Pinkie Pie Guide to Nuclear Reactors

Thanks to everyone who has read and commented on chapter 2 of Rock Farms and Nuclear Reactors. It's really great to see just how many readers have gone along with my crazy idea of casting Pinkie Pie as a nuclear engineer.

The story developed as I wrote it. I originally was just thinking of doing a 'Pinkie Pie builds a nuclear reactor' one-shot; then I decided to bring rock farms into it; and then I realised I should also explore some of the wider issues surrounding nuclear power (more on this in chapter 3).

Just a few notes on the background physics, for those who are interested:

Pinkie's Pressurised Water Reactor is loosely based one of the preferred design for nuclear power plants currently under construction. Using water as a neutron moderator makes operation much more stable, as when it gets hotter, the water gets less dense, so fewer neutrons are moderated, and with fewer slow neutrons, the reaction rate falls, so it gets cooler. Older graphite moderated nuclear reactors, such as the Chernobyl design, don't have this feature, so they are much less stable.

Nuclear fuel is made by enriching natural uranium, to give a higher fraction of U-235; or by reprocessing used fuel rods, to give a mixture of uranium and plutonium – used fuel will contain some plutonium as the high neutron flux will transmute uranium-238 to plutonium-239. This transmutation can also be done in breeder reactors, where a blanket of fertile uranium surrounds the core. Breeder reactors were developed during the cold war to make plutonium for nuclear weapons. There were some civilian project, such as the Superphoenix reactor in France, with the aim of breeding more fuel than they consumed. However they are complicated and expensive – they get much hotter, so you need a more effective coolant, such as liquid metal. As the price of uranium dropped, and concerns about weapons proliferation grew, they fell out of fashion. There has, however, been some new interest recently, as a possible way of using thorium as a nuclear fuel.

Thorium is not fissile, but add a neutron, and it can be transmuted to uranium-233, which is. This fuel cycle produces less long-lived radioactive waste; and thorium has a greater natural abundance. But you need some way to produce the neutrons to start and sustain the reaction, so thorium power plants are still some way off.

Happy Hearth's Warming Eve!

Comments

[Avenging-Hobbits]

img.pandawhale.com/post-8766-YEAH-SCIENCE-Breaking-Bad-gif-og7N.gif

I love science

[Tatsurou]

Hmm...
Thorium reactors aren't necessarily as far off in the MLP verse as it would be in reality, as one could conceivably use magic to capture stray neutrons from a fission reaction to apply it to the thorium, or possibly generate them. The level of fine control to generate a neutron might be somewhat intimidating, but it wouldn't take all that much energy.

[Blue_Paladin42]

Thorium is not fissile, but add a neutron, and it can be transmuted to uranium-233,

And then nuclear power made alchemy real.
But in seriousness, that is bleeding awesome. I Nuclear Power.

[keaton-furman-prower]

I've learned more about nuclear energy in this story than any physics teacher has ever been able to explain

[Federhengst]

Just a notice: Nearly every nuclear reactor build in the last 30 years is water moderated (Wikipedia tells me that there aren’t any graphite reactors left in the US). While you are right that water is a better moderator than graphite (and it doesn’t burn), there are still other problems . So let Pinkie please be VERY careful :-).