"In responding to this incident, our first concern was for the safety and continued welfare of the employees involved," said Director John Browne. "We will continue to provide our support to these workers in the days and weeks to come to ensure that they receive all appropriate treatment, and that they and their families have as much information and counsel as they need or desire."
Four of the employees underwent chelation therapy at the Laboratory's Occupational Medicine facility within two hours of the incident, after tests of the employees' nasal passages indicated possible exposure to plutonium at levels that would warrant the treatment. One employee had significantly higher levels of contamination than the other three who received chelation therapy. The other four employees' nasal smears indicated no significant intake and did not warrant treatment. All the employees went home after consultation and treatment. They are scheduled to return to work on Monday.
In chelation therapy, exposed workers receive a drug known as calcium trisodium pentatate that captures plutonium so it can be excreted from the body before it is incorporated into tissues or bone. The treatment is most effective when given within hours of exposure. Exposed workers make the final decision about whether to undergo chelation therapy after discussing treatment options and exposure risks with medical experts.
Although the presence of plutonium on nasal swipes does not necessarily confirm actual intake of plutonium, the four employees underwent chelation therapy as a precaution. Additional monitoring of an exposed employee's excreta over weeks and months and follow-up testing will determine actual intake and the resulting level of exposure. The four employees will be monitored for intake levels and may undergo further chelation treatment if such treatment is warranted. Follow-up visits for the exposed employees were scheduled for today at the Laboratory's Occupational Medicine facility.
Medical experts at the Occupational Medicine facility confirmed their response and treatment of the exposed workers with outside medical experts. Doctors at Oak Ridge Institute for Science Education's Radiation Emergency Assistance Center confirmed that the Los Alamos workers were getting the best treatment options available.
Thursday's incident occurred at around 2 p.m. in room 206 of Building PF-4 at TA-55. Eight employees were in the room at the time the incident occurred. Two adjoining rooms were unoccupied at the time of the incident.
In room 206, employees use plutonium-238 to fabricate and develop tiny heaters that can be used in civilian and defense applications. The tiny heaters that keep certain pieces of equipment in the Cassini satellite warm and functional during its voyage through space on its way to Saturn were fabricated in room 206. The plutonium isotope used for these heaters is not the same as the isotope used for nuclear weapons. Plutonium-238 has a half life of roughly 87 years, compared to its weapons-counterpart cousin, plutonium-239, which has a half life of about 24,000 years. Both isotopes emit mostly alpha particles -- radioactivity that can be stopped by a sheet of paper.
On Thursday, one of the employees working in room 206 was performing a maintenance evaluation of a glovebox. While the employee was working on the glovebox, continuous air monitors in room 206 sounded, indicating the presence of airborne radioactive material. Continuous air monitors also sounded in the two unoccupied adjoining rooms.
The eight employees working in room 206 exited the room into the corridor after the alarm sounded. Radiological control technicians surveyed the employees for contamination once the employees had safely evacuated the room. Four employees had plutonium contamination on their skin; they were immediately decontaminated. All eight submitted nasal swipes. None of the employees received any traumatic physical injuries as a result of the incident.
All the employees were transported to the Laboratory's Occupational Medicine facility for evaluation and possible treatment after the incident. Meantime, technicians sealed entrances to the two rooms adjacent to room 206 to curtail the potential spread of contamination. By the end of the day Thursday, radiation levels in room 206 were decreasing.
Rooms in PF-4 are maintained at negative pressure with respect to corridors in the building: Air pressure of the rooms is lower than the air pressure of the corridors to prevent migration of room air out into the corridors.
Laboratory and DOE officials are developing a plan for reentering the rooms and decontaminating them. A decision will be made soon about a course of formal investigation of the incident.
Los Alamos National Laboratory, a multidisciplinary research institution engaged in strategic science on behalf of national security, is operated by Los Alamos National Security, LLC, a team composed of Bechtel National, the University of California, The Babcock & Wilcox Company, and the Washington Division of URS for the Department of Energy's National Nuclear Security Administration.
Los Alamos enhances national security by ensuring the safety and reliability of the U.S. nuclear stockpile, developing technologies to reduce threats from weapons of mass destruction, and solving problems related to energy, environment, infrastructure, health, and global security concerns.