The Y-12 National Security Complex in Tennessee, the nation’s designated Uranium Center of Excellence and primary home for bomb-grade uranium, has once again loaded too much U-235 into a shipment.
The newly revealed incident took place in-house at the Oak Ridge facility and involved a sample taken from an operation in the 9212 uranium-processing complex and sent to the plant’s analytical lab – where the overload was detected and reported.
It was a reminder of an incident last summer in which Y-12 mistakenly sent 10 times the intended amount of highly enriched uranium to a company in New York. That led to multiple investigations, and the U.S. Department of Transportation fined Y-12 $33,620 for multiple violations of shipping regulations.
According to newly released reports by staff of the Defense Nuclear Facilities Safety Board, the latest incident involved uranium-laden material (magnesium oxide) that was loaded into a sample bottle. The sample reportedly weighed 197 grams – almost double the nuclear criticality safety limits.
The sample bottle was loaded last fall, but it wasn’t discovered until it was sent to the analytical lab – along with some other samples — in late January.
A couple of the safety board’s weekly activity reports discussed the Y-12 incident and the follow-up. One report was posted on the DNFSB website, while a second report was released by Consolidated Nuclear Security – the government’s managing contractor at Y-12 – upon request.
The sample was taken from a processing operation at Y-12’s 9212 uranium complex in October 2015.
“The contaminated material was a specific type of sand used in Building 9212 reduction operations that contain residual amounts of uranium-235,” the Jan. 29 staff report by the DNFSB stated.
According to the report, the sample was sent to the lab so that the sand’s particle sizes could be evaluated. That information was reportedly needed for some design modifications that were being planned at 9212.
“Operating outside of established work control protocols, the responsible supervisor instructed the operator to collect a representative sample but did not give instruction on the quantity of material required nor note the NCS (nuclear criticality safety) limit of 100 grams for uranium-bearing solids in sample bottles,” according to the DNFSB.
The overloaded sample was placed inside the shipping container, along with other sample bottles. While most of the bottles apparently were fine, the personnel at Oak Ridge reportedly did not follow through with a requirement that each bottle be checked individually for nuclear safety limits.
Y-12 spokeswoman Ellen Boatner emphasized that the incident last summer and the one more recently were different, although they both involved too much uranium in a shipment. Boatner said the 2015 incident resulted from human error, while the more recent concern was mostly due to the complexity of procedures, she said.
“Operators did not apply all aspects of a complex set of rules,” she said via email. “Actions have been taken to clarify this rule set and preclude recurrence.”
Because of the incident last year and other issues, Consolidated Nuclear Security has reportedly stepped up its oversight of the loading and shipping process and taken other actions.
CNS temporarily suspended sample shipments to the Oak Ridge plant’s analytical lab, but that was later lifted.
A standing order enacted by the contractor now prohibits operators from performing the sampling-and-transfer procedures by memory.
The Y-12 group that packaged the problem sample last fall was different than the one that did the packaging for the off-site shipment last summer, Boatner said.
