We don't need OPEC or ANWR . . . haven't we harnessed the atom?

Great Debates
21

My first reply seems to have been eaten by the board (what was that about “trusting the CGI”? :slight_smile: ). So, being too stupid to do otherwise, let me try again.

We will look at deuterium-tritium (D-T) fusion, this being the only kind that’s likely to be achieved in my lifetime[sup]1,2[/sup].

Deuterium is, I believe, available from ordinary water as a proportion of about 0.016% of the hydrogen (due to gravitational enrichment). Unless we’re planning on building Sol II, then, we don’t have to worry about it in the foreseeable future.

Tritium, OTOH, does not exist in nature save in vanishingly small quantities, as it is weakly radioactive with a half-life of 12.3 years. We’ll have to make it (more on this below).

The D-T reaction is: D + T -> [sup]4[/sup]He + n. About 18MeV of energy is released by this reaction, of which 80% is carried by the neutron.

Now the neutron can actually be useful. Two reactions can be used to make tritium:[ul]
[li][sup]6[/sup]Li + n -> [sup]4[/sup]He + T[/li][li][sup]7[/sup]Li + n -> [sup]4[/sup]He + T + n[/li][/ul]
The first assumes a thermal (slow) neutron, and is exothermic; the second assumes a fast neutron (as is produced by the D-T reaction) and is endothermic. [sup]7[/sup]Li is about 13 times as abundant as the lighter isotope; depending on how we tweak our tritium production, we have sufficient lithium to supply with tritium for several thousands to several tens of thousands of years, so we’ll stamp this problem “Solved”, too.

The problem comes with the total neutron flux. Assume that the reactor is producing 1GW of power. Then, depending on power recovery from the tritium-making blanket, we’re producing 1-4 GW of neutron flux; call it 2.5 GW. Assume that the blanket is 99.9% efficient at capturing neutrons, so only 2.5 MW gets through. If someone is standing 10 meters outside of the blanket, he’s intercepting about 0.04% of this flux (assumption: he presents a surface of about one-half square meter). 1 rad is 0.01J/kg; if he weighs 70 kg, then the dose rate is about 1430 rad/s. A ‘Q’ factor of 20 is safe to assume for fast neutrons, so that we’re talking over 28,000 rem/s. Can you say, “dead before he hits the floor”? :slight_smile:

Of course, we can deal with this the same way in which we deal with neutron flux from fission reactors, but we’ll also have the same problems (neutron embrittlement of materials, generation of LLW).

A fusion reactor won’t generate HLW (unless we’re talking here about something exotic like a fusion-fission breeder using [sup]238[/sup]U outside the tritium blanket), so I suppose that we can say that fusion won’t suck as badly as fission. OTOH, we have fission now; a working
inertial fusion reactor (IFR) using D-T is probably 20-50 years away. Research on this should continue, and at about an order of magnitude greater of funding, but you can’t get a baby in a month by impregnating nine women; don’t expect that, even if that extra funding is provided, we’ll be seeing an IFR on-line before 2010 at the earliest.

[sup]1[/sup][sub]Of course, “my lifetime” is not equivalent to “the lifetime of any of the Teeming Thousands”. OTOH, I will really need to see some evidence before I concede that any of them will live to the age of 250.[/sub]
[sup]2[/sup][sub]Don’t even talk to me about weak-force-mediated reactions like p-p.[/sub]

22

Coincidentally, I was watching The 20th Century with Mike Wallace at about 3:00 EST, and they mentioned TMI, so I can give you an actual quote (as best as I can remember, anyway).

"The radioactive xenon released…forget…1000 millirems per hour, which is 10 times the maximum allowed for a human in an ENTIRE YEAR (I think I forgot something else, but it really wasn’t significant).

Needless to say, this is something to take seriously, and in my mind explains why we don’t build nuclear stations anymore (at least not now).

Again, I think nuclear power is our future, but for now I’ll take the devil I know over the god that I don’t. We accept coal miners’ disease as a part of doing business. They decide to go into the mines. They know what’s gonna happen. Are YOU willing to accept passive radiation poisoning that comes from nuclear power plants if something goes wrong? I’m not.

23

If Cranston hosts O’Reilly, it’ll go down as one of the all-time most memorable TV moments, considering Cranston has been dead for several weeks. :eek:

I grew up a couple of miles from a nuke plant and later worked in one as an engineering intern (I got out of the business because it was, and still is, going nowhere, but maybe people will smarten up and that will change.) Considering that the only large-scale option with present technology is coal, anyone who has an environmental problem with nuclear power should do two things:

  1. Go to the coal-mining region of Appalachia, and observe the strip mines, flat-topped mountains, abandoned pits, 30-year underground fires, cemeteries full of flattened and gassed miners, rusted streams, slag piles, and slag ponds behind their earthen dams (one burst in 1972 and over a hundred people drowned just like that; compare that to Three Mile Island).

  2. Visit a coal-fired power plant. Don’t forget to wash the fly ash out of your hair and honk up all that brown dust out of your lungs. Then visit a nuke plant - you could eat off the floor at the one I worked at.

24

thedoorsrule1045 writes:

I will be (fairly) charitable, and merely note that Wallace is probably so old as to be genuinely senile, if he is not merely suffering from Alzheimer’s.[list=1]
[li]The average person gets about 360 mrem (millirem) per year, not 100. There might be a place on this planet where you can only get 100 mrem/year, but if so, I don’t know where it is.[/li][li]The limits on radiation exposure aren’t (for reasons mentioned above) a mere 100 mrem/year. They are 500 mrem/year for the general population, and 5 rem/year for workers in various industries where radiation is an unavoidable consequence of the jobs (I believe that the U.K. proposed a limit of 1.5 rem/year for occupationally exposed workers where the radiation has no value-added, e.g. air crews, but I don’t know if that regulation was ever put in place).[/li][li]Claiming that radioxenon, or anything else, emits 1000 mrem/hr, or any amount, is basically pure yivshish; the rem is a unit of human effects of radiation (it is an acronym of röntgen equivalent in man).[/li][/list=1]
There are, certainly, dangers posed by fission. There are also dangers posed by coal-burning (incidentally, I suppose that you know that it exposes you to more radioactivity than fissioning plutonium does? You are willing to accept the passive radiation poisoning that comes from coal-fired plants when everything goes right, yes?) Wallace’s ignorant blathering is also a danger; someone might mistakenly assume that he knows what he’s talking about.

25

The waste facility in New Mexico may be fabulous, but the waste has to get there somehow. Trains, ships, trucks, planes have accidents. Unless there’s an accident-proof way of moving the waste around, the WIPP’s excellence may be a moot point.

Also, I think City Gent was lamenting the process of coal mining and it’s use in power plants. Uranium comes from mines, too, and it’s extraction and purification is not exactly a clean, foolproof process.

26

But you mine a lot LESS of it.

And if you do have an accident transporting nuclear waste, it won’t be the end of the world. It will just be an expensive, tedious cleanup job. There’s nothing magical about radioactive waste - you clean it up, you check the area for radiation, you clean up anything you find that’s contaminated.

Certainly, the effort it takes to clean up an oil spill is orders of magnitude greater than what it would take to clean up if a Semi split a bunch of containers open on a highway.

And anyway, we can engineer containers that can withstand accidents at highway speeds. Guaranteed. And, I’m sure that a convoy of waste would have a closed highway to itself and probably a military escort a mile long. And it’d go 20 miles per hour.

Here’s a prediction for fusion: If we ever do come up with fusion power that is sustainable and cost-effective, the environmentalists will wrap it up in red tape and protests just like they have with fission. Because guess what? There is still radiation. There is still low-level waste. And the containment areas still get bombarded with radioactive particles and eventually become radioactive.

27

A fair point - and I also posted a while ago about how I discovered there are a surprisingly large number of fatalities per year due to coal and ash truck accidents on roads. Thankfully, very very few plants recieve coal via truck.

Oh really? I’ve been to more than 2/3 of the coal plants in the US, maybe 3/4 of them - it gets hard to remember. Please tell me where one would go to have this happen? (OK, there was the plant in Spain that rained gypsum and lime dust from the sky, but… :wink: )

Seriously - even I admit that nuclear plants are far, far cleaner than coal. But we do need hyperbole here.

28

And, last I checked nuclear plants emit less radiation than coal plants, due to the residue of radon gas that comes from the coal. In fact, I once read that the natural radioactivity in the granite of Grand Central Station raised the ambient radiation in the station to levels higher than the maximum allowed by the NRC for workers inside nuclear plants, let alone outside the plant.

29

I mean, we do not need hyperbole here…oh, never mind.

30

thedoorsrule1045 wrote:

You were told how safe the Three-Mile Island nuclear power plant was in 1979, and then 2 months later, nobody died!! No one has even been confirmed to have gotten sick from the small amount of radiation leaked into the environment by the TMI plant’s partial meltdown – except for a few paranoid hypochondriacs who came down with psychosomatic symptoms because they panicked and thought they’d gotten radiation poisoning.

Even in the case of the Chernobyl disaster, which was far worse than the TMI incident, only one person (a firefighter who doused the red-hot exposed reactor core) was killed in the short-term as a result of the radiation. The city did have to be evacuated, though, and is still radioactive enough that it is uninhabitable.

31

City Gent wrote:

What are Uranium-mining regions like?