Yes, it is really true. There are 4 billion tons of Uranium dissolved in Earth's seawater.

https://www.forbes.com/sites/jamesconca/2016/07/01/uranium-s...

(Above link says 1000 1000 MW reactors for 100,000 years, but doesn't mention how much that is with reprocessing--that is hundreds of times the rate of global nuclear power production today).

The question is, how much does it cost to extract it?

https://www.forbes.com/sites/jamesconca/2016/07/01/uranium-s...

> There are 4 billion tons of Uranium dissolved in Earth's seawater.

There are also many tonnes of gold dispersed in rivers and seawater. It is however not economical to extract it.

Also, uranium mining is often causing a lot of health problems. Like in the German SAG/SDAG Wismut:

https://en.wikipedia.org/wiki/Wismut_(mining_company)#Impact...

So, would the Eastern German governments political friends have been less susceptible to these health effects?

And, in order to not wander too far off topic of energy economics, how is the extraction of uranium from seawater going to be economical?

It’s just silly to introduce “Antifa” (which isn’t a singular thing) into a discussion about the pros and cons of nuclear power.

Even 150 years is _enough_ time for us to bootstrap to the next technology level. Which would be something like having robots mine the asteroid belt for manufacturing resources, and getting a massive solar farm up somewhere in orbit over earth and sending the power down. Many different science fiction works have covered variations on this plan.

As with any fuel, both statements are not wrong. We have comparatively little easily exploitable resources but if we had a huge demand, we could exploit much more.

Couple decades-centuries worth of Uranium deposit exist that are readily usable, then the depleted Uranium(10-100x mass) can be converted into Plutonium as drop in replacement.

It is possible that we exhaust both and still have no fusion or asteroid mining after couple centuries from now, but we’d have to be extremely lazy to be in that position.

> the depleted Uranium(10-100x mass) can be converted into Plutonium as drop in replacement.

This needs breeder technology which is a different kettle of fish. The only existing plant was the Japanese Monju plant which was closed due to numerous problems and accidents, including a dangerous liquid sodium fire. You can read about it here:

https://en.wikipedia.org/wiki/Monju_Nuclear_Power_Plant

OP is correct. You don't need breeder technology to produce plutonium. In fact, the US produced enough in 1945 to build and detonate two plutonium-based atomic bombs. There are hundreds of tons of plutonium that have been produced and stockpiled worldwide, not including the thousands of nuclear warheads in existence and the thousands that can/could be decomissioned.

> You don't need breeder technology to produce plutonium. In fact, the US produced enough in 1945 to build and detonate two plutonium-based atomic bombs.

You can extract plutonium from spent fuel, I agree to that. This is what makes spent fuel processing expensive and this is what was used in 1945 and also turns any fuel waste into a proliferation issue. But converting depleted uranium (U-238) from spent fuel into fissile plutonium or whatever isotope, like GP suggested, is a different thing which would necessarily need some nuclear reaction.

https://en.wikipedia.org/wiki/Uranium

However, you DO need breeder technology to treat all the 238U as a fuel. With burner reactors, the 239Pu produced is less than the fissionable material consumed, and most of the 238U ends up not being usable.

I'll add that with current technology, you can't reprocess MOX fuel another time (too many higher isotopes of Pu and transuranics beyond Pu are produced), so any Pu in it after it's consumed must be disposed of.

There’s nothing complicated in breeder technology, it’s just that it allows constant supply of nuclear material at desired concentrations, aka serial production of nuclear weapons, so politics and regional security needs to be sorted out first.

I have, perhaps, the privilege, to have grown up in Germany in the 80s and at that time there was a really big societal discussion around nuclear energy in general and breeder technology in particular. A focus point was the breeder project in Kalkar, the SNR-300and many physicists and technicians chimed in into that discussion. I say privilege because it was a discussion unlike anything I've seen in this decade, people went very much into the details how such a technology works and what as a society we want from it.

https://en.wikipedia.org/wiki/SNR-300

One main point of the discussion was that such a breeder reactor uses fast neutrons and this has the effect that it is far less controllable. Normal fission power plants use slow neutrons, that is neutrons which come from a nuclear reaction, and are slowed down by a moderator, which is water. Breeder reactors do use fast neutrons and need a far higher energy density. One consequence this has is that they need really exotic and difficult to handle coolants, such as liquid sodium. I therefore call bullshit in that there is nothing complicated in them.

Also, such reactors have a different safety behavior. A key task of any nuclear technology is to keep the chain reaction of atoms and neutrons under control. This happens at the microsecond scale, and some chain reaction needs to be going for the reactor to not fizzle out, so it is anything but trivial.

If the reaction in a normal pressured-water fission reactor becomes too strong, this has the effect that immediately the water heats up. This makes the water less dense, and this reduces the effect of its moderation, which makes the neutrons faster, which reduces their potential to react with uranium atoms, and therefore it slows down the reaction. This achieves self-control. What happens when this self-control is lost, is perhaps best illustrated by the Chernobyl accident.

A fast breeder reactor does not have such an inherent control via the moderator and coolant. It was therefore judged by the public to be more complicated, and more dangerous.

A funny thing is that during that discussion, the proponents of nuclear energy said again and again that nuclear power plant's are safe and that they in particular can't explode.

I still remember the twitter post with these pictures:

https://www.youtube.com/watch?v=7lrJCqNpeZ8

On the subject of safety: if a prompt supercritical accident were to occur in a fast reactor, as happened at Chernobyl (which of course was not a fast reactor), the result could be even more extreme. If the rearrangement of fuel in the resulting event were to cause some small fraction of the core to compress into an even smaller volume (and this is difficult to rule out a priori), the reactor could explode like a nuclear bomb. Imagine an event where the entire contents of the core was ejected by a kiloton (or larger) explosion.

For this reason, I suspect only a homogenous fast reactor (molten salt reactor using chloride salts, for example) could be licensed.

I was like 200-300mi/km from that thing when that happened. That morning the plant was nice sky blue, on evening it was like archival photos of Dresden bombing, that weekend many of news shows were explaining how concrete walls worked as blowoff panel using mock-ups and what could be going on up there in Unit 4’s spent fuel pool, and by the end of that decade the Japanese society as a whole showed deterioration by equivalent of that amount on a national scale.

I’m still pro-nuke though! In fact the whole situation made me so. Before I was naively thinking we better seek alternate fuels.

There are in fact concerns about the amount of nuclear fuel available.

See for example:

https://arxiv.org/abs/0909.1421

and in more length:

http://theoildrum.com/files/O_118_Michael_Dittmar.pdf

The author also notes that, as of today, nuclear energy contributes only a very small part of the delivered energy mix.