A problem waved off as unimportant when a technology is launched can become as large as the technology's main risk decades later. Nuclear waste was dismissed in the 1950s as a minor detail, and half a century on it draws as much controversy as reactor safety.
When a society cannot agree on one permanent place for a dangerous byproduct, the byproduct does not go away; it piles up wherever it was made. Without a long-term plan, high-level radioactive waste sits scattered across 121 sites in 39 states.
A disposal site can be studied in great geological detail and still be shut down for political reasons. Decades of technical work on a planned repository ended with its closure in 2010, leaving the country with no long-term plan.