The nuclear lab was set to remain closed, at least through Wednesday.
Rod Torrez, a fire spokesman, said crews worked Monday to beef up the defensive perimeter by widening the fire lanes next to New Mexico Route 4, which runs through the lab's 40-square-mile property.
Kevin Roark, a lab spokesman, said no new fires have broken out there since a small one-acre blaze Monday. Torrez said winds had died down enough by Tuesday to allow the operation of helicopters that carry large water buckets to douse the fire. High winds precluded aerial operations yesterday.
Roark said the lab has cleared "large defensible areas" that contain nuclear materials, adding those materials are locked away in steel and concrete vaults. Roark said the National Nuclear Security Administration has deployed a Radiological Assistance Program team team as a precaution to identify and manage any releases of radioactive material.
Torrez, chief of interpretation at the National Parks Service's Bandelier National Monument, which is 22 miles from Los Alamos, said the blaze has burned between a third and a half of the park's 33,000 acres, but so far has left unscathed the almost 900-year-old cliff dwellings.