HPC is the country’s first nuclear plant for three decades. Restarting the new build industry hasn’t been easy or without its own costs, but EDF have done it and created thousands of skilled jobs for people and businesses in the South-West and across Britain. EDF is delivering on milestones and overcoming challenges on a daily basis.
Getting this far has cost more money than anticipated. EDF has had to spend both time and money to ensure that the design of the EPR meets the requirements for the UK regulatory framework, and the resulting changes have led to greater quantities of equipment, steel and cable. Earthworks are complete, but challenging ground conditions meant an overspend to finish them on time. 
Now that the detailed design implementation is more advanced and more contracts have been placed, we have a better appreciation of our future costs. That certainty reduces our risk at Hinkley Point C and the benefit of a fully adapted UK design will be passed directly to Sizewell C as a near identical plant. The benefits of replication are clear to anyone on site who can see the extraordinary progress on our second reactor, unit two currently running 106 days quicker than unit one showing series effect in action. For SZC, the costs break down is shown very roughly in the picture below.
Source: Sizewell C Project Update Oct 2019.