On June 6, 1963, several men working at the Nevada Test Site were accidentally exposed to fission product gases in a tunnel. The men were subsequently monitored using a 3 in. × 3 in. NaI collimated crystal and a multichannel analyzer. A phantom was constructed and the assembly was calibrated with several isotopes, the results being used in an extrapolation to find the efficiencies for 133I and 135I. Over 100 spectra were recorded, tracing the history of 131I, 133I and 135I from 8 hr after exposure to two weeks. Activity to dose conversion factors were developed for the various isotopes of iodine and dose estimates were calculated for the exposed individuals. These same dose conversion factors have been applied to predicted iodine ratios from the fission of 235U and an estimate of activity-dose conversion factor vs. time of gas release has been made.
©1964Health Physics Society