HEMISPHERICAL TOTAL EMISSIVITY OF POTENTIAL STRUCTURAL MATERIALS FOR VERY HIGH TEMPERATURE REACTOR SYSTEMS: HAYNES 230

摘要

The hemispherical total emissivity of Haynes 230, which is regarded as a leading candidate material for heat exchangers in very high temperature reactor (VHTR) systems, was measured with various surface conditions using the ASTM C 835-06 protocol. The emissivity increased from 0.18 at 621 K to 0.235 at 1356 K for Haynes 230 as received sample. The emissivity increased signif- icantly when its surface roughness was increased, or it was oxidized in air, or it was coated with graphite dust, as compared to the as-received material. Higher emissivity has a positive impact on high-temperature reactor operations, particularly for safety, since higher emissivity implies faster decay heat removal in postaccident VHTR environments.