To realise the construction pit, a hole was dug measuring approximately 50 metres by 50 metres and 21 metres deep. This was done in several stages. First, trenches were dug 1,5 metres wide, into which concrete was poured to realise the diaphragm walls. These walls were anchored, and within these walls, 380 bored piles were placed, after which the soil was excavated and underwater concrete was poured to hold the empty pit in place and to base the reactor on later. The works were carried out by BESIX and completed in May 2025.