Corrosion and mitigation of structural materials in chloride-based molten salt reactors: Mechanisms, challenges, and design strategies

초록

Chloride-based molten salt reactors are promising advanced nuclear systems because of their favorable neutronic characteristics and high actinide solubility, but their deployment is limited by severe corrosion of structural materials in chemically aggressive and irradiation relevant environments. This review aims to provide an integrated understanding of corrosion and mitigation in chloride-based molten salt reactors by connecting degradation mechanisms with broader materials challenges and design strategies. The analysis shows that corrosion is governed by the coupled effects of impurities, fission products, and irradiation rather than by a single factor. Moisture, oxygen, dissolved metallic ions, and other impurities destabilize salt chemistry, disturb redox balance, and accelerate selective dissolution and intergranular corrosion. Fission products further intensify degradation through distinct pathways: tellurium directly promotes embrittlement and grain boundary damage, whereas europium, antimony, and selenium contribute through redox perturbation or direct reaction layer formation. Irradiation adds another level of complexity by generating defects, elemental redistribution, phase instability, and gas accumulation, thereby altering both the material and its response to molten salt attack. These findings indicate that effective mitigation requires an integrated strategy combining salt purification and redox control with protective coatings, surface engineering, and alloy design. Overall, corrosion in chloride-based molten salt reactors should be understood as a coupled chemical and microstructural degradation problem, and reliable deployment will depend on structural materials and protection strategies validated under relevant reactors combined environments.

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