Radiothermal heating of planetary cores is established scientific fact. It's not a fission reactor because there's no chain reaction, just a lot of unstable elements in one place. Some details are controversial, but not the basics. (I have a geochemistry PhD)
Yes, I think that is the where the debate is over the exact nature of things. Fission happens spontaneously, even the bismuth in Pepto Bismol has a bit of a fission going on, slowly decaying into thallium.
²⁰⁹Bi decay to ²⁰⁵Tl is alpha decay — the bismuth nucleus splits into an alpha particle (helium) and a thallium nucleus. I think you’d be hard pressed to find a nuclear physicist or engineer who calls that “fission”.
Here’s the Wikipedia article on fission. It’s a rather different process:
Can you link to what you are reading? I am a nuclear engineer, I suspect they are using a very loose definition of critical, one that would imply the entire universe itself is critical.
Maybe the fault is with me for using the word "reactor" a bit loosely.
I don't think anyone knows for sure what is going on down there.
My theory is that it's both critical and quiescent, with a violent
dynamic at play. Gravity will concentrate the heaviest and least
stable elements as you'd expect. As that happens pockets of dense
matter in close neutron proximity will approach critical and heat
billions of tons of matter which then convects outwards, dispersing
the mixture. Think of a lava lamp.
are there estimates for how much heat is produced this way? any other way? (solar magnetic field interaction?) how much is the residual heat dissipation?
edit: ah, just read the title of the link posted in the top level comment. apparently it's "half of the heat" :)
