LOS ALAMOS: A wildfire near the desert birthplace of the atomic bomb advanced on the Los Alamos laboratory and thousands of outdoor drums of plutonium-contaminated waste as authorities stepped up efforts to protect the site and monitor the air for radiation. Officials at the premier US nuclear-weapons lab gave assurances that dangerous materials were safely stored and capable of withstanding flames from the 95-square-mile fire, which at one point was as close as 50 feet from the grounds. Residents downwind are worried about the potential of a radioactive smoke plume if the flames reach thousands of barrels of waste stored in above-ground tents....