DOE OSTI2017
The University of Wisconsin Nuclear Reactor converted from HEU to LEU fuel in 2009. As part of the conversion process, an MCNP model was developed to predict flux distributions and depletion in the core. This core model included an unforeseen excess reactivity bias, resulting in an overestimate of core reactivity, and requiring the core configuration to be shuffled in 2011. The original model was constructed by hand and in order to account for radial and axial burnup in the fuel, and to include sufficient detail in the geometric features, the input file was over 17,000 lines long. Given the challenges in assessing the quality of such a long and complicated MCNP model, this project was designed to build an MCNP model based on a minimal set of input quantities in a modular and repeatable fashion. A Python code was implemented to write the MCNP input file from fundamental reactor data, both geometric and material. The recent conversion to LEU fuel provides a unique opportunity to characterize fuel composition quite accurately in the core. The goal of this project is to produce an accurate, maintainable model that can be used with future reactor physics experiments.
21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗