Nuclear Power

[Jim]

I'm not going to offer an opinion because I've done very little research and this is such a technical question. OTOH, if there is relative safety, maybe we should go more towards nuclear power to alleviate global warming. I'd be very curious to know what the group thinks.

[Sisyphus]

I'm in favor of nuclear power, myself. It's more cost efficient (and could actually be made even more so), produces more power absolutely, produces no air pollution whatsoever, and is not dependant on the whims of fundamentalist psychopaths. New plants have fail-safes to the point where you could drop bombs on them and suffer nothing worse than a blackout. The only real issue is the disposal of radioactive waste, of which I can't seem to find a straight answer about how much of a problem it really is. Seems like hot rocks must be usable for something, though...

 

On the other hand, it would be subjugating ourselves to yet another non-renewable resource, so that could be an issue, also.

 

I think, until there are reliable renewable sources of power, nuclear is probably a better backup than oil. In other words, wind is great, but something needs to take up the slack on a still day.

[-Demosthenes-]

I think nuclear is worth pursuing, but I personally think that solar has much more potential. If I'm not mistaken we can run out of fission material (like Uranium), but the sun will be there for a while. It's not as cheap, but in the far away future I think it'll be necessary. But maybe not.

[swansont]

"No pollution" ignores the construction of the plant, but it's certainly less pollution per kWh produced over the life of the plant than for fossil fuels.

 

A problem in the US is education. People are afraid of nuclear power and radiation, but partly because they don't understand anything about the technical issues and can't objectively assess the risk.

[Sisyphus]

A problem in the US is education. People are afraid of nuclear power and radiation' date=' but partly because they don't understand anything about the technical issues and can't objectively assess the risk.[/quote']

 

Yeah. "Nuclear" is just one of those science fiction words that people are irrationally afraid of. Just like cloning.

[SkepticLance]

Disposing of nuclear waste is a political problem, not technical. There are already several quite acceptable methods available. The trouble is that agitators will not permit these methods to be used.

 

For example : The worst isotopes in waste have short half lives (that is why they are so radio-active.). If nuclear waste is stored in a secure warehouse for 20 years, these short half life isotopes will then have decayed. What is left can be dissolved in acids and pumped into the ocean. The dilution factor is so immense that the remaining radio-active isotopes will almost immediately reach a concentration lower than that of the Uranium 235 naturally present.

 

If this answer is considered unacceptable (politically) then all we need to do is dig a big enough hole in the right place and leave it there. Choosing the right place is the key. It should, ideally, be extremely arid, geologically very stable, and unpopulated.

 

Australia has many ideal sites. South Africa ditto. Even some parts of Siberia are not too bad, though my first choice would be Australia. Again, the reason it is not happening is political; not technical or environmental. Agitators will not permit this to happen.

[Saryctos]

If nuclear waste is radio-active, why is it considered waste, and not just less efficient nuclear fuel? It seems like a good way to reduce waste would be to combine it(smelting?) into more potent material and recycle it into a nuclear plant untill you've used it all up(or it becomes so inefficient that it's not worth doing).

 

Also, I feel I should point out that nuclear, and carbon based fuels are the ONLY usable source of energy in this solar system, everything else is just a diluted form. This statement mainly points at Solar,Wind, and Geo-thermal.

 

While people are scrambling over "the end of oil", why not look to the future and ask where we'll get our fuel from once we've devoured all the matter within this solar system? The problem here is just fundamental, we use fuels to generate usable energy, but then don't bother to harness that usable energy again. Conservation of energy should be our friend, not our enemy.

[-Demosthenes-]

Disposing of nuclear waste is a political problem' date=' not technical. There are already several quite acceptable methods available. The trouble is that agitators will not permit these methods to be used.

 

For example : The worst isotopes in waste have short half lives (that is why they are so radio-active.). If nuclear waste is stored in a secure warehouse for 20 years, these short half life isotopes will then have decayed. What is left can be dissolved in acids and pumped into the ocean. The dilution factor is so immense that the remaining radio-active isotopes will almost immediately reach a concentration lower than that of the Uranium 235 naturally present.

 

If this answer is considered unacceptable (politically) then all we need to do is dig a big enough hole in the right place and leave it there. Choosing the right place is the key. It should, ideally, be extremely arid, geologically very stable, and unpopulated.

 

Australia has many ideal sites. South Africa ditto. Even some parts of Siberia are not too bad, though my first choice would be Australia. Again, the reason it is not happening is political; not technical or environmental. Agitators will not permit this to happen.[/quote']

 

How much would it cost to shoot it into space?

[sunspot]

The problem with nuclear power is not just the waste, but the waste of time, money, and effort caused by those who irrational fear the worse case scenario. The solution was supose to be fusion power. However, the push appears to be taken the wrong path, since we are not much closer than 20 years ago. I noticed that nobody showed much faith in the fusion program either.

[[Tycho?]]

People show plenty of faith in the fusion progam, its just expensive and time consuming. I wouldn't expect fusion power plants before 2050, assuming all goes well from here on in.

[Pangloss]

How much would it cost to shoot it into space?

 

I think that's actually been discussed in the past. I believe the consensus is that it's too expensive with current technology, but it's possible that the advent of private, commercial space development could produce a reasonable avenue in the not-too-distant future. Of course low earth orbit isn't enough here -- obviously you'd prefer to do something more along the lines of tossing it into the sun.

 

Note that the key here is not so much what the cost of solar-dumping, but rather the cost of solar-dumping as compared with the cost of current dumping, which of course is fairly expensive compared with something like normal trash, since you have to build containment vessals and monitor seepage over time, etc.

[swansont]

For example : The worst isotopes in waste have short half lives (that is why they are so radio-active.). If nuclear waste is stored in a secure warehouse for 20 years' date=' these short half life isotopes will then have decayed. What is left can be dissolved in acids and pumped into the ocean. The dilution factor is so immense that the remaining radio-active isotopes will almost immediately reach a concentration lower than that of the Uranium 235 naturally present.

[/quote']

 

 

That's actually why the short-lived isotopes are not the worst. They rapidly decay away to low levels. The really long-lived ones are not much of a problem because they don't have high activity levels to begin with. The worst ones are the ones with intermediate half-lives (thousands of years, give or take an order of magnitude or two), since they have significant activity and they don't decay away quickly.

[SkepticLance]

Swansont.

We could end up arguing semantics here. I defined 'worst' as being those that have greatest short term radio-toxicity. True that long term isotopes have more 'long term' problems if we define long term as more than 20 years. However, they also cause less damage when well diluted, due to their smaller radio-emissions over a short period of time.

[SkepticLance]

Demosthenes.

"Shooting waste into space."

The answers are less clear than immediately obvious.

First : Quantity. Total nuclear waste each year is hundreds of thousands of tonnes. Obviously not possible to lift all that into orbit, much less fling it into the sun or other safe repository.

 

However, most of that waste is impurity. The actual tonnage of radio-active isotopes in that waste is a little over 100 tonnes per year. If it were practical and economic to purify it all here on Earth, and remove all the isotopes, leaving the rest purified, then it might be possible to lift 100 tonnes per year.

 

Sadly, we currently lack the technology for that level of purification.

 

Second : How to lift lots of mass into space. Again,current technology is inadequate. However, this may not always be the case.

There is a team working on development of a carbon nanotube 'cable' into space. They CLAIM it will be done by 2018. I seriously doubt that. However, such a 'cable car' into space may be ready in a few more decades.

The team recently built a one mile cable, which they lifted by balloon, one mile into the air. That is a long way from the approximately 80,000 kilometer cable they will eventually need, running vertically from the Earth into space.

 

If and when it is actually done, we can predict we will have advanced maglev propulsion. At that point it would be feasible, at least in theory, to accelerate a mass of 100 tonnes or more over the full length of the cable, and fling it into space with no more cost that the electricity required. If the timing of the release was right, it would continue to a 'safe' destination, such as escape from the solar system entirely.

[Pangloss]

That's actually why the short-lived isotopes are not the worst. They rapidly decay away to low levels. The really long-lived ones are not much of a problem because they don't have high activity levels to begin with. The worst ones are the ones with intermediate half-lives (thousands of years, give or take an order of magnitude or two), since they have significant activity and they don't decay away quickly.

 

Thanks for posting that, it was really interesting. I had no idea it worked that way, but I guess it makes perfect sense.

[zyncod]

In terms of the supply, the remaining economically mineable uranium is 5-6 million tons (not very much). However, by extracting uranium from seawater (there is a surprising amount of it in there), the world's energy needs could be met for the next 5 billion years (Breeder reactors: A renewable energy source, American Journal of Physics, vol. 51, (1), Jan. 1983).

 

Hands up if you think humanity's going to be around in 5 billion years? No? So the supply, at least, is not really a problem.

[bascule]

A problem in the US is education. People are afraid of nuclear power and radiation, but partly because they don't understand anything about the technical issues and can't objectively assess the risk.

 

It's fairly difficult to explain the difference positive versus negative void coefficient makes in terms of reactor safety. People look at reactors with negative void coefficient and worry that they might be the next Chernobyl, even though a loss of coolant would just cause the core to scram in a reactor with negative void coefficient...

 

Fission is a nice stopgap measure, but my hope is for something like pyrofusion or sonofusion to be made into a portable, energy efficient reactor... then everyone can just produce their own power, rather that relying on a central power production/distribution grid.

[swansont]

It's fairly difficult to explain the difference positive versus negative void coefficient makes in terms of reactor safety.

 

Not to me

 

People look at reactors with negative void coefficient and worry that they might be the next Chernobyl, even though a loss of coolant would just cause the core to scram in a reactor with negative void coefficient...

 

One problem is that people tend to improperly weight the sources of information when they don't have the ability to discriminate and determine the quality of that information — they give too much credence to bad sources, because they sound plausible. So, they think that e.g. the "The China Syndrome" is a credible source of information, along with anything they find on the internet. And the media's reporting of science is no help, since they love to dramatize. e.g. "radiation" invariably becomes "deadly radiation." I recall being appalled at the reporting of the technical aspects of Chernobyl and just how wrong many of the explanations of reactor operations were.