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Pu-238 incident at LANL
Fellow RADSAFE'rs ...
The following article appeared in the Saturday, March 18, 2000 edition of the Albuquerque Journal.
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Saturday, March 18, 2000
DOE Team Will Probe Lab Incident
By Ian Hoffman
Journal Staff Writer
The U.S. Department of Energy is flying experts into Los Alamos on Monday to investigate the probable inhalation of cancer-causing plutonium by five nuclear workers.
Energy Secretary Bill Richardson on Friday ordered a Type A investigation, a level of inquiry generally used when workers are killed or seriously injured. Details of the incident so far suggest Thursday's plutonium incident at Los Alamos could be the worst in almost seven years.
Los Alamos doctors injected the four most highly contaminated workers on Friday with their second dose of chelation agents, in hopes the workers will excrete the plutonium before the metal is deposited in bone, liver or testes.
It will be at least a week before scientists get a rough sense of the workers' actual doses and months before they have hard estimates. But Dr. David Michaels, DOE's assistant secretary for environment, safety and health, said his office advised Richardson to launch a Type A investigation out of caution.
"It's our view that we should treat this very conservatively," Michaels said Friday. Michaels and U.S. Rep. Tom Udall, D-N.M., were preparing for hearings in Espaņola today on compensation for Los Alamos workers made ill by exposure to plutonium, radiation, chemicals and other toxic metals.
"Clearly my heart goes out to the workers involved in this situation," Udall said.
"My thoughts are with the workers involved in the incident at Los Alamos," Sen. Pete Domenici, R-N.M., said in a faxed statement. "This is a serious situation, and I, like other New Mexicans, look forward to assurances from DOE and the lab that everything is under control."
Airborne radioactivity alarms sounded just before 2 p.m. Thursday in room 206 of the top-secret plutonium facility at Los Alamos' Technical Area 55. Eight employees evacuated the room, which holds a glove box for making tiny heat and power generators out of plutonium-238. The heaters and generators are installed in space probes, undersea instruments and nuclear warheads.
With a glove box, workers reach inside gloved portals to handle radioactive or hazardous materials inside a windowed box. The glove box in room 206 is ordinarily filled with argon gas to prevent oxygen from reaching the plutonium, which can spontaneously combust. At the time of the plutonium release, a worker was performing a "maintenance evaluation," looking at the argon supply line underneath the glove box to determine the reason that no gas was flowing into the box, according to a preliminary report.
What happened next is not clear. The report suggests the worker did nothing expected in a plutonium release from the glove box. "It should be noted that during the evaluation, at no time were any valves manipulated nor attempts to breach systems," the report said.
Investigators expect to make their final report in six to eight weeks.
"When an accident like this happens, we must learn from it and do everything possible to prevent similar accidents from happening again," Richardson said Friday.
Soon after room 206's continuous air monitors, or CAMs, alarmed, so did CAMs in two adjoining but unoccupied rooms. The eight workers evacuated to an outside corridor, where technicians swept them with radiation monitors. Four workers had radioactive particles on their skin and were decontaminated, a process usually involving repeated washings or the application and removal of adhesive tape.
Five of the workers had positive nasal swipes, four of them with high enough levels of radioactivity in their nostrils for doctors to recommend chelation. One worker had "significantly higher levels" than the others, the report said.
Nasal swipes are a quick, early indicator for "uptake" or the inhalation of radioactive material, but they are highly unreliable in predicting the amount inhaled. A nasal swipe often will pick up radioactivity from particles too large to enter the lungs.
Los Alamos officials have traditionally released nasal swipe counts as a rough gauge for the seriousness of an accident or release. They refused to release the nasal counts for Thursday's incident, however.
"At this point, we don't want to release those numbers out of concern for the employees' feelings," said lab spokesman James Rickman.
It could take a week or two for doctors to get a sense for the workers' doses from the results of urine and feces tests, which show the amount of plutonium leaving the body over time and the effectiveness of the chelation therapy.
The four workers with the highest nasal counts underwent intravenous chelation within an hour of the release and were sent home. Lab officials said the workers will return to their jobs Monday.
"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," lab director John C. Browne said in a statement.
When inhaled, plutonium-238 behaves much like plutonium-239 that is used in nuclear weapons; they both eject large alpha particles at lung membranes, and they tend to migrate to other potential cancer sites, such as bones, liver and testicles. But plutonium-238 is much more radioactive -- it kicks out alpha radiation more intensely -- and so poses a greater cancer risk.
Los Alamos has had at least one plutonium inhalation incident every year of the last decade, though the numbers have been declining for the last three years, according to lab officials.
The most recent case in which chelation was administered was in June 1997, a year when a total of seven workers had positive nasal swipes. Inhalations of plutonium-238 are much rarer; six workers were contaminated by the metal, one by inhalation, in November 1995. The last time as many workers appeared to have inhaled plutonium at the same time was in August 1993.
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Jim Hardeman, Manager
Environmental Radiation Program
Environmental Protection Division
Georgia Department of Natural Resources
4244 International Parkway, Suite 114
Atlanta, GA 30354
(404) 362-2675 fax: (404) 362-2653
Jim_Hardeman@mail.dnr.state.ga.us
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