There are two kinds of financial guarantees that we ask from an operator. First of all, we ask for a financial guarantee for operations. If something goes wrong in the operation, there has to be enough money to repair whatever needs repairing. Similarly for decommissioning, there has to be money accumulating in a separate pot that would provide sufficient funds to decommission the site.
As for regular insurance for workers, I think they get commercial rates. Somebody might be able to help me on this.