Nuclear power is considered a renewable energy source by alot of people, as a source to rely on instead of finite fossil fuels. However nuclear fuel is finite as well (there is only so much uranium to go around).
How much longer can we run our nuclear power plants? Can we switch to other forms of nuclear material other than uranium & plutonium (something like cesium)? Can we cost effectively (or will we be able to in the future) make more uranium or plutonium or other kinds of nuclear fuels?
The current known reserves will last about 50 to 100 years depending on who you ask. Here’s a cite that says 65 years and talks about a lot of the issues:
engineer beat me to a link. Here they say fifty years worth of Uranium 235. (how do you do the superscipt markup?)
However with breeder reactors you can make more fuel than you use by turning U 238 (not fissionable) into Plutonium 239 (is fissionable).
From the link above:
This is fine if you are prepared to deal with a whole lot of Plutonium. Lots of people think this is not a good idea.
Why is it a bad idea? We get more fissionable material out of the deal, and can therefore have more power/have it last longer? Does plutonium make worse nuclear waste than uranium?
Fun facts about Plutonium:
It stays radioactive for ages
It blows up
It is nasty stuff
Really quite nasty stuff
The 50-100 years estimate is based on known uranium ore deposits, burning U-235 only in once-through reactors with no fuel reprocessing. With breeder reactors we can extend this greatly, as it allows us to use the far more plentiful U-238 as fuel.
It’s possible to “mine” uranium dissolved in seawater. Although it’s not economically competitive at the moment, the amount of uranium in the oceans far exceeds known uranium ore deposits.
It is also possible to design reactors to use Thorium as a fuel source. Thorium is significantly more plentiful than Uranium in the earth’s crust, although it requires processing in a breeder reactor to be used as fuel.
I have seen estimates that, between seawater mining and breeder reactors, sufficient nuclear fuel exists to provide us with power for over 10,000 years. I don’t have a cite for this at the moment.
I read years ago that thorium is more common than lead. Even if the uranium does run out, couldn’t we use thorium? Or is thorium too difficult to refine? I know that the uranium we really want, for power, is not U238 but U235, which decays at a much faster rate than the billions-of -years half life of U238.
[aside] Green zircons contain a certain amount of U and Th in place of the zirconium, which causes the crystal structure to break down, giving it markedly different properties from those shown by zircons of other colors.
Blows up like “we need to get a new truck to carry it” blows up or like nuclear explosion blows up?
It doesn’t blow up at all, unless you try really hard to make it do so. What they’re worrying about with critical mass is more a matter of “It heats up and releases a bunch of dangerous radiation”. But even that’s not much of an issue, since it’s a known danger, and once you know about it, it’s easy to design your procedures to eliminate the risk of a critical mass.
The real concern with breeder reactors is that some of the material produced could be used in bombs. That’s fine, so long as the power company (or whoever’s running the reactor) keeps control of it, but what if it gets stolen? So breeder reactors are currently considered too great of a security risk, in the United States. Of course, other countries do have them, and many of those countries probably have weaker security than the US, so if malefactors do manage to steal some fissionable material from a reactor, it probably wouldn’t be from an American reactor in the first place.
That’s significantly less than the 4.5 billion years for uranium.
Not unless you really try, and so does uranium.
Agreed on that note, but probably only moderately more nasty than some of the other chemicals that we routinely handle.
Depends on what you mean by ‘provide us with power’. Fast breeder reactors alone give us 10, 000 years supply of Uranium at current usage rates without the use of seawater.
However if we had to totally abandon fossil fuels tomorrow then seawater mining and fast breeders could still supply all the world’s energy needs for about 10, 000 years without ever using another molecule of oil, gas or coal.
The 65 years figure is based on 4 million tonnes of new, known conventional resources. Or to put it another way we can get 4 million tonnes out of the deposits we have already thoroughly explored and done test mining on.
However if we factor in undiscovered conventional resources (ie. what we will find if we bother to look a little harder), military surplus and re-enrichment of ‘spent’ fuel we increase the amount of Uranium available to 17million tonnes. IOW using just today’s technology with no fast breeders etc. we have about 326 years worth of Uranium, not 65 years.
If we factor in extraction from seawater and phosphates then we have around 4 trillion tonnes of Uranium available or approximately 8, 350 years worth of fuel at current usage rates.
The use of fast breeder reactors and fuel recycling allows these figures to be increased to 10, 000 years supply just from conventional resources (ie no seawater) and a quarter of a million years if we include seawater.
Reference: www.nea.fr/html/pub/newsletter/2002/20-2-Nuclear_fuel_resources.pdf
Note that this is just for current nuclear energy production. Currently nuclear provides just 6.5% of the world’s energy compared to 85% from fossil fuels. If nuclear were to take over from fossil fuels entirely we would need to divide those figures by at least 14. Because of problems with distribution, transport, conversion etc. of nuclear power it’s probably closer to a 25-fold increase in demand for nuclear power. So realistically we have enough conventional fuel for about 25 years if we need to switch to an entirely nuclear economy tomorrow. Using just seawater and phosphates as fuel we could manage about 300 years. Using just fast breeders and conventional Uranium supplies we could manage about 400 years. But using seawater and fast breeders we could sustain our society on just nuclear and hydro for about 10, 000 years.
Hopefully Jesus will have come back by then and solved the energy crisis. If not, you’d assume for all intents & purposes nuclear power is totally renewable as it is techincally only about 60 years old so far and we have already done so much with it that in the course of several hundred years we could pretty much create endless (for our purposes) renewable forms of nuclear power.
With nuclear power, it’s important to remember that the cost of the fuel itself is only a tiny fraction of the overall cost of power. So even if it costs us 100 times as much to get Uranium from sea water or other hard-to-obtain sources, the delivered price of nuclear power does not go up that much.
Since we do know how to extract uranium from seawater, and no new technical breakthroughs are required, it’s safe to say that we have enough uranium available to power society for thousands of years.
Yes, but that’s irrelevant. A preposterously long half-life like U-238’s means the amount of radiation produced is very slight (the element is relatively stable); so slight that if you were to hold a baseball-sized chunk, you’ll die of old age before the radiation hurts you.
Conversely, an extremely short half-life, like Polonium-218’s 3.1 minutes, means the amount of radiation produced is intense (the element is highly unstable), but short-lived. After ten cycles, a mere 31 minutes, the radiation will drop to less than 0.1%.
Plutonium is intense enough to be dangerous yet stable enough to stay dangerous for a long time. It’s also corrosive and toxic. I’m hoping for fusion.
Over those time frames it really becomes a moot point anyway. 6000 years ago agriculture was the pinnacle of biological science and flint was the cutting edge of cutting edge technology. 600 years ago energy came from wood and hooves. Trying to predict or even understand what technology will exist in 10, 000 years is like a caveman trying to predict nuclear fusion and space flight.
So yeah, for all intents and purposes fission is infinite and probably renewable.