Corrosion of AGR Fuel Pin Steel Under Conditions Relevant to Permanent Disposal
Corrosion of AGR Fuel Pin Steel Under Conditions Relevant to Permanent Disposal
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AGR 燃料棒钢在永久处置相关条件下的腐蚀
DOI：
10.1016/j.proche.2016.10.035
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
Anwyl C
中科院分区：
文献类型：
--
作者：
Anwyl C
英国先进气冷反应堆（AGR）的燃料棒由20/25/Nb不锈钢包层包裹的陶瓷UO 2燃料组成。目前正在对AGR乏燃料进行后处理，但目前正在审查在密封的地下地质处置设施中直接处置乏燃料的备选方案。假设数千年来，环境中的地下水会穿透这些屏障，与燃料表面和钢包壳接触。在模拟地下水电解质中，对20/25/Nb钢的未敏化样品进行了电化学研究，结果表明，在这种储存库中发现的氧化电位应力下，腐蚀电流很低，通常为μA/cm 2量级。因此，虽然包层可能被认为是被动的短时间段，但GDF项目中涉及的非常长的时间尺度意味着这些电流足以在几十年内导致包层整个厚度的腐蚀。此外，电化学电位从预期的不到50 mV的增加足以在几个小时内引发严重的点蚀。因此，可以假设，在处置库环境中存在包壳腐蚀的风险，并且所产生的腐蚀产物可能对乏燃料陶瓷的化学性质具有影响。
Fuel pins from the UK's Advanced Gas-cooled Reactors (AGR) consist of ceramic UO2fuel encased in a 20/25/Nb stainless steel cladding. Spent AGR fuel is currently reprocessed, but the option of direct disposal of spent fuel in a sealed, underground Geological Disposal Facility (GDF) is now under examination. It is assumed that over several thousand years groundwater from the environment will penetrate these barriers and come into contact with the fuel surface and steel cladding.Electrochemical studies on unsensitised samples of 20/25/Nb steel in simulant groundwater electrolytes have been performed, and show low corrosion currents, typically of the order μA/cm2, at the oxidative potential stresses found in such repositories. Whilst the cladding may therefore be considered to be passive short time periods, the very long timescales involved in a GDF project mean that these currents are sufficient to cause corrosion of the full thickness of the clad in a matter of decades.Furthermore, an increase in electrochemical potential from that expected of less than 50 mV is sufficient to initiate severe pitting corrosion in a matter of hours. It can therefore be assumed that there is a risk of cladding corrosion in a repository environment, and the corrosion products created may have implications for the chemistry of the spent fuel ceramic.