强γ辐照下Q235碳钢在甘肃北山地区地下水模拟液中的腐蚀行为

利用1.11×10¹⁶ Bq（30万Ci）高强度⁶⁰Co源γ辐照装置，对甘肃北山地区地下水模拟液中高放废物处置罐候选材料Q235碳钢进行了辐照腐蚀试验。采用水化学参数分析、称重、扫描电镜(SEM)、X射线能谱（EDS）和红外光谱（FT-IR）等技术手段，分析了辐照剂量（时间）对辐照腐蚀演化的影响规律，并与未辐照试验进行了对比。结果表明，在长时间强γ辐照下，模拟液辐照分解导致氧化性增强、pH值由弱碱性变为酸性、电导率下降明显，而未辐照的模拟液pH值和电导率未见明显变化；利用质量变化率计算得到的辐照腐蚀速率约为未辐照腐蚀速率的5.5倍，辐照明显加速了Q235碳钢的腐蚀。SEM-EDS和FT-IR分析表明，随着辐照剂量的增加，腐蚀层中出现泡状或针状产物，表面由致密变为稀疏；腐蚀层化学组成以Fe、O为主，含有不同相的羟基氧化铁（α-FeOOH和γ-FeOOH）和氧化铁（α-Fe₂O₃）。

Corrosion Behavior of Q235 Carbon Steel in Simulated Groundwater in Gansu Beishan Area with High-strength γ Irradiation

Q235 carbon steel is a candidate material of the high level waste (HLW) disposal container. The irradiation corrosion test of Q235 carbon steel was carried out with the high-strength ⁶⁰Co radioactive device (1.11×10¹⁶ Bq) in the simulated groundwater in Gansu Beishan aera. Water chemical parameter analysis, weighing, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and Fourier transform infrared spectroscopy (FT-IR) were used to analyze the effects of irradiation dose (time) on the evolution of irradiation corrosion. The results show that the oxidizability of the simulated groundwater is enhanced, the pH value changes from 7.81 to 4.75, which means that the solution changes from weakly alkaline to strongly acidic under the long-term high-strength γ irradiation. Besides, the electrical conductivity decreases obviously, but there is no significant change for the pH value and electrical conductivity of the non-irradiated solution, and the irradiation corrosion rate calculated by mass change rate is about 5.5 times that of non-irradiation. SEM-EDS and FT-IR analysis shows that bubbles or needles appeare in the corrosion layer. The corrosion layer surface changes from dense to sparse as the radiation dose increases. The chemical composition of the corrosion layer is mainly Fe and O, and the corrosion layer contains different phases of iron oxyhydroxide (α-FeOOH and γ-FeOOH) and iron oxide (α-Fe₂O₃).