![]() Fine structure is apparent in two different representations of the data. The dispersion of kinetic energies at symmetry is also smaller than that found in time-of-flight experiments. The difference between the maximum average kinetic energy and that at symmetry is about 32 MeV for U 235, 18 MeV for U 233 and 20 MeV for Pu 239. There is a pronounced minimum at symmetry, although not as deep as that found in time-of-flight experiments. For each fissioning system the average total kinetic energy goes through a maximum for a heavy fragment mass of about 132 and for the corresponding light fragment mass. The data have been analysed to give mass yield curves, average kinetic energies as a function of mass, and other quantities of interest. As a result the statistics are good enough to see definite evidence for fine structure over a wide range of masses and energies. For each fissioning system over 10 6 events were recorded. Special care has been taken to eliminate spurious-events near symmetry to give an accurate measure of such quantities as the average total kinetic energy at symmetry. We have used solid-state detectors to measure the kinetic energies of the coincident fission fragments in the thermal-neutron-induced fission of U 235, U 233 and Pu 239. Thermal-Neutron-Induced Fission of U 235, U233 and Pu239 This values are compared with previously predicted values and showed good agreement. Cumulative fission yields of 148 cesium, 90 krypton, 130 iodine, 144 lanthanum, 89 krypton, 136 xenon, 137 xenon and 140 cesium are calculated. Fission rate is calculated by fission track method. Gamma rays are assigned to the responsible fission products by matching gamma rays energies and half lives. The measuremets were done at Tsing-Hua open pool reactor using 3 to 4 mg of 93.15% enriched 235 uranium samples. 4 figures, 2 tablesĬumulative fission yield of Ce-148 produced by thermal-neutron fission of U- 235Ĭumulative fission yield of 148 cesium isotopes and some other fission products produced by thermal-neutron fission of 235 uranium is determined by Germanium/Lithium spectroscopic methods. Least-squares methods are used that take proper account of data uncertainties and correlations. Experimental data that include beta, gamma, and total measurements are combined with summation calculations based on ENDF/B in a consistent evaluation. The number of fission products of each species were measured by gamma spectrometry of co-located thick deposits.ĭispersion of the Neutron Emission in U thermal fission.īeta and gamma decay heat evaluation for the thermal fission of 235 Uīeta and gamma fission product decay heat curves are evaluated for the thermal fission of 235 U. ![]() Fissions were counted in thin deposits using fission ionization chambers. Irradiations were performed at the E元 reactor, at the Caliban and Prospero critical assemblies, and at the Lancelot electrostatic accelerator in CEA-Valduc. The yields of more than fifteen fission products have been carefully measured using radiochemical techniques, for 235 U(n,f), 239Pu(n,f) in a thermal spectrum, for 233 U(n,f), 235 U(n,f), and 239Pu(n,f) reactions in a fission neutron spectrum, and for 233 U(n,f), 235 U(n,f), 238 U(n,f), and 239Pu(n,f) for 14.7 MeV monoenergetic neutrons. (author)įission Product Yields of 233 U, 235 U, 238 U and 239Pu in Fields of Thermal Neutrons, Fission Neutrons and 14.7-MeV Neutrons The results showed that the average fission cross section ratio is 3.83+-0.25. No significant differences were observed with the thin and the thick films. ![]() The chemically etched tracks were counted by an optical microscope. The experiments were carried out with a set of total six enriched 235 U and depleted 238 U deposits with different masses and Makrofol films of 0.025mm and 0.060mm thicknesses. International Nuclear Information System (INIS)įission cross section ratio of 235 U to 238 U has been measured in the fast neutron field generated by the 235 U fission plate installed on the thermal column of the Tehran Research Reactor (TRR) with a Makrofol solid state nuclear track detector. Nuclear power plants are designed in such a way that they cannot form a supercritical mass of fissionable material and therefore cannot create a nuclear explosion.Measurement of the 235 U/238 U fission cross section ratio in the 235 U fission neutron spectrum ![]()
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