The primary transportation risk is that spent fuel contains cesium metal, which is reactive with air and water, so if you expose it to air you get a fire.
It seems like a pretty obvious solution to this would be to purposely do the reaction under controlled conditions before transporting it, so then you're transporting stable cesium compounds instead of elemental cesium metal.
This is what I get for giving people the benefit of the doubt. Here's some text from that PDF the GP linked:
> Cesium will be the primary radionuclide released in a nuclear waste accident because it is present in what is called the fuel-clad gap. This gap is the space between the fuel pellets and the inside wall of the metal tube that contains the fuel. This “gap cesium” can be released in any event where the cladding is breached. Cesium is a highly reactive metal and even a small break in the seal will release significant amounts of it. Cesium burns spontaneously in air, and will explode when exposed to water.
Obviously the "highly reactive" applies to elemental cesium and is meant to imply that a collision would be a serious problem because exposing it to air would cause a big fire and release a plume of radioactive material. If that isn't the case then it seems like the thesis of the paper is rubbish?
The idea that cesium is present in metallic form is chemically very dubious.
Cesium is extremely reactive, as is noted. In particular, it will readily reduce U(+4) to U(+3). Nuclear reactor fuel is primarily uranium dioxide, so there is ample material there for this putative metallic cesium to react with. Cesium is the most electropositive element, so it will give electrons to (reduce) almost anything.
The state of cesium in the vapor gap will be relatively volatile cesium compounds, like cesium iodide. The core temperature of a uranium dioxide fuel pellet greatly exceeds the normal boiling point of this salt.
Yes, but when we want to store something in the range of million years, it is a bit early to say that 30 years are sufficient as a ultimate proof that nothing leaks.
Now I believe it can be done safely, but only if monitored all the time with good care. But that is expensive and humans tend to skimp.
You don't need nuclear waste to be stored for millions of years, after a hundred or so anything of exceptional danger has decayed and what is left will be such a low level of radiation that common clay bricks are just as much of a risk. The "hotter" a nuclear material is, the faster it decays, and materials that remain radioactive for thousands of years are not especially radioactive.
Again, when you bury uranium half a kilometer deep in an area with no aquifer, how will it ever result in contamination?
The only real scenarios are deliberate excavation, and a meteor impact directly on the waste repository. Neither of which are particularly likely scenarios.
Because the ground is not static. And we are just starting to understand what is going on down there. So yes, there are sites that remained quite unchanged (like with the natural fission reactor), but personally I remain sceptical with such statements.
Are we supposed to hold off on developing the only geographically independent and non-intermittent form of clean energy because of some vague nebulous fear that waste buried half a kilometer deep in bedrock will come back up to the surface and harm people... somehow?
No, but maybe we should not pretend all is super safe and always will be, when we cannot know currently.
Or rather we do know that the initial promises of reactor safety were also quite overconfident. So people assume the same of permanent storage of the waste.
