As far as I'm aware we are not currently sealing dry casks in concrete and forgetting about them. They need to be maintained and managed.
Then the facilities are probably still in use.
If the waste were sealed underground by a 100m long concrete plug in any access tunnel there isn't going to be a lot of call for guards.
As far as I'm aware we are not currently sealing dry casks in concrete and forgetting about them. They need to be maintained and managed.