Slashdot Mirror
Megatons To Megawatts Program Comes To a Close
necro81 writes "In the aftermath of the Cold War, the disintegrating Soviet Union had tens of thousands of nuclear weapons and tons of weapons-grade fissile material. In the economic and political turmoil, many feared that it would fall into unfriendly hands. However, thanks to the doggedness of an MIT professor, Dr. Thomas Neff, 500 metric tons of weapons grade material made its way into nuclear reactors in the United States through the Megatons to Megawatts program. During the program, about 10% of all electricity generated in the U.S. came from weapons once aimed at the country. Now, after nearly 20 years, the program is coming to an end. The final shipment of Soviet-era uranium, now nuclear fuel, has arrived in Baltimore."
Sadly, nuclear power is dying due to ignorance. Coal kills thousands (maybe 15+) in the US alone every year, and tens to hundreds of thousands worldwide every year. Yet what do we hear in the news? Fukushima. Where you can count the death toll with 0 fingers, and even in 50 years it'll be less than coal kills in the US in a single year.
You can argue that Coal is a false choice (it isn't, it's what we have now) but even natural gas kills an order of magnitude or more people yearly than nuclear power, and yes _Solar_ kills more people.
I think the point is that the fuel is being aimed at us again.
The enemy disposes of your nuclear waste for you!
The warheads were only Megatons because they were fusion weapons.
We only used the fission trigger part to generate power'
Your pedantry is misplaced: your error is thinking of the warheads individually.
Instead, there were ~20k nuclear warheads worth of HEU involved (500 metric tons). Since even the inefficient gun-type Little Boy weapon had an estimated yield of 15 kt for 64 kg of HEU, the program represents a minimum of 120 megatons worth of yield—even falsely presuming they couldn't achieve better yields with that HEU than using a gun-type weapon approach.
The program's name is perfectly cromulent.
The warheads were only Megatons because they were fusion weapons.
No, this is a common misconception.
A basic nuke compacts a lump of (e.g.) plutonium to above the critical mass using convential explosives. The momentum caused by the explosives holds it together while the chain reaction grows exponentially. Eventually it flies apart, generally before the fission fuel is used up because the explosives don't hold it together very long.
You can introduce fusion by hollowing out the pit and filling it with tritium, giving a boosted fission bomb. That boosts the power a bunch (yay!).
However, the thing to note is nuclear explosions are much bigger than conventional ones, and if a conventional explosion is good at holding the fissile material together, then a nuclear one ought to be much better, and it is.
So basically, you pack lithium deuteride around another fissile pit. When the nuke goes off, it irradiates the deuterium creating tritium and compresses the second pit giving another nuclear explosion. It's a much more efficient one second time since it's held together longer and you also have much more tritium, so both the fusuion and fission but yield a lot more energy.
At this point you have two relatively small fission explosions, one mid sized fusion one and one large fusion one. Most of the energy comes from the fusion. It's also relatively clean in that the amount of nasty byproducts to energy ratio is low.
The logic continues. It a small fission explosion is really good at compressing, then a large fusion/fission one ought to be REALLY REALLY good. A third stage can therefore be added (allegedly this is not usually the case).
But it still doesn't usually end there. The nuclear reactions yield what is technically known as an ass-load of neutrons. If you wrap the entire thing in natural or even depleted uranium, the neutrons cause it to undergo fission. Lots of fission. It's generally thought that this stage more than doubles the yield and comes at next to no extra cost, size or weight (the bomb has to have some sort of heavy casing anyway).
Anyway, that's a summary of the wikipedia article and a few other bits and bobs.
TL;DR in most cases a bit over half of the energy comes from fission.
SJW n. One who posts facts.
Nuclear is relatively safe but has rather extreme risks, which makes it extremely expensive. A lot of nuclear fans don't seem to appreciate why low probability but very high cost risks are a problem.
Nuclear safety is expensive. Nuclear insurance against incredibly expensive accidents is literally priceless, in that no commercial insurance company will offer it so the government has to. The cost of centralizing so much capacity in a form that can randomly shut down at any time (and regularly does) creates a lot of cost to the grid for reserve capacity. Compared to most other forms of energy nuclear is just very, very costly and that is what is killing it off.
The only places where new nuclear is being built is where the government is funding it. For example in the UK the government provides insurance and has guaranteed well above market rates for any electricity produced.
IFRs are interesting but have their own problems (such as spontaneously catching fire if there is a sodium leak, as happened in Japan) and are a long way from a proven commercial scale design. With all the other costs and risks involved (and by risk I mean the risk that some design issue creates massive extra costs or cancellation) it is unlikely that any company will want to invest in developing one. Even if they did it would be a decade or more before it was even built and operating, by which time Germany will be nuclear free and the market is likely to have changed dramatically in light of that.
const int one = 65536; (Silvermoon, Texture.cs)
SJW, n: "Someone I don't like, and by the way I'm a fuckwit" - AC