Identifying Inconsistencies in Fission Product Yield Evaluations with Prompt Neutron Emission

Abstract

We present a self-consistency analysis of fission product yield evaluations. Anomalous yields are determined using a series of simple conservation checks and comparing charge distributions with common parameterizations. The summed average prompt neutron multiplicity for both products as a function of the heavy product mass is derived directly from the independent fission product yields with a procedure utilizing average charge conservation. This procedure is validated with Monte Carlo simulations of the de-excitation of the fission fragments in a Hauser-Feshbach statistical decay framework. The derived is compared with experimental data, when available, and then used to determine the prompt neutron multiplicity for the various evaluations. The propagated errors on from the average charge conservation method are significantly lower than the simple summation rules, which reveals that some evaluations are inconsistent with prompt neutron data. We propose possible solutions to remedy the observed inconsistencies and identify sources of the observed differences in between the various evaluation libraries.

Keywords:

• Yield evaluations
• fission product yields
• prompt neutron emission

Acknowledgments

The author would like to thank Patrick Talou, Ionel Stetcu, and Alejandro Sonzogni for helpful discussions and comments. This work was supported by Los Alamos National Security LLC, U.S. National Nuclear Security Administration, and U.S. Department of Energy under contract DE-AC52-06NA25396. This publication is LA-UR-17-27790.