Civil Engineering Reference
In-Depth Information
Table 7.3
Design basis earthquakes of German nuclear power plants as an example [
25
]
Design
basis
intensity Subsoil class
Max. horizontal
acceleration
(m/s
2
)
Max. duration
of earthquake
(s)
Probability
of exceeding
Reactor
10
5
/a
Isar II konvoy
PWR
VI 1/4
Loose sediment
1.1
0.75
3.5
10
5
/a
KGG B + C
BWR-72
Gundremmingen
VII
Loose sedi-
ment/
sediment
1.0
0.5 vertical
10
10
5
/a
KKP-II
Philippsburg
pre-konvoy
PWR
VII 1/2
Thick
sediment
2.1
9
10
5
/a
GKN-2 konvoy
VIII
Rock
1.7
8
10
5
/a
KKE Emsland
konvoy-
PWR
VIII
1.3
2.6
7.3
10
6
/a
Brokdorf
pre-konvoy
PWR
VI
Silt, sand,
peat
0.5
4
Fig. 7.5
Damping elements in the foundation of a nuclear power plant [
26
]
In addition, pipes and other components inside the reactor building can be
supported by restraining and damping measures to prevent excessive oscillatory
movements [
28
] (Fig.
7.6
).
The dampers of rubber or neoprene in the bottom foundation of the reactor
building attenuate both vertical and horizontal accelerations in the reactor building
during an earthquake. Peak accelerations are shifted into a higher frequency range,
which mitigates the risk of damage [
26
,
27
,
29
].
These restraining and damping measures applied to pipes and components,
and the use of rubber and neoprene dampers in the bottom foundation of
reactor buildings, allow new nuclear power plants as well as commercial high
risers in big cities to be designed safely against higher seismic intensities of the
kind which may occur in seismic areas.
