Lots of sabre rattling about tactical nuclear weapons being potentially used by Russia in the Ukraine conflict but its all a bluff.
Putin is a little boy in an old man's body. The two main reasons why he won't use nukes are as follows:
Putin, like all Russian bully boys who want to be seen as great, is a land pirate. Russia has the largest area of land of any country because they select their leaders based on the bully's ability to just go steal and occupy land by force. The attidue is just lie to yourself and say "that land is mine, it always been and always will be."
It's the same attitude for at least one other country in which a bunch of Europeans with zero genetic ancestors who owned land in an area claim the same thing for land thousands of kilometers away.
If you keep saying you own it over and over again, and you censor the speech of the actual title holders, then you can get away with stealing a fully furnished nation. Not just the land, but all the buildings amenities n what not sitting on said land meanwhile paying nothing and crying like victims as the gross theft goes on for years.
Since Putin is claiming Ukraine as Russian territory, it doesn't match the propaganda or bluff for Russians to nuke their own territory.
Finally, as we saw from Chernobyl, radioactive particles can get caught in the winds and blow over to Russia. They certainly don't want to irradiate themselves.
Stealing Ukrainian land enables Russia to grow food - something the majority of their own land is not suited to - and the Russians certainly don't want to eat radioactive food.