Estimation of the volumetric expansion ratio due to the corrosion of metals is an essential part of the safety assessment of low‐level radioactive waste disposal facilities in Japan, because such volumetric expansion can disrupt the barrier function of these facilities. In the present study, the corrosion products of iron were predicted from potential–pH diagrams and the results of a synthesis test, and the volumetric expansion ratios of the corrosion products were evaluated. Under a basic set of conditions expected at a disposal facility over a storage period of a thousand to tens of thousands of years, Fe₃O₄, Fe₂O₃, and FeOOH were predicted as the major stable corrosion products of iron. The maximum volumetric expansion ratio determined from the true density of these products was 2.9, and the maximum volumetric expansion ratio, assuming the generation of voids in the corrosion products, was 3.7, which is the Pilling–Bedworth ratio of Fe(OH)₂. The volumetric expansion ratio may increase in the presence of carbonate ions in a long‐term environment with a reduced pH.

中文翻译：

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在日本的低放射性废物处理设施中预测铁的腐蚀产物

对金属腐蚀造成的体积膨胀比的估算是日本低放射性废物处置设施安全评估的重要组成部分，因为这种体积膨胀会破坏这些设施的屏障功能。在本研究中，从电势-pH图和合成试验的结果预测了铁的腐蚀产物，并评估了腐蚀产物的体积膨胀率。在一千种至数万年的储存期中，在处置设施预期的一组基本条件下，Fe ₃ O ₄，Fe ₂ O ₃据预测，FeOOH是铁的主要稳定腐蚀产物。由这些产品的真实密度确定的最大体积膨胀比为2.9，假设腐蚀产物中产生空隙，则最大体积膨胀比为3.7，这是Fe（OH）₂的皮尔-贝德沃思比。在pH值降低的长期环境中，存在碳酸根离子时，体积膨胀率可能会增加。