CHARACTERISTICS OF THE CHEMICAL FORMS OF C-11, N-13, AND O-15 INDUCED IN AIR BY THE OPERATION OF A 100-MEV ELECTRON LINEAR-ACCELERATOR

To characterize airborne radioactivity induced by the operation of high-energy accelerators, the fractions of aerosol and gaseous components, and the chemical forms of C-11, N-13, and O-15 produced in the air of a target room of a 100 MeV electron linear accelerator were studied. Measurements of radioactivity using a particulate air sampling filter and a gas flow-through ionization chamber showed that more than 98% of C-11, N-13, and O-15 were present as gaseous forms. Their chemical forms, detected by means of radio-gas chromatography, were C-11 as CO2;N-13 as N-2 and NO; and O-15 as O-2 and NO. Machine operating conditions, which affect the compositions of the induced radionuclides and of their chemical forms, and the resulting effect on the estimation of internal doses are discussed.