Iron containing approximately 0.01 wt. % carbon was quenched from 700°C and irradiated in the BNL reactor at 57°C for various lengths of time. The rate of decay of the Snoek internal friction peak was observed at 57°C after irradiation. After a 4-hour irradiation the rate of decay of the peak was one order of magnitude faster than the rate of decay in an unirradiated specimen. Longer irradiation times up to 48 hours caused no further acceleration of the decay rate. This observation implies that in the irradiated specimens there are ten times more precipitation nuclei than in the unirradiated specimens. This is confirmed by electron microscope studies which also show a factor of ten greater concentration of precipitate particles in specimens irradiated for 5 hours at 57°C as compared to an equivalent unirradiated specimen. Electron microscope studies also show that longer irradiation times do not increase further this number of precipitates. Although these experiments clearly demonstrate the enhancement of nucleation by neutron irradiation, it is not known why the incipient nuclei created by irradiation times of longer than 5 hours do not form observable precipitate particles.