Carter was a first-responder at an early nuclear emergency.
https://www.washingtonpost.com/history/2023/02/20/jimmy-carter-nuclear-reactor-navy/The world was in the grip of the Cold War in 1952 when a nuclear reactor began melting down.
That reactor, located at Chalk River Laboratories in Ontario, had suffered an explosion on Dec. 12. Radioactive material had escaped into the atmosphere, and millions of gallons of radioactive water flooded into the reactor’s basement. Thankfully, no one was injured, but the Canadians needed help to disassemble the reactor’s damaged core.
The United States sent 28-year-old Jimmy Carter.
.....
Then the partial meltdown happened, and Lt. Carter was one of the few people on the planet authorized to go inside a nuclear reactor.
Carter and his two dozen men were sent to Canada to help, along with other Canadian and American service members. Because of the intensity of radiation, a human could spend only 90 seconds in the damaged core, even while wearing protective gear.