Greenpeace activists broke into Cattenom nuclear power station in France and set off fireworks.
The group believes the stunt proves that nuclear facilities are easy to access.
A spokesman claimed the protesters stood 100 metres from radioactive fuel storage pools.
“French and Belgian nuclear facilities and points at their vulnerability to outside attacks […]
While these [fuel storage] pools can contain the highest volume of radioactive matter in a nuclear plant, they are very poorly protected,” a Greenpeace report says.
EDF Energy, the company which runs the Cattenom power station, said the group was intercepted 8 minutes after the breach had been registered.
“The intruders remained outside the buildings and outside the nuclear zone. This breach had no impact on the safety of the installation” the statement adds.