Metallurgical analysis of a tube ruptured in the lead bismuth corrosion test facility

Abstract

Metallurgical analysis and fractography studies were carried out for a 316SS tube that was filled with lead-bismuth (Pb-Bi) when it ruptured while being used for the sampling line in a Pb-Bi forced convection test loop. This report focused on investigating the major factor of the tube rupture in the liquid Pb-Bi. The rupture occurred while the loop temperature was being increased from room temperature to 250°C. The rupture occurred for a tube which had been used with Pb-Bi at 400°C for 3,500 h and 23 increasing temperature cycles. The tube expanded locally around the ruptured part, which indicated that the rupture was caused by the thermal expansion of the Pb-Bi in the tube. More severe liquid metal corrosion was observed at the inner tube surface around the ruptured part than elsewhere in the tube. The fracture mechanism in the rupture face could be classified into two types, i.e. brittle fracture without any sign of dimple marks in the inner region of the tube wall and ductile fracture in the outer region of the tube wall. © Atomic Energy Society of Japan.