system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How is it that countries can safely test their nuclear weapons without causing permanent damage?
gpt
Typically they test them in unpopulated and unused locations, deep underground, or otherwise far away from anything of value (Since, after all, they'd destroy anything of value).

Nuclear weapons also don't tend to leave that much residual radiation. They are relatively small amounts of radioactive material, which are widely dispersed, and generally have shorter halflives, compared to an event like Chernobyl, where tons of long lived burning material was released. 

As you'll note, Hiroshima and Nagasaki aren't unpopulated, but rather began to rebuild not long after they were hit with nuclear weapons.