Caveat: No cold fusion!


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?


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!


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



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

  • 1
    $\begingroup$ Simple: They're dragons. They can do whatever you want them to. $\endgroup$
    – Frostfyre
    Commented Jul 22, 2015 at 3:05
  • $\begingroup$ A biological creature that can survive unaided in the void of space has probably changed to the point where its not really all that biological anymore...for question 3 you should also define what strong nuclear force is. $\endgroup$
    – James
    Commented Jul 22, 2015 at 3:08
  • $\begingroup$ This is a little confusing. Both the weak and strong forces are involved in fission. The strong force creates an unstable helium nucleus, and then the weak force allows beta decay, since the weak force mediates flavor changes. The issue is that the strong force is also involved in fusion, which is caused by the interplay between strong and electromagnetic forces, though the weak force might come into play if an unstable isotope is created. Since both processes involve the strong force, what do you mean? $\endgroup$
    – Obie 2.0
    Commented Jul 22, 2015 at 3:22
  • $\begingroup$ You could always consider the example of the Godzilla. This is THE example of a species subsisting on nuclear material. I'm not really sure about the mechanism though. $\endgroup$ Commented Apr 24, 2016 at 10:15

4 Answers 4


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.

  • $\begingroup$ Wow. This is a great answer. But what about the radiation? The melanized pads you mentioned would never absorb at 100% efficiency, so this would mean that radiation would leak out into areas of the body which wouldn't be able to cope with the radiation. If this could be addressed, the answer would be perfect. Almost $\endgroup$ Commented Apr 24, 2016 at 10:13
  • $\begingroup$ What? That doesn't make sense. Each layer of melanized tissue absorbs some fraction of the total radiative energy. More layers-> less radiation leakage. With thick enough pads the 'leakage' can be reduced to arbitrarily low levels. Not to mention biological organisms have well-understood DNA repair mechanisms for coping with high radiation flux, the radiotrophic fungi above are an excellent example. $\endgroup$
    – Resonating
    Commented Apr 25, 2016 at 16:23

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.

  • $\begingroup$ I totally agree with you on magic hence I deliberately omitted using science tag, I'm totally aware of the preposterous crazy question but there is no harm in asking anyway. We've water bear that don't pant at all and I don't mind having dragon growing leaves instead of feathers but I wish my dragon can spit atomic breath! to anyone not answering any of my questions lol. $\endgroup$
    – user6760
    Commented Jul 22, 2015 at 6:09
  • $\begingroup$ If you dragon somehow has a functioning nuclear reactor inside of it, atomic breath is almost plausible. $\endgroup$
    – Obie 2.0
    Commented Jul 22, 2015 at 6:22

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!


If Evolution means Darwinian Natural Selection, then there is a problem: in order to get from point A (in phenotype space) to point B, there needs to be a path where each step is an improvement at the time the step is made. (It is OK if the improvement was a protection against a predator that subsequently went extinct, as it was an improvement at the time). Natural Selection has no way of anticipating a future benefit: I'll take this hit now, because it will be useful to my n-descendants. So with Natural Selection, you need a viable path from a non-nuclear dragon to a nuclear one. One alternative is to dream up a universe where evolution isn't by Natural Selection. @Obie 2.0, has suggested Magic, and that might well be a better idea than Darwinian Evolution. Various fantasy writers have tried laws of magic, maybe you need to laws for magical evolution? Maybe something quantum mechanical? The organism can evolve from A to B if there is some possible future where B is "better" than A? Are you averse to having some ancient super race the genetically engineered the dragons?


You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .