Neutron science center cleanup operations suspended

Contact: James Rickman, elvis@lanl.gov, (505) 665-9203 (00-052)

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LOS ALAMOS, N.M., April 12, 2000 -- In order to address worker health concerns that arose this week, officials at the U.S. Department of Energy's Los Alamos National Laboratory have suspended operations in two areas at the Laboratory's Manuel Lujan Jr. Neutron Scattering Center. Laboratory managers announced the "stop work" to employees at the Lujan Center today and Tuesday.

Under Laboratory policy, workers can stop work if they have a concern about the safety of their activities. The "stop work" was precipitated by worker concerns that known mercury contamination in two areas known as Experimental Rooms 1 and 2 was being spread to other areas. Workers were in the process of cleaning and decontaminating ER-1 and ER-2 so neutron physics experiments at the facility could resume this year. The cleanup began in October 1999.

"We have no indication that mercury contamination at the facility presents a risk to employees or the environment," said Geoff Greene, deputy division director of the Los Alamos Neutron Science Center. "But because concerns have been raised, it is prudent to suspend operations in ER-1 and ER-2 until we can address safety issues and provide complete information to our workers. We want workers at the Lujan Center to be actively involved in the evaluation and resolution of the situation. Most of all, we want workers at the Lujan Center to be safe and to feel safe."

The Lujan Center is part of LANSCE, a facility that uses a high-energy linear proton accelerator to generate neutrons for a number of scientific and defense applications. The facility is open to scientists who come to Los Alamos to use neutrons to gain insight into material properties and nuclear physics; the facility has played a role in helping scientists better understand the nature of the universe as well as helping industry design better consumer products.

At the Lujan Center, mercury is used in "shutters" to stop neutron beams. On a few occasions in the past, mercury has spilled onto the floor in experimental areas. When this has occurred, the material is cleaned up with special vacuum machines by workers wearing appropriate protective clothing and gear.

Mercury is a dense, heavy, toxic material. Mercury can be found in some household thermometers and dental fillings. Mercury has a high surface tension and tends to pool easily. When disturbed, the material can separate into extremely tiny beads that scatter and can become trapped in cracks or pores in floor material. These tiny, trapped beads can be missed by the vacuum and remain in the facility in minute quantities.

Mercury evaporates easily and can become a breathable vapor, which can cause health problems. However, not all spilled mercury becomes vapor since the beads eventually develop a chemical coating or get covered with dust, greatly reducing the rate at which they vaporize.

Mercury detectors in ER-1 and ER-2 have indicated vapor levels well below exposure limits established by the Occupational Health and Safety Administration in areas where employees would normally work and breathe.

Workers cleaning up experimental areas at the Lujan Center wear protective clothing and respirators as a standard precaution. Multiple types of samplers are used to detect and measure mercury vapors. Workers also wear special filters on their respirators that change color to indicate prolonged exposure to the material. Workers have not observed any filter color changes at the Lujan Center.

In cases when spot detectors found local concentrations of mercury, employees involved with the cleanup were given blood or urine tests to check for acute exposure to mercury. None of the employees tested has shown evidence of any exposure to the material.

Employees expressed concern about the possibility that mercury was being spread from the experimental rooms to other areas. Managers at the facility promptly suspended work in the two experimental rooms until ES&H personnel could say definitively whether the mercury poses a danger to workers or the environment. Greene addressed employees at separate meetings Tuesday afternoon and this morning.

Greene said operations in ER-1 and ER-2 will not resume until he and others are sufficiently certain that mercury does not impose an unnecessary risk to employees at the facility.

"The bottom line is we will not resume activities in that area until both staff and management are certain that the work can be done safely," he said.

More news releases from the Los Alamos Neutron Science Center (LANSCE)