ben_w 13 hours ago

On the scale that useful nuclear reactors operate, a "tiny nuclear reactor" is the size of a shipping container.

Even a tiny RTG is in the same range as a dumbbell.

  • Traubenfuchs 13 hours ago

    While not reactors, how about nuclear batteries without heavy shielding?

    • ben_w 12 hours ago

      Nuclear batteries are a superset of RTGs.

      There are other kinds of nuclear battery, but the ones I've heard of outside labs, are extremely low power betavoltaics.

      • cap11235 10 hours ago

        The biggest issue for weight is that you are using trans-uranic materials. By their fundamental nature, they are heavy as fuck.

        • ben_w 7 hours ago

          Nope.

          Betavolatics can be just about anything that emits an electron. Could be tritium. Low power due to long half life and low decay energy, but not because it is low-Z.

          RTGs can be anything that gets hot from its own radiation. Loads of things with a short half-life and high decay energy, so phosphorus-32 would be a low-Z option, and polonium-210 (which still isn't transuranic) if you're completely disregarding safety.

          Big part of the mass budget is shielding, not source. This gets proportionally worse for small sources, as you need a certain thickness (proportional to r^2), while the emitter power is proportional to volume (r^3).