system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: If nuclear fallout is such a huge concern. How are nations able to test nuclear weapons within their borders.

If it's because it's done in remote places. Does that mean areas far away from major cities likely to be attacked are safe?
gpt
Nuclear fallout is very minimal from standard nuclear weapons, hence how people live in Hiroshima and Nagasaki just fine today.  

Nuclear tests will often be underground, underwater, or an airburst.  The Japanese bombing was airbursts, which maximize destruction by create minimal fallout.

Regardless, nuclear fallout is not a huge concern except in a full-scale nuclear war or reactor meltdowns.  In that case, thousands of nuclear weapons would be dropped.  It's not something that happens in any significant quantity from a single weapon. Chernobyl is an example of an instance that did cause consider nuclear fallout, and the reactor core is still humming away, buried in concrete underground.