You won't ever get a source because it's not true. The only place emitting that much radiation was basically in the middle of the reactor where humans would never go anyway.

And on top of it, nothing nuclear even exploded. It was a steam explosion. The explosion caused a meltdown which, as you mentioned, was very radioactive for a very short time. The meltdown caused the reactor to stop reacting, as we would expect.

And the final cherry on top is that less than 100 deaths can be positively linked to this over 4 decades. The rest is bad science, inconclusive data, and fear mongering. Google the solar deaths in the same timeframe.

But we still get the ignorance all over the place, and we'll end up putting it off right until the last moment when renewables can't power industry well enough to keep up with maintenance and replacements, or we run out of neodymium for wind turbines, or we poison the land with cobalt from a solar panel accident of some kind.