Design study of heat transport and power conversion systems for micro molten salt reactor

Summary Recently, due to climate change and global warming, carbon free power generation is becoming important. Among various heat sources to replace fossil fuels, a Molten Salt Reactor (MSR) can be a successful alternative power source. The MSR uses liquid nuclear fuel instead of solid fuel which enables to have high power density, compact size, and inherent safety features. The MSR Experiment (MSRE) which was conducted by Oak Ridge National Laboratory (ORNL) had demonstrated these possibilities. However, since the MSRE focused on the nuclear reactor design and operation rather than generating electricity, many issues are still needed to be addressed to fully evaluate potential of an MSR. One of the key issues is to calculate the optimal pinch temperature range of the primary and secondary heat exchangers of the MSR heat transport system. Thus, in this study, to calculate the optimal pinch temperature range of the heat exchangers of the MSR heat transport system, heat transport system, and power conversion system for MSRE are designed conceptually. A Plate Fin type Heat Exchanger (PFHE) is newly suggested and evaluated in this paper for MSR heat transport system application to achieve high compactness and satisfactory performance. Furthermore, to calculate the optimal pinch temperature range from an economic point of view, a PFHE annual cost model is utilized to estimate the cost of PFHE with respect to the pinch temperature. An optimal pinch temperature range is recommended from the study for the early design phase of MSR, which is 5 ~ 15 K. A conceptual design of heat transport and power conversion system is performed for the micro molten salt reactor. A Plate Fin‐type Heat Exchanger (PFHE) is newly suggested and evaluated for the application to the intermediate heat exchangers. An optimal pinch temperature range is derived from a design study. The sensitivity of the optimal pinch temperature range to the cost components is investigated. As a result, the range of optimal pinch temperature for molten salt reactor and coolant systems is recommended.