seismic fragility functions based on actual earthquakes
TRANSCRIPT
1971 San Fernando (M6.5)1973 Pt. Mugu (M5.9)1987 Whittier (M5.9)
1986 Palm Springs (M6.0)1991 Sierra Madre (M5.4)
1992 Landers (M7.6)1994 Northridge (M6.7)
1975 Ferndale (M5.5)1980 Humboldt County
(M7.0)1992 Cape Mendocino
(M7.0)
1982 Chalfant (M6.0) 1989 Loma Prieta (M6.9)
1979 Imperial (M6.6)1987 Superstition
(M5.6)
1997 Michoacan (M7.3)
1995 Manzanillo (M7.6)
1985 Mexico (M8.1)
1986 San Salvador (M5.4)
1991 Costa Rica (M7.4)
1985 Valparaiso (M7.8)
2010 Maule (M8.8)
2007 Pisco (M8.0)1987 New Zealand
(M6.2)
1993 Guam (M8.0)
2001 Gujarat (M7.7)
2011 Tohuku (M9.0)
1990 Luzon (M7.3)
Earthquake Investigations
Peak Ground AccelerationSome of the Data Sites
Stro
ng
Mo
tio
n D
ura
tio
n
0.000
0.500
1.000
1.500
2.000
2.500
0.0000 5.0000 10.0000 15.0000 20.0000 25.0000 30.0000 35.0000
Devers SubstationPalm Springs Earthquake
Llolleo Water PlantChilean Earthquake
Placerita CogenNorthridge Earthquake
Rinaldi SubstationNorthridge Earthquake
Wanta Hydro PlantTaiwan Earthquake
Sylmar Converter StationNorthridge Earthquake
Coalinga Near-Field SitesCoalinga Earthquake
Gro
un
d S
pe
ctra
l Acc
ele
rati
on
(g)
Frequency (Hz)
Ground Motion Response Spectra from Database Sites
Overall earthquake failure rate for some 22 categories of mechanical, electrical & electronic equipment: 2 – 3% , i.e., on the order of 100 failures of out ~4,000 items of equipment.
Perhaps half of failures might apply to nuclear plant equipment installations.
The Most Important Information Comes from Failure
2
4
14
12
10
8
6
Cu
rre
nt
Surg
e &
Ele
ctri
cal B
urn
ou
t
Top
plin
g d
ue
to
Lac
k o
f A
nch
ora
ge
Soil
Sett
lem
en
t
Bea
rin
gsUn
rest
rain
ed Is
ola
tio
n M
ou
nts
An
cho
rage
Fai
lure
Dis
lod
ged
Co
mp
on
ent
Wat
er S
pra
y
Inst
ance
s o
f Lo
ss-o
f-Fu
nct
ion
Bu
cklin
g
Vib
rati
on
Dam
age
Sway
& Im
pac
t
16
Ce
ilin
gs
Po
rce
lain
Pip
e/D
uct
Lo
ads
Causes of Loss of Function in Equipment based on EPRI Database
An “instance” of loss-of-function applies to one-or-more equipment items in the same location damaged by the same cause.
Mis
cella
neo
us
Most Common Earthquake Failure: Current Surge Burn-Out:
Fifteen Instances of Failure
Example Category of SSC:
Instrument & Control Panels
0
20
40
60
80
100
120
140
0 0.2 0.4 0.6 0.8
Nu
mb
er
of
Co
ntr
ol P
ane
ls
Peak Ground Acceleration (g)
Instrument & Control Panels
PanelsSubjected to
MMI VII - VII+
PanelsSubjected to MMI VIII - IX
300
200
100
0
One out of 167 I&C Panels. Failure rate = 0.60%.
Thirteen out of 341 Panels Failure rate = 3.8%.
Instances of Damage Likely Not Applicable to Nuclear Plant Installations
Instances of Damage Applicable to a Nuclear Plant Installations
No Damage Resulting in Loss of Function
-2
-1.5
-1
-0.5
0
0.5
1
1.54.5g4.5g
1.0g
1.6g
4.5g
2.7g
0.61g
0.14g
0.22g
0.37g
Pe
ak G
rou
nd
Acc
ele
rati
on
Nat
ura
l Lo
g o
f P
eak
Gro
un
d A
cce
lera
tio
n
-3 -2.5 -2.0 -1.5 -1.0 -0.5 0Sigma to the Left of the Median
0.13% 0.62% 2.27% 6.7% 16% 31% 50%
Extrapolated AM
= 2.1g
MMI VIII – IX Sites: Failure Rate = 13/341
= 3.8%
MMI VII – VII+ Sites: Failure Rate = 1 / 167
= 0.60%
Fragility Derived from the Failure Rate of Devices in I&C Panels
0.00E+00
1.00E-01
2.00E-01
3.00E-01
4.00E-01
5.00E-01
6.00E-01
7.00E-01
8.00E-01
0 0.5 1 1.5 2 2.5 3 3.5
Peak Ground Acceleration
Pro
bab
ility
The Contribution to Core Damage Frequency (CDF) of any SCC is the Convolution of the Site Seismic Hazard Function and the SSC
Fragility Function: ∫F (a) dH(a)/da da
Typical Seismic FragilityFunction for Single
Failure: F (A)
Typical Seismic Hazard Function: H(a) x 1,000
Oconee Pilgrim
North AnnaIndian Point
CallawayAverage
0.1 0.20 0.30 0.50 0.80 1.3 2.0 3.0
Peak Ground Acceleration (g)
10
-81
0-7
10
-61
0-5
10
-41
0-3
An
nu
al
Ex
ceed
an
ce P
rob
ab
ilit
y
Vogel
Watts Bar
DC Cook
Robinson
Peach Bottom
Seismic Hazard Functions for the Ten Nuclear Plant Sites Rated by the NRC as Priority 1
0.00E+00
1.00E-01
2.00E-01
3.00E-01
4.00E-01
5.00E-01
6.00E-01
7.00E-01
8.00E-01
0 0.5 1 1.5 2 2.5 3 3.5
Peak Ground Acceleration
Pro
bab
ilityConvolution of the Seismic Hazard with
Fragility for I & C Panels
•Seismic FragilityFunction: F (A)
Increments in the Integral:
∫ F (a) dH(a)
Seismic Hazard Function: H(a) x 1,000
Observations & Conclusions
• For seismic fragility functions, F(a), anchored to actual earthquake experience, the contribution to the convolution integral, and hence the contribution to core damage frequency, is minor above PGA ≈ 1.0g.
• Only F(a) in the range of about 0.20g – 1.0g is of importance. This is the range where fragility is shaped by failure rates observed in actual earthquakes, and the range of representation by the earthquake database.
“The problem is we don’t design nuclear plants to withstand
earthquakes; we design them to withstand finite element
analysis.”-- Enrico Fermi, 1939