More tests ordered for plutonium-exposed Idaho lab workers

An undated publicity photograph released to Reuters on November 8, 2011 shows the ''material and fuels complex'' facility at the The Idaho National Laboratory, a U.S. Energy Department nuclear research site in eastern Idaho.

SALMON, Idaho (Reuters) - Doctors at a nuclear research lab in Idaho on Wednesday ordered further medical tests of 16 workers accidentally exposed to low-levels of radiation from plutonium fuel in a decommissioned reactor.

Officials at the Idaho National Laboratory said radioactive contamination was detected on the skin or clothing of at least six of the workers after Tuesday's mishap, and two were confirmed to have inhaled radioactive particles.

The accident, which lab officials said occurred during routine procedures, was believed to be the worst in at least four years at the sprawling site, which occupies 890 square miles in the high desert of eastern Idaho.

But officials there said it posed no risk to the public or environment. The lab said there was no release of radiation beyond a single room in the reactor building, which lies about 38 miles from the city of Idaho Falls.

An initial equipment inspection pointed to possible damage inside a small plutonium fuel container that was the source of the exposure.

The results of full-body scans conducted of the exposed workers prompted doctors on Wednesday to order additional lung examinations of three workers, and urine and stool samples to be taken from all 16, lab officials said. All are technicians employed by laboratory contractor Battelle Energy Alliance.

Lab spokesman Earl Johnson said none of the workers reported feeling ill or showed symptoms of radiation sickness.

The lab, the U.S. Energy Department's leading nuclear research facility, initially reported that 17 workers had been exposed, but that number was revised the next day.

Just four of the exposed technicians agreed to precautionary treatments, such as special intravenous fluids, designed to help flush any radioactive particles from their bodies, and all were permitted to return home after an initial round of testing, lab spokeswoman Sara Prentice told Reuters.

Officials said it may be weeks before the full extent of radiation doses received by members of the group is known.

"We're still collecting and analyzing samples from all 16; there is a lot of work to be done to get the correct information," Prentice said.

POSSIBLE DAMAGE INSIDE FUEL CONTAINER

The accident occurred inside a deactivated nuclear reactor located within a complex of facilities used for remotely handling, processing and examining spent nuclear fuel, radioactive waste and other irradiated materials.

The technicians were exposed when a foot-long, rectangular container of plutonium fuel inside the reactor was opened during work to prepare the material for shipment to another facility, Johnson said.

"This was a procedure that has been done many times before," Prentice added.

The technicians were dressed in lab coats and wearing gloves, but the work they were performing requires no respirators or other special protective gear, Johnson said.

Sixteen workers were in the room, but "only a couple" were handling the fuel container in question, he said.

A subsequent inspection of the container, shaped like a covered cake pan, showed its exterior did not appear to be damaged, but "there may have been damage" to a layer of stainless steel that envelopes the fuel inside, Prentice said.

Further lung examinations were ordered for two workers whose body scans tested positive for radiation in their lungs and for a third worker whose lungs showed an "anomaly," Johnson said.

A review of the incident by the lab was under way, and a special team of Energy Department investigators was expected in Idaho next week to launch its own inquiry. In the meantime, new curbs have been placed on the handling of some radioactive materials at the complex where the accident occurred.

Some 6,000 employees and contractors work at the Idaho lab, which opened in 1949 as a national reactor testing station.

According to lab records, Tuesday's incident appeared to be the most serious accident at the lab since June 2007, when a worker was treated for minor burns and smoke inhalation from a small laboratory fire, though no radiation release was reported in connection with that incident.

(Editing by Steve Gorman and Cynthia Johnston)