Characterisation of Full-Scale Inactive Cement-Based Intermediate Level Nuclear Wasteforms After One Decade of Storage

Abstract

This paper presents the results of a laboratory-based programme to characterise full-scale, 500L cement-based wasteforms stored for over a decade. The wasteforms were prepared from inactive intermediate level waste (ILW) simulants, representing a range of ferric-based flocs produced during spent fuel reprocessing, using a blended ordinary Portland cement (OPC) / pulverised fuel ash (PFA) grout. The characterisation includes petrographic analysis, determination of moisture/density relationships, acid neutralisation capacity (ANC), and extraction analysis as a function of depth. The results of the study, conducted on full depth cores, indicate that the chosen matrix was well suited to the ferric floc waste that it was designed to contain. Carbonation and desiccation of the high water/solids wasteforms was limited to the near surface and the beneficial morphological and chemical characteristics of the matrix showed very little spatial variability.