Capability of native Yucca Mountain microorganisms to corrode 1020 carbon steel

This project addressed the ability of native Yucca Mountain bacterial isolates to corrode metal designated as the outer barrier for nuclear waste containment. Microorganisms implicated in microbially-influenced corrosion recovered from the deep subsurface at Yucca Mountain include iron-oxidizing, sulfate-reducing, and exopolymer-producing bacteria. Test systems composed of a 1020 carbon steel coupon immersed in soft agar or soft agar and ground rock were designed to evaluate the biofilm formation and corrosion capabilities of these microorganisms at elevated temperature. Results indicated that incubation at 50{dollar}\sp\circ{dollar}C decreased the ability of these microorganisms to corrode carbon steel immersed in soft agar. However, corrosion rates were dramatically increased by the presence of a rock surface. Enhanced corrosion rates were also observed in each medium when the system was allowed to colonize at ambient temperature prior to incubation at 50{dollar}\sp\circ{dollar}C