Astronuc said:
As far as I know, the waste canisters are handled remotely in a vault in an engineered storage facility, or they can be stored underwater or in a vertical shaft.
Yes, I know this.
If they are transported to another facility, they are shipped in a special steel shipping container.
Yes.
This container has very thick walls and weighs x10 more than canisters it contains.
So, adding some protection to the canisters not only would make them less "hot", but will (1) either enhance transport safety: if container is breached, the exposed canisters will "shine" less, or (2) allow to use lighter container. For example, if canister walls are made 2.5 cm thick, the transport container can be made nearly twice as light.
The processing of the waste, the loading and unloading of the canisters, and handling and final disposal are done remotely. The walls of the facilities are rather thick in order to absorb the radiation.
I do not question the shielding of existing processing and storage facilities.
I would like to learn more about rationale behind canisters' dimensions and wall thickness. I already wrote about wall thickness; regarding canister width - it seems that wider canister would be better because the vitrified waste in its center is substantially shielded by the waste at the walls, making its contribution to the total gamma level greatly attenuated. Basically, bigger (wider) canister holds more waste but isn't "hotter" than smaller one.
Again, I am not implying that the design is stupid. I might be ignorant about many other design constrains and considerations affecting the design, such as thermal energy dissipation, resistance to damage when dropped, etc.