Associate
The RBMK reactor at Chernobyl overheated, developed a dangerously high internal pressure and exploded when they put the control rods in (neutron flux actually went up due to a design fault). RBMK reactors used a huge graphite matrix as their moderator, which caught fire at Chernobyl and so released more fission products and transuranics into the atmosphere in the smoke. The fragments of fuel rods contaminating the 1,000 square mile exclusion zone around the reactor created "hot spots" which people still have to avoid. Everyone who visits that area has to carry a Geiger counter and watch out for hot-spots.
The effect of breaching a reactor core (from the outside with explosives) at the Zaporizhzhia nuclear power plant would not be as severe as the Chernobyl disaster because they use a PWR (Pressurised Water Reactor) design. (Although, interactions between hot steam and zircalloy cladding can produce hydrogen from the cooling water leading to secondary hydrogen explosions which could damage the containment building and release more radiation.) Nevertheless, you would have to be mad or evil to deliberately do it.
Actually, radiation did blow into Poland, Romania and Sweden etc thanks to the Chernobyl disaster. We also detected its radioactive cloud when it blew over our school here. When news of the disaster came out our Physics teacher set up a Geiger counter on the roof and linked it to a BBC computer (so it could collect readings every 5 minutes and store them then plot the data). We also detected the cloud when it had been around the world and came over again!
Putin could wait for the wind to blow easterly before he blows up the reactor to minimize the fallout reaching NATO members but then he contaminates his own backyard. Although, given that he is clearly a psychopath I doubt he would care about the suffering of his own people anyway.
