Molten Chloride Salt Fast Reactors (MCSFRs) are considered as a reliable advanced nuclear reactor technology. These reactors offer inherent safety features and high thermal efficiency. Additionally, the reactor can also be used for a closed fuel cycle. Despite these benefits, one of the major issues that is faced in the Molten Chloride Fast Reactors (MCSFRs) is that the reactors are prone to corrosion and the fuel salt chemistry disrupts during prolonged operation. In this study, a systematic review and meta-analysis of the MCSFRs is done to understand the advanced fuel salt chemistries and material corrosion. Based on more than 20 significant studies, the research identifies the corrosion mechanisms in molten. Chloride salts and compares the performance of various materials. These materials include Ni-based alloys, FeCrAl alloys, refectory metals, and ceramic composites. Furthermore, the impact of salt chemistry, temperature, and flow dynamics on material degradation is also studied in detail. It is found that Ni-based alloys provide better corrosion resistance. Among the Ni-based alloys, the one with 15-20 wt.% Cr is the most superior. Additionally, it is also found that advanced inspection technologies such as throughput screening and in-situ corrosion monitoring are important in identifying the ideal corrosion-resistant material. The study also shows that it is important to refine testing protocols to identify the best corrosion-resistant material to cater to material optimization and innovative fuel salt compositions.
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Abstract
Problem Statement
MCSFRs have the potential to revolutionize nuclear energy generation through their intrinsic safety and closed fuel cycles. The extreme corrosiveness of molten chloride salts at high temperatures represents a major challenge that limits the operational lifetime and reliability of structural materials. Further fragmentation in the field includes disagreements regarding the best materials to use, how they perform over long time scales in an irradiated environment, and what standardized testing methods to use, thus impeding the realization and utilisation of innovative designs such as the MCSFR.
Introduction and Literature Review
MCSFRs need structural materials that do not corrode in molten chloride salts (e.g., LiCl-KCl) at temperatures of 700–900°C, retaining their mechanical stability under irradiation. Ni-based alloys such as Hastelloy-N exhibit considerable corrosion resistance in the early studies (Guo et al., 2018; Pillai et al., 2023), but the literature also reveals a considerable lack of knowledge related to their behavior under dynamic flow conditions and neutron damage. Previous studies have mainly emphasized short-term, static experiments, with limited incorporation of enhanced monitoring strategies or high-throughput materials finding (Wang et al., 2022; Kim & Couet, 2024).
Methodology
This study includes a systematic review and a meta-analysis of 20 peer-reviewed articles (2014–2025) analyzing corrosion rates, degradation mechanisms, and material innovations for MCSFRs. Databases searched were Scopus, Web of Science, and INIS, utilizing the keywords of ‘molten chloride corrosion’ and ‘accident-tolerant fuels’. study prioritized the inclusion of studies that reported quantitative measures of corrosion (>500h tests) and mechanistic evaluations. Corrosion rates were aggregated using random-effects models in meta-analysis; narrative synthesis addressed heterogeneous methodologies.
Results
Ni-based alloys containing 15–20 wt% Cr showed the continuous lowest corrosion rates (5–20 µm/year), well beyond stainless steels (2–5×) (Kim et al., 2024). Ionic mobility led to much faster degradation by chloride salts than fluorides, and flow conditions increased corrosion rates by 2–3× (Guo et al., 2018). Ni-20Cr-10Fe was identified as optimal (60% less mass loss than conventional alloys) (Wang et al., 2022) in a high-throughput screen. Evident deficiencies included minimal radiation damage studies (< 10% of papers) and brief test times (< 1,000h in 85% of tests).
Conclusion
Ni-Cr alloys are front-runners for MCSFRs but need to be validated in the under-irradiation, flowing-salt environment. Future experiments should focus on radiation-corrosion synergetics in standardized protocols and long-term (> 10,000 hours) testing. Redox control (e.g., UCl₃ additions) and ceramic coatings (e.g., SiC-SiC) innovations could also improve the material's resilience. Solving these problems will speed the deployment of MCSFRs that have been shown to provide safe and sustainable nuclear energy solutions.