Analysis of 316L stainless steel pipe of lead–bismuth eutectic cooled thermo-hydraulic loop

AISI 316L stainless steel pipe, used in lead–bismuth eutectic (LBE) loop for integrated test of operability and safety (HELIOS) of proliferation-resistant environment-friendly accident-tolerant continual and economical reactor (PEACER) was investigated to evaluate its corrosion resistance properties. The dimension of the pipe is as follows: length 1 m, outer diameter 7.65 cm, and thickness 0.5 cm. The flow rate of LBE through the pipe under natural circulation was between 0.1 and 0.2 m/s with dissolved oxygen concentration of 10−6 wt.%. The maximum and minimum operating temperature of the investigated pipe in HELIOS was 673 K and 523 K, respectively. The surface morphologies of the inner wall were examined using the field emission scanning electron microscope (FESEM) and cross-sectional analysis was carried out using the focused ion beam (FIB) technique. Energy dispersive X-ray (EDX) and X-ray diffraction (XRD) were employed for identification of the elements and their phases in scales. The surface of the inner wall of the pipe was covered with mixed layers of LBE, iron oxides and plumboferrite. Cross-sectional analysis revealed oxide scale consists of two layers, the inner layer composed of chromium and iron oxides, and the outer layer iron oxides and plumboferrite.

► LBE technology is proposed for partition and transmutation of radioactive waste.
► 316L SS pipe used in the loop for LBE circulation is examined.
► The results will be useful for the validation of laboratory generated data.