Evaluating the Effect of Decay and Fission Yield Data Uncertainty on BWR Spent Nuclear Fuel Source Term

Knowledge of spent nuclear fuel (SNF) source term, for example decay heat, reactivity and nuclide inventory of SNF, is essential in the safe handling and final disposal of SNF. The computational characterization of SNF has many sources of uncertainties. One of these is the uncertainties present in nuclear data. This work continues the identification of the major uncertainty components in the decay and fission yield data in relation to the SNF source term. The uncertainties of decay and fission yield data are propagated from ENDF-6 file format nuclear data library to the SNF source term using a sampling based technique in the Monte Carlo particle transport program Serpent 2. Studied components of the SNF source term are produced multiple times as functions of burnup and cooling time with randomly perturbed decay and fission yield data. Similar work has been previously conducted for a VVER-440 type fuel assembly. In this work, a boiling water reactor (BWR) type fuel assembly is studied. The study is conducted varying the void fraction to examine its effect on the uncertainties of the SNF source term components caused by the uncertainties in the decay and fission yield data. Other nuclear data related uncertainties are ignored in this study, and only fixed, nominal depletion conditions are considered