This calculation demonstrates how uncertainties in half-life and branching fraction affect postclosure isotopic concentrations and the quantification of those effects in terms of reactivity.

The results of an extensive update of the decay data of the ORIGEN-S library are presented
in this report. The updated decay data were provided for both the ORIGEN-S and ORIGEN2
libraries in the same project. A complete edit of the decay data plus the available half-life
uncertainties are included in Appendix A. A detailed description of the types of data contained in the
library, the format of the library, and the data sources are also presented. Approximately 24% of the