You know Russia has nukes right? If they want a region to be unlivable for centuries they can already do that.

The most obvious way is to bury it deep underground. The next best way is just to store it for now. Either way it's not that big of a deal to manage, because there just isn't that much of it.

What exactly did 'strife in Ukraine' prove? To my knowledge that haven't been any leaks of nuclear material in any of the plants there.

Nuclear waste is much easier to deal with than carbon waste, actually. There's just so much carbon waste and it goes up in the air.