/sci/ - Science and Mathematics

>a thorium reactor's plutonium production rate would be less than 2 percent of that of a standard reactor, and the plutonium's isotopic content would make it unsuitable for a nuclear detonation.

Shit, it just keeps getting better.

>LFTR designs have a freeze plug at the bottom of the core—a plug of salt, cooled by a fan to keep it at a temperature below the freezing point of the salt. If temperature rises beyond a critical point, the plug melts, and the liquid fuel in the core is immediately evacuated, pouring into a subcritical geometry in a catch basin. This formidable safety tactic is only possible if the fuel is a liquid.

Shit, why aren't we using this already?

>>3374

For the same reason England didn't switch to electricity after it was discovered. Monopolies don't want to give up their profits.

>>3374

Looks like India is the only country on the ball. India has projected meeting as much as 30% of its electrical demands through thorium by 2050. They also have the largest supply of thorium in the world.

>>3375

This and the fact that you can use uranium to build weapons.

I seem to recall some major disappointments with regards to Thorium fission. I don't recall all the details, but Thorium breeders aren't any less viable– the claim that Thorium use will reduce proliferation is bullshit (and the proponents know it).

I have higher hopes for photovoltaic or even CSP power on the renewable (or quasi-renewable for nuclear) front.

While thorium is a great fuel and we should be building more reactors the uranium/plutonium fuel cycle could be significantly improved if we were allowed to use breeder/burner reactors to completely consume the raw uranium (U238 and U235 mixed) instead of refining it to a higher concentration of U235 and relying on that for 2/3 or more of the heat emitted.

For anyone who doesn't know all Thorium reactors are breeder reactors that make make U233 and U233 can absolutely be used to make nuclear weapons. If an isotope is fissile enough for a reactor (not an RTG) it's fissile enough for a bomb.

The real advantage of Thorium reactors is that they're breeders so they can use relatively unrefined fuel (only chemical isolation, you don't need to isolate a specific isotope) and turn the normally non-usable mildly radioactive long-term waste products into fuel and consume it either in the same reactor in a continuous loop or after a refueling operation, or in a different reactor optimized to consume the bred fuel.

I really would like to see a broader adoption of nuclear energy but it doesn't look likely to happen any time soon. Enivro-crusaders are doing their best to deny nuclear power any recognition as a carbon-free energy source and dismantle nuclear energy in developed countries. Ironically this has actually led to a rise in CO2 emissions in Germany, Japan, and elsewhere as they switched back to coal (brown too, the worst kind) when they shut down their nuclear power stations.

>>3587

On the other hand Germany has made great strides in solar and wind power now since they switched off nuclear.

>>3588

>great strides

That's a pretty big number. But it wasn't worth the money they paid.

https://www.youtube.com/watch?v=6-ZSXB3KDF0

This is in reference to the Netherlands solar road but the principal is the same. Solar works best at or near the equator and if you're not in a hot desert like the Sahara or Death Valley or Mexico or even the Australian Outback it isn't a very good option. In a place like Alaska, Canada, Greenland, northern or central Europe, Russia, etc. it would leave the grid nearly dead for half the year.

Also we're not talking about capacity factors and wind and solar have the worst by far. Which is at the bottom depends on where you put the collection station (solar is shit away from the equator, wind is shit anywhere that's not windy) but nuclear enjoys the top spot for reliability with 90% or higher. It also potentially has the highest efficiency if liquid metal or salt with low neutron capture cross section is used for the coolant instead of water (light or heavy).

Just because we can build a machine to do something like gather wind energy doesn't mean that machine is going to break even. Wind and solar are heavily subsidized by governments and when the subsidies are cut off as we saw during Spain's economic collapse in 08-09 the price of the wind and solar energy had to rise to the actual cost and it became uncompetitive with coal (dirty) and nuclear (clean).

Solar is good on rooftops as a supplementary power source, something to use as a backup when the power goes out. The only good way to store it long-term in a way that doesn't require literally more lithium than exists on earth is making ammonia and storing it in low pressure tanks for later use in fuel cells. And that's something that Greenpeace isn't screaming about in front of TV cameras.

Environmentalism isn't about the environment any more, it's about destroying specific industries that refused to kowtow and dismantling the economic system that created the computer you're using to read this sentence. The majority of the scientific community favors nuclear energy as the baseload power source of the 21st century and genetically engineered food to feed the world'

s growing population but the environmentalists oppose both because they fear what they don't understand and are motivated by spiritualism more than science. France got to where they are now with nuclear in the span of a decade, we could too. And if coal were used to make plastics, carbon fiber, graphene, fertilizer, and pesticides you'd probably be able to get Republicans in coal states to support such a transition.

Nuclear is the answer to our energy demand for the next century, not wind or solar or tidal.

I might make a thread about this later, but for now I think this is an opportune time to ask about this…

I'm working on a story for Analog that may turn into a book later. I'm trying to refit the USS Pampanito before I put it to text, and I'm trying to figure out how to go about it. One of the things I want to replace is the diesel engine in the back of the boat as a source of power. Would it be possible to replace it with a compact thorium reactor of some sort? I'm also thinking of supplementing the electrical systems of the boat with a new thing I've been reading about; some sort of gill system using graphene. Apparently they've found that you can generate electrical power if you drag a droplet of water over a graphene sheet, and it has to be seawater. If you convert the forward artillery on the deck of the Pampanito into a railgun, you would want a lot of power in order to allow it to lob rounds at its targets. Are these ideas viable?

>>3631

>environmentalists oppose both

Nice generalization faggot. I'm an environmentalist and I support both.

>>3640

This just means you don't buy into the identity politics bullshit…. good on you, I guess.

>>3639

It's possible but only with something like the BES-5 or SNAP-10 reactors. These were cooled by liquid sodium-potassium alloy to bring the melting temperature down from pure sodium. You could make a reactor small enough to fit in the engine compartment of a Balao but those satellite reactors only cranked out a few kWh but they stood only about 10-12 ft tall. Using the water outside you'd certainly get a higher thermal efficiency, maybe even enough to drive the ship at a decent speed but I wouldn't be comfortable with running water through pipes submerged in liquid alkali metals or the other way around. While emerging research suggests that as little as 5/1000 of hexanol is enough to suppress the reaction it has to be on the interface between the water and the metal. If you had a leak in either direction your sub would get caught in the most violent non-nuclear explosion before you knew there was a problem. Using an intermediate transfer fluid would increase the safety factor but at the expense of efficiency. How well this could work depends on the specifics on the reactor and how it's been incorporated into the Pampanito.

Bottom line: is it possible to fit a breeder reactor in a Balao or similarly sized sub? Yes. Can you run the sub off that? Maybe but likely not well.

>>3639

> I'm also thinking of supplementing the electrical systems of the boat with a new thing I've been reading about; some sort of gill system using graphene. Apparently they've found that you can generate electrical power if you drag a droplet of water over a graphene sheet, and it has to be seawater. If you convert the forward artillery on the deck of the Pampanito into a railgun, you would want a lot of power in order to allow it to lob rounds at its targets. Are these ideas viable?

This one isn't. A hint: where does the energy come from? Answer: it's converted from the kinetic energy of the water (or graphene sheet, depending on your point of reference).

Which means that you're going power plant -> rotation -> gearbox -> propeller -> forward motion of the boat -> electricity.

Each step in that process loses a fair chunk of power.

Much easier to just go power plant -> rotation -> alternator.

Not to mention that if you used this process you wouldn't be able to generate power when the boat wasn't moving.

Also: with a nuclear reactor, the best method tends to be a steam turbine powering a generator. Which means that you're already got electrical power right off of the bat.

If you want interesting methods… Hmm.

There's an interesting power storage method called a compulsator. (Roughly speaking: an alternator integrated into a flywheel that's designed for spiked output. Often used for things like… railguns!). I could see a nuclear reactor connected to a steam turbine connected to a standard alternator, and also via a clutch to a compulsator. You would need a clutch though or else you'd be likely to cause fatigue cracks in the turbine blades. And the clutch would have to be absurd. It may be easier (albeit less efficient) to jut do the standard alternator-motor pair. Also, that way in an emergency you could reverse the motor as a generator for a couple minutes.

So nuclear reactor powers a steam turbine running a generator. Separately, there's a box that's a flywheel with integrated motor and compulsator. Spin it up until you're at the maximum safe speed, or until you can't afford to wait any longer, then dump the entire energy into the railgun.

A couple of things:

1) Compulsators tend to spin absurdly fast. But at the same time tend to be rather light. Even so… you'll need to check - it's entirely possible that you'll either need two in an opposed pair or you'll need some rather massive bracing to deal with the gyroscopic effects.

2) Ditto with straight reaction-wheel effects. If you have an opposed pair, and due to battle damage, etc, one of them fails to dump power, the entire opposed pair could easily tear itself out of whatever it's mounted to (unless it's braced as above).

3) It pretty much has to be magnetic bearings and in a vacuum. And even so it will spin down over time unless it's kept up to speed.

4) If it breaks apart, you might as well as have set off a bomb. Look up turbine engine failures, and remember that this is spinning much faster, and that kinetic energy scales as speed squared.

As for interesting power generation methods? Steam turbines are boring, but efficient to the point where it would be questionable to do much of anything else, unfortunately.

That being said, if you're using a liquid metal cooled reactor, it's possible that a magnetohydrodynamic generator would work. Normally it uses a hot plasma (i.e. some hot flames), but it wouldn't be implausible that a MHD could run on a liquid metal.

Again, see >>3655 on the discussion of very hot metals near seawater, though.