With nuclear power plants, system components must be protected against effects so that they can do their job in operating conditions as intended and if accidents arise [92]. This puts additional requirements on waterproofing structures. Including external effects (earthquakes, aircraft impact, explosion pressure waves) and internal effects from accidents as the case may be, structure waterproofing is subject not only to static, but also to higher transient dynamic loads.

7.3 Black tank

As a general rule, waterproofing structures to protect against water penetration are carried out in accordance with the DIN 18195 series of standards. How this structural waterproofing behaves under what are normally long-term static loads is sufficiently known; but the design constraints developed from the series of standards above are not always sufficient for nuclear structures. Special load cases which act on the structures which carry the structural waterproofing can cause deformation and displacement which affect the structural waterproofing.

In these special load cases, as well as the localised high levels of pressure from the working load, a number of other types of stress can also arise:

— transient higher transverse compression stress

— transient intermittent transverse tension stress (gaping gap opening/nominal fracture point between structures and their environments)

— transient intermittent shear stress at the waterproofing level.

How structural waterproofing behaves in terms of bridging cracks is also important.