Nuclear energy and renewables, both being low-carbon energy sources that are likely to play an increasingly larger role in energy systems of the future, are increasingly being considered from an integrated standpoint. However, the deployment of baseload nuclear reactors as part of such integrated systems may present some challenges in long-term planning, such as surplus energy generation, inflexibility, and increased energy storage requirements. On the other hand, flexible advanced nuclear reactors can be utilized to tackle the limitations of baseload reactors, such as inflexibility of load-following and high initial capital cost.

This paper aims to investigate from techno-economic aspects whether energy modelers should use a flexible nuclear reactor model, specifically a small modular pressurized water reactor technology, or a baseload reactor model of comparable size in long-term integrated nuclear renewable (NR) integrated energy system planning simulations. We mathematically develop an off-grid NR integrated system in a MATLAB environment. An advanced small modular reactor is incorporated in this study and is operated in a baseload and flexible mode of operation for comparative analysis. Two metaheuristic optimization algorithms, pelican optimization algorithm and particle swarm optimization, are employed to obtain and validate the optimal configurations of two different NR systems (e.g. baseload reactor system and flexible reactor system). A sensitivity analysis is conducted to reinforce the key research findings.

The results indicate that a flexible nuclear reactor reduces the total annualized cost by a very small amount (roughly 2%) and the energy storage sizing by around 3% for NR integrated system planning, compared to a baseload reactor. This study provides insights into the operational assumptions (e.g. baseload or flexible operation) to consider during the modeling of a long-term planning problem of for NR integrated systems.