Evaluation of neutron-induced independent fission yields for 37 fissioning systems

A new independent fission yield (IFY) library is evaluated and verified, which contains 37 fissioning systems dominating fission rates under typical irradiations. 20,951 experimental data items for chain yields and 5,017 for fractional independent yields are collected and analyzed to produce recommended experimental data. The systematics models (Katakura five-Gaussian model for chain yields, Zp model for fractional independent yields) and Hauser-Feshbach theory for isomeric yield ratios are used to predict the unmeasured data, after fitting parameters of systematics models to the recommended experimental data. The generalized least-square method is used to adjust the IFYs to conform to physical constraints, and simultaneously the covariances of IFYs are produced. The new IFY library is verified in various application scenarios, including calculations of fission pulse decay heats, delayed neutron yields, fission product inventories in spent nuclear fuel, and physics simulations of an operated pressurized water reactor. It is shown that results obtained with IFYs evaluated in this work have comparable accuracy to those based on the existing evaluated nuclear data libraries. Notably, the delayed neutron yields calculated based on IFYs of this work generally show better agreement with measured data; the inventories of fission products in spent nuclear fuel, such as 134,137Cs, 145-150Nd, and 150,152Sm, calculated with IFYs of this work are closest to the measured data.