The folks at the Y-12 nuclear weapons plant are mighty particular when measuring quantities of bomb-grade uranium, tracking the material virtually down to the atom to make sure that even the smallest amounts aren’t lost or diverted.
Therefore, it must have been a big surprise last month when a Y-12 engineer determined that a uranium bomb part had gained weight during a machining operation.
“A process engineer discovered that the documented post-machining weight of an enriched uranium part was greater than its documented pre-machining weight,” staff members with the Defense Nuclear Facilities Safety Board stated in their April 24 report to board headquarters in Washington, D.C.
As it turned out, there was some human error involved.
Members of Y-12’s Nuclear Material Control and Accountability team traced the source of the discrepancy to a “documentation error” by a worker in the plant’s 9212 uranium-processing complex. The worker reportedly logged the part’s assay (enrichment level) as the part’s weight.
According to the defense board’s report, “Special Nuclear Materials Operations personnel missed several opportunities to identify the discrepancy, including a procedurally-directed check to verify that the weight of item, as measured upon receipt in Building 9215 (where the machining apparently took place), matched the weight of the item recorded in Building 9212.”
The board memo said the responsible production team managers at Y-12 are evaluating ways to reduce error rates and prevent a recurrence.
Photo caption: Y-12 worker holds a “button” of highly enriched uranium. (NNSA photo)
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.