Burn Out Meaning

(idiomatic) To make (someone) unavailable for work involving exposure to ionizing radiation by employing (the person) in such work until the person's accumulated exposure reaches the maximum permitted for an administrative period, typically a year.

Example: To extinguish due to lack of fuel.
  The candle finally burned out.
1847, Charlotte Brontë, Jane Eyre, Chapter XVIII
  Mr. Mason, shivering as some one chanced to open the door, asked for more coal to be put on the fire, which had burnt out its flame, though its mass of cinder still shone hot and red. The footman who brought the coal, in going out, stopped near Mr. Eshton's chair, and said something to him in a low voice, of which I heard only the words, "old woman,"—"quite troublesome."
  After six months of twelve-hour workdays, most people just burn out and quit.
  The repairs on this nuclear reactor have burned out every welder in the province.