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‘Criticality safety event’ occurred at LANL’s plutonium facility

SANTA FE – There’s been a “criticality safety event” at Los Alamos National Laboratory during plutonium work that resulted in a pause in operations and the “disqualifying” of workers.

LANL in 2016 was the only one of the Department of Energy’s nuclear facilities to receive a failing “red” safety rating in the area of “criticality,” or prevention of nuclear chain reactions that could lead to radiation releases.

Los Alamos National Laboratory. (Journal File)

A report by the Los Alamos staff of an independent federal oversight board says that on Aug. 18, a crew that had cast a “shell,” part of the construction of plutonium pits that are the triggers for nuclear weapons, then moved the shell “into a location that already contained plutonium metal,” exceeding plutonium limits. The violation was discovered three days later when the shell was moved again.

“Following discovery, the crew conducted two additional nuclear material movements that they felt were necessary for product quality and security, rather than declare a potential process deviation as required by procedure and training,” says the report by the Defense Nuclear Facilities Safety Board.

When too much plutonium is put in close quarters, a reaction can take place and lead to bursts of radiation that can be deadly. A critical report earlier this year by the Center for Public Integrity highlighted at a 2011 incident at LANL where eight plutonium rods were placed side-by-side for a celebratory photograph, which the report says was described internally at lab “as the most dangerous nuclear-related incident at that facility in years.”

No comment was available Friday from the lab or the National Nuclear Security Administration’s Los Alamos Field Office.

Los Alamos is under a mandate to resume production of pits, which haven’t been made since 2011. The DNFSB report of the recent criticality incident said “this was the first shell cast in the facility in about four years and the second time that a restarted operation encountered conduct of operations issues related to the criticality safety of material movements shortly after resuming nuclear work,” referring to a 2016 incident.

LANL’s Plutonium Facility management briefed the NNSA Field Office on actions taken after the incident, including pausing all casting operations, “disqualifying” the involved workers, requiring a group leader’s authorization “for all future moves in the casting room” and mandating that all group leaders “observe at least three material movements,” says the DNFSB report, which was posted online among the board’s regular updates of safety issues at the nation’s nuclear weapons facilities.