Worst case, the zirc coated overheats and catches fire separating from the fuel rod/pellets and causes a massive fires, which will certainly disperse the material into the atmosphere and surrounding area. If that happens, the reactor areas would have to be evacuated and would at this point go into complete meltdown. The only thing at that point would be hoping the CV holds and that the steel/concrete/graphite basins hold if the core melts it’s way through the PV.
Ugly. Don’t want to even think about it at this point. All was still well in my mind until I head this shit about the SFP’s