A new evaluation of fission product yields for the neutron induced fission of U-233 and Th-232

Abstract

Worldwide R&D efforts in establishing the reactor technology with the Thorium-Uranium (Th-U) fuel cycle have significantly grown in the recent past. The study of fission product yields has a major impact on the understanding of the fissioning process and plays a vital role in the development, design and safety analysis of advanced nuclear energy systems. A new evaluation of fission product yields based on a new database of measurements up to 2013 will allow more reliable and accurate model calculations of the Th-U fuel cycle. This work is undertaken to study the mass and charge distributions of fission products for the fuel nuclei U-233 and Th-232 induced by thermal, fast, and about 14MeV neutrons. First, the available experimental data is analyzed systematically and evaluated. Second, it is necessary to predict the unmeasured fission yields and their errors by the systematics, due to the lack of experimental data. The mass distributions are well described by a superposition of 5 Gaussian functions, which is called the Multi-Gaussian model. The charge distributions are calculated on the basis of ZP model. Their parameters are derived based on evaluated data. Finally, the fission product yield library related with the Th-U fuel cycle is well established. The evaluated data is improved compared to the major international evaluated libraries, including ENDF/B-VII.1, JENDL-4.0 and JEFF-3.2.