M.A.I.N.B.

Currently, most nuclear reactors are massive groupings of fuel assemblies in only a few vessels... Three Mile Island had thousands of fuel assemblies "burning" at a time, so there could be millions of individual uranium pellets in one reactor at a time.

This is dangerous. When a tremendous amount of fuel is used within a single vessel for one massive reaction, the radiation level in the core is incredibly high, and it only takes one failure to cause a catastophre.

It's also unnecessary. If you take 2 fuel pellets and squeeze 'em together hard enough to alter the density, a small fission reaction occurs. The heat output typically reaches only slightly above the boiling point of water. Because the size of the reaction is so much less, the radiation emissions are miniscule, and get immeasurably small with distance in only yards from the reaction.

what if we were to encase small reactions in individual, tiny cases, and use massive amounts of these. Because each reaction is isolated from the other, Only the heat output grows and not the radiation levels. Run these all on a single coolant system, and drive turbines like always.

To get an idea of why this works, think of Cadmium, a heavy metal which is quite toxic to humans.

A fair amount of it is present in a Nickle-Cadmium rechargeable battery, as suggested by the name. But if you break one open, although it may make you sick, it probably will not kill you, and it is unlikely to affect anyone else. Now think of a tank of cadmium-laced water. It holds the same amount of cadmium as, say, 2000 batteries. If it breaks, it will make a lot of people sick and may kill quite a few of them.

Finally, consider those 2000 batteries. If one breaks, it does not affect the others, so they hold just as much cadmium much more safely.

That's the idea here... if one unit fails, it doesn't affect the others and cause a major catastrophe.

This design has the extra benefit of being easier to maintain and fuel, since each of the cells has its own radiation shields. You can replace them individually, rather than refuelling the entire reactor at once. Best of all, it produces precontained waste!