Workers at the only U.S. factory for dismantling nuclear weapons risked an explosion this month by taping together broken pieces of high explosive being removed from the plutonium trigger of an old warhead, federal investigators said.
The unorthodox handling of the unstable explosive increased the risk that the technicians would drop it and set off a “violent reaction,” the Defense Nuclear Facilities Safety Board said Tuesday in a letter to Energy Secretary Spencer Abraham.
Such a reaction could have “potentially unacceptable consequences,” board chairman John T. Conway said in the letter, which raised disquieting questions about safety at the Energy Department’s Pantex nuclear weapons plant near Amarillo, Texas.
No one was hurt and nothing exploded.
However, the National Nuclear Security Administration, which oversees the Energy Department’s nuclear weapons programs, is investigating, spokesman Bryan Wilkes said Friday.
“Safety remains a priority for us,” Wilkes said. “We are working to address the issues in the letter.”
Conway’s letter did not make clear whether the explosive had been separated at the time from the softball-sized chunk of plutonium that forms the “pit,” or trigger, of a thermonuclear warhead. To prevent a thermonuclear blast, the pit would have to have been separated from the larger warhead.
But if the explosive were still connected to the trigger, an explosion could have injured or killed workers, and could have spread plutonium or other radioactive materials around the facility.
The taping and removal of the explosive did not go as planned, and only quick thinking by the technicians prevented them from dropping the explosive, Conway wrote.
Conway said that taping the explosives together was just one of several mistakes made by Pantex officials that risked an explosion. Pantex officials also downplayed the risk, Conway noted, calling the cracks in the explosive and the fact that workers taped it together a “trivial” change in procedures.
Jud Simmons, a spokesman for Pantex plant operator BWX Technologies Inc., did not return telephone messages on Friday.
The problem occurred when workers were dismantling the plutonium “pit” from a nuclear warhead. The pit is the sphere of plutonium metal surrounded by explosives. When those explosives detonate, the plutonium is compressed, causing a nuclear explosion. In a thermonuclear weapon, that explosion sets off an even stronger nuclear blast.
Workers found the explosives around the pit were cracked, making them more unstable and easier to detonate, Conway wrote. Their solution was to tape together the cracked explosives and move them to another location.
In his letter, Conway said problems with that included:
• Failing to consult the explosives’ manufacturer to determine how unstable the cracked explosives might be;
• Performing an incomplete and inadequate safety review before going ahead;
• Allowing workers to perform the taping and removal without practicing on a mock-up;
• Failing to have experts who had developed the procedure watch the taping and removal to try to spot any problems.
Conway’s letter does not elaborate on what might have happened if the explosive had detonated.
About 250,000 people live within 50 miles of the Pantex plant.
The Nuclear Facilities Safety Board has an inspector stationed at the Pantex plant and at the nation’s other nuclear weapons sites. Weekly reports by that inspector, William White, show several concerns with safety at the plant, including flaws in the software designed to control the movement of nuclear and explosive materials around the site.
White reported in October that Pantex technicians had made a mistake while dismantling a W62 warhead from a Minuteman missile. A drill damaged part of the warhead’s nuclear core, prompting officials to evacuate the facility until experts determined that no radiation had leaked, White wrote.