If I recall, they have already burned up some robots.
I believe that is correct.
The new information is that the degree of radiation leakage is significantly larger than what they imagined. Furthermore, according to the new information, the proposed route that they had planned on using to get the robots in position, will have to be re-routed,
since it appears that the grating has melted away due to fuel debris.
Quote:" If the deposits are confirmed as fuel debris, it would be the first time the utility has found any at the three units that suffered meltdowns "