Molten salt reactor nuclear energy systems are being pursued commercially worldwide because they are flexible, efficient, and inherently safe. Although these nuclear energy systems are attractive for many reasons, liquid-fueled designs pose specific and unique measurement challenges for safeguards and nuclear material accountancy. In traditional fixed fuel nuclear power plants, the nuclear fuel is contained in the reactor core and can be counted, but in molten salt reactors, the fissionable material is contained in the molten salt matrix and circulates through the core and other components of the system. Furthermore, online reprocessing and continual feed-removal may exist. Understanding and accounting for nuclear material in this scenario is not trivial. Since validated, ground-truth experimental data for liquid-fueled irradiations are not yet available, this research leveraged the nuclear modeling code suites at the Oak Ridge National Laboratory including SCALE and the Transient Simulation Framework of Reconfigurable Models (TRANSFORM). Modifications were made to both software codes to develop a model to represent the molten salt reactor fuel cycle. The model is the Molten Salt Demonstration Reactor—a 750 MWth reactor with low-enriched uranium fuel. This research summarizes and describes the historical measurements performed in the Molten Salt Reactor Experiment that operated at ORNL until 1969 and presents the results of a signatures study based on the Molten Salt Demonstration Reactor model. Direct measurements of fissile material are likely not possible in real-time, but correlations between isotope signatures and the nuclear material (isotopic composition/quality and quantity) are discussed. In addition, existing and required new instrumentation development is evaluated.
Year
2020
Abstract