The last hydrogen fluoride cylinder was recently removed from the Y‑12 National Security Complex in Oak Ridge, Tenn., clearing the way for a new uranium-purification technology for nuclear weapons that could switch on in 2024.
Hydrogen fluoride was used in an antiquated wet-chemistry conversion and purification process for making enriched uranium metal at the plant’s Oxide Conversion Facility (OCF), which will now be closed, according to a Monday statement from Y-12.
The last cylinder was shipped back to the vendor on June 13, a Pantex spokesperson told the Exchange Monitor in an email. The milestone eliminates a major contributor to the hazardous chemicals stores in Building 9212, which housed the Oxide Conversion Facility.
“We got rid of the hazard and the [hydrogen fluoride] process,” said Jordan Webb, a Y‑12 supervisor. “We shut it down.”
Oxide-to-metal purification and conversion was historically performed at Y-12 until the National Nuclear Security Administration temporarily outsourced it to Nuclear Fuel Services while Y-12 modernizes its uranium enrichment facilities. Nuclear Fuel Services, a subsidiary of naval nuclear reactor manufacturer BWX Technologies, holds a five-year, $428-million contract to perform the work.
Y-12’s new electrorefining (ER) system is safer for technicians and takes up less space than the legacy procedure for purifying uranium metal was supposed to running this year but will now come online in 2024, according to Y-12’s Oct. 9 statement.
Hydrogen fluoride gas can cause serious skin burns, blindness, and damage to throat and lung tissue if inhaled. It can also corrode metal, glass and plant tissue, Webb said.
“It reacts to everything, including the skin,” he said. “With the last cylinder gone, “we took the OCF to a safe state,” he said. “We’re capping the hydrogen piping to the facility and removing any uranium holdup in the piping and filters. That recovered uranium can be made into a usable form.”
After isolating hydrogen to the facility, the dock containing the hexafluoride equipment and the remainder of the OCF was placed in a safe state, the statement said.
Y-12 used the facility for the conversion of uranium oxide to uranium metal for the uranium-fueled secondary stages of nuclear weapons. The site is now working on the B61-12 nuclear gravity bomb the National Nuclear Security Administration is refurbishing. The first B61-12 canned subassemblies rolled off the line at Y-12 in December.
Sixteen hydrogen fluoride cylinders were used at OCF since 2005, the year the facility was restarted after an accidental hydrogen fluoride leak in 1992 shut down its operations, Y-12 said.
The new electrorefining process, developed by Argonne National Laboratory in Lemont, Ill., will replace the OCF, which used technology from the 1950s. Electrorefining uses molten salts in electrochemical processes to purify uranium into uranium crystals, which will be melted in a furnace to create high‑purity uranium buttons for weapons work. A similar process is used to purify aluminum, titanium, nickel, copper, and other metals.
Electrorefining also requires about one‑quarter of the floor space that OCF did and is performed in inert gloveboxes that are safer for workers to use.
The NNSA is replacing much of the legacy uranium-handling equipment at Y-12 as the agency builds its next-generation Uranium Processing Facility. Conversion and purification is wrapped up with those upgrades and, like the Uranium Processing Facility itself, has been delayed because of supply chain and labor problems.
