Follow Slashdot stories on Twitter

 



Forgot your password?
typodupeerror

Comment Re:Achem (Score 1) 234

Like other posters pointed out: you likely don't know what thermodynamics even is. Hint: thermo has something to do with temperature. Thermodynamcs is about entropy and heat not about magnetic fields or electric fields.

Do you? Try googling the next time... some random examples:
http://www.phys.unsw.edu.au/~gary/SM3_7.pdf
http://www.ifw-dresden.de/institutes/iff/research/TMO/Magnetism

Classically thermodynamics was all about heat and temperature and as been developed to accurately describe steam engines. Since then this has evolved and been applied to many other situations. Thermodynamics is about describing macroscopic properties of a large ensemble of particles (this includes photons and such) by their microscopic behaviour. This is not limited to simple mechanical effects like gas molecules bouncing off of each other.

Comment Re:Energy Independence (Score 1) 438

So we agree, coal plants generate more radioactive waste than nuclear plants.

No, that's not true. Coal only contains minor radioactive components that are all around us anyway. In nuclear reactors additional highly active material is produced and other components get activated. But it is completely contained and therefore you can control it much better. In that we agree.

It's been a while since I last did a paper on this stuff, but here's a semi recent link:

From the abstract I guess we talk about different things. Transuranic components are not the waste I talked about. They surely can be used for another fission cycle. But the resulting lighter elements thereafter can not be fissioned in a proper chain reaction for energy production and are thus waste.

Coal plants are just treating the pollution as an externality, that and NIMBY are the only reasons it's "cheaper". We've already agreed the nuclear plant is safer. If you want to talk about "terrorists" or boogey men attacking something, drive past the billion gallon LNG tanks in New Jersey and tell me how dangerous natural gas is first.

Ok, first we do agree that coal plants are worse than nuclear. For the time beeing nuclear is IMHO the only real option of energy production. But that doesn't mean it's an optimal solution. There might not have been accidents for a long time but these things are not completely safe. And the worst case scenario of a nuclear plant accident is way worse than of any other power plant. The only good longterm energy source I see is fusion. Inherently safe and only short-lived radioactive waste.
Second, the nowadays so popular terrorist scare tactics might work well in the US, but not where I live.

Fast breeder reactors were indeed in use 20 years ago, they continue today and that usage is, outside the US, increasing. The so-called security concerns are that the US doesn't want other nations to be able to POSSIBLY make weapons out of that plutonium that is a by-product of using U238.

Well, according to http://www.world-nuclear.org/ only 4 breeders are operational at the moment, in contrast to >300 non-breeders. The weapon-making-issue is not what I had in mind. Breeders have a way lower power / volume ratio than other types of reactors, making them economically less interesting. This might change however when the Uranium resources deplete. Plus you have in some types liquid sodium as coolant which has to be handled safely, again increasing the costs. Quite sad that higher costs seems to be a stronger argument than a superior technology...

I'd love to see an accessible paper that shows coal is as clean as and still cheaper than nukes that isn't from a loon, including the cost of storing that arsenic, cesium and other "nasty stuff" that goes up the coal plant smokestack, unfiltered, much less recapturing the CO2 in any fashion.

Most coal plants nowadays use filters which get almost anything out except the CO2. Some of the stuff like sulphur oxides can even be turned into useful stuff like plaster. Extracting the CO2 is currently work-in-progess. The costs for both types of energy are almost the same. Give or take a cent, varies from country to country.

Comment Re:Energy Independence (Score 1) 438

Yes, the radioactivity near coal plants is higher than near nuclear plants due to the radioactive isotopes of carbon as well as differrent contaminations in the coal. Although this is almost negligible in comparison to the dose you get from medical examinations for example.

Most nuclear waste is _not_ usable in other reactors, i.e. the fission products are itself radioactive, yes, but not fissile. For a powerplant you can't just throw in any radioactive material, only few are able to sustain a chain reaction.
Breeding reactors do not use the fission products. The pellets contain non-fissile material like U238 which is transformed by the neutrons into fissile material. If this is fissioned you have to replace it, too. Anyway, breeders are not really used today due to other potential security issues (e.g. liquid sodium), about a handful worldwide.

Even modern reactor types can go critical, there is no absolute safety if you rely on a chain reaction. You can only design the core such that a meltdown is highly improbable. Therefore most reactors have a ceramic basin underneath the core which is especially built to catch it in case it melts.

Comment Re:Still problems? (Score 3, Interesting) 438

I'd say building a laser capable of firing with this frequency is the smaller problem. They're already designing the next generation of lasers which can do this (see HiPER). IMHO the targets pose a way larger problem. Right now they are all hand-crafted and hand-picked. Target laboratories produce maybe a few dozen per day but a full blown reactor needs about half a million per day! And since they are cryogenic you have too cool them until the very last moment before the laser hits them. The latest system to do this takes ~ 3 hours to bring a single target in place. Even if you fire them with a some kind of gun into the target chamber you have to ensure they are aligned on a micron scale in a chamber with about 10m diameter (NIF).

So far this was of big deal as laser experiments have always been single shot experiments. Current big lasers can shoot only once in a few hours, plenty of time to prepare each shot and align the target. High reprate lasers (with high energy) only start to emerge and people begin to focus on high reprate target production.

Slashdot Top Deals

You do not have mail.

Working...