Federal inspectors have gone to the Nuclear Fuel Services plant in Erwin after higher-than-expected levels of nitrous oxide fumes damaged pipes last week while processsing radioactive scrap metal. Nuclear Regulatory Commission spokesman Joey Ledford said no fumes escaped the plant and no employees were injured in the Oct. 13 incident. The workers were processing Department of Energy metals containing low levels of uranium, but that work since has been idled. Nitrous oxide is a chemical compound that can be used as a dental anesthetic commonly known as “laughing gas.” It is also a major horsepower booster in gasoline engines. The 793-employee NFS plant is owned by Lynchburg, Va.-based Babcock & Wilcox Co.