Stress Corrosion Cracking Study Of316Stainless Steel In Pwr Primary Water Conditions

Now the safety and economy of the PWR nuclear power plant arethreatened by the stress corrosion cracking problem of primary loopequipment. However the current major research methods in our country onstress corrosion cracking are all accelerated assessment methods such asslow stretches, electrochemical and stress/strain, which unable to getquantitative data to describe the crack growth rate of material that underreal operating conditions.In order to fill in the gaps in the study of this filed, we studied316Lused as auxiliary piping and316stainless steel used as core bolt insimulating PWR primary loop water chemical condition with the reversecurrent direct current potential drop (RC-DCPD) method.This article mainly discusses temperature, dissolved oxygen, andeffects of zinc on stress corrosion cracking behavior of materials. The crackgrowth rate of316L at325℃,2ppm is20.8mm/year, whereas crackgrowth rate can reach to2.48mm/year when we pumped in argon and canreach to even lower in hydrogen contented water.When we studied the effect of temperature we found that crack growth rate in2ppm dissolved oxygen increases with temperature increasehowever the maximum crack growth rate appear at250℃when wepumped in argon. And the experimental results show that when thedissolved oxygen content <200ppb the crack growth rate of316L increaseswith the increase of the dissolved oxygen, but when the DO content>200ppb the increase rate slows down.In order to verify the mitigation effect of zinc on stress corrosioncracking, we injected zinc acetate (40、20、10ppb) into water loopcontinuously. When the zinc content in water is10ppb crack growth rateof316stainless steel significantly decreased.