Evaluating the Seismic Diversity and Robustness of Nuclear Power Plants

Figures & data

Figure 1. Fault tree of a dual parallel system [7]

Figure 2. Fault tree of a triple parallel system

Figure 3. Process to evaluate the seismic diversity and robustness

Figure 4. Contours of the predicted inter-period correlation coefficient vs. T1 and T2 proposed by Baker and Jayaram [38]

Table 1. List of target sites and characteristics of seismic environment for each site

Site name	Abbreviation	Characteristics of seismic environment (Major affecting seismic sources)
Tokachi	TKC	Mega earthquakes (17th century type) and active fault earthquakes
Miyagi	MYG	Mega earthquakes (off the Pacific coast of Tohoku region) and active fault earthquakes
Tokyo	TKY	M8 class earthquakes along the Sagami Trough and M7 class direct earthquakes
Mie	MIE	Large earthquakes along the Nankai Trough and active fault earthquakes
Ehime	EHM	Earthquakes in the Median Tectonic Line fault zone
Kumamoto	KMM	Earthquakes in Futagawa･Hinagu fault zone
Tottori	TTR	Active fault Earthquakes in Chugoku region and inland crustal earthquakes (representative of Sanin district)
Fukui	FKI	Active fault Earthquakes in a relatively dense neighborhood
Gifu	GIF	Active fault Earthquakes in a relatively dense neighborhood
Niigata	NGT	Earthquakes on the eastern edge of the Sea of Japan and active fault earthquake
Soya	SOY	Earthquakes on the eastern edge of the Sea of Japan and active fault earthquake (representative of the Sea of Japan side of Hokkaido)

Figure 5. Location map of the site and major seismic sources [40]. (The specific site locations are plotted on the J-SHIS’s map.). National Research Institute for Earth Science and Disaster Resilience (2019), J-SHIS, National Research Institute for Earth Sience and Disaster Resilience, <https://doi.org/10.17598/nied.0010>

Figure 6. Hazard curve of the acceleration response spectrum (T = 0.3 s)

Figure 7. Hazard curve of the acceleration response spectrum (T = 3.0 s)

Figure 8. Contribution of the earthquake type to the hazard curve (T = 0.3 s)

Figure 9. Contribution of the earthquake type to the hazard curve (T = 3.0 s)

Figure 10. Median capacity of seismic designed and isolated devices

Figure 11. Relationship between inter-period correlation and failure probability (TKY, β = 0.3, β’ = 0.2)

Figure 12. Relationship between capacity variability and failure probability (TKY, ρ = 0.25, β’ = 0.2)

Figure 13. Failure probability for each site (ρ = 0.25, β = 0.3, β’ = 0.2) [9]

Table 2. List of earthquakes with a high contribution to hazard curves

Site	Earthquake Type	Mw	Distance (km)	Contribution to Hazard(%)
				T = 0.3 s	T = 3.0 s
	Plate-boundary	8.4	45.3	6.2	9.4
	Crustal	7.5	9.2	4.6	37.9
TKC	Plate-boundary	8.6	45.3	4.1	6.2
	Plate-boundary	8.5	45.3	2.5	3.8
	Plate-boundary	8.5	45.3	2.5	3.8
	Crustal	6.9	4.2	57.6	86.1
	Crustal	6.4	4.2	2.5	0.6
MYG	Crustal	6.5	4.2	2.5	0.9
	Crustal	6.5	4.2	2.4	1.1
	Crustal	6.6	4.2	2.3	1.5
	Plate-boundary	7.9	26.7	26.9	25.2
	Plate-boundary	8.0	26.7	26.4	36.3
TKY	Plate-boundary	8.2	26.7	4.8	13.0
	Plate-boundary	8.4	26.7	3.6	9.8
	Plate-boundary	8.6	26.7	2.4	6.5
	Crustal	6.7	2.0	57.1	78.5
	Crustal	6.4	2.0	4.9	2.7
TTR	Crustal	6.5	2.0	4.6	3.3
	Crustal	6.5	2.0	4.3	3.9
	Crustal	6.6	2.0	3.9	4.4
	Crustal	7.0	7.1	69.2	91.5
	Crustal	6.6	7.1	2.0	0.7
SOY	Crustal	6.7	7.1	1.9	0.9
	Crustal	6.5	7.1	1.9	0.0
	Crustal	6.8	7.1	1.9	1.2

Note: This table shows a list of the top 5 seismic sources that contribute significantly to the hazard curves with a natural period of 0.3 s at each site, and the sum of the contributions of the 5 seismic sources may not total 100%.

Table 3. Slope of the hazard curve of the acceleration response spectrum

Site	Sa(H = 10^−5)/Sa(H = 10^−2)
	T = 0.3 s	T = 3.0 s
TKC	5.6	6.3
MYG	8.0	11.3
TKY	6.3	8.3
TTR	14.9	26.0
SOY	26.3	25.9

※ Large value means gentle slope (MYG, TTR, SOY).

※ Small value means steep slope (TKC, TKY).

Table 4. Cases to analyze the robustness

Case No.	Earthquake Type	M (MW)	Shortest Distance (km)
1	plate-boundary		50
2		8.5	100
3		(8.5)	150
4			200
5	plate-boundary		25
6		8.0	50
7		(8.0)	100
8			150
9	Crustal		10
10		7.0	25
11		(6.54)	50
12			100
13	Crustal		5
14		6.0	10
15		(5.76)	25
16			50

Figure 14. Failure probability of single device and dual system (TKY, ρ = 0.25, β = 0.3, β’ = 0.2)

Figure 15. Failure probability of single device and triple system (TKY, ρ = 0.25, β = 0.3, β’ = 0.2)

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