Machined uranium chips caused the fire that prompted last week’s evacuation of the Y-12 National Security Complex’s Building 9212, a site spokesperson said this week.
“In the event on February 22, chips of uranium metal from machining activity had been processed for storage in accordance with standard operating procedures,” a Y-12 spokesperson wrote Thursday in an email to the Exchange Monitor. “While in process, the material experienced rapid exothermic oxidation—a known hazard for which we have established plans. It occurred under an exhaust hood, within process equipment. Our processes, protocols, and procedures—which are designed to protect employees, the public, and the environment—were followed.”
The spokesperson said that no equipment was damaged by the fire but that “affected equipment is out of service” pending a review and any corrective actions Y-12 site operations contractor, the Bechtel National-led Consolidated Nuclear Security, determines it should take to prevent a repeat of the accident.
The spokesperson did not say which program was using Building 9212 at the time of the accident. The building is the hub of Y-12’s operations to build uranium-fueled secondary stages for nuclear weapons.
The fire broke out at about 9:15 a.m. Eastern time on Feb. 22. “A couple hundred employees” evacuated the building, the Y-12 spokesperson said at the time. By roughly 1:15 p.m. the same day, Y-12 sounded the all-clear and advised incoming shift workers to report to Building 9212 at the usual time.
Y-12 last week said the fire caused “no off-site impacts.”
Uranium is pyrophoric, meaning that under certain conditions it can spontaneously combust in the presence of oxygen.
Meanwhile, a few days after the fire at Y-12 on Feb. 27, the Defense Nuclear Facilities Safety Board received a letter from the Department of Energy’s National Nuclear Security Administration (NNSA) about combustion hazards at Y-12.
The defense board, the independent federal health-and-safety watchdog for DOE nuclear-weapon sites other than nuclear Navy sites, had recommended that “Y-12 should improve controls to prevent and mitigate facility worker impacts from a uranium pyrophoric fire with a sudden energy release.”
In an enclosure appended to the Feb. 27 letter signed by NNSA Administrator Jill Hruby, the NNSA wrote that “Y-12 personnel have performed a comprehensive review of the hazard evaluation studies for operations involving reactive materials and have determined that credible scenarios have been evaluated and current control strategies are adequate.”
