Hundreds of homes on Treasure Island in San Francisco will soon be tested for radiation, even though people have been living in these homes for years. The Navy held an open house today to answer questions from anxious residents, many of whom are concerned about contamination on the former naval base. Contractors will use special instruments to check for radiation inside some 600 homes. The NBC Bay Area Investigative Unit first reported unexpected findings of radiation in an unoccupied building that was near several residences. A Navy spokeswoman said that finding, along with requests from residents, is prompting the scans. Contractors will begin their tests in a couple of weeks.