Life extension of the elderly AGR reactors is not a done deal; EDR have to demonstrate safety to Office for Nuclear Regulation: "In recent inspections the actual core degradation was at the high end of expectations, which has undermined confidence in EDF’s ability to respect safety case limits."
www.onr.org.uk/our-expertis... January 2025
More general information on the erosion and then cracking of the graphite blocks which the cores of the AGRs are made of. Apart from that the AGR is a very safe design; inherently safer than PWRs, just ultimately more expensive MWh for MWh www.onr.org.uk/our-work/wha...