This study was planned to investigate the potential fertility in terms of semen quality of eight men 3 1/2 years after they had been exposed accidentally to ionizing radiation of nuclear origin. It had been established that at least five of these individuals received sufficient total-body radiation (236 to 365 rads) to produce symptoms of acute radiation syndrome and that at least five had been found to be virtually sterile within four months after the accident. As determined at intervals by semen quality, a virtually sterile state was maintained for at least 21 months. Disturbances in morphology of the few spermatozoa present in the ejaculate were observed during this time. A reasonable to good level of potential fertility was attained at 41 months after exposure.
MacLeod J, Hotchkiss RS, Sitterson BW. Recovery of Male Fertility After Sterilization by Nuclear Radiation. JAMA. 1964;187(9):637–641. doi:10.1001/jama.1964.03060220011002