Newly released reports have spotlighted an incident in which too much uranium-bearing material was loaded into a sample bottle — violating nuclear safety rules — and transferred from one facility to another inside the Y-12 nuclear weapons plant.
The problem was discovered after the magnesium oxide sample, containing residual amounts of fissionable U-235, arrived at the Oak Ridge plant’s in-house analytical lab, where it had been sent for evaluation.
The situation was discussed in a couple of weekly activity reports by staff members of the Defense Nuclear Facilities Safety Board. One of those reports was posted on the federal safety board’s website, and Y-12 contractor Consolidated Nuclear Security released the other report upon request and responded to questions.
The sample was originally 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 report by safety board staff stated. The sample was reportedly taken so that the sand’s particle size could be analyzed — information that was needed for a “planned design modification” at the uranium operation.
“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 report, the sample weighed 197 grams — almost double the nuclear safety limit — and was transferred to the lab in late January.
Highly enriched uranium has to be handled according to strict procedures to prevent an uncontrolled nuclear chain reaction.
The overloaded sample was included with other samples in a container that was transferred to the analytical lab, and Y-12 personnel reportedly yoverlooked a requirement that each of the sample bottles be checked for nuclear-safety limits.
The overloaded sample was reminiscent of an incident last summer in which Y-12 mistakenly sent 10 times the intended amount of enriched uranium to a New York firm, resulting in a $33,620 fine from the U.S. Department of Transportation for shipping violations.
However, Y-12 spokeswoman Ellen Boatner said the two incidents were different.
The incident last summer was blamed on human error, while the more recent concern was the mostly the result of the complexity of procedures, she said.
“Operators did not apply all aspects of a complex set of rules,” Boatner said via email. “Actions have been taken to clarify this rule set and preclude recurrence.”
The entire process of shipping uranium, either in-house or outside the plant, has reportedly drawn additional oversight at Y-12 over the past year.
Consolidated Nuclear Security ordered a number of actions in the wake of the latest incident, including direct oversight of sampling activities and a temporary suspension of uranium samples to the analytical lab.
A standing order enacted by the contractor also prohibits operators from performing the sampling-and-transfer procedures by memory.
A feature on Atomic City Underground allows readers to sign up for email updates and receive a notice each time new information is posted on the news blog. Just put your email address in the box on the lower right of the blog’s front page and follow instructions. Thanks to all loyal readers.