This thesis is a parameter study of the effects of branching fraction uncertainty from nuclear decay on isotope quantities at later times. Development of how to calculate and accurately draw random samples of branching fractions is done. Overall effects as well as isotope quantity uncertainty distributions are also explored. Isotope quantities are calculated using exponential moments methods with transmutation matrices. Uncertainty from both half-lives and branching fractions is carried through these calculations by Monte Carlo methods. Results of the study show that uncertainty from branching fractions dominates most isotopes present from neutron fission after approximately one month. Another result is that only 20% of isotopes present at any given time have uncertainty from both half-lives and branching fractions that are of the same order of magnitude. The final program is both flexible in the number and type of isotopes it can input and output, as well as computationally efficient
