Study On Corrosion Behavior Of Sintered 316L Fiber Felt In LBE At 500 ?

Lead Bismuth Eutectic(LBE)alloy has been chosen as the promising candidate coolant for Lead-cooled Fast Reactor(LFR),due to its good nutronics,thermodynamic properties and chemically inert.During the operation of the LBE cooled reactor,PbO impurities and corrosion impurities such as Fe,Cr,Ni and its oxides may be generated in the coolant due to possible seal failure and corrosion of the material,which may seriously threaten the safe operation of the reactor.Filtration purification is one of the most effective ways to remove impurities from LBE at present,and the research on filter performance is one of the key issues in filter technology development.In this thesis,the corrosion behavior and tensile properties of the filter material sintered 316L fiber felt were studied in LBE under different oxygen concentrations.The main conclusions of study are as follows:1.Corrosion behavior of 316L fiber felt in LBE with different oxygen concentrations In this thesis,the corrosion behavior of 316L fiber,the raw material of the filtering material 316L fiber felt,was investigated in stagnant LBE with various oxygen concentration Co(e.g.10-8 wt%,10-6 wt%and 8×10-4 wt%)at 500 ? for 500 h.The results of SEM,EDS and XRD showed that:(1)with the increase of oxygen concentration,the corrosion type of 316L fiber in LBE gradually changed from dissolution to oxidation,and the corrosiveness of 316L fiber was smallest at the oxygen concentration of 10-6 wt%;(2)the oxide scales formed on the surface of the 316L fibers with 10-8 wt%(0.6 ?m)and 8×10-4 wt%(0.8?m)were thicker and not protective compared to that at 10-6 wt%(0.1 ?m);(3)LBE penetrated the non-protective oxide scale,resulting in serious corrosion by dissolution and LBE penetration for the 316L fiber.Therefore,when the fiber felt is applied to filter out the impurities in LBE,it is necessary to control the oxygen concentration in LBE to minimize the corrosiveness.2.Tensile properties of 316L fiber felt vary with LBE corrosion time Based on the operating regime of China Lead-based Research Reactor(CLEAR-I),the tensile properties of sintered 316L fiber felt exposed to stagnant LBE with 10-6 wt%oxygen concentration was investigated at 500 ? for 500 h,1000 h and 1500 h,respectively.The results showed that compared to the original fiber felt,the tensile strength of the fiber felts decreased to 67%,33%and 15%after 500 h,1000 h and 1500 h,respectively.It was found that the binding strength of joints gradually decreased with exposure time due to the compact single-layer(Fe,Cr)3O4 spinel formation on 316L fibers,which also resulted in the decrease of diameter of the 316L fiber.Therefore,the tensile strength of the sintered felt dramatically decreased after corrosion.