An improperly sealed ventilation system caused the radioactive leak that contaminated three workers at Los Alamos National Laboratory’s plutonium facility earlier this year, requiring one of the employees to receive medical treatment, according to an internal federal review.

The review says a misaligned connection between the ventilation system and a glove box allowed radioactive material to slip through a degraded gasket on an old, unused port, raising questions about how these systems are inspected and maintained.

A glove box is a sealed compartment with attached gloves that workers use to handle radioactive material. The review looked at a January radioactive release involving a glove box, one of several such incidents reported in recent years.

In its newly posted June 3 report, the Defense Nuclear Facilities Safety Board gave a summary of the review conducted by the National Nuclear Security Administration, a U.S. Energy Department branch.

The nuclear security agency’s review made 27 conclusions and listed nine areas that need correction to prevent similar incidents.

“Glove boxes are required to maintain confinement even under loss of ventilation,” the safety board said in its recap. “In this event, the glovebox failed to perform its safety function.”

Nuclear security officials said Wednesday the full review wasn’t ready to be released.

The agency’s field office has requested Triad National Security LLC, the lab’s primary contractor, provide a corrective action plan within 30 days that addresses the report’s nine judgments.

The agency is calling for improved glove box management as plans for the lab to produce 30 nuclear bomb cores — or pits — per year by 2026 will increase the amount of plutonium and radioactive waste workers handle.

On Jan. 7, a worker discovered a breach on the right side of a glove box and notified the radiological control technicians who sounded the alarm, prompting the six-person crew to evacuate the room.

The radioactive release contaminated two workers’ faces, heads and protective gear.

Nose swabs revealed three workers in the room might have breathed in airborne contaminants. One of them had to undergo chelation therapy, which purges heavy metals from the blood and is used in some cases of radiation exposure.

The report notes that subsequent tests showed the workers’ radiation doses did not exceed the threshold for creating a formal accident investigation board, but the nuclear security agency went ahead with the probe for learning purposes and to document the shortcomings.

The findings include:

• Insufficient oversight and lack of formal guidelines on how glove boxes should be configured; in this case, how securely they are connected to ventilation systems.
• Inadequate control of hazards posed by glove box accessories, such as old ports and defective gaskets in the vent systems.
• Overreliance on workers’ skills to avoid mishaps.
• Confusion over who is responsible for managing glove boxes.

Inspectors have noted that since 2011, facility personnel have monitored and planned to address about 40 accessories with questionable seals, including four that failed in this event, the safety board’s report said.

In an email, lab spokeswoman Laura Ann Mullane wrote the investigation gave the lab a chance to examine operations and identify how training, oversight and maintenance could be improved.

“Our reliance on glove boxes and their safe operation are critical to accomplishing our mission and ensuring the safety of our workforce,” Mullane wrote.

The lab is developing a “holistic strategy” toward glove box safety by addressing potential problems at every level, from upper management to glove box operators, Mullane wrote.

Triad is reorganizing its plutonium operations, which includes adding a control manager to oversee glove box work, make these compartments safer and install new ones, she wrote.

Crews are working to upgrade glove boxes and remove aging, flawed accessories as part of the plutonium facility’s modernization, Mullane wrote.

A watchdog group said the corrective actions on compartments where radioactive materials are handled is long overdue and never should have been put off this long.

“They’re behind the curve all the time,” said Scott Kovac, the research and operations director for the nonprofit Nuclear Watch New Mexico. “They shouldn’t have problems with gloves and gaskets at this late point. They’ve had 20 years or more to work on this.”

The lab tends to work from the assumption that everything is fine, and then goes into crisis mode when something goes awry, Kovac said. That makes its approach reactive rather than preventive, he added.

“They need to start from the position of making sure everything is absolutely OK, and they don’t do that,” Kovac said.

Another critic said deteriorating gaskets and misaligned hookups on old ventilation systems are the latest signs the lab is struggling to convert an aging facility into a plant that can produce almost triple the pits the lab has ever made in a year.

“There will be small problems, and there will be large problems,” said Greg Mello, executive director of the nonprofit Los Alamos Study Group. “I’m not positive about LANL’s ability to get on top of all of these problems.”

Having to make pits “reliably and relentlessly” will be far more difficult than in the past when the lab had the luxury of suspending production for months if something went amiss, Mello added.

But Mullane wrote improving the glove boxes will bolster the existing layers of defense for workers, including protective gear, air monitoring systems and alarms.

“The air monitoring system detected a radiation release, the alarm was triggered and workers performed exactly as their training teaches them,” Mullane wrote. “Consequently, no worker received a measurable uptake of radiation.”