Long-term aqueous contamination of stainless steel in simulant nuclear reprocessing environments
Long-term aqueous contamination of stainless steel in simulant nuclear reprocessing environments
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DOI：
10.1016/j.jnucmat.2023.154551
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发表时间：
2023-06-06
影响因子：
3.1
通讯作者：
Sharrad, Clint A.
中科院分区：
文献类型：
--
作者：
Barton, Daniel N. . T.;Grebennikova, Tatiana;Sharrad, Clint A.
不锈钢暴露在核后处理设施的苛刻酸性环境中时，随着时间的推移会受到各种放射性核素的污染。现有的研究污染的不锈钢与有问题的放射性核素主要集中在单一污染物系统。因此，更全面的了解是开发和优化去污和退役策略的必要条件，从而最大限度地减少废物量和相关成本。这项工作的目的是了解污染物的吸收行为AISI 304不锈钢在混合元素系统（铯，锶）在较长的时间内（长达420天）和温度和表面光洁度对污染物的吸收在较短的时间内（长达28天）的影响。将钢试样浸入12 M HNO 3中以加速铯和锶离子（1 mM）的腐蚀，并保持在50 ℃。通过使用ICP-OES的溶液分析评估了吸收程度，确定在所有测试的情况下锶的吸收超过铯，在50摄氏度时锶和铯的最大吸收值分别为0.208 g m-2和0.170 g m- 2。动力学建模证实，摄取遵循伪二级行为。暴露后对不锈钢试样进行了表征，发现420天后出现颗粒脱落和大量溶解，导致表面吸收水平降低。X射线光电子能谱发现了通过与铬腐蚀产物共沉淀形成的铬酸铯和铬酸锶的证据，证实了先前研究的观察结果。此外，使用LA-ICP-MS的深度分析发现污染物扩散到大块衬底中（30 - 40 nm）的证据，这对开发和优化可以最大限度地减少过量废物产生的去污方法具有重要意义。
Stainless steels are contaminated with a wide range of radionuclides over time when exposed to the harsh acidic environments in nuclear reprocessing facilities. Existing research into the contamination of stainless steel with problematic radionuclides has predominantly focused on single-contaminant systems. Hence a more comprehensive understanding is a necessity for the development and optimisation of decontamination and decommissioning stra-tegies, thus minimising waste volumes and associated costs. This work aims to understand contaminant uptake behaviour on AISI 304 stainless steel in a mixed element system (Cs, Sr) over extended time periods (up to 420 days) and the effects of temperature and surface finish on contaminant uptake over shorter time periods (up to 28 days). Steel coupons were immersed in 12 M HNO3 to accelerate corrosion with both caesium and strontium ions (1 mM) and maintained at 50 degrees C. The extent of uptake was assessed through solution analysis using ICP-OES, identifying that strontium uptake exceeded caesium's in all tested scenarios, with maximum uptake values of 0.208 g m-2 and 0.170 g m- 2 obtained at 50 degrees C for strontium and caesium, respectively. Kinetic modelling confirmed that uptake followed pseudo-second order behaviour. Stainless steel coupons were characterised after exposure, which found grain dropping and bulk dissolution had occurred after 420 days, leading to reduced levels of surface uptake. X-ray Photoelectron Spectroscopy found evidence of caesium and strontium chromates formed via co-precipitation with chromium corrosion products, confirming observations by previous studies. Furthermore, depth profiling with LA-ICP-MS found evidence of contaminants diffusing into the bulk substrate (by 30 -40 nm), which has significant implications for the development and optimisation of decontamination approaches which can minimise excess waste generation.