Materials design for Tellurium capture to prevent corrosion in molten salt reactors via atomic-scale thermodynamic modeling and experimental validation

초록

Tellurium (Te), a fission product present in molten salt reactors (MSRs), promotes intergranular cracking and accelerates corrosion of structural alloys. Here, we develop a materials-selection framework for Te capture that couples atomic-scale thermodynamic modeling with targeted corrosion experiments in chloride melts. Using neural-network interatomic potentials, we compute the site-specific chemical potentials of Te inside a metal species X (μ<inf>X,site</inf>Te) to quantify the driving forces for surface Te adsorption, telluride formation, and Te migration into grain boundaries (GBs) and grain interior. The computed results identify three potentially useful candidates regarding Te-metal interaction, namely Ni, W, and Nb. Ni possesses a distinctly strong driving force for telluride formation, while W possesses strongly unfavored telluride formation. Interestingly, only Nb shows the thermodynamic driving force for Te migration into grain boundaries from the surface tellurides. Also, GB diffusion is facilitated in Ni and Nb ( E <inf>a,GB</inf> ≈ 0.49 and 0.34 eV, respectively) but not in W ( E <inf>a,GB</inf> ≈ E <inf>a,bulk</inf> ≈ 0.53–0.52 eV). Experiments in NaCl–KCl with 1 wt% Te at 800 °C for 100 h corroborate these trends. Ni forms a continuous Ni₃Te₂ surface layer accompanied by core thinning (−18.8%), while W and Nb exhibit only minor thickness reductions (−2.4% and −2.6%) and no adherent Te-rich layer; tellurides for W and Nb appear only as detached debris. Co-immersion experiments of Ni with Stainless Steel 316 inside NaCl–KCl–EuCl₃ salts show extensive Te ingress into Ni and Fe deposition onto its surface, whereas SS316 contains no detectable Te, indicating the successful role of Ni as a Te capture material. These results support complementary deployment: Ni as a proactive absorber for rapid Te uptake, and W as a durable barrier that limits inward Te transport, providing practical guidance for Te management in MSRs.

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