Analysis of the strong motion records obtained from the 2007 Niigataken Chuetsu-oki earthquake and determination of the design basis ground motions at the Kashiwazaki Kariwa Nuclear Power Plant (Part1: Outline of the strong motion records and estimation o

Full text

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20th International Conference on Structural Mechanics in Reactor Technology (SMiRT 20) Espoo, Finland, August 9-14, 2009 SMiRT 20-Division 4, Paper 3189

1

Analysis of the strong motion records obtained from the 2007 Niigataken

Chuetsu-oki earthquake and determination of the design basis ground motions

at the Kashiwazaki Kariwa Nuclear Power Plant

(Part1: Outline of the strong motion records and

estimation of factors in large amplification)

Ryoichi Tokumitsu

a

, Masatomo Kikuchi

a

, Isao Nishimura

a

, Yoshiaki Shiba

b

,

and Shinya Tanaka

c

a

Nuclear Asset Management Department, Tokyo Electric Power Company, Tokyo, Japan, e-mail: tokumitsu.r@tepco.co.jp

b

Earthquake Engineering Sector, Civil Engineering Research Laboratory, Central Research Institute of Electric Power Industry, Chiba, Japan

c

Architectural Department, Tokyo Electric Power Services CO., LTD., Tokyo, Japan

Keywords: The Niigataken Chuetsu-Oki Earthquake, The Kashiwazaki Kariwa Nuclear Power Plant, Source Effect, Propagation Effect, Site Effect.

1

ABSTRACT

In the Niigataken Chuetsu-Oki Earthquake of July 16, 2007, a large ground motion was observed at the Kashiwazaki Kariwa Nuclear Power Plant, which was larger than the average ground motion of the magnitude of the Niigataken Chuetsu-Oki Earthquake. In addition, even in the Kashiwazaki Kariwa Nuclear Power Plant, there was large variation in recorded ground motion at different parts of the observation point.

In this paper, we examined the source, propagation and site effect of the Niigataken Chuetsu-Oki Earthquake, with the analysis of observed records and ground motion simulation analysis, in order to investigate the characteristics of the seismic ground motion observed at the Kashiwazaki Kariwa Nuclear Power Plant in the Niigataken Chuetsu-Oki Earthquake.

As a result, it is concluded that the short-period source spectrum in the Niigataken Chuetsu-Oki Earthquake was larger than the average event of Mj6.8, and it made the ground motion about 1.5 times higher. And we concluded that the ground motion became about 2 times larger because of the propagation effect. In addition, we concluded that the folding structure below the Kashiwazaki Kariwa Nuclear Power Plant made the ground motion about 2 times larger in southern part of the site.

2

INTRODUCTION

The Niigataken Chuetsu-Oki Earthquake occurred on July 16, 2007, with the epicenter in the Sea of Japan off the Niigata Prefecture. The magnitude of the event was Mj6.8 determined by Japan Meteorological Agency. With this earthquake, strong ground motion was observed at the Kashiwazaki Kariwa Nuclear Power Plant of the Tokyo Electric Power Company, which was larger than the average ground motion of Mj6.8 supposed from the attenuation relationship of Noda et al. (2002). In addition, in the Kashiwazaki Kariwa Nuclear Power Plant, there were large variations in recorded ground motion at different parts of the observation point, especially records in the southern part of the site were larger than these in the northern part of the site.

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3

OUTLINE OF THE SITE, THE EVENT AND THE OBSERVATION RECORDS

Fig. 1 shows the location of the Kashiwazaki Kariwa Nuclear Power Plant and the epicenter of the Niigataken Chuetsu-Oki Earthquake. The site is located along the coast of the Sea of Japan in the Niigata Prefecture, Japan, and the distance to the epicenter is about 16km from the site.

Fig. 2 shows the plan of the Kashiwazaki Kariwa Nuclear Power Plant, including the location of seismic observation points. The site covers an area of 4 square kilometers. There are seven power units in the site, Units 1-4 located in the southern part of the site, Units 5-7 in the northern part of the site. We have been monitoring the ground motion on the base mat of each reactor and turbine building. We have also installed down-hole array seismometers in the free field near Unit 1 and 5, but the observation records of the Niigataken Chuetsu-Oki Earthquake were overwritten by the records of aftershocks and lost, due to insufficient amount of the memory.

Tokyo

Osaka

Fukuoka

Sapporo

Niigata Kashiwazaki Kariwa Nuclear Power Plant

The Sea of Japan

Kashiwazaki Kariwa Nuclear Power Plant

Nagaoka

Ojiya Kashiwazaki The Sea of Japan

Epicenter

Figure 1. Location of the epicenter of the Niigataken Chuetsu-Oki Earthquake and the Kashiwazaki-Kariwa Nuclear Power Plant

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Unit1 Unit2

Unit3

Unit4 Unit7

Unit6

Unit5

Reactor Building Turbine Building

Unit1 Free field Unit5 Free field

Service hall Free field The seismic ground motion

observation points

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3

Unit 1

0 10 20 30 40

-800 -400 0 400 800 (c m /s

2 ) Max=311cm/s2

0 10 20 30 40

-800 -400 0 400 800 (c m /s

2 ) Max=680cm/s2

Unit 2

0 10 20 30 40

-800 -400 0 400 800 (c m /s

2 ) Max=304 cm/s2

0 10 20 30 40

-800 -400 0 400 800 (c m /s

2 ) Max=606cm/s

2

Unit 3

0 10 20 30 40

-800 -400 0 400 800 (c m /s

2 ) Max=308cm/s2

0 10 20 30 40

-800 -400 0 400 800 (c m /s

2 ) Max=384cm/s2

Unit 4

0 10 20 30 40

-800 -400 0 400 800 (c m /s

2 ) Max=310cm/s2

0 10 20 30 40

-800 -400 0 400 800 (c m /s

2 ) Max=492cm/s2

Unit 5

0 10 20 30 40

-800 -400 0 400 800 (c m /s

2 ) Max=277cm/s2

0 10 20 30 40

-800 -400 0 400 800 (c m /s

2 ) Max=442cm/s2

Unit 6

0 10 20 30 40

-800 -400 0 400 800 (c m /s

2 ) Max=271cm/s2

0 10 20 30 40

-800 -400 0 400 800 (c m /s

2 ) Max=322cm/s2

Unit 7

0 10 20 30 40

-800 -400 0 400 800 (c m /s

2 ) Max=267cm/s2

time(s) -8000 10 20 30 40

-400 0 400 800 (c m /s

2 ) Max=356cm/s2

time(s)

NS EW

(a) Acceleration waveforms

0.01 0.02 0.05 0.1 0.2 0.5 1 2 5 10 0.5 1 2 5 10 20 50 100 200 500 50 100 20

0 500 10

00 20

00 (cm

/s )

2

0.0 1 0.1

1 10

(cm )

?ü Sú(•b) ‘¬ “x (cm/s) Unit 1 (h=0.05) Unit 1

0.01 0.02 0.05 0.1 0.2 0.5 1 2 5 10 0.5 1 2 5 10 20 50 100 200 500 50 10 0 20 0 50 0 10 00 20 00 (cm

/s ) 2

0 .01 0

.1

1 10

(cm )

?ü Sú(•b) ‘¬ “x (cm/s) Unit 1 (h=0.05) Unit 2

0.01 0.02 0.05 0.1 0.2 0.5 1 2 5 10 0.5 1 2 5 10 20 50 100 200 500 50 100 200 50

0 100

0 200

0 (cm

/s ) 2

0 .01 0

.1

1 10

(cm )

?ü Sú(•b) ‘¬ “x (cm/s) Unit 1 (h=0.05) Unit 3

0.01 0.02 0.05 0.1 0.2 0.5 1 2 5 10 0.5 1 2 5 10 20 50 100 200 500 50 100 200 50

0 100

0 200

0 (cm

/s ) 2

0 .01 0

.1

1 10

(cm )

?ü Sú(•b) ‘¬ “x (cm/s) Unit 1 (h=0.05) Unit 4

0.01 0.02 0.05 0.1 0.2 0.5 1 2 5 10 0.5 1 2 5 10 20 50 100 200 500 50 100 20

0 50

0 100

0 200

0 (cm

/s ) 2

0 .01 0

.1

1 10

(cm )

?ü Sú(•b) ‘¬ “x (cm/s) Unit 1 (h=0.05) Unit 5

0.01 0.02 0.05 0.1 0.2 0.5 1 2 5 10 0.5 1 2 5 10 20 50 100 200 500 50 10 0 20 0 50 0 10 00 20 00 (cm

/s ) 2

0 .01 0

.1

1 10

(cm )

?ü Sú(•b) ‘¬ “x (cm/s) Unit 1 (h=0.05) Unit 6

0.01 0.02 0.05 0.1 0.2 0.5 1 2 5 10 0.5 1 2 5 10 20 50 100 200 500 50 10 0 20 0 50 0 10 00 20 00 (cm

/s ) 2

0 .01 0

.1

1 10

(cm )

?ü Sú(•b) ‘¬ “x (cm/s) Unit 1 (h=0.05) Unit 7

0.01 0.02 0.05 0.1 0.2 0.5 1 2 5 10 0.5 1 2 5 10 20 50 100 200 500 50 100 200 500 1000 2000 (cm /s )

2 0. 01 0.1 1 10 (cm )

_ü _ú(•b)

‘¬ “x (cm/s) sp_acc_1R2ew.waz sp_acc_2R2ew.waz sp_acc_3R2ew.waz sp_acc_4R2ew.waz sp_acc_5R2ew.waz sp_acc_6R2ew.waz (h=0.05) V el o ci ty (c m /s ) Period(s) NS

0.01 0.02 0.05 0.1 0.2 0.5 1 2 5 10 0.5 1 2 5 10 20 50 100 200 500 50 100 200 500 1000 2000 (cm /s )

2 0.01 0.1 1 10 (cm )

_ü _ú(•b)

‘¬ “x (cm/s) sp_acc_1R2ew.waz sp_acc_2R2ew.waz sp_acc_3R2ew.waz sp_acc_4R2ew.waz sp_acc_5R2ew.waz sp_acc_6R2ew.waz (h=0.05) V el o ci ty (c m /s ) Period(s) EW

(b) Response spectra

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0.01 0.02 0.05 0.1 0.2 0.5 1 2 5 10 0.5 1 2 5 10 20 50 100 200 500 50 100 20

0 500 100

0 200

0 (cm

/s )

2

0.0 1 0.1

1 10

(cm )

?ü Sú(•b) ‘¬ “x (cm/s) Unit 1 (h=0.05) Unit 1

0.01 0.02 0.05 0.1 0.2 0.5 1 2 5 10 0.5 1 2 5 10 20 50 100 200 500 50 100 20 0 50 0 10 00 20 00 (cm

/s ) 2

0 .01 0

.1

1 10

(cm )

?ü Sú(•b) ‘¬ “x (cm/s) Unit 1 (h=0.05) Unit 2

0.01 0.02 0.05 0.1 0.2 0.5 1 2 5 10 0.5 1 2 5 10 20 50 100 200 500 50 10 0 200 50

0 100

0 200

0 (cm

/s ) 2

0.0 1 0

.1

1 10

(cm )

?ü Sú(•b) ‘¬ “x (cm/s) Unit 1 (h=0.05) Unit 3

0.01 0.02 0.05 0.1 0.2 0.5 1 2 5 10 0.5 1 2 5 10 20 50 100 200 500 50 10 0 200 50

0 100

0 200

0 (cm

/s ) 2

0.0 1 0

.1

1 10

(cm )

?ü Sú(•b) ‘¬ “x (cm/s) Unit 1 (h=0.05) Unit 4

0.01 0.02 0.05 0.1 0.2 0.5 1 2 5 10 0.5 1 2 5 10 20 50 100 200 500 50 10 0 200 50

0 100

0 200

0 (cm

/s ) 2

0.0 1 0

.1

1 10

(cm )

?ü Sú(•b) ‘¬ “x (cm/s) Unit 1 (h=0.05) Unit 5

0.01 0.02 0.05 0.1 0.2 0.5 1 2 5 10 0.5 1 2 5 10 20 50 100 200 500 50 10 0 20 0 50 0 10 00 200

0 (cm

/s ) 2

0 .01 0

.1

1 10

(cm )

?ü Sú(•b) ‘¬ “x (cm/s) Unit 1 (h=0.05) Unit 6

0.01 0.02 0.05 0.1 0.2 0.5 1 2 5 10 0.5 1 2 5 10 20 50 100 200 500 50 100 20

0 500 10

00 20

00 (cm

/s ) 2

0 .01 0

.1

1 10

(cm )

?ü Sú(•b) ‘¬ “x (cm/s) Unit 1 (h=0.05) Unit 7

0.01 0.02 0.05 0.1 0.2 0.5 1 2 5 10 0.5 1 2 5 10 20 50 100 200 500 50 100 200 500 1000 2000 (cm /s )

2 0.01 0.1 1 10 (cm )

_ü _ú(•b)

‘¬

“x

(cm/s)

1_†‹@_iNS•ûŒü_j

2_†‹@_iNS•ûŒü_j

3_†‹@_iNS•ûŒü_j

(h=0.05) V el o ci ty (c m /s ) Period(s)

NS 0.01 0.02 0.05 0.1 0.2 0.5 1 2 5 10

0.5 1 2 5 10 20 50 100 200 500 50 100 200 500 1000 2000 (cm /s )

2 0. 01 0.1 1 10 (cm )

_ü _ú(•b)

‘¬ “x (cm/s) 1_†‹@_iEW•ûŒü_j 2_†‹@_iEW•ûŒü_j 3_†‹@_iEW•ûŒü_j (h=0.05) V el o ci ty (c m /s ) Period(s) EW

Figure 4. The response spectra on the free surface of the base stratum for each unit, estimated from the records on the base mat. Solid black line shows the standard response spectrum of Mj6.8 from the attenuation relationship of Noda et al. (2002).

Fig. 3 shows the acceleration waveforms and the response spectra observed on the base mat of each reactor building during the Niigataken Chuetsu-Oki Earthquake.

The design basis seismic ground motions of Japanese nuclear power plants are defined on the free surface of the base stratum, where the S-wave velocity is 0.7km/s or more. The depths of the free surface of the base stratum below each unit in the Kashiwazaki Kariwa Nuclear Power Plant are about 150-250m. So it is important to evaluate ground motions caused by the Niigataken Chuetsu-Oki Earthquake on the free surface of the base stratum of each unit. We estimated the ground motions on the free surface of the base stratum from ground motion records on the base mat of reactor buildings and amplitude ratios between the free surface of the base stratum and the base mat of reactor buildings, estimated from soil and structure model of reactor building of each unit. Fig. 4 shows the response spectra on the free surface of the base stratum evaluated from the response spectra on the base mat of each reactor building. The response spectra on the free surface of the base stratum are larger than those on the base mat of each reactor building, showed in Fig. 3, due to the effect of soil-structure interaction.

The standard response spectrum of Mj6.8, supposed from the attenuation relationship of Noda et al. (2002), is also showed as bold line in Fig. 4. The spectra of seismic ground motion of the Niigataken Chuetsu-Oki Earthquake observed in the site are larger than that of the attenuation relationship of Noda et al. (2002). In addition, the EW response spectra of Units 1-4 are larger than those of Units 5-7.

4

STUDY ON THE SOURSE EFFECT

In regard to the source effect, we estimated the moment density distribution on the fault through the inversion analysis using the empirical Green’s function method, with the observation records of the Kashiwazaki Kariwa Nuclear Power Plant and other regional records.

Fig. 5(a) shows the fault location we assumed as the Niigataken Chuetsu-Oki Earthquake, and the observation points we used for the inversion analysis. We referred the size of the fault from the Headquarters for Earthquakes Research Promotion. For the inversion analysis, we used the records on the base mat of Unit 1 and Unit 5 reactor building, and observation points within 50 km from the center of the assumed fault plane including the records obtained in K-NET, KiK-net and F-net by National Research Institute for Earth Science and Disaster Prevention, and the records of Japan Meteorological Agency. We used the aftershock of Mj4.4, showed the epicenter in Fig.5(a), as an empirical Green’s function. Fig. 5(b) shows the moment density on the fault estimated from the inversion analysis. We can recognize three asperities from Fig. 5(b).

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5

parameters we estimated. Fig. 6 shows the comparison of the waveforms of the Unit 1 and 5 on the base mat between the observation and calculation from the characterized source model. The waveforms are in the broadband frequency range from 0.1 to 10 Hz. These waveforms are in good agreements.

We evaluated the short-period source spectrum by the following,

2 2

1 2

4

, i #i "ai!

i

i A r

A

A %% = $

& ' (( ) *

=

+

(1)

where Ai is the short-period source spectrum from each asperity, ri is the equivalent radius, ai is the stress

drop of each asperity, and is the S-wave velocity in the source region. Estimating from eqn.(1) with the parameters of the characterized source model shown in Table 1, the short-period source spectrum is evaluated as 1.83x1019Nm/s2. It is about 1.5 times larger than the average short-period source spectrum evaluated from the seismic moment by the National Research Institute for Earth Science and Disaster

Prevention (9.3x1018Nm), and the scaling rule between the seismic moment and short-period source

spectrum.

Unit 1 Unit 5

(a) Epicenters of main shock and aftershock used as an

empirical Green’s function, and the observation points used for the inversion analysis. Solid and open triangles show the K-NET and KiK-net stations respectively. Square shows the F-net and Japan Meteorological Agency stations.

Unit 1 Unit 5

(b) The relationship of the moment density

derived from the inversion analysis and the characterized source model. Red and yellow images represent the moment density. Three blue rectangles show the asperities of the characterized source model. Star shows the epicenter of main shock.

Figure 5. Location of the fault of the Niigataken Chuetsu-Oki Earthquake and the Kashiwazaki-Kariwa Nuclear Power Plant. The rectangle with solid and broken line shows the fault plane.

Table 1. Characterized source parameters of the Niigataken Chuetsu-Oki Earthquake.

Whole fault Asp.1 Asp.2 Asp.3

Seismic moment (1018Nm) 9.30 1.83 2.11 1.43

Rupture Area (Km2) 540 31.4 39.2 31.4

Averaged slip (m) 0.55 1.87 1.72 1.46

Stress Drop (MPa) 1.8 25.47 20.84 19.91

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Accelelration (cm/s2) Velocity (cm/s) Displacement (cm)

NS

Accelelration (cm/s2) Velocity (cm/s) Displacement (cm)

NS

EW (a) Unit 1

EW (b) Unit 5

Figure 6. Comparisons of the waveforms of the Unit 1 and 5 on the base mat between the observation (black line) and calculation from the characterized source model (red line) in the frequency range from 0.1 to 10 Hz. Numbers above the waveforms are the peak values.

5

STUDY ON THE PROPAGATION EFFECT

In order to evaluate the propagation effect of the Niigataken Chuetsu-Oki Earthquake, we analyzed the characteristics of the ground motion records obtained in the Kashiwazaki Kariwa Nuclear Power Plant in the past. Table 2 lists the events used for the analysis, and Fig. 7 shows the epicenter of the events of Table 2. For the analysis, we used the ground motion records obtained in the borehole array of Unit 1 and Unit 5, as free field records, shown in Fig. 2. The presences of ground motion records of each point are shown in the right side of Table 2. From these records, we calculated the ground motions on the free surface of the base stratum by 1-D wave propagation analysis with the soil model of each observation point.

Fig. 8 shows the spectral ratios between the response spectra of ground motions on the free surface of the base stratum and the average response spectra supposed from the attenuation relationship of Noda et al. (2002). Spectral ratios of the events occurred in the offshore area are shown as blue lines, and those occurred in the inland area are shown as red lines. The bold line of each color is the average of the spectral ratios. The average of the spectral ratio that the epicenter is in the offshore area is higher than that the epicentre is in the inland area.

From the analysis, we concluded that the ground motion of the offshore event becomes larger than that of the inland event, and we supposed that the ground motion of the Niigataken Chuetsu-Oki Earthquake, which had the characteristic of the offshore event, was more 2 times as large as the average ground motion.

Kashiwazaki Kariwa Nuclear Power Plant

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7

Table 2. List of the analyzed event. Parameters are referred from the Japan Meteorological Agency. Circle shows the existence of observation records in the free field near Unit 1 and 5 in Fig. 2.

epicenter Existence of the

observation record No. Origin Time

Longitude Latitude

Mj Depth km

Unit 1 Unit 5

1 1986. 12. 30 9: 38 137 55.30' 36 38.40' 5.9 3.3

2 1987. 03. 24 21: 49 137 54.20' 37 28.90' 5.9 21.6

3 1993. 02. 07 22: 27 137 17.80' 37 39.40' 6.6 24.8

4 1995. 04. 01 12: 49 139 14.88' 37 53.47' 5.6 16.16

5 2004. 10. 23 17: 56 138 52.00' 37 17.60' 6.8 13.08

6 2004. 10. 23 18: 03 138 59.00' 37 21.20' 6.3 9.38

7 2004. 10. 23 18: 07 138 51.90' 37 20.90' 5.7 14.9

8 2004. 10. 23 18: 11 138 49.80' 37 15.20' 6.0 11.52

9 2004. 10. 23 18: 34 138 55.80' 37 18.40' 6.5 14.17

10 2004. 10. 23 19: 45 138 52.57' 37 17.74' 5.7 12.35

11 2004. 10. 25 6: 04 138 56.81' 37 19.80' 5.8 15.2

12 2004. 10. 27 10: 40 139 02.00' 37 17.51' 6.1 11.6

13 2004. 11. 08 11: 15 139 01.92' 37 23.76' 5.9 0

14 2007. 03. 25 9: 41 136 41.10' 37 13.20' 6.9 11

15 2007. 07. 16 15: 37 138 38.60' 37 30.20' 5.8 11

: E vents of the offshore area ! !: Average of the offshore area ! ! : Events of the inland area ! ! : Average of the inlan d areaa

0.01 0.02 0.05 0.1 0.2 0.5 1 2 5 10

0.05 0.1 0.2 0.5 1 2 5 10 20 50

Periods(s) ƒX

ƒy ƒN ƒg ƒ‹ ”ä

No01_198612300938NS.rto2 No01_198612300938EW.rto2 No02_198703242149NS.rto2 No02_198703242149EW.rto2 No03_199302072227NS.rto2 No03_199302072227EW.rto2 No04_199504011249NS.rto2 No04_199504011249EW.rto2 No10_200410231945NS.rto2 No10_200410231945EW.rto2 No11_200410250604NS.rto2 No11_200410250604EW.rto2 No12_200410271040NS.rto2 No12_200410271040EW.rto2 No13_200411081115NS.rto2 No13_200411081115EW.rto2 No14_200703250941NS.rto2 No14_200703250941EW.rto2 No15_200707161537NS.rto2 No15_200707161537EW.rto2 h_K1_sf_sea_4eq.waz h_K1_sf_land.waz 1.waz

R

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(

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b

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/

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al

)

Period (s)

(a) Unit 1 free field

0.01 0.02 0.05 0.1 0.2 0.5 1 2 5 10

0.05 0.1 0.2 0.5 1 2 5 10 20 50

Periods(s) ƒX

ƒy ƒN ƒg ƒ‹ ”ä

No01_198612300938NS.rto2 No01_198612300938EW.rto2 No02_198703242149EW.rto2 No02_198703242149NS.rto2 No03_199302072227NS.rto2 No03_199302072227EW.rto2 No04_199504011249NS.rto2 No04_199504011249EW.rto2 No05_200410231756NS.rto2 No05_200410231756EW.rto2 No06_200410231803NS.rto2 No06_200410231803EW.rto2 No07_200410231807NS.rto2 No07_200410231807EW.rto2 No08_200410231811NS.rto2 No08_200410231811EW.rto2 No09_200410231834NS.rto2 No09_200410231834EW.rto2 No10_200410231945NS.rto2 No10_200410231945EW.rto2 No11_200410250604NS.rto2 No11_200410250604EW.rto2 No12_200410271040NS.rto2 No12_200410271040EW.rto2 No13_200411081115NS.rto2 No13_200411081115EW.rto2 No14_200703250941NS.rto2 No14_200703250941EW.rto2 No15_200707161537NS.rto2 No15_200707161537EW.rto2 h_K5_sf_sea_4eq.ave h_K5_sf_land.ave 1.waz

R

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(

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b

s

/

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Period (s)

(b) Unit 5 free field

Figure 8. The spectral ratios between the response spectra of ground motions on the free surface of the base stratum and the average response spectra supposed from the attenuation relationship of Noda et al. (2002).

6

STUDY ON THE SITE EFFECT

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for the offshore events are shown in Fig. 9(a), and Fig. 9(b) is those for inland events. The bold red line is the average of the spectral ratios. The average spectral ratio for the offshore events is about 1.5-2.0, while that for the inland events is almost 1.0.

From these spectral ratios, we can conclude that seismic ground motion that comes from the offshore area are amplified larger at Unit 1, the southern part of the site, than at Unit 5, the northern part of the site, and we assume these characteristics of spectral amplitude to be the site effect.

In order to clarify the site effect of the Kashiwazaki Kariwa Nuclear Power Plant, we also conducted the ground motion simulation with the 2-D soil model in the area below the site. For details of the 2-D simulation analysis, please refer to Part2.

: Response spectral ratio of each event ! ! ! : The average of spectral ratios

0.01 0.02 0.05 0.1 0.2 0.5 1 2 5 10 0.05

0.1 0.2 0.5 1 2 5 10 20 50

Periods(s) ƒX

ƒy ƒN ƒg ƒ‹ ”ä

Ratio_No03_199302072227NS.waz Ratio_No03_199302072227EW.waz Ratio_No14_200703250941NS.waz Ratio_No14_200703250941EW.waz Ratio_No15_200707161537NS.waz Ratio_No15_200707161537EW.waz k1_k5_sea_3eq.prn

1.waz

R

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(

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1

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(a) Offshore events

0.01 0.02 0.05 0.1 0.2 0.5 1 2 5 10 0.05

0.1 0.2 0.5 1 2 5 10 20 50

Periods(s) ƒX

ƒy ƒN ƒg ƒ‹ ”ä

Ratio_No04_199504011249NS.waz Ratio_No04_199504011249EW.waz Ratio_No10_200410231945NS.waz Ratio_No10_200410231945EW.waz Ratio_No11_200410250604NS.waz Ratio_No11_200410250604EW..waz Ratio_No12_200410271040NS.waz Ratio_No12_200410271040EW.waz Ratio_No13_200411081115NS.waz Ratio_No13_200411081115EW.waz Ratio_—!ˆæ_5EQ_ave.waz 1.waz

R

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(b) Inland events

Figure 9. The response spectral ratios between the recorded ground motion of Unit 1 and Unit 5 free field.

7

CONCLUSION

From the results, we concluded that the short-period source spectra in the Niigataken Chuetsu-Oki Earthquake was higher than the average event of Mj6.8, and the ground motion became about 1.5 times higher. We also concluded that the ground motion became over 2 times larger due to the propagation effect for offshore events. In addition, the ground motion in the southern part of the site is amplified 2 times larger than that in the northern part due to the site effect.

REFERENCES

Noda S. , K.Yashiro, K.Takahashi, M.Takemura, S.Ohno, M.Tohdo and T.Watanabe, RESPONSE

SPECTRA FOR DESIGN PURPOSE OF STIFF STRUCTURES ON ROCK SITES OECD-NEA

Workshop on the Relations between Seismological DATA and Seismic Engineering, Oct.16-18, 2002, Istanbul, pp.399-408

A Report on Analysis of Seismic Observation Data Obtained at the Time of the 2007 Niigata-Chuetsu-Oki Earthquake at the Kashiwazaki-Kariwa Nuclear Power Station, and the Formulation of the Design-basis Seismic Motion, Tokyo Electric Power Company, 2008

Kazuo D. , M.Watanabe, T.Sato, T.Ihii, SHORT-PERIOD SOURCE SPECTRA INFERRED FROM

VARIABLE-SLIP RUPTURE MODELS AND MODELING OF EARTHQUAKE FAULTS FOR STRONG

Figure

Figure 2. Plan of Kashiwazaki-Kariwa Nuclear Power Plant including the seismic ground motion observation point

Figure 2.

Plan of Kashiwazaki-Kariwa Nuclear Power Plant including the seismic ground motion observation point p.2
Figure 1. Location of the epicenter of the Niigataken Chuetsu-Oki Earthquake and the Kashiwazaki-Kariwa Nuclear Power Plant

Figure 1.

Location of the epicenter of the Niigataken Chuetsu-Oki Earthquake and the Kashiwazaki-Kariwa Nuclear Power Plant p.2
Figure 3. Acceleration waveforms and the response spectra observed on the base mat of each reactor building of the Niigataken Chuetsu-Oki Earthquake

Figure 3.

Acceleration waveforms and the response spectra observed on the base mat of each reactor building of the Niigataken Chuetsu-Oki Earthquake p.3
Figure 4. The response spectra on the free surface of the base stratum for each unit, estimated from the _ü  _ú(•b)_ü  _ú(•b)records on the base mat

Figure 4.

The response spectra on the free surface of the base stratum for each unit, estimated from the _ü _ú(•b)_ü _ú(•b)records on the base mat p.4
Table 1. Characterized source parameters of the Niigataken Chuetsu-Oki Earthquake.

Table 1.

Characterized source parameters of the Niigataken Chuetsu-Oki Earthquake. p.5
Figure 5. Location of the fault of the Niigataken Chuetsu-Oki Earthquake and the Kashiwazaki-Kariwa Nuclear Power Plant

Figure 5.

Location of the fault of the Niigataken Chuetsu-Oki Earthquake and the Kashiwazaki-Kariwa Nuclear Power Plant p.5
Figure 6. Comparisons of the waveforms of the Unit 1 and 5 on the base mat between the observation (black line) and calculation from the characterized source model (red line) in the frequency range from 0.1 to 10 Hz

Figure 6.

Comparisons of the waveforms of the Unit 1 and 5 on the base mat between the observation (black line) and calculation from the characterized source model (red line) in the frequency range from 0.1 to 10 Hz p.6
Figure 7. The distribution of the epicenter of the analyzed events. The number of each event corresponds to the number in Table 2

Figure 7.

The distribution of the epicenter of the analyzed events. The number of each event corresponds to the number in Table 2 p.6
Table 2. List of the analyzed event. Parameters are referred from the Japan Meteorological Agency

Table 2.

List of the analyzed event. Parameters are referred from the Japan Meteorological Agency p.7
Figure 8. The spectral ratios between the response spectra of ground motions on the free surface of the base stratum and the average response spectra supposed from the attenuation relationship of Noda et al

Figure 8.

The spectral ratios between the response spectra of ground motions on the free surface of the base stratum and the average response spectra supposed from the attenuation relationship of Noda et al p.7
Figure 9. The response spectral ratios between the recorded ground motion of Unit 1 and Unit 5 free field

Figure 9.

The response spectral ratios between the recorded ground motion of Unit 1 and Unit 5 free field p.8

References

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