EDF Energy has begun testing Flamanville 3 on the nearby Normandy peninsula, the first reactor to be commissioned in France for decades.
Flamanville 3 is undergoing what EDF calls a ‘divergence operation’.
This involves creating a stable nuclear reaction at very low power, just 0.2% of what it can achieve. This is then accelerated to 25% of power and if everything tests as planned, the reactor will be connected to the grid.
EDF says it hopes to achieve this by late autumn. Once fully operational it will contribute significantly to France's power needs.
The installation - which can be seen from the Channel Islands on a clear day - is a third generation EPR pressurised water reactor.
It is being switched on after a 12-year delay due to issues with the concrete base slab and some components needing to be retooled. This has taken it billions of euros over budget.
A recent report concluded that the nuclear risk from Flamanville for the islands was modest, and did not recommend special measures being taken.
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