Durability study of AlMg2 in high-purity cooling water: A 15-year case from the RSG-GAS nuclear reactor

• G.R. Sunaryo¹, R. Kusumastuti², D.S. Wisnubroto³, S.L. Butarbutar¹, Sriyono¹ and D.T. Jatmiko⁴

¹ Research and Technology Center for Nuclear Reactor, Research Organization for Nuclear Energy, ORTN-BRIN, South Tangerang, Indonesia
² Research Organization for Nanotechnology and Material, ORNM-BRIN, South Tangerang, Indonesia
³ Research and Technology Center for Radioactive Waste and Fuel Cycle Research Center, ORTN-BRIN, South Tangerang, Indonesia
⁴ Directorate of Nuclear Power Facilities Management, BRIN, South Tangerang, Indonesia

Abstract: This study presents a long-term corrosion assessment of AlMg2, an aluminum–magnesium alloy extensively used as fuel cladding in nuclear research reactors. The evaluation was conducted after 15 years of uninterrupted exposure in the high-purity primary cooling water of the 30 MW RSG-GAS reactor in Indonesia. The objective was to determine the extent of surface degradation and elemental alteration under chemically controlled conditions. Surface morphology and elemental composition were analyzed using optical microscopy, Scanning Electron Microscopy (SEM), and Energy Dispersive X-ray Spectroscopy (EDS). Results indicated minimal corrosion, with pit depths remaining below 5 µm and the total affected surface area limited to less than 0.01%. These observations confirm the alloy’s high resistance to crevice corrosion. Elemental analysis of the passive oxide layer identified aluminum, oxygen, and magnesium as the dominant constituents, with trace carbon likely originating from post-exposure adsorption of airborne hydrocarbons or interaction with atmospheric CO₂. The findings affirm the long-term structural integrity and durability of AlMg2 under sustained reactor operation, reinforcing its suitability for application in water-cooled research reactors and prospective small modular reactor (SMR) technologies.

Keywords: AlMg2 alloy corrosion, passive oxide film, fuel cladding material, RSG-GAS research reactor, primary cooling water, long-term exposure, surface elemental analysis, scanning electron microscopy, nuclear material aging, passive oxide layer, long-term exposure, crevice corrosion

Int. J. Corros. Scale Inhib., 2025, 14, no. 2, 962-979
doi: 10.17675/2305-6894-2025-14-2-27

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