Nuclear Power (merged threads)

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Re: Nuclear Power, what's your issue with it?

Postby thoughtfully » Thu Jun 05, 2008 1:41 am UTC

Folks also complain about radioactive substances launched into space. Well, getting stuff to the bottom of a deep sea trench is way more treacherous. We've put hundreds of people into space, but only a couple to the bottom of the Marianas Trench. Plus, the risk is greater, although by how much is certainly debatable. Douglas Adams has a famous quote about interstellar distances being totally beyond the capacity of humans to imagine, and one could argue the same thing about pressures in the deep sea.

EDIT: and how, exactly, does one ensure subduction? It seems to me that any body resting on the subduction fault will just slip along over it rather than get sucked down. Any shape that might work for subduction would also tend to break up easily.

Anyway, my solution to nuclear waste has already been covered: stop wasting it!
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Re: Nuclear Power, what's your issue with it?

Postby Korandder » Thu Jun 05, 2008 3:08 am UTC

However with ocean trenches unlike space craft there is no risk of the craft exploding on take off spreading radioactive debris over hundreds of square kilometers. This has happen before when a Soviet radar satellite powered by a nuclear reactor crashed in the Canadian arctic. Never mind how expensive it is to launch anything into space, especially at escape velocity.
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Re: Nuclear Power, what's your issue with it?

Postby thoughtfully » Thu Jun 05, 2008 3:26 am UTC

Korandder wrote:However with ocean trenches unlike space craft there is no risk of the craft exploding on take off spreading radioactive debris over hundreds of square kilometers. This has happen before when a Soviet radar satellite powered by a nuclear reactor crashed in the Canadian arctic. Never mind how expensive it is to launch anything into space, especially at escape velocity.


Quite so. Rather it is a risk of imploding. Depending on the depth and location, the debris can still get a pretty wide dispersal. There tends to be more stuff living in the ocean, too, since it is three dimensional.

Serious ocean going enterprises are not cheap, either. They can run 40,000 dollars a day, just for one ship. Anyway, the comparison was to geologic storage, not anything in space.
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Re: Nuclear Power, what's your issue with it?

Postby Bassoon » Thu Jun 05, 2008 5:12 am UTC

Isn't the waste less radioactive than before the fission? Why don't we just put it back where we found it, if it is? After all, it was in the environment in the first place.

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Re: Nuclear Power, what's your issue with it?

Postby endolith » Thu Jun 05, 2008 5:59 am UTC

Bassoon wrote:Isn't the waste less radioactive than before the fission? Why don't we just put it back where we found it, if it is? After all, it was in the environment in the first place.


In the long term, but it's much more toxic in the short term. If you touch nuclear fuel, you're fine. If you touch nuclear waste, you're dead.

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Re: Nuclear Power, what's your issue with it?

Postby e946 » Thu Jun 05, 2008 7:00 am UTC

My understanding is that it's "less radioactive" in that it has less energy than the stuff that was mined, but it is also way more dense, so it takes a much, much smaller amount to be harmful than the raw stuff.

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Re: Nuclear Power, what's your issue with it?

Postby Dream » Thu Jun 05, 2008 9:52 am UTC

Bassoon wrote:Isn't the waste less radioactive than before the fission? Why don't we just put it back where we found it, if it is? After all, it was in the environment in the first place.

You might want to continue mining there, for more uranium.
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Re: Nuclear Power, what's your issue with it?

Postby endolith » Thu Jun 05, 2008 2:55 pm UTC

e946 wrote:My understanding is that it's "less radioactive" in that it has less energy than the stuff that was mined


Damned laws of thermodynamics!

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Re: Nuclear Power, what's your issue with it?

Postby Minerva » Thu Jun 05, 2008 4:38 pm UTC

Well, the fission products removed from a reactor almost certainly have a lot more specific activity than the uranium or plutonium that went into it.

It should be remembered that radioactivity and nuclear fission are not the same thing. Nuclear fissionability of a particular nuclide does not imply that it's especially radioactive, or even that it's radioactive at all.

Uranium just isn't very radioactive at all - if it was highly radioactive, there just wouldn't be so much of it in the Earth.

Yes, in this house, we obey the laws of thermodynamics. But that doesn't mean that the fission products have less radioactivity - what they most certainly must have less of than the original uranium is mass.

The fission products are highly radioactive materials - but as it must be remembered, you can't have radioactivity without radioactive decay. The more radioactivity, the faster it's decaying.
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Re: Nuclear Power, what's your issue with it?

Postby bigglesworth » Thu Jun 05, 2008 6:24 pm UTC

endolith wrote:
e946 wrote:My understanding is that it's "less radioactive" in that it has less energy than the stuff that was mined


Damned laws of thermodynamics!


Actually, because of the mass defect, they have more energy than when they were mined.
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Re: Nuclear Power, what's your issue with it?

Postby ks_physicist » Thu Jun 05, 2008 10:11 pm UTC

There is already one about 25 miles away. I would be perfectly happy to have another dozen or so in the same radius, because that would mean we had actually committed to an alternative to oil/gas/coal as a primary energy source.

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Re: Nuclear Power, what's your issue with it?

Postby zealo » Fri Jun 06, 2008 8:08 am UTC

thoughtfully wrote:
Korandder wrote:However with ocean trenches unlike space craft there is no risk of the craft exploding on take off spreading radioactive debris over hundreds of square kilometers. This has happen before when a Soviet radar satellite powered by a nuclear reactor crashed in the Canadian arctic. Never mind how expensive it is to launch anything into space, especially at escape velocity.


Quite so. Rather it is a risk of imploding. Depending on the depth and location, the debris can still get a pretty wide dispersal. There tends to be more stuff living in the ocean, too, since it is three dimensional.

wouldn't implosions only be an issue if there are air cavities? why would there be air cavities?
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Re: Nuclear Power, what's your issue with it?

Postby thoughtfully » Fri Jun 06, 2008 10:50 am UTC

zealo wrote:wouldn't implosions only be an issue if there are air cavities? why would there be air cavities?


That's a good point, if you'e just dropping canisters off the side of your boat. If you care about where it goes, you need a more sophisticated system, with propulsion and some sort of lights or sonar, and generally a tether to the surface for control.

The pressure does put stresses and strains on the components. There is a huge difference between fourteen pounds a square inch and many thousands of them. A lot of space probles have been destroyed by high pressures, for instance.

Stopped functioning at 23 atmpopheres, which is equivalent to a depth in water of around 220 meters:
http://en.wikipedia.org/wiki/Galileo_pr ... ntry_probe

Probes to Venus have a long history of coping (or not) with very high atmospheric pressures:
http://en.wikipedia.org/wiki/Venera

The Japanese sent an ROV to the bottom of Challenger Deep in 1995, and later lost it when the tether broke in bad weather.
http://www.abc.net.au/science/news/stories/s897958.htm

You have to fill all the cavities with a nonconducting, uncompressible fluid (usually oil), and build all your components to much higher tolerances. And it had better stay liquid down to the freezing point of water. Generally, there is some sort of pressure vessel anyway, since engineering systems to work under pressure is problematic.

Geologic storage is still a lot cheaper and less risky, though. Oh, and we can always get it back when we get our panties unbunched over fast breeders.

It is rather amazing though, that critters as sophisticated as large octopuses get along just fine at some fairly impressive depths. If we ever had nonrigid tech that could stand in for the tech we use now, it would be pretty cool. But not for getting rid of trash.

I can't seem to find a link for deepest octopuses, although I did find a reference for deep molluscs in general:
http://www.conchologistsofamerica.org/a ... 1_leal.asp

Deepest Vertebrate
http://www.extremescience.com/DeepestFish.htm


EDIT: I recently also reminded that volcanic activity is common near subduction zones, and that subducted material can be ejected right back into the ecosphere this way. Presumably somewhat diluted.

Actually, I'm not sure that a rigorous analysis of this wouldn't show that the dilution wouldn't be to near or below background levels. From the graphics, it appears that there might be a lot of dilution before it gets to the volcanic areas. Depends on the details, it would seem. So much for bumper sticker goodness :)
Last edited by thoughtfully on Mon Jun 09, 2008 6:11 pm UTC, edited 2 times in total.
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Re: Nuclear Power, what's your issue with it?

Postby Izawwlgood » Fri Jun 06, 2008 5:34 pm UTC

I remember a national geographic bit about pulling up these deep sea critters, and most of them are either stunned or in the process of dying via violent decompression.

but that said, i recall reading that octopus and squid compensate with sulfur and ammonia containing body fluids to maintain buoyancy and equilibrium at those depths, instead of water.
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Re: Nuclear Power, what's your issue with it?

Postby bigglesworth » Mon Jun 09, 2008 4:20 pm UTC

Yeah, nowadays samples are kept in pressurised containers for the journey up.
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Re: Nuclear Power, what's your issue with it?

Postby gedtheflayer » Tue Jun 10, 2008 7:39 pm UTC

I know that most of the problems with nuclear power lie in the waste management, but nuclear power seems like a no brainer when it comes to using these materials. We've got these glowing green rocks we found in the ground, and two readily available uses for them: we can either harness them to create enormous amounts of electricity and stave off peak oil, or we can use them to more effectively blow the crap out of each other and render vast stretches of land functionally unusable due to radiation. I know that we only have a limited amount of the stuff, but some sort of buffer between running out of burnable hydrocarbons and implementing completely renewable power couldn't hurt.
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Re: Nuclear Power, what's your issue with it?

Postby gmalivuk » Wed Jun 11, 2008 5:00 am UTC

Izawwlgood wrote:
endolith wrote:But it could certainly convert a 50mile x 50mile grassland into a desert.


By blocking all the available sunlight to the grass? I doubt it.

Remember, plants are only using like 1% of the available sunlight for photosynthesis (and they are far more efficient then we are!), so unless your paneling was completely and utterly covering swaths of ground (which it doesn't it rotates to follow the sun) you wouldn't be covering much for long.

If you're letting enough sunlight get through for plants to survive, you're not doing solar energy collection very efficiently.

Can you think of any method that will use only the 99% of solar energy that plants aren't using? Because I'm going to go ahead and guess that current technology is in no position to do that.
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Re: Nuclear Power, what's your issue with it?

Postby Antimony-120 » Wed Jun 11, 2008 5:12 am UTC

gmalivuk wrote:
Izawwlgood wrote:
endolith wrote:But it could certainly convert a 50mile x 50mile grassland into a desert.


By blocking all the available sunlight to the grass? I doubt it.

Remember, plants are only using like 1% of the available sunlight for photosynthesis (and they are far more efficient then we are!), so unless your paneling was completely and utterly covering swaths of ground (which it doesn't it rotates to follow the sun) you wouldn't be covering much for long.

If you're letting enough sunlight get through for plants to survive, you're not doing solar energy collection very efficiently.

Can you think of any method that will use only the 99% of solar energy that plants aren't using? Because I'm going to go ahead and guess that current technology is in no position to do that.


MAGIC!...er wait, you said current technonology.

Anyhow, I can agree with this one, working summers in landscaping I can tell you that a tarp left on the ground for two weeks will turn the square of ground under it into a dead zone that is visible for at least a year. And while the panels may not be covering each piece for "too long" its a simple thing to prove that the amount of energy you get out of a solar panel is proportional to the amount of sunlight that never reaches the ground. Certainly you might be able to rig up some sort of system whereby it goes in a checkerboard pattern and switches the open and closed spots every so often so that no piece of ground is "starved" for sunlight, but you do so at the cost of having to cover twice as much ground with this checkerboard as you would with a solid array. And moreover, this system still doesn't solve the problem that it's disruptive to the area beneath it, as shadier areas grow vastly different plants than sunlight ones.
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Re: Nuclear Power, what's your issue with it?

Postby Delmieth » Wed Jun 11, 2008 11:45 am UTC

I know this is going back a while, but I wonder if I might be able to ask a few questions..
I am becoming more open minded about nuclear power, but there are a couple of things which I have been reading that dont make sense/

Minerva wrote:Some physicists have estimated that the efficient use of uranium, plutonium and thorium - not ridiculous once-through fuel cycles - will provide an energy resource that will last for approximately the same length of time as the hydrogen in the sun. You don't get much more "renewable" than that.

Nuclear waste is not a substance - it's something that certain stupid governments do, with stupid, grossly inefficient, once-through LEU fuel cycles in light water reactors, and no recycling of fuel.
If nuclear waste is such a problem, then stop wasting it!

Is solar power inefficient and expensive? Yes!


Where is this data about the lenght of time nuclear fuel will last coming from? Would these scientists who are running these tests happen to be funded by the nuclear industry?
And what about a combined renewable energy solution? has the option of solar, wind, hydro, tidal, and geothermal been explored because, to my mind at least they seem to compensate for each others weaknessess...

Mettra wrote: For now, our supreme number one bet is on nuclear fission. Fusion is perhaps a short way off, perhaps a long way off. We have fission right now, and if we can build a 26km gun that fires proton beams 100m under the ground and collides them at .999c, by god we can build an airtight nuclear plant. From the standpoint of modern engineering technology/capability, it'd probably be safe to have mini-reactors in apartment complexes or city blocks. We are so far advanced beyond even 10 years ago, we make it look like living in caves. Today we don't just use plutonium and uranium, we have reactors that run on all kinds of materials, reactors that 'create' their own fuel or use several types of fuel, reactors that run on the WASTE products of other reactors!, self-safety designs with a negative temperature coefficient of reactivity - this is the space age for nuclear reactors. Thank god (in a way) for Chernobyl and all the terrible mistakes we made because it kicked us in the ass and made us get serious about building these things safely and taking their operation seriously.


Can you provide data to back up these statements, such as it being the 'space age' for nuclear reactors? That seems a highly subjective, and frankly dangerous statement to make.

Mettra wrote:The piece of the puzzle that we do need to worry about is waste management. Unfortunately, a lot of 'waste' these days is wasted. It could be used in several reactor designs. But there is some waste that we haven't found a good way to deal with. Further advances in engineering will iron these issues out. The problems caused by this kind of waste, actually, are less ominous than the problems caused by fossil fuels. We are slowly taking away our ability to survive on this planet by changing the conditions such that the air is an intolerable mix of gases. Most of the waste produced by a nuclear plant is steam which, as the astute among you know, is just water.


You are placing your faith in future advances? Fossil fuels are not really a good comparison, given what we know about them. Could you please clarify this.

Like I say, I am merely seeking clarification and data for my own sake, not necessarily attacking your aguments
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Re: Nuclear Power (merged threads)

Postby Haploanddogs » Wed Jun 11, 2008 4:04 pm UTC

"Yes, in this house, we obey the laws of thermodynamics. But that doesn't mean that the fission products have less radioactivity - what they most certainly must have less of than the original uranium is mass.

The fission products are highly radioactive materials - but as it must be remembered, you can't have radioactivity without radioactive decay. The more radioactivity, the faster it's decaying."

This is incorrect due to a misunderstanding in this thread between radioactivity and Potential energy. For something to be fissionable simply means that more energy can be extracted from it by breaking it than it takes to break it. Every material that is atomically heavier than Iron contains this potential energy. Many of these materials are meta-stable and are not radioactive at all.
The Nuclear Waste that comes out of a Nuclear Reactor is Orders of Magnitude more Radioactive than it was originally. For a good example of what I mean lets look at U-238. With a half-life of 4.5 Billion Years it is so inert that it is difficult to tell the difference between it and the background. After being fissioned it is a witches brew of plutonium, Rubidium, Xeonon, and many other ruthlessly radioactive materials. Due to the fact that fuel cladding and pipes have been added more mass will be highly radioactive than the original amount of mass mined into uranium pellets.
This is critical to understanding nuclear power. Although I think it is by far the best option we cannot sugar coat its problems.

And Obviously this maintains the Second law as we are simply releasing Nuclear Potential Energy. But NUCLEAR POTENTIAL ENERGY DOES NOT EQUAL RADIOACTIVITY

Sorry for the rant

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Re: Nuclear Power (merged threads)

Postby Haploanddogs » Wed Jun 11, 2008 4:20 pm UTC

“it'd probably be safe to have mini-reactors in apartment complexes or city blocks. We are so far advanced beyond even 10 years ago, we make it look like living in caves. Today we don't just use plutonium and uranium, we have reactors that run on all kinds of materials, reactors that 'create' their own fuel or use several types of fuel, reactors that run on the WASTE products of other reactors!, self-safety designs with a negative temperature coefficient of reactivity - this is the space age for nuclear reactors. Thank god (in a way) for Chernobyl and all the terrible mistakes we made because it kicked us in the ass and made us get serious about building these things safely and taking their operation seriously.”

This is completely ridiculous. The reason our current nuclear reactors are safe is because they have multiple redundant independent safety systems. They have Walls of lead, and tens of thousands of tons of Concrete. It is important to understand that Radiation shielding does NOT SCALE. So if I have lets say 2 kilo Curries of Radioactivity hot in Neutrons I will need lets say 45 cm of lead around it. Now if I have 2 Mega Curries of the same radiation I will still need the same amount of shielding!
Now as for nuclear reactors that run on other types of fuel, which do you mean? We have lots of cool independent reactors such as RTGs, Fast Neutrons Breeders, and a few others that run on non-uranium, but not many. At the moment they all have significant safety issues. Which is not to mean that they are not safe, simply that they have not had long term testing. If you want to understand why that is important look at the test bed reactors of the United States, and see what kind of problems we originally had. They were not trivial.
“self-safety designs with a negative temperature coefficient of reactivity” Now what I assume you are talking about here is a temperature depended k factor. This is known as a “Void Coeffienct” and is based on that water moderates neutrons, and as the tempature increases the water becomes less dence, and finally turns to steam. In other words as the nuclear plant heats up, it produces less neutrons, which makes the heat flux lower. This is true of all BWR plants .
“Thank god (in a way) for Chernobyl and all the terrible mistakes we made because it kicked us in the ass and made us get serious about building these things safely and taking their operation seriously.”
I disagree here as all American Nuclear plants were built before the accident, and Chernobyl was a completely unnecessary loss of life due to human error.

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Re: Nuclear Power, what's your issue with it?

Postby Yakk » Wed Jun 11, 2008 5:27 pm UTC

Delmieth wrote:Where is this data about the lenght of time nuclear fuel will last coming from? Would these scientists who are running these tests happen to be funded by the nuclear industry?


Almost certainly some organization related to nuclear energy was involved in funding the research of scientists looking into nuclear energy, be it extremely indirectly or directly.

However, the calculations used are relatively easy to get at.

Here is an example of such calculations:
http://en.wikipedia.org/wiki/Renewable_ ... lear_power

It contains links to citations.

And what about a combined renewable energy solution? has the option of solar, wind, hydro, tidal, and geothermal been explored because, to my mind at least they seem to compensate for each others weaknessess...


Of the above, Geothermal and Hydro are the only "on demand" power sources that can generate energy when needed at peak times. Both of those require special local conditions that aren't all that common to be efficient using todays technology. Geothermal is a high-capacity cost, low marginal-cost plant if I remember rightly -- so a system that leaves it idle during the "off-times" ends up being inefficient, and the benefit of an additional unreliable power source (like wind, solar or tidal) will be not that great.

Hydro is currently used heavily, but there are very strict limits on how much it can be used, because it requires certain types of geography to be efficient. It has limited and bulky abilities to store "excess" energy when it isn't demanded.

In essence, for those to work together without brown-outs or a large change in power demand curves, you'd need geothermal sufficient to deal with most of the off-peak, Hydro peak capacity sufficient to deal with the difference between off-peak and peak, Tidal used as a reliable means to reduce Hydro sustained power usage, and then Wind/Solar being used as unreliable means to reduce drain on the Hydro.

All of this requires huge geo and hydro plants.

Now, if you found a way to more efficiently store huge amounts of energy safely, things get better for that set of things. LH2 tanks maybe?
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Re: Nuclear Power, what's your issue with it?

Postby TheStranger » Wed Jun 11, 2008 9:04 pm UTC

Delmieth wrote:Can you provide data to back up these statements, such as it being the 'space age' for nuclear reactors? That seems a highly subjective, and frankly dangerous statement to make.


The current leading edge reactors are very safe (Look at the safety record of France and Japan)

Reactors small enough to power a single building are probably not practical... however there are some very interesting small scale reactors coming down the pipeline.
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Re: Nuclear Power (merged threads)

Postby Mettra » Wed Jun 11, 2008 10:29 pm UTC

Haploanddogs wrote:This is completely ridiculous. [1]

The reason our current nuclear reactors are safe is because they have multiple redundant independent safety systems. They have Walls of lead, and tens of thousands of tons of Concrete. It is important to understand that Radiation shielding does NOT SCALE. So if I have lets say 2 kilo Curries of Radioactivity hot in Neutrons I will need lets say 45 cm of lead around it. Now if I have 2 Mega Curries of the same radiation I will still need the same amount of shielding! [2]

Now as for nuclear reactors that run on other types of fuel, which do you mean? We have lots of cool independent reactors such as RTGs, Fast Neutrons Breeders, and a few others that run on non-uranium, but not many. [3]

At the moment they all have significant safety issues. [4]

“self-safety designs with a negative temperature coefficient of reactivity” Now what I assume you are talking about here is a temperature depended k factor. [5]

“Thank god (in a way) for Chernobyl and all the terrible mistakes we made because it kicked us in the ass and made us get serious about building these things safely and taking their operation seriously.”
I disagree here as all American Nuclear plants were built before the accident, and Chernobyl was a completely unnecessary loss of life due to human error. [6]


[1] If it's really completely ridiculous, you wouldn't have been able to respond intelligently. Perhaps that's a bit much on the hyperbole.

[2] I can't find where I said anything counter to this. My point in the quoted portion was talking about the advances in engineering and understanding, not impossible physics.

[3] You're right. Right now we don't have many of these operational. But that wasn't my point - the tools available to us and the designs available to us was what I was talking about. The fact that, for political reasons, we are wasting what could be used as fuel is what I was specifically talking about there.

[4] I think you might have to be more specific here. Of course a nuclear plant is going to have safety issues, just as a lawnmower is going to have safety issues. If there was really a significant threat of destruction or loss of life, we simply wouldn't have so many nuclear plants - and so many people wouldn't be willing to make the case for them. If I misunderstood you here, please correct me.

[5] Here you are correct. However, it is also true for many non-BWR plants. I didn't fully explain this for a few reasons, mostly laziness. I figured most informed persons would realize that I wasn't stating the stupidly obvious, and those not quite up on the subject could take away an interesting trinket. I apologize for the incompleteness and the bad example. I was intending to just throw out a few features for those still in doubt to chew on.

[6] I'm not entirely sure of your point about many of our reactors being built before Chernobyl. Reactors don't run themselves after all. It's the knowledge and technical expertise of the crew that allows us to have them without any major problems. It's true that newer designs will be better designs, but the engineering knowledge and skill gained from the improved field applies to old tech too. Chernobyl was a terrible waste, I agree. The practices and decisions, however, are an example we can all look at and say 'if we screw around enough, we could screw up bad - and that could be serious'. It is probably singlehandedly responsible for this discussion - and it's good that we can have it.

@Delmieth:

Unfortunately, there is nothing that I can say or do to 'back up' my lack of fear. The statements I made in that particular quotation are (as far as attitude goes) completely subjective. It's just the viewpoint of a physicist in a crowd of many here. In my time I have 'done the math' so to speak and have calmed every fear that I ever had of large-scale nuclear disasters and even long-term 'localized' negative effects. Many people that I respect and that are far more knowledgeable than I in this field have added to this effect. If you think that my statements are dangerous, I won't argue with you - I would say that I disagree, and I would hope that someone better-equipped than I can come along and show you the papers, the experiments, the work, the progress, and the working examples that all add up to my attitude on the matter. Unfortunately, I am not well-equipped to make a case that will satisfy everyone in this discussion.

You'll have to forgive me for the badly worded "there is some waste that we haven't found a good way to deal with". That's not true at all, taken without the context that it so desparately needs. We can deal with any problem that could possibly come up with nuclear waste. Most of the progress (or lack thereof) on that front is political. Engineering-wise, what I was trying to say is that our current methods are inconvenient and we could probably be clever and do something better. I am not placing any faith in anything. We are able to deal with any problem that could result from any of our reactor designs right now. What I was saying was that the future is only going to make it easier and cheaper.

---
Honestly, reading over that post, I ultimately regret making it. Things were left unsaid, some things were said poorly and others incompletely. I'll chalk it up to a bad day.

/edit - I felt like I did a disservice by not adding anything of significance to the thread with this post.

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Re: Nuclear Power (merged threads)

Postby Haploanddogs » Wed Jun 11, 2008 11:06 pm UTC

{[1] If it's really completely ridiculous, you wouldn't have been able to respond intelligently. Perhaps that's a bit much on the hyperbole.


Yeah, it was a bit of Hyperbole, but I really don't think any kind of Reactor can be scaled down to a reasonable level due to the way we fission elements. Firstly need a rather high amount of enriched material, or you need incredible amounts of electrical energy, if we wanted to use directed fission. The first it dangerous in a small setting, and the second is impractical for home use. To be able to have 4 redundant safety systems simply requires very large plants.

You're right. Right now we don't have many of these operational. But that wasn't my point - the tools available to us and the designs available to us was what I was talking about. The fact that, for political reasons, we are wasting what could be used as fuel is what I was specifically talking about there.


My issue with novel fuel reactors with non-uranium or Pu is that they do no have long term, eg over a decade, long runs. I think these would be needed to establish safety.

Chernobyl Stuff

I think I misunderstood your original point. I would agree that Nuclear safety is much better now because of public reaction to Chernobyl. I though you were addressing the technical things we learned from Chernobyl, which from an American nuclear side did not help much as we had already learned those lessons back in the 50s.

In my time I have 'done the math' so to speak and have calmed every fear that I ever had of large-scale nuclear disasters and even long-term 'localized' negative effects.
[/quote]
What Math is this? As in a technical evaluation of the Plants themselves, or a personal risk assessment? I would agree wholeheartedly that they are the safest power source, but only if very carefully controlled.

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Re: Nuclear Power (merged threads)

Postby Mettra » Thu Jun 12, 2008 1:02 am UTC

Haploanddogs wrote:Yeah, it was a bit of Hyperbole, but I really don't think any kind of Reactor can be scaled down to a reasonable level due to the way we fission elements. Firstly need a rather high amount of enriched material, or you need incredible amounts of electrical energy, if we wanted to use directed fission. The first it dangerous in a small setting, and the second is impractical for home use. To be able to have 4 redundant safety systems simply requires very large plants. [1]

What Math is this? [2]

As in a technical evaluation of the Plants themselves, or a personal risk assessment? I would agree wholeheartedly that they are the safest power source, but only if very carefully controlled. [3]


[1] Significant progress has been made in making reactors smaller and still usable.

http://www.atomicinsights.com/AI_03-20-05.html

Sure it's not perfect and there are numerous issues, but this kind of stuff is not pie in the sky anymore. This is very localized power generation (hence the apartment complex/block reference of mine). Maybe it's not as safe as some would like. But we are really getting there. This is all I was trying to say. I'm not trying to say that we have reactor designs that you can stuff in your basement, set it and forget it, and not have any safety issues. But we have understanding and engineering abilities that are allowing us to think small.

[2] I think you are reading a little bit too deep into my words. I put the phrase in quotations. I was referring to my background as a physicist and personal research on the matter itself and generally my past experience with the nuclear debate. I can't put all that assurance into words or web page links or anything or I would have written a book. The poster was questioning my subjective statement, and I was simply saying that 'yes it is subjective'.

[3] To be honest, I am completely shocked that we have such rigorous and mostly intelligent regulation in the nuclear industry - it certainly is not the doing of politicians. It is a very safe power source for this reason (among others), but any massive power source can also be a source of danger in the same way that utility knives can cut your arm off. Our regulation is fine, though, and I have complete confidence in the methods and practices of those that maintain the plants. I have zero fears that nuclear will be opened up to the general public or anything like that. Some people have the impression that the scientists and engineers working at these plants are just crazy old guys doing wacky experiments that could cause devastation - but I've met these people and seen them at work, and the level of professionalism and preparedness is staggering. Careful control is required, but what I'm saying is we're there, we've got it.
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Re: Nuclear Power (merged threads)

Postby Haploanddogs » Thu Jun 12, 2008 1:28 am UTC

- but I've met these people and seen them at work, and the level of professionalism and preparedness is staggering. Careful control is required, but what I'm saying is we're there, we've got it.


I completely agree. When I was working in Reactor Engineering in BWR, I met no crazy people, and the job was rigorousness controlled to a point I would not have believed. The controls placed upon Nuclear power come from different sources however. There is government legislation, and the president appoints the head of the NRC, but the NRC is fully funded by the nuclear plants themselves, and the plants apply much higher standards to themselves than the government does.

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Re: Nuclear Power (merged threads)

Postby Delmieth » Thu Jun 12, 2008 7:58 am UTC

As much as I do not want to badmouth your convictions, I personally cannot put much faith in anecdotal evidence. What you two have experienced in person may not be the widespread case.
Also, call me a conspiracy theorist nutter, but I have huge problems with industry being responsable for the plant safety, government regulations or not.
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Re: Nuclear Power (merged threads)

Postby Izawwlgood » Thu Jun 12, 2008 1:33 pm UTC

gmalivuk wrote:f you're letting enough sunlight get through for plants to survive, you're not doing solar energy collection very efficiently.

Can you think of any method that will use only the 99% of solar energy that plants aren't using? Because I'm going to go ahead and guess that current technology is in no position to do that.


I'm referring to the fact that many plants don't need direct sunlight to subsist, and solar panels don't come in the form of a blanket/sheet of all light absorbing material stretched over miles, and most plants found in the deserts I've seen solar panels up in are either chapporal or scrub anyway, and prefer the shade. Obviously if you blanket Joshua trees or grassland you'll see stunted growth under the paneling, but I've seen weeds growing up around solar panels so I'm inclined to believe that solar panels aren't going to result in massive dead zones.

Delmieth wrote:As much as I do not want to badmouth your convictions, I personally cannot put much faith in anecdotal evidence. What you two have experienced in person may not be the widespread case.
Also, call me a conspiracy theorist nutter, but I have huge problems with industry being responsable for the plant safety, government regulations or not.


You just listed your own convictions. Who do you propose be responsible?
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Re: Nuclear Power (merged threads)

Postby endolith » Thu Jun 12, 2008 1:45 pm UTC

Izawwlgood wrote:I've seen weeds growing up around solar panels so I'm inclined to believe that solar panels aren't going to result in massive dead zones.


You can believe as hard as you want, but that's not going to change the fact that plants need light to grow.

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Re: Nuclear Power (merged threads)

Postby Mettra » Thu Jun 12, 2008 3:39 pm UTC

Delmieth wrote:As much as I do not want to badmouth your convictions, I personally cannot put much faith in anecdotal evidence. What you two have experienced in person may not be the widespread case.
Also, call me a conspiracy theorist nutter, but I have huge problems with industry being responsable for the plant safety, government regulations or not.


The difficulty here is that apparently neither of us can demonstrate anything to anyone without leaving doubts. There's not a link farm I can give you to quell your fears, and there's not a link farm you can give me to excite mine.

While you may feel that my evidence is anecdotal (and therefore that my feelings are irrational), I feel that your fears are irrational. The only possible difference here is that I am a physicist and have had some close experience with the issue. Further, our position in a stand-back sort of way is very different.

You are automatically in a position to challenge anything that I say. All it takes for you is one link to one news story about something crooked going on. That is just the nature of your position and mine. Unfortunately I don't believe you'll ever have a good one to link to in your lifetime.

My position is different. Obviously I am not in a high enough echelon to convince you of anything. Would you listen to someone that worked as a low-level grunt at a plant? What about a guy that transports the fuel? How high does it have to go? There is a bit of an issue when it takes a statement from the highest ranking officials before anyone believes anything. There are many people with doubts and only a few with those high positions - and they are generally quite busy and don't have free time throughout the day to come onto forums and such. Anything they say is still anecdotal evidence as well. So I think you're going to have to abandon that generic notion and instead distinguish between 'meaningful' and 'unmeaningful' information.

Another unfortunate asymmetry of your position in general is that you can make no real difference in just having it. This thread is aimed at sorting out issues that people personally have with the nuclear issue. But that's only to give some people peace of mind. It's not set up so that one day we can just all have a vote when we decide to go nuclear, and we're campaigning for the primaries right now. The people in charge of everything (not the politicians, mind you) already disagree with you. In order for you to change their position, you would have to have a very particular and very strong point of view backed up by a lot of work on your part.

This is simply because of the nature of the arguments you want to have - they involve (at their fullest) technical details that even most physicists and engineers (me included) aren't familiar with. The guys running the show (the people in the plant dealing with the ins and outs every day) are very specialized. To be able to effect something, you'd have to be just as specialized and somehow still disagree.

In summary, you really gain nothing by having generic fears. If you have specific issues, I'm sure someone would be more than happy to explain them in full gruesome detail. I think it would be a terrible waste for anyone to live their life having such concerns unadressed.

However, in the long run, you are not in a position to make a difference. There has been an inconcievable amount of work done on the subject, and you're simply not going to shatter it all or even weaken it all. It's kind of like Newton's laws. Even though special relativity surpassed them, they're still right. Even though knowledge increased by leaps and bounds, the old stuff still works flawlessly in its domain. I implore you to read over that link I posted.
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Re: Nuclear Q&A with Industry

Postby BattleMoose » Fri Jun 13, 2008 7:18 am UTC

om617 wrote:
You know the future? Can I have some stock tips?


Colgate Palmolive, Procter & Gamble, Northrop Grumman, General Dynamics.

Also, if you believe that there is a large market for combating global warming/climate change/atmospheric Carbon Dioxide levels, see below for an industry that would be worthy of investment:

Image
Carbon figures are for life cycle, not operation.
Nuclear clearly has a greater impact on the environment than does solar or wind. It's strengths lie elsewhere, as detailed in much of the thread so far. It is less damaging than hydrocarbons, but more damaging than the best renewables.


See above.


Not to be funny, but I really would like the actual reference of where these graphs come from. I have no reason to doubt it, and indeed such data would be useful, but I have to be able to reference it correctly. Thank you.

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Re: Nuclear Power (merged threads)

Postby Vaniver » Fri Jun 13, 2008 8:52 am UTC

The image files are sourced here- this is their main site, and this appears to be the article in question.

Hooray for detective work!
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Re: Nuclear Power (merged threads)

Postby Delmieth » Fri Jun 13, 2008 2:53 pm UTC

Mettra wrote:
Delmieth wrote:As much as I do not want to badmouth your convictions, I personally cannot put much faith in anecdotal evidence. What you two have experienced in person may not be the widespread case.
Also, call me a conspiracy theorist nutter, but I have huge problems with industry being responsable for the plant safety, government regulations or not.


The difficulty here is that apparently neither of us can demonstrate anything to anyone without leaving doubts. There's not a link farm I can give you to quell your fears, and there's not a link farm you can give me to excite mine.

While you may feel that my evidence is anecdotal (and therefore that my feelings are irrational), I feel that your fears are irrational. The only possible difference here is that I am a physicist and have had some close experience with the issue. Further, our position in a stand-back sort of way is very different.

You are automatically in a position to challenge anything that I say. All it takes for you is one link to one news story about something crooked going on. That is just the nature of your position and mine. Unfortunately I don't believe you'll ever have a good one to link to in your lifetime.

My position is different. Obviously I am not in a high enough echelon to convince you of anything. Would you listen to someone that worked as a low-level grunt at a plant? What about a guy that transports the fuel? How high does it have to go? There is a bit of an issue when it takes a statement from the highest ranking officials before anyone believes anything. There are many people with doubts and only a few with those high positions - and they are generally quite busy and don't have free time throughout the day to come onto forums and such. Anything they say is still anecdotal evidence as well. So I think you're going to have to abandon that generic notion and instead distinguish between 'meaningful' and 'unmeaningful' information.

Another unfortunate asymmetry of your position in general is that you can make no real difference in just having it. This thread is aimed at sorting out issues that people personally have with the nuclear issue. But that's only to give some people peace of mind. It's not set up so that one day we can just all have a vote when we decide to go nuclear, and we're campaigning for the primaries right now. The people in charge of everything (not the politicians, mind you) already disagree with you. In order for you to change their position, you would have to have a very particular and very strong point of view backed up by a lot of work on your part.

This is simply because of the nature of the arguments you want to have - they involve (at their fullest) technical details that even most physicists and engineers (me included) aren't familiar with. The guys running the show (the people in the plant dealing with the ins and outs every day) are very specialized. To be able to effect something, you'd have to be just as specialized and somehow still disagree.

In summary, you really gain nothing by having generic fears. If you have specific issues, I'm sure someone would be more than happy to explain them in full gruesome detail. I think it would be a terrible waste for anyone to live their life having such concerns unadressed.

However, in the long run, you are not in a position to make a difference. There has been an inconcievable amount of work done on the subject, and you're simply not going to shatter it all or even weaken it all. It's kind of like Newton's laws. Even though special relativity surpassed them, they're still right. Even though knowledge increased by leaps and bounds, the old stuff still works flawlessly in its domain. I implore you to read over that link I posted.


Where to start...

Firstly, I agree with you, we have differing opinions, and there is little we can do to change it. However, I did admit that I am slowly changing my viewpoint, and to start with I really had no problem with the technology itself, but rather the way it is implemented. I am not asking for highly specific facts, but rather facts that are straightforeward and clear. I am fully aware that anyone (including myself) presenting facts from the POV of their own opinion will tend to skew them in their favour. The art here is formulating an opinion, whilst reconciling several wildly different viewpoints. I did not mean to attack your opinion or experience however if you look at it from my point of view, one person saying they have experienced the safety of nuclear technology first hand should not be taken as absolute truth.

I disagree with your asessment that I am in a position to challenge everything you say. As you say yourself, this is a place for people to voice concerns or convictions and to have them solved or discussed. This is exactly what I am doing.

Thirdly, you state that I can make little difference just having my opinion. I make no pretence that I am an expert in this field of debate, but this seems a preconcieved conclusion at best. If everyone had this dysmally apathetic idea, then nothing would be changed for the better. Also, I do not live in the US- I was under the impression this was a global debate- but the 'People in Charge of Everything" have not made up their mind at all, it is still very much open for debate. You can give an example of France utilising nuclear power, and I can bring up Iceland who have used renewables to supply something like 70% of their energy requirements for a long time now.

And finally, mine are not generic fears at all, and I believe I have made that clear. My concerns only extend to mining, and waste disposal, as well as the availability of alternatives.
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Re: Nuclear Power (merged threads)

Postby Yakk » Fri Jun 13, 2008 3:11 pm UTC

The amount of mining required to produce uranium for nuclear power is small on the scale of current mining operations for dozens, if not hundreds, of materials. That is because you get a lot of energy from very little uranium.

And, assuming you include the raw materials required for infrastructure, Nuclear power still requires less mining than many alternatives. Solar farms covering the landscape from horizon to horizon usually means that a huge amount of raw materials where mined out of the land and used to build those Solar farms. Hydro dams required that the raw materials be mined. Wind farms require not just the wind blades, but towers to support them. And these constructs don't last forever -- they have to be torn down and rebuilt periodically.
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Re: Nuclear Power (merged threads)

Postby endolith » Fri Jun 13, 2008 3:49 pm UTC

Yakk wrote:Solar farms covering the landscape from horizon to horizon usually means that a huge amount of raw materials where mined out of the land and used to build those Solar farms.


Can anyone quantify this? How much of each raw material is needed to produce solar panels?

Delmieth wrote:and I can bring up Iceland who have used renewables to supply something like 70% of their energy requirements for a long time now.


Not every country has glacial waterfalls and volcanic activity.

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Re: Nuclear Power (merged threads)

Postby Yakk » Fri Jun 13, 2008 4:45 pm UTC

I can do back-of-napkin calculations...

At 25% solar panel efficiency, 5 kWh/m^2/day insolation, over a year a 10m x 10m tilted solar panel energy collector will produce just under 50 MWh of energy.

In comparison, a nuclear power plant might produce on the order of 500 MW ... every hour. Over a year, that's 4,380,000 MWh of energy.

So to replace our single nuclear power plant, assuming 100% efficient energy storage (which cannot be achieved, but let's be generous to solar power), you'd need 87600 of those 10 meter by 10 meter solar energy collectors.

If you place them in a field with a 5 meter gap on each side (so the panels can rotate and face the sun), that works out to a 6 km by 6 km solar farm.

Let's estimate the amount of raw materials used.

10 m x 10 m surface area needs, say, an average of 10 cm of metal backing. (more in the main trunk, less on the extremes). That's 10 m^2 of metal, weighing on the order of 50 tonnes.

87600 of these makes it 919,800,000 tonnes of metal -- or about a trillion tonnes.

High-grade uranium ore is up to 20% uranium, but is relatively rare. Let's use 1% uranium instead (a lower grade ore).

1 kg of uranium produces about 50,000 kwh of energy. Or 87.6 (heh) tonnes to run that plant for a single year. Times 100 (for the ore), and we get 9e4 tonnes of ore mined per year. Over 30 years, that's ~2.7e5 tonnes of uranium mined, or roughly 0.028% of the amount required for that solar farm.

This neglects the nuclear plant itself -- but the nuclear plant isn't anywhere near on the order of 6 x 6 km. I also neglected the concrete required for the foundations of the solar panels.

Even with a 90% recycling ability for the raw materials of the solar collectors, the amount of raw material needed to generate energy for solar is still orders of magnitude higher than the nuclear fuel required.

(Note: this is back-of-napkin calculation level rigor -- I didn't spend much time vetting the numbers used. The goal was to point out that it requires a huge solar farm to compete with the power generation of a nuclear plant, and that the huge energy density of uranium means that a tiny amount of mining is required in order to produce a huge amount of energy.)
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Re: Nuclear Power (merged threads)

Postby endolith » Fri Jun 13, 2008 5:14 pm UTC

Yakk wrote:on the order of 500 MW ... every hour


You mean "on the order of 500 MW continuously". Power is a rate. :)

10 m x 10 m surface area needs, say, an average of 10 cm of metal backing.


Is that a realistic thickness? Seems like it would be more skeletal structure.

But that's just the metal structure. I meant the solar panel material itself.

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Re: Nuclear Power (merged threads)

Postby Yakk » Fri Jun 13, 2008 5:51 pm UTC

Sure -- but unlike solar, it is running every hour. (Yes yes, 80% to 95% of capacity, and they do have to shut down some models to swap out fuel bundles, etc).

So no, I wasn't saying 500 MW per hour -- I was saying that "every hour of the day and year, that power plant is putting out 500 MW for the entire hour". The solar collectors will be putting out power during the daytime, and not at night. :p

...

As for the 10 cm estimate: *nod*, -- so toss out a factor of 10. When your end conclusion is 0.03%... Note that I was accounting for uranium ore, while using refined metal for the solar collectors. That'll produce at least a factor of 10, bringing it back to 0.03% of the mass...

I was also trying to account for things like the base of the solar collector that has to rotate it around. :)

I cannot find a decent estimate for the mass of one of those parabolic mirror energy collectors.
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Re: Nuclear Power (merged threads)

Postby bigglesworth » Fri Jun 13, 2008 6:22 pm UTC

My opinion is that geothermal will become more viable than solar.
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