The victim was a site supervisor working for main contractor Bylor – a joint venture of Bouygues and Laing O’Rourke.
An internal project memo seen by the Enquirer said he suffered a “fatal crush injury whilst working on a platform near to the Nuclear island.”
The update added that all but essential work has been halted on site and will not restart until it is safe to do so with no normal site work taking place on Monday.
An official statement said: “We are very sad to confirm that one of our team was involved in a fatal construction traffic incident this morning during planned work activities. The incident is being investigated by the Police and the Health & Safety Executive and we will co-operate fully with the authorities.
“Work at the site has been stood down and we are offering support to colleagues affected by this tragic event. Our thoughts are with his family, friends and colleagues at this very difficult time.”