It won’t explode, radiation is limited to how far it would travel. The problem is that Chernobyl is on the Pripyat River which feeds into the Dnieper River which passes through Kiev.
I should have spent more time but I went for ride instead, it will probably rain tonight so I took the opportunity to get out for a while, it was grey and overcast but it was a good couple of hours pottering around the Pentlands.