A Los Alamos National Laboratory worker failed to close a cooling system valve, causing a 200-gallon spill of contaminated water that resulted in some of the liquid flowing into an air vent and an inactive glove box used for handling radioactive materials.
The July 19 incident at the lab’s plutonium facility, known as PF-4, has spurred an internal probe, according to the Defense Nuclear Facilities Safety Board, a government watchdog.
The safety board’s most recent weekly report said the spill resulted from a worker not closing a valve after refilling a water tank, coupled with another spring-closed valve not clamping shut.
Workers discovered mildly radioactive water on the facility’s first floor near a pump room and a small amount of water in the basement, a lab spokesman wrote in an email, adding all of it was contained within the building.
“There was no risk to employees, public health and safety, or the environment,” he wrote. “The majority of cleanup is complete, and the laboratory is conducting a fact-finding mission to determine the cause of the incident and will develop appropriate corrective actions.”
The safety board expressed some concern about the water draining into a vent and then through a glove box, a sealed compartment with attached gloves that workers use to handle radioactive items.
The report suggests an inflow of such water into an active glove box containing radioactive components, debris or residue could be hazardous.
Personnel will “evaluate whether water ingress into glove boxes through the ventilation system could result in an unanalyzed criticality scenario,” the report said.
Criticality is a nuclear chain reaction strong enough to continue by itself, which could trigger an explosion. Criticality can happen by placing too much radioactive material close together.
The report didn’t specify the purpose of the water, but it is commonly used in vault baths to cool certain plutonium containers.
The July spill is much smaller than the 1,800 gallons released in March when a worker also left open a valve. In that incident, an internal alarm failed to alert personnel working in the operations center.
In the most recent spill, lab workers were quickly alerted but mistook the alarm as one that goes off during routine maintenance, so they didn’t respond, the report said.
One critic of the lab’s nuclear operations said employees not being able to distinguish routine alarms from a real alarm requiring immediate action is troubling.
If an alarm system that’s supposed to improve safety instead causes more confusion — partly because workers aren’t taught the difference between one type of signal and another — then a mishap can escalate, said Greg Mello, executive director of nonprofit Los Alamos Study Group.
Confusion is more likely to occur now at PF-4 because new crews are there changing systems to gear up for producing plutonium pits for nuclear warheads, and many of them are unfamiliar with how everything works, Mello said.
In a high-hazard environment like this, production and safety are so closely intertwined as to be part of the same mission, Mello said.
“You can’t be too careful over there at PF-4,” he said. “The truth is, one accident can shut that place down for a long time.”