The average power plant block involves erecting formwork for approx. 500,000 m2 of concrete surface [29].

Precisely in terms of time and costs, it is essential to plan the use of formwork and scaffolding beforehand, as this may affect the performance schedules that the designers produce, such as producing evidence of specific building conditions and additional reinforcement resulting. With complex construction projects, contractors specialising in planning, constructing and providing formwork are involved at an early stage.

The aim in principle is to use formwork and scaffolding elements which are as large as possible and can be used frequently, even if building power plants often involves constructing irregular shapes with variable slab thicknesses and formwork heights.

Making the cupola of a reactor building in a pressurised water reactor presents particular demands. At the Philippsburg 2 nuclear power plant, the safety enclosure of steel plate under the cupola could not withstand any major stresses, so the concreting load had to be borne by projecting formwork construction (Figure 4.17).

When building nuclear power plants, slipforming can be used not only for box — and annular-shaped sections such as chimneys, but also in building large freestanding walls, making consoles without further ado or ‘slipping in’ cutouts. The slipforming method was adopted when making the bioshield at the Kriimmel nuclear power plant. Using heavy concrete and the many cutouts involved had to be included in considerations.

The OL3 construction project used climbing formwork and/or self-climbing formwork for the more standard building structures such as safety containment and aircraft impact structures (Figure 4.18).

The compact layout of the nuclear island components calls for using a special single­headed formwork. The walls enclosing the UKA, UFA, UKS, UJH and UKE construc­tion modules are separated in some cases by as little as 30-40 cm. These narrow spaces must be kept clear at all times.

The confined working space involved rules out double-headed formwork for whichever module comes later in time. Tying and releasing ties on double-headed formwork on the outside of the enclosing wall would be impossible, as the working space required is not available.

The solution adopted in this case was therefore as follows: on the inside of the enclosing wall of the following module, the ‘Trio’ framework formwork section system by the Peri company is used, which transmits its load via Peri SB framework sections to the

lower ceiling or wall-ceiling node point of the lower level. The load is led into the concrete via cast-in tension bars.

The external formwork was made via a special steel formwork section pre-stressed against the outer wall of the preceding building.

The formwork is installed, fixed and removed from the top.

Formwork can be removed once concreting is complete without leaving parts in the join.