What would happen to the surrounding countries if a nuke were set off at Chernobyl?
What do you mean? The effect would be the same as any nuclear blast, anywhere. Exploding at the site of a comparitively-minor radioactive event makes no difference.
F :eek: ORGET ABOUT THE SUROUNDING COUNTRIES,when the reactor at Chernobyl went,the fallout reached as far as the U.S.I would think it create a huge cloud of radiation,circling the globe many times.Remember,there are 4 reactors there,well 3,and remnants of one!
While this may be true, this does not negate what GorillaMan said. Ultimately, it’d be no worse than anywhere else. It’s like driving a car at 60 mph with a tail wind of 10 mph. It’d just be additive to the overall effects of the destruction.
Hey, it’s not like it’s the end of the world, right? :dubious: Well, I guess size does matter! 
- Jinx
Considering that people could return to Hiroshima and Nagasaki not long after the bombs, and that large areas around the Chernobyl ground zero won´t be suitable for residence for the next 500 years I wouldn´t call the Chernobyl incident a “a comparitively-minor radioactive event”. In terms of fallof and contamintation it was much worse than your average nuclear blast, with all that highly radioactive reactor bits flying around the country side and everything.
So, I don´t think an A-Bomb sould really make much of a difference, it would be like spitting on the ocean.
Firstly, modern nuclear bombs are a thousand times more powerful than those in WW2. Secondly, the speedy return to Hiroshima and Nagasaki was only permitted thanks to a very limited understanding of the dangers of radiation, and the two cities still have an elevated cancer rate today.