Gamma-Ray Spectra of Fractionated Fission Products
NAVAL ORDNANCE LAB WHITE OAK MD
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To determine the effects of fractionation on gamma-ray exposure rates in fission-product fields, spectra of gamma-rays emitted by fractionated products of thermal neutron fission of 235U were studied. Controlled fractionation was brought about by sweeping the rare gas fission products out of sealed samples at 10 to 15 seconds after fission using programmed automatic equipment. Spectra were measured at nine selected times viz., 14, 12, 1, 2, 5, 10, 24, 48 and 72 hours after fission. The detector used was a calibrated and highly collimated 5 inch x 5 inch NaIT1 crystal. The gamma-ray spectra were unfolded from the pulse-height distributions by means of an iterative method. The number of fissions that had occurred in each sample was determined by radiochemical analysis for 99Mo. The type and time of fractionation studied in this work is of particular interest in predicting the effects of nuclear explosions, but is also applicable to certain possible nuclear reactor incidents.
- Radioactivity, Radioactive Wastes and Fission Products