SANTA FE, N.M. - Firefighters inside a nuclear weapons complex in New Mexico scrambled on Thursday to clear brush near barrels of plutonium-contaminated waste stored just a few miles from a monster blaze roaring through surrounding forests.
The so-called Las Conchas Fire has charred nearly 93,000 acres of thick pine woodlands on the slopes of the Jemez Mountains since erupting on Sunday near the Los Alamos National Laboratory, and was poised to become New Mexico's largest ever wildfire by day's end.
"We're seeing fire behavior we've never seen down here, and it's really aggressive," Los Alamos County Fire Chief Douglas Tucker told reporters, adding that earlier hopes of lifting evacuations in the area by this weekend had been dashed.
Thick smoke billowing over the region prevented officials from obtaining the accurate aerial views they needed for an afternoon update of acreage burned.
The state's biggest blaze on record, the Dry Lakes Fire of 2003, scorched more than 94,000 acres of the Gila National Forest. By comparison, the largest blaze in Arizona, the Wallow Fire, has blackened 538,000 acres since it erupted May 29 of this year. It is still burning.
The New Mexico fire, believed to have been sparked by a downed power line, has burned mostly in the Santa Fe National Forest and lapped perilously close to the Los Alamos weapons lab and adjacent town, home to some 10,000 residents.
Both have remained evacuated since Monday. Laboratory and fire officials say no structures within the sprawling lab complex have been damaged, and no release of radiation or other hazardous materials has been detected.
A firefighting force that has grown to roughly 1,200 people managed by Wednesday to carve containment lines around 3 percent of the fire's perimeter on the eastern and southern flanks, keeping flames from invading the lab complex.
Those lines continued to hold on Thursday even as the blaze, driven by erratic wind gusts of up to 40 miles per hour, grew larger and advanced farther to the north, burning more than 6,000 acres of an Indian reservation, the Santa Clara Pueblo, officials said.
"We are devastated to witness the destruction of our precious homeland," Santa Clara Pueblo Governor Walter Dasheno said in a statement, adding the reservation has lost two-thirds of its forest lands to wildfires over the past 13 years.
About 150 miles to the south, a separate wildfire caused by lightning blazed largely out of control in and around the Mescalero Apache Reservation. By evening, the Donaldson Complex Fire had burned nearly 73,000 acres, almost 7,000 acres of it on tribal land, and forced about 50 people to flee their homes, authorities said.
Contaminated waste worries
One concern at Los Alamos has been the presence of about 20,000 metal barrels of plutonium-contaminated waste, such as old, tainted clothing and equipment, stored on a corner of the complex within about 3 miles of the fire's edge.
Lab officials say most of the low-level radioactive waste is kept on pavement and the 55-gallon sealed drums are built to withstand heat three times the temperature of a wildfire.
Still, crews worked on Thursday to clear a wider area around the storage site of vegetation, using industrial-sized mowers and large grinding machines called "Masticators" to reduce grass, shrubs and small trees to mulch.
Similar measures were being taken in several other areas around the complex, including a power-line corridor near a radioactive liquid waste treatment facility and the lab's explosive materials firing site.
"These activities will help further protect the laboratory from wildfire," lab director Charles McMillan said.
Situated on a hilltop 35 miles northwest of Santa Fe, the lab property covers 36 square miles and includes about 2,000 buildings. Established during World War Two as part of the top-secret Manhattan Project to build the first atomic bomb, the complex remains one of the leading nuclear weapons manufacturing facilities in the United States.
The Los Alamos complex also contains 3 metric tons of highly radioactive weapons-grade plutonium, stored in concrete and steel vaults in the basement floor of a building near the center of the complex, with an air-containment system surrounding it. Lab officials say those storage structures are fire safe and pose no threat to public safety.
(Writing by Steve Gorman; Editing by Greg McCune)