FLOOD PROTECTION | SAFETY & SECURITY
In order to meet high nuclear safety standards, the closing function of the TFP system was reduced to the essentials. Double floating systems were designed according to specified buoyancy, which run in guide rods and close a constructed base plate tightly in the event of a tsunami or flood. This system is bolted into a specially developed modular mounting frame for maximum flexibility and integrated into the debris protection system. Carried out in accordance with nuclear-specific
quality standards such as KTA 1401 and IAEA 50-C-Q, this comprehensive approach illustrates the need and the ambition with which the TFP system was developed to provide the highest safety standards for nuclear power plants. For example, as part of the design process the TFP system parameters were calculated in accordance with the earthquake verifications of the KTA regulations in order to prove its effectiveness under seismic conditions. To achieve effective earthquake decoupling, special spring damping elements were installed that meet the nuclear requirements. These elements play a crucial role in absorbing vibrations and help to maintain the structural integrity of the system during seismic events. This TFP system can be installed in conjunction with the
debris guard in both the intake and exhaust air path of a ventilation system. The debris protection is divided into a lower and upper section, with the lower section connected to the ground and the upper section connected to the building. In addition to keeping debris out, the debris shield is designed to break tsunami waves and severe flooding and direct water to the TFP system. This function is critical to protecting the system from the effects of extreme hydrodynamic forces. Thanks to its design, the TFP system is a passive system
and fully redundant. It can also withstand large masses of mud and floating debris, extreme weather conditions, as well as high earthquake loads. This approach fulfils all of the previously defined requirements and the system therefore also falls into the desired IAEA Passive Category C. The selection of appropriate space conditions for the
installation of the TFP system and the associated protection devices is of great importance. Taking the spatial requirements into account ensures that the installation and periodic inspections of the TFP system can be carried out properly. Part of the development of the TFP system was the
iterative approach to creating the finite element model (FEM) in order to simulate the high earthquake loads. An overload (elastic deformation) was deliberately provoked in the first prototypes in order to determine the material and design limits while an additional calculation in accordance with ASME guidelines is also currently being implemented. TÜV SÜD IS GmbH was further consulted to determine the pressure loss for a TFP module and the ZETA value of the component using a specially designed pressure loss test rig. The determined pressure losses are necessary for the overall design of the system in which the TFP system is to be integrated in order to generate as little additional pressure losses as possible, especially in an existing system. In addition, a specially specified tsunami test stand
from INNOMECOM AG enables individual TFP modules to be subjected to specific mud and water masses. Tsunami and/ or flood characteristics, such as high water velocities and various forms of sludge, can be tested on each TFP module on this test stand. It is also possible to take into account the individual sludge compositions of the existing coastal and soil structures adjacent to a nuclear power plant. The proof of function on the tsunami test stand for the TFP system was independently verified by TÜV SÜD IS GmbH under specified tsunami conditions. The result is a patent-pending TFP system which can make an additional contribution to safety and to protecting nuclear facilities in the event of tsunamis and flooding with its robust design, passive and self-sufficient function, extensive testing and independent verification However, it is important to emphasise that no single protective measure or strategy can completely eliminate all risks. A comprehensive approach to safety, based on a combination of different protection devices and measures, is therefore crucial. ■
Far left: The TFP system can be installed in conjunction with the debris guard in both the intake and exhaust air path of a ventilation system
Left:
The prototype of the TFP module showing the double float system
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