LOS ALAMOS, N.M. -- The government sent a plane equipped with radiation monitors over the Los Alamos nuclear laboratory Wednesday as a 110-square-mile wildfire burned at its doorstep, putting thousands of scientific experiments on hold for days.

Lab authorities described the monitoring as a precaution, and they, along with outside experts on nuclear engineering, expressed confidence that the blaze would not scatter radioactive material, as some in surrounding communities feared.

"Our facilities, our nuclear materials are all safe, they're accounted for and they're protected," said lab director Charles McMillan.

The twin-engine plane, which can take digital photographs and video as well as thermal and night images, was sent to New York City to take air samples after the Sept. 11 terrorist attacks. It has flown over wildfires and areas damaged by Hurricane Katrina. It monitored the 2002 Winter Olympics in Salt Lake City. It also helped locate debris from the disintegrated space shuttle Columbia.

"It can look for a wide variety of chemical constituents in a plume and the plumes can originate from fires, from explosions, from a wide variety of sources," said lab spokesman Kevin Roark.

And in a testament to the sophisticated research done at Los Alamos, the plane was developed with technology from the lab, the desert installation that built the atomic bomb during World War II.

The pillars of smoke that can be seen as far as Albuquerque, 60 miles away, have people on edge. The fire has also cast a haze as far away as Kansas. But officials said they analyzed samples taken Tuesday night from some of the lab's monitors and the results showed nothing abnormal in the smoke.

Anti-nuclear groups have sounded the alarm about thousands of 55-gallon drums containing low-grade nuclear waste -- gloves, tools and other contaminated items -- about two miles from the fire.

Lab officials said it was highly unlikely the blaze would reach the drums, and that the steel containers can in any case withstand flames and will be sprayed with fire-resistant foam if necessary.

Kevin Smith, site manager for the National Nuclear Security Administration, said the lab's precautions have been scrutinized by dozens of experts.

The lab has been shut down since Monday, when all of the city of Los Alamos and some of its surrounding areas -- 12,000 people in all -- were evacuated.

The plane is just one part of an elaborate air monitoring network surrounding the lab. The lab and the New Mexico Environment Department have dozens of monitors on the ground throughout the region.