Kazumi Aoto

Corrosion Behavior of FBR Candidate Materials in Stagnant Pb-Bi at Elevated Temperature

Three materials proposed for use in fast breeder reactors—FBR grade type 316ss, high chromium type martensitic steel and oxide dispersion strengthened martensitic type steel—were subjected to corrosion tests in stagnant lead-bismuth eutectic (LBE) containing 10-6 wt% of oxygen at 500–650—C for up to 5,000 h. After each test, the specimens were analyzed metallurgically using a scanning electron microscopy with energy dispersive X-ray analyzer and an X- ray diffractometer. It proved that, at temperatures not higher than 550°C, martensitic steels containing chromium to more than 9wt% presented good resistance against corrosion by the formation of spinel layer on the base metals, though outer porous oxide formed on the steels was detached and/or dissolved into LBE. At temperatures above 600°C, the oxide layer thickness diminished. This alteration in corrosion behavior seems to be ascribable to a change taking place at 570°C in the stable form of iron oxide from magnetite to wustite. At the temperatures, dissolution attack was observed at some portions. It was estimated that the oxide became to lose its adhesion to the base metal.

Studies on Materials for Heavy-Liquid-Metal-Cooled Reactors in Japan

Recent studies on materials for the development of lead-bismuth (Pb-Bi)-cooled fast reactors (FR) and accelerator-driven sub-critical systems (ADS) in Japan are reported. The measurement of the neutron cross section of Bi to produce 210 Po, the removal experiment of Po contamination and steel corrosion test in Pb-Bi flow were performed in Tokyo Institute of Technology. A target material corrosion test was performed in the project of Transmutation Experimental Facility for ADS in Japan Atomic Energy Research Institute (JAERI). Steel corrosion test was started in Mitsui Engineering & Shipbuilding Co., LTD (MES). The feasibility study for FR cycle performed in Japan Nuclear Cycle Institute (JNC) are described.Copyright

Corrosion Behavior of Steels in Lead-Bismuth Eutectic: In Stagnant LBE Test at Low Oxygen Partial Pressure

Corrosion test of three chromium-molybdenum steels — 2.25Cr-1Mo, Mod.9Cr-1Mo and 12Cr-steel (ASME P122) — has been performed in stagnant lead–bismuth eutectic (LBE) at low oxygen partial pressure at 550 °C up to 2,000 hours. After the test, the specimens were metallurgically examined using a scanning electron microscopy. All steels had good resistance to LBE under this test condition, and the difference of the effect of chromium concentration in the steels on corrosion behavior was not observed. Corrosion depth of the steels was a few microns, and chromium solution into LBE was observed on the surface. Very thin chromium oxide layer was partly observed on the surfaces of all steels. At the area, no corrosion was occurred. The behavior was the same as the results of martensitic steels tested in stagnant LBE containing 10−7 wt% to 10−8 wt% of oxygen.Copyright