An Exploration of the Effect of Temperature on Different Alloys in a Supercritical Carbon Dioxide Environment

In the constant effort to increase efficiency, safety margins, and lower cost, a new breed of nuclear reactors, Generation IV, is being developed in which supercritical carbon dioxide (SCO₂) is a prime coolant candidate. SCO₂ allows for higher efficiencies, reduced pumping power, lower plant temperature, and more compactness compared to the other gas coolants currently being examined. However, limited corrosion data currently exists for materials that are potential pressure boundary candidates under high pressures and temperatures in SCO₂ environments. The goal of this investigation was to understand the effect of temperature on corrosion on potential structural materials in a SCO₂ environment A total of 7 different alloys, 6 nickel based and 1 austenitic stainless steel (AUSS), were examined in three sets of experiments. The experiments exposed the specimens to SCO₂ at temperatures ranging from 650 "C to 750 °C, pressures from 12.5 to 20 MPa, and for durations of up to 1000 hours. The nickel based alloys demonstrated very promising results as the weight gain rates were almost an order of magnitude lower than the stainless steel. The average nickel based sample exposed to SCO₂ at a temperature of 750°C and a pressure of 12.5 MPa showed a weight gain rate of 0.0063 mg/cm 2*day, while the stainless steel sample had a weight gain rate of 0.096 mg/cm 2*day after a duration of 1000 hours. This was expected as the combination of nickel and chromium forms a higher integrity and more stable passive film than iron and chromium. Additionally, nickel has a lower oxygen affinity than iron and therefore the migration of cations into the scale is lower.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Nuclear Science and Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2009

Author dc:creator

• Dunlevy, Michael William

Advisor dc:contributor.advisor

• Ronald G. Ballinger.

• Nuclear Science and Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/57777

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/57777