MBase: The Molecular Basis of Advanced Nuclear Fuel Separations

使用过的核燃料中95%以上是铀和钚，它们可以回收和再利用。然而，由于用过的燃料具有强烈的放射性，这需要非常复杂的过程。这些工艺还可用于从残留放射性废物中分离高危险材料，以简化放射性废物管理。然而，使用过的燃料的工业再加工主要依赖于已有50年历史的溶剂提取工艺(Purex)，该工艺最初是为简单得多的燃料开发的。因此，现代燃料可能很难再加工。因此，我们将并行探索两种不同的核燃料分离方法，一种基于已建立的Purex技术，另一种基于更新的发展--离子选择膜(ISMS)。ISMS是一种多孔的、具有化学反应的膜，它可以结合溶液中的金属，然后根据条件再次释放它们，从而允许高度选择性的分离。在溶剂萃取系统中，我们将重点讨论溶剂萃取、第三相形成以及一组长寿命、高危险的废同位素(裂变产物锶和次氡系元素)的分离。有了ISMS，我们将首先证明它们在铀/钚分离中的有效性，然后将这些研究扩展到次要氡系元素。在整个过程中，我们将使用感兴趣的元素，而不是类似物或低活性模型，并在现实的辐射环境中工作。在项目的两个方面，我们将探索潜在的物理和化学过程，然后，在此基础上，我们将开发一系列定量模型，从相行为到单元操作，最后到流程模型。我们将根据与我们的工业合作伙伴确定的情景，使用所产生的模型来探索燃料后处理的不同选择。

Over 95% of used nuclear fuel is uranium and plutonium, which can be recovered and reused. However, because used fuel is intensely radioactive, this requires very complex processes. These processes can also be adapted to the separation of high hazard materials from the residual radioactive wastes, to simplify radioactive waste management. However, industrial reprocessing of used fuel primarily relies on a 50 year old solvent extraction process (Purex), which was originally developed for much simpler fuels. As a result, modern fuels can prove difficult to reprocess. We will therefore explore two different approaches to nuclear fuel separation in parallel, one based on the established Purex technology and the other on a much more recent development, ion selective membranes (ISMs). ISMs are porous, chemically reactive membranes which can bind metals from solutions then release them again, depending on conditions, thus allowing highly selective separations.In the solvent extraction system, we will focus on a common problem in solvent extraction, third phase formation, and on separation of a group of long lived, high hazard waste isotopes (the fission product technetium and the minor actinides). With the ISMs, we will first prove their utility in uranium/plutonium separation, then extend these studies to the minor actinides. Throughout, we will work with the elements of interest, rather than analogues or low activity models and in realistic radiation environments. In both strands of the project, we will explore the underlying physical and chemical processes then, building on this understanding, we will develop a series of quantitative models, building from phase behaviour to unit operations and finally to process flowsheet models. We wil use the resulting models to explore different options for fuel reprocessing, based on scenarios defined with our industrial partners.