Civil Engineering Reference
In-Depth Information
As a result of the structural vibrations, the mechanical components and systems
are excited to vibration according to the coupling with the structure of the building,
similar as in case of an earthquake. These induced vibrations can influence the
integrity and functionality of the facility.
A consequence of an aircraft impact can also be the load due to flying wreckage
or falling debris. In the case that a structure is not designed to withstand an airplane
crash, the structure can collapse and endanger safety-related facility components.
An example of this is the exhaust air chimney, which could fall on the reactor
structure. Internal structures can also collapse and create debris loads.
Further resultant consequences are fuel fires (kerosene) or explosions. Fire, great
heat, smoke and/or pressure waves can compromise important safety-related facility
components.
12.2 Design Requirements
To reduce the remaining risks of a possible airplane crash on the reactor building of
a power plant as well as on buildings which have to be protected with respect to the
safe residual heat removal (referred to as safety-relevant buildings), the following
requirements have to be taken into account during the design:
• Protection against penetration of the outer shell
• Assurance of the global structural stability
• Protection against the effects of vibrations
• Protection against the effects of wreckage and debris
• Protection against kerosene fires and their consequences
Explicit requirements were already specified in the RSK-Guidelines [
1
] (referred
to as RSK-LL in the following) in 1981. Among other things, a load-time function
is described for the impact of an airplane upon which the design must be based. The
global structural stability of the safety-related buildings must be assured, taking into
account the possible protective effect of the other surrounding building structures.
Perforation has to be avoided to prevent consequential damages. In addition to this,
no concrete fragments can be allowed to spall from the rear side of a target
structure, so long as safety-relevant mechanical components could be compromised
and their failure cannot be assured through the principle of spatial separation. This
case is called inherent protection. The effects of wreckage and debris, as well as
those of kerosene fires and the induced vibrations caused by an aircraft impact must
be considered during the design process according to the RSK-LL. Neither the
simultaneous occurrence of a single error and an airplane crash nor the simulta-
neous maintenance case must be postulated in the design.
Within the framework of consultations for the revision of the nuclear regulations,
a defense-in-depth concept was suggested by the RSK in 2005 (cf. [
2
]). The load
case of an airplane crash is not a classical design load case for incident management
even after the attacks on the World Trade Center on September 11, 2001, but is
