It is “likely” that some of a group of 15 Los Alamos National Laboratory employees were internally contaminated with plutonium-238 oxide that leaked out of a ruptured glove-box glove on June 8, the Department of Energy nuclear-weapon facility said this week.
“Early bioassay results indicate low level intakes are likely in some of these workers,” a Los Alamos spokesperson said Thursday by email. “The Laboratory is currently awaiting test results for all 15 AMPP [Actinide Material Processing & Power Division] employees so it would be inappropriate to comment further until those comprehensive results are available.”
One of those 15 employees, whose protective clothing, skin, and nostrils registered the strongest traces of alpha radiation on the day of the accident, has already received chelation therapy — a treatment to remove heavy metals from inside the body.
“Field indicators of air samples and positive nasal swabs were used to evaluate whether an intake likely occurred and the rough magnitude of such intake,” the lab spokesperson wrote Thursday. “Based on this evaluation and consultation with internal dosimetrists, [DOE’s Radiation Emergency Assistance Center/Training Site], and [Los Alamos] occupational medicine, the AMPP employee was offered and accepted chelation treatment.”
On the day of the release in the lab’s Plutonium Facility, nasal swabs on the person who later had chelation therapy revealed 224 and 544 disintegrations per minute of alpha particles.
In a report about the incident released last week, the independent federal Defense Nuclear Facilities Safety Board said there was “significant airborne radioactivity” in the room, which according to the Los Alamos spokesperson remained closed at deadline Friday for Nuclear Security & Deterrence Monitor.
According to the defense board report, “continuous air monitors sounded when an operator pulled out of the glovebox gloves after weighing and packaging plutonium-238 oxide powder.”
Plutonium-238 is used in research for nuclear weapons programs, and as a heat source for spacecraft. The lab did not say exactly what project the 15 employees were working on when the leak occurred.
In line with the lab’s usual practice, all employees with potential exposures after the release “continue to work outside of radiological operations until there is data to sufficiently bound doses or dose assessments are completed,” the Los Alamos spokesperson said.
The spokesperson would not say how long these assessments might take to complete. Meanwhile, lab management contractor Triad National Security last month established a task force to investigate the incident. Its report is due by next week.
After a separate plutonium-238 incident in 2018, it took Los Alamos just inside two weeks to detect signs that a worker had internal plutonium contamination.
The Plutonium Facility is where Los Alamos will prepare surplus plutonium for downblending and disposal as part of the agency’s Surplus Plutonium Disposition Program: the replacement for the Mixed Oxide Fuel Fabrication Facility. It is also where the NNSA plans to cast new pits, fissile warhead cores, for future W87-1 intercontinental ballistic missile warheads. The first war-ready pits are supposed to be cast in fiscal 2024.
