Acoustic emission on melting/solidification of natural granite simulating very deep waste disposal

Highlights: ► One of the design options in the UK envisages very deep borehole disposal where the host granite can be partially melted and then recrystallised. ► The acoustic emission was detected from the melting and solidification of natural granite in conditions simulating very deep borehole disposal. ► The cumulative number of signals, their durations and frequencies were monitored. ► Acoustic emission from the granite was also studied in part by monitoring phase transformation on heating and cooling of quartz. - Abstract: Acoustic emission (AE) signals resulting from the melting and solidification of natural granite were monitored and analysed. The experimental work was conducted in laboratory conditions simulating very deep borehole disposal (DBD) of high level wastes such as sealed radioactive sources (SRS) or spent nuclear fuel (SNF). The cumulative number of signals, their durations and frequencies were the main characteristics of the monitored processes. The recorded AE could be associated with the complex changes in volume and shape of the constituent minerals associated with solid–liquid and solid–solid phase transformations within the granite. AE from the granite was also studied in part by monitoring phase transformation on heating and cooling of quartz.