How does a dragon evolve to harness energy from nuclear source?

Question

Caveat: No cold fusion!

Questions

Q1: Where can my dragon source for nuclear energy on Earth set in medieval age and how does it convert this energy for fight or flight?

Difficulty:⚠

Q2: How can my dragon naturally produce sustainable nuclear energy inside its body efficiently and safely meaning it cannot suffer from radiation poisoning (due to fission)? I need my dragon to migrate vast distance of interstellar space!

Difficulty:⚠⚠⚠

Q3: Same as Q2 but utilize strong nuclear force instead.

Difficulty:⚠⚠⚠⚠⚠⚠

Note

Comment below if you disagree with the difficulty rating, you may attempt one, or all of the questions.

Answer 1

Okay, so skip the active nuclear reactor here. It's too hot, too big, and too heavy. Think RTG. In fact, let's think Cesium-137. A beta emitter that produces gamma radiation from it's barium daughter nuclide, Cesium-137 has a half-life of about 30 years and is soluble in water. Beta radiation is pretty easily absorbed, and there are fungi that eat gamma rays, in fact specifically Cs-137 gamma rays.

So imagine a dragon that piles U-235 bricks in a big water bath, letting it get to just barely subcritical. The accelerated fission produces loads of cesium-127 as a decay product. Your dragon drinks this boiling radioactive water and secretes the cesium into an internal organ ringed with pads of melanized tissue that eat the gamma radiation as if it were sunlight. Presto radio, a 60 year meal. Filling!

Perhaps instead of constructing primitive fission reactors it precipitates uranium as crystals just under the skin, in its scales. High-energy neutrons from interstellar radiation catalyze fission very slowly, enriching the scales with cesium-137. The scales slowly migrate, displaced by new scales laid down. When they're 'aged' into energetic deliciousness, they're broken down and the cesium 'eaten'.

You could also just use bricks of U-237 or strontium-90, a thermocouple, and fix carbon dioxide into food directly from electricity. It's less cool but is way simpler.

Answer 2

Let me first say that some kind of magic would make this much easier. The conditions required to initiate nuclear fission or fusion are not likely the sort that would develop readily in Earth-like creatures. I believe that your best bet is, as you seem to be considering, making the dragon a space-dwelling creature. Perhaps it originated as a terrestrial organism that used solar energy to propel itself, storing the energy for rainy days. If it were quite large (but ideally thin), and virtually covered in solar panels, and had sufficiently good batteries to survive dark periods, that sort of thing could happen. Of course, a creature whose skin can absorb solar energy more efficiently than a solar panel, and whose body can store it more effectively than current batteries, will probably not resemble Earth life, in terms of its genetic code, the molecules that make up its body, or its overall appearance. It might have a lot of silicon in its skin, for example.

Now, a creature that can survive on solar energy might not have to breathe, which would be ideal for navigating space. I simply do not think that nuclear fission would evolve first as an energy source, even in the presence of ideal fuel, because the energy barrier for starting it is pretty high, relative to biological energy scales. But a creature that could extract huge amounts of energy from solar power might be able to overcome it. Once the "dragon" can produce solar energy, it might be able to evolve the ability to use nuclear fission (assuming that nuclear isotopes are common on its home planet) as a backup energy source. How a creature would evolve a controlled fission mechanism without blowing itself up, I cannot imagine. Even if such a mechanism managed to evolve, the dragon would need a heavily shielded inner fission chamber, to protect its batteries and solar cells from the radiation and heat. Maybe it could release the heat by breathing "fire"? Again, to have any chance of dissipating the heat produced, the dragon has to be pretty large. But this makes flight even more unlikely, and means that the dragon probably has to have bones made of something pretty exotic. Perhaps your planet has very weak gravity (very small). But then it will not have an atmosphere, which means the dragon would have difficulty flying. Perhaps your planet also has some sort of fuel, and the dragon flies by expelling it at high speeds, perhaps using a mechanism powered by its solar intake (or by the fuel itself). This would also help it get into space.

Then we have the problem of how its solar panel skin can survive the descent back to its planet from space. Maybe it has a layer that it can extend for protection, although again, this is not going to be anything like what we call a biological material on Earth. Once in space, it can collect even more solar energy, but has to be careful not to run out of whatever propellant it collected on the planet. It might also be able to use solar sails to change direction, although it would likely only evolve these after living in a space environment for a while.

But what is more, you want it to travel between solar systems! I think the best bet for this creature, if its brain is also silicon, is to shut itself down, put its brain in deep-freeze, and reactivate only when it nears another star, or when necessary to adjust course. Presumably this creature is highly intelligent, if it can figure out, in its head, the proper trajectory to a distant star system.

Of course, what you end up with is a dragon built like something from Transformers: Age of Extinction, but you probably realize that the best way to have a nuclear reactor spaceship dragon is to have a nuclear reactor dragon spaceship.

Answer 3

Years ago, I considered something similar with mutant giant squid. In this case, real animals keep symbiotic bioluminecent bacteria to use as a lure or for countershading the eyeball in an otherwise transparent animal.

So I thought a squid could keep pods hosting symbiotic bacteria attached to long feeding tenticles. Bacteria (simple procaryotes) develop all kinds of different metabolisms to make use of food sources, and some eventually became organelles in complex cells.

The pods are held a long distance from the body, to keep clear of the radiation hazard. The pods eventually degrade from radiation damage, but are discarded and regrown (something else squid actually do)

---

• What do dragons normally do that could be bent to a new task? What family of animals are they related to?

• Consider symbiosis.

as for directly using the strong nuclear force, see this answer, though it relies on "cold fusion".

Perhaps the idea behind the Farnsworth Fuser, but that doesn't produce a net gain in real life. I think my biofuser is actually more plausible!