Employees had placed the equipment on a shower grate to drain its liquid — which was pretested and met the standards for this type of disposal — unaware the grate was a weight-activated device that triggers the shower, Mullane wrote.

There was a delay in the shower kicking on after the equipment was set on the grate, confusing the workers who didn’t immediately realize that was what caused water to pour out of the shower, she wrote.

As soon as they understood weight on the grate had caused the shower to turn on, they quickly removed the equipment, Mullane wrote. However, the incident resulted in about 150 gallons of water overflowing outside the shower area.

“While we strive to ensure that these types of events never happen, we also prepare for every possible scenario,” she wrote. “As a learning organization, we use past experiences to improve our response to events such as this.”

The safety board noted there were five previous mishaps causing water overflow in the lab’s plutonium facility since 2018.

The incidents include vault baths, used to cool certain plutonium containers, overflowing twice in 2021 through a mixture of workers’ errors and faulty equipment. And last year, a cooling mechanism that’s part of a HEPA air filtering system was accidentally activated, releasing 4,700 gallons of water that took crews weeks to clean up.

An anti-nuclear activist argued the shower mishap shows subpar training of workers that ultimately is the managers’ responsibility.

“If training is inadequate, management is at fault,” Greg Mello, executive director of Los Alamos Study Group, wrote in an email. “If personnel are in the wrong job, that too indicates a management problem.”

Lab managers might downplay the incident, but it reflects an ongoing problem of things being rushed, including training, to push the facility toward producing plutonium pits, he wrote.

“There are way too many of these incidents,” Mello wrote. “It’s not a trivial thing to have a flood in a plutonium facility.”

In a separate March 7 incident at the Area G waste site, a radiological control technician left with radioactive wipes used to sample contaminated surfaces.

The technician took the double-bagged wipes from the facility but forgot to turn them in. After arriving home, the employee discovered they were in his vest pocket.

The technician informed N3B, the contractor in charge of cleaning up the lab’s legacy waste, he had accidentally taken the wipes home. A team was sent to retrieve the materials.

The team “confirmed the swipes were well within safe radiological levels and presented no harm to the public or the environment and that no further testing was required,” said Stephanie Gallagher, a spokeswoman for the federal Environmental Management Los Alamos Field Office.

Mello thinks the outcome could have been worse.

“Taking the radioactive smears off-site was dumb, but the individual was favored by sufficient packaging and luck,” he wrote.

Correction: This story has been amended to reflect the following correction. A previous version of this story incorrectly indicated the location of one of the two March 7 incidents at Los Alamos National Laboratory. The March 7 incident when a radiological control technician left with radioactive wipes used to sample contaminated surfaces occurred at the Area G waste site, not the plutonium facility.