WASHINGTON — An accident that occurred as a decades-old nuclear warhead was being dismantled at the government's Pantex facility near Amarillo, Texas, could have caused the device to detonate, a nonprofit organization charged Thursday. The Project on Government Oversight said the "near miss" event, which led the Energy Department to fine the plant's operator $110,000, was due partly to requirements that technicians at the plant work up to 72 hours per week. The Pantex plant, 17 miles northeast of Amarillo, is the country's only factory for assembly and disassembly of nuclear weapons. The organization said it was told by unidentified...