Yes, yes, a hundred times worse. There is no comparison on Earth that can be made to a nuclear plant meltdown. As just one tiny example, recent reports show that the rates of some types of cancer in children around Chernobyl are ten times the pre-meltdown rates. The problem will be seepage, leakage, venting, dripping, spewing, drifting, draining, and generally diluting to the environment, the wasted, melted nuke. That will go on for eons.
Nuclear power plants the world over are dangerous to the surrounding areas.
The effluent from a meltdown would pollute everything downstream. There is NO WAY to handle them without risking a release. And releases have happened many times, and they happen continuously, and the effects are cumulative upon the Earth. A particle of plutonium, for instance, if deposited in the lung, will irradiate the nearby cells with 10s of thousands of REM of exposure. The nearest cells will certainly die, but further-away ones may only be damaged.