One of the major challenges for the nuclear industry is the safe and sustainable immobilisation of radioactive wastes (RAW). Currently, the most commonly used immobilisation matrices for low and intermediate level wastes are based on ordinary Portland cement. For the more difficult to immobilise nuclides, such as caesium (Cs⁺) and strontium (Sr²⁺), researchers have been studying alternative immobilisation matrices, of which alkali-activated materials (AAM) are a very promising option. However, the differences in precursor compositions and the use of different types of activating solutions make it difficult to fully understand the effects of precursor composition on the immobilisation of introduced nuclides. Therefore, six different compositions of laboratory-synthesised Ca-Si-Al slags were developed to serve as precursors for low-alkaline AAMs to study their immobilisation behaviour. Immobilisation capacities up to 97.6% Cs⁺ and 99.9% Sr²⁺ were achieved with 1 wt% and 0.1 wt% waste loading, respectively, when leaching for 7 days at 20 °C in Milli Q water. Cs⁺ immobilisation is higher at lower Si/Al and Ca/(Si + Al) ratios. Immobilisation of Sr²⁺ is higher at a lower Ca/(Si + Al) ratio and independent of Si/Al ratio. The results of this study offer a deeper understanding of the immobilisation behaviour of AAMs and can encourage further research and application of AAMs for RAW immobilisation.

核工业的主要挑战之一是放射性废物（RAW）的安全和可持续固定化。当前，用于中低水平废物的最常用固定基质是基于普通波特兰水泥。对于更难固定的核素，例如铯（Cs ⁺）和锶（Sr ²⁺），研究人员一直在研究替代的固定基质，其中碱活化材料（AAM）是非常有前途的选择。但是，前体组成的不同以及使用不同类型的活化溶液的方法使得难以充分了解前体组成对引入的核素固定化的影响。因此，开发了六种不同成分的实验室合成的Ca-Si-Al炉渣作为低碱性AAM的前体，以研究其固定行为。当在Milli Q水中于20°C浸出7天时，分别以1 wt％和0.1 wt％的废物负载量实现了高达97.6％Cs ⁺和99.9％Sr ^2+的固定能力。Cs ⁺在较低的Si / Al和Ca /（Si + Al）比下，固定化较高。Ca /（Si + Al）比率较低且与Si / Al比率无关，Sr ^2+的固定化较高。这项研究的结果为AAM的固定行为提供了更深入的了解，并可以鼓励AAM在RAW固定方面的进一步研究和应用。