First, I can promise that there aren't any magic switches saying "turn knob to funnel wattage towards the old, glorious Motherland from this energy grid node". Second, I don't think Russia is sending nuclear physicists and energy analysts into one of the furthest offensives of the war. I imagine that if Russia senses they're not going to hold Zaporizhzhia, they might sabotage it, but they probably have no way of knowing, at this point. And if they opt to inflict a meltdown, it'll affect the entire Eastern European region, just like Chernobyl did. Choosing to discontinue nuclear fission is a bad choice. It's also impossible, so where would you safely transport the fissile material to? Trying to re-route the power from the fission is also a bad choice, especially when unfamiliar with the energy infrastructure. I can see why Russia hasn't made any substantive moves yet. Where are you getting your information?