38, Reply)

fucking shitloads of studies, yep
they are fairly flexible, although too big and the heat is a problem. Plus, they self-poison.
( the mighty badger Aphrodite, on a bar stool, by your side, Thu 18 Oct 2012, 14:41, Reply)

There was a piece a few years back
about a guy who signed up for every piece of junk mail he could, and then every morning loaded it into a device that compressed it into bricks and used them to power his furnace.

Not practical on a large scale, I suspect.
( The Light in Chains don't touch the Pope's boner, Thu 18 Oct 2012, 14:38, Reply)

Shhhh, don't tell people what i do for a living!

( Naked Ape call me Caitlyn, Thu 18 Oct 2012, 13:46, Reply)

pfft

(quintsy, Thu 18 Oct 2012, 13:50, Reply)