SUMMARY

Molten Salt Reactors (MSRs) are a proposed Gen IV nuclear reactor design that utilizes nuclear fuel dissolved in high-temperature molten salts. MSRs feature safety and economic benefits through their low operating pressure, combined fuel and coolant into one component, and high operating temperatures. The potential benefits of MSRs have sparked interest in their development as a Gen IV design. Due to the historically limited demand for modeling MSRs, there has been no established tool explicitly designed for such a task.
The SCALE reactor modeling software suite, developed and maintained by Oak Ridge National Laboratory (ORNL), has been selected as a tool to verify MSR modeling capabilities due to its development under contract with various institutions within the U.S. government. SCALE has experienced widely verified and benchmarked use in the modeling of light water reactors (LWRs) and it would prove beneficial for this software suite to be configurable for MSRs.
This thesis aims to determine the sensitivity of a given SCALE MSR depletion model to user-defined simulation parameters for the goal of accurately simulating the depletion of graphite-moderated, Fluoride-salt MSRs whilst minimizing the computational resources necessary.
Within this objective, studies are performed on the effects of various inputs to the reactor simulation such as depletion sub-interval schemes (burnsteps); trace-element tracking (addnux parameter), self-shielding methods; and cross-section libraries. Overall, the results yielded by these inputs are evaluated based on the computation resources used and on the accuracy of keff and radionuclide concentrations.
The work of this report is intended to lay the groundwork for future SCALE depletion modeling of MSRs. This modeling is intended to be serviceable for reactivity, shielding, and fuel cycle analysis of MSRs and will thus provide support in making design decisions effectively.