................Almost two weeks after an unexplained puff of radioactive materials forced the closing of a salt mine in New Mexico that is used to bury nuclear bomb wastes, managers of the mine are planning to send workers back in and are telling nearby residents that their health is safe.The Waste Isolation Pilot Plant, 28 miles east of Carlsbad, has been in operation for 15 years, burying wastes in an ancient salt bed deep beneath the desert, mostly without incident, and some experts have said that the site should be considered for additional kinds of nuclear waste.But late on Feb. 14, at an hour when no one was in the mine, an air monitor indicated the presence of radioactive contamination. An automated system cut off most of the ventilation and routed the exhaust through filters that are supposed to capture 99.97 percent of all contamination, turning off fans and changing the air flow, in less than one minute.This most likely minimized the contamination that reached the surface, according to the mine’s monitors, who were on hand to reassure anxious Carlsbad residents at a town-hall-style meeting Monday night. The monitors told the residents that there had been no health risk at all and that the radiation levels detected near the mine’s surface — far from town — were well below concern.
There was some small release of radiation, however. The Carlsbad research center registered the materials — plutonium and americium — on filter materials installed on air monitors in the surrounding desert.
There is still no explanation for the release, at least none in the news stories.
The materials registered on the surface are consistent with the material buried at the plant, but the quantities released are far below the levels at which the Environmental Protection Agency would recommend any action, officials said.Even in the desert, the danger to humans was small, the mine’s operators said. The highest reading from the monitors indicated that a person could have inhaled radioactive material that would emit a dose, over the person’s lifetime, of 3.4 millirem, an amount roughly equal to three days of natural background radiation. But to get the dose, the person would have had to stand for hours in the desert, on the downwind side of the plant.