Corrosion and Compatibility in Advanced Reactor Systems ENVIRONMENT CANDIDATE MATERIALS liquid metals Na iron based alloys Pb-Bi iron based helium/graphite Ni based alloys supercritical water Fe,Ni,Ti,Zr, based alloys stress corrosion cracking molten salt Hugh Isaacs BNL

liquid metal compatibility solubility in liquid metal construction alloys interstitials O, C, N, H solid surfaces extraction insertion products mass transport gradients in liquid activity in solids reaction

Na

Na/Na 2 O Pb/PbO Ellingham-Richardson-Diagram

Pb/Pb-Bi corrosion inhibition of ferritic steels by ppm Zr, Ti forms nitrides or nitrides+carbides on steel surfaces 6000 h CrMoV steel 300–500 ppm Mg 300 h 2CrSiMoV steel 300–500 ppm Mg ppm Ti 600 C

oxygen concentration effects on steels flowing Pb 550C 3000 h

Pb/Pb-Bi Pb 15Cr–11Ni–3Si–MoNb low oxygen 550C 2000 h Groynin (1998) controlled oxygen

He 1000C 1000h oxidizing conditions reducing conditions Inconel 617 Hynes 230 Wright 2008

Quadakkers 1988 strongly reducing highly oxidizing highly carburizing best region carburizing under oxide “thermodynamic” representation of alloy behavior He

Supercritical water Ferritic–martensitic Austenitic Ni-based weight gain largest weight gain < ferritic-m little weight gain than ferritic–martensitic complex parametrics except below the pseudo-critical Cr reduces rate good grain boundary eng. precipitate hardened pit lowest rates at 300 ppb O implant Y - major improvement Zirconium Titanium std alloys corrode optimized comps ~ austenitic optimized comp > austenitics alloy systems under study Was et al. (2007)

Stress Corrosion Cracking Supercritical water austenitic IGSCC > ferritic-martensitic acidic additions increase cracking higher Cr increases susceptibility to HCl increased pressure increases SCC ferritic -m in pure systems resistant to 600 C

Temperature K log p CO =