The Current Status of Liquid Fuel and Material Technology Development for Chloride-Based Molten Salt Reactors (MSRs) at KAERI Part I. Liquid Fuel Fabrication and Natural Convection Loop Operation for Corrosion Characteristics

• Published in: Journal of nuclear fuel cycle and waste technology (Online) Vol. 23; no. 1; pp. 77 - 95
• Main Authors: Lee, Chang Hwa, Yoon, Dalsung, Kim, Taeho
• Format: Journal Article
• Language: English
• Published: 한국방사성폐기물학회 01.03.2025
• Subjects: 원자력공학; Molten salt reactor (MSR); Liquid fuel fabrication; Corrosion; Natural convention loop
• ISSN: 1738-1894; 2288-5471
• DOI: 10.7733/jnfcwt.2025.007

The efficient fabrication of uranium-based liquid fuels and the structural integrity of reactor materials are critical challenges for the deployment of chloride-based molten salt reactors (MSRs). As part of KAERI’s ongoing MSR development, this study investigates an optimized uranium chlorination process and a corrosion assessment of candidate structural materials under conditions more closely resembling actual reactor cores. To enhance process efficiency and scalability, metallic uranium was converted into uranium trihydride (UH3) via hydriding, achieving 34.1% efficiency. UH3 was chlorinated with ammonium chloride (NH4Cl), yielding uranium trichloride (UCl3) with a conversion rate over 98% and purity above 99%, as confirmed by ICP-OES. The UCl3 was used to fabricate various uranium-based liquid fuels for MSR applications. Simultaneously, the corrosion behavior of SS304, SS316, and Hastelloy-N was evaluated using a natural convection loop filled with a NaCl– MgCl2 eutectic salt mixture. The system operated for 500 hours at 500–580°C to replicate MSR conditions. Corrosion analysis revealed that SS304 suffered severe degradation, SS316 showed moderate resistance, and Hastelloy-N demonstrated superior stability, although some cold leg samples experienced mass gain due to corrosion product deposition. These findings provide key insights into optimizing liquid fuel synthesis and selecting corrosion-resistant materials for safe, long-term MSR operation.