Characterization of 316 stainless steel surfaces used in BWR recirculation piping

The effect of surface treatments such as sandblasting, acid pickling, and electropolishing on surface topography and composition has been investigated for 316 nuclear grade stainless steel. The build-up of radioactive cobalt-60 on sandblasted surfaces is much higher compared to that on acid pickled surfaces. Compared to sandblasted surfaces, acid pickling produces smooth surfaces and also generates grain boundary grooves, which can be effectively removed by subsequent electropolishing. Sandblasting produces rough and textured surfaces. Electropolishing of such surfaces reduces the roughness but does not produce as smooth a surface as a pickled surface. The techniques used in the surface analyses were scanning electron microscopy (SEM), X-ray energy spectroscopy (XES), and Auger electron spectroscopy (AES). (orig.)