May Russia be wise in taking over Chornobyl and not use it rashly. One nuclear reactor that once exploded had a very terrible effect, don't let it happen again.
I've heard Putin's remarks about nuclear, and I believe that Putin and Russia are not so barbaric to destroy the world without really strong reasons.
Maybe they don't plan to do it on purpose. However, there are military units at the nuclear plant that Moscow does not control. They can act on their own, and no one can be sure that their actions are appropriate.