The Office for Nuclear Regulation (ONR) said it was taking action for offences under Section 2 (1) of the Health and Safety at Work Act.
Activists claim they are trying to prove how easily nuclear power plants can come under attack
Jon Holmes decided to find out more about Hinkley Power Plant with correspondent Cornelius
Within hours of getting the green light from French energy firm EDF, the building of the £18bn Hinckley Point nuclear power station will be delayed by a government review. Who is right?