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 temperature 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
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 exhibits 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 keywords of ‘molten chloride corrosion’ and ‘accident-tolerant fuels’. study prioritized 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 (>10,000hours) testing. Redox control (e.g., UCl₃ additions) and ceramic coatings (e.g., SiC-SiC) innovations also could improve the material resilience. Solving these problems will speed the deployment of MCSFRs that have been shown to provide safe and sustainable nuclear energy solutions.