Bituminized waste products (BWPs) were produced by conditioning in bitumen the co‐precipitation sludge resulting from the industrial reprocessing of nuclear spent fuel. For some intermediate level long‐lived (ILW‐LL) classified BWPs, a long‐term disposal solution in France is underground geological disposal. One of the challenges for BWPs in geological disposal conditions is their swelling behavior due to water uptake. This swelling, if sufficiently important, could lead to mechanical coupling with the host rock, resulting in the application of pressure that could damage it. Consequently, the swelling behavior of BWPs must be considered in safety studies for the underground storage facility after site closure. The present work is a continuation of a previous one and focuses on investigating both experimentally and numerically the BWPs’ swelling behavior due to water uptake under confined leaching conditions. The swelling of simplified BWPs was experimentally monitored for about 2.5 years during leaching tests under constant counterpressure. The numerical model is extended from a previous work that incorporates coupled homogenization of transport terms (diffusion, permeation, osmosis) with mechanics via Maxwell's viscoelastic model. An original nonlinear poro‐viscoelastic model taking into account large strains is proposed in this paper to better model the BWPs leaching behavior under confined conditions. The experimental results of leaching tests under constant counterpressure are generally well predicted by the resulting numerical model. The role of the poorly soluble salts BaSO4 within the solid BWP matrix is investigated.

中文翻译：

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密闭浸出条件下吸水导致的沥青化废物膨胀行为的研究：实验和建模


沥青化废物 （BWP） 是通过在沥青中调节核乏燃料工业后处理产生的共沉淀污泥来生产的。对于一些中级长寿命 （ILW-LL） 分类的 BWP，法国的长期处置解决方案是地下地质处置。在地质处置条件下，压埋水处理厂面临的挑战之一是它们因吸水而引起的膨胀行为。这种膨胀如果足够重要，可能会导致与主岩的机械耦合，从而导致施加的压力可能会损坏它。因此，在场地关闭后地下储存设施的安全研究中必须考虑 BWP 的膨胀行为。目前的工作是前一项工作的延续，重点是从实验和数值上研究 BWP 在密闭浸出条件下由于吸水而引起的膨胀行为。在恒定反压下的浸出测试期间，对简化 BWP 的溶胀进行了约 2.5 年的实验监测。该数值模型是从以前的工作扩展而来的，该工作通过 Maxwell 的粘弹性模型将传输项（扩散、渗透、渗透）的耦合均质化与力学相结合。本文提出了一种考虑大应变的原始非线性多孔粘弹性模型，以更好地模拟 BWP 在受限条件下的浸出行为。在恒定反压下浸出测试的实验结果通常可以通过生成的数值模型很好地预测。研究了难溶性盐 BaSO4 在固体 BWP 基质中的作用。