加鋅水化學光電化學效應對不銹鋼及鎳基合金腐蝕電位之影響

Photo-electrochemical Effect of Zinc Water Chemistry on the Electrochemical Corrosion Potentials of Stainless Steel and Nickel Alloys

本研究針對一般水化學及加氫水化學環境中，進行測試不同鋅濃度對SS304不銹鋼及Alloy182鎳基合金表面膜特性的影響。以紫外光模擬反應器爐心內部Cherenkov輻射光照進行高溫高壓水質中光電化學測試。實驗結果顯示Alloy 182鎳基合金表面膜主要具備n型半導體特性，在紫外光照射下，電化學腐蝕電位皆往陰極方向偏移。而SS304不銹鋼表面膜卻會因水質氧化性或加鋅濃度有不同半導體特性，但多為n型半導體，只有加氫水化學環境中有輕微p型半導體特徵。從SS304不銹鋼及Alloy 182鎳基合金紫外光照射測試結果顯示，在氧化性一般水化學或還原性加氫水化學中注鋅，反應器爐心內部Cherenkov輻射光照不會對於SS304及Alloy 182電化學腐蝕電位造成負面影響，而降低加氫水質對應力腐蝕破裂抑制效應。

This study will evaluate the photo-electrochemical effect of zinc water chemistry under simulated irradiated BWR water environments and attempt to establish a data base of electrochemical behaviors of SS304 stainless steel and Alloy 182 nickel-based metal under UV conditions. The experimental results reveal that Alloy 182 nickel-based alloy generally possesses n-type semiconductor characteristics in both oxidizing normal water chemical (NWC) and reducing hydrogen water chemistry (HWC) conditions with zinc addition. Upon UV irradiation, the ECP of Alloy 182 shifts in the cathodic direction. The semiconductor properties of SS304 stainless steel will vary depending on the oxidizing degree and added zinc concentrations of the water chemistry. In most conditions, SS304 will exhibit n-type semiconducting characteristics. Under hydrogen water chemistry, however, a weak p-type property may immerge. From on the experimental photoelectrochemical results, regardless of the zinc concentrations and oxidizing natures of water chemistry control methods, the Cherenkov irradiation will not significantly increase the electrochemical corrosion potentials of SS304 stainless steel and Alloy 182 nickel-based alloy in the anodic direction. The protective effect of hydrogen water chemistry on the stress corrosion cracking susceptibility of in-core SS304 and Alloy 182 components will not be reduced by the addition of zinc.