The Oxide Conversion Facility at the Y-12 nuclear weapons plant has scarcely operated in recent years, and it’s not operating now. A recently released report by staff of the Defense Nuclear Facilities Safety Board said there was a plan to resume operations in early April. But that didn’t happen, and a federal spokesman at Y-12 didn’t offer much detail about what’s going on with OCF.
“OCF remains out of service at this time,” said Steven Wyatt of the National Nuclear Security Administration. Wyatt confirmed that the facility last operated in the March of 2013, but that run was reportedly of short duration and it hadn’t operated in about a year before that.
The most recent issue was a small leak of hydrogen fluoride that occurred when operators were getting ready to install a new HF cylinder for the oxide-conversion system, causing multiple evacuations. It was noted in a DNFSB report dated April 11. There are still issues being explored, with the suspect cylinder being returned to the vendor.
Oxide conversion is an essential part of processes used to recycle weapons-grade uranium and get it ready for reuse in nuclear warheads or put on the shelf for other projects. The process converts uranium from an oxide form to uranium tetrafluoride — known as “green salt” — which then goes through a reduction process to form a purified uranium metal.
There have been an array of problems, breakdowns and technical issues with Oxide Conversion that have kept it mostly down, if not out, for years. Even in the best of times, OCF only runs on an as-needed basis. But it’s pretty clear that it hasn’t been running as much as the NNSA and the Y-12 contractor would like. While there are other sources of uranium metal at Y-12 that can be used for life-extension projects, etc., the absence of OCF means that the recycling of scraps can’t be completed — and some of those materials may be backlogged at this point.
A March 28 report by staff of the federal safety board said, “Enriched Uranium Production personnel continue to progress in their efforts to resume operations at OCF. Last week, craft personnel replaced the value stem assembly that system engineers believe was the source of a leak in the primary confinement barrier of the vaporizer enclosure (where alarms had been detecting hydrogen fluoride). The system subsequently passed a helium leak check and pressure decay test. Operators must now completed a small set of surveillances before OCF can return to operation.”
It’s not clear why that didn’t happen, but the OCF is part of the uranium processing operations in the antiquated 9212 complex at Y-12 and there’s a conservative bent to make sure work doesn’t create unsafe conditions.
In a memo a year ago, safety board staff assigned to Y-12 said other than the problem with OCF, the rest of the recycling system had improved significantly.
“As a result, Enriched Uranium Production personnel produced nearly double the quantity of purified UO3 (the feed material for the Oxide Conversion Facility) relative to the quantity produced during the first seven months of the fiscal year combined.”
However, without the OCF in operation, the production of uranium metal apparently gets stalled at that point. Wyatt said the shutdown has not kept Y-12 from meeting its production requirements.
Other technologies are in development at Y-12 to potentially replace OCF and some of the wet-chemistry operations that are used to recycle the highly enriched uranium.
The recently released Red Team report recommended making room at the plant’s Beta-2E facility to conduct uranium recovery operations with electro-refining (ER) and direct electrolytic reduction (DER). ORNL Director Thom Mason, who headed the Red Team evaluation of alternatives for carrying out Y-12′s uranium missions, said it would be ideal if those activities were in place well before the time comes to shut down the 9212 complex (targeted for 2025).
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