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Risk‐informed design of seismically isolated nuclear power plants

Andrew Whittaker, Ph.D., S.E.Professor 

Director, MCEERChair, ASCE Nuclear Standards Committee

Department of Civil, Structural and Environmental Engineering

University at Buffaloawhittak@buffalo.edu 1

Seismic isolation: basis

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Seismic isolation: bearings

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Seismic isolation: impediments

• Lack of new build nuclear construction

• Technology unfamiliar to nuclear A/E firms– 30 year US history for buildings and infrastructure

• No prior use in US nuclear facilities

– DOE complex or commercial nuclear fleet

• Benefits not quantified

– Now addressed: improved safety and ROM cost

• Lack of risk‐based regulatory guidance– Now addressed: ASCE/SEI Standard 4‐16, 3 NUREG/CRs, MCEER reports, journal 

articles

• Lack of analysis tools

– Now addressed: LS‐DYNA, ABAQUS, OpenSees, all V+V’d

• Lack of appropriate SPRA tools– Now addressed: published techniques, ASCE/SEI 4‐16

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5 10 15 20 25 30Frequency (Hz)

0

0.5

1

1.5

2

2.5

Me

dia

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loo

r sp

ect

ral a

cce

lera

tion

(g

)

Model 1

Model 2

Model 3

Model 4

5 10 15 20 25 30Frequency (Hz)

0

1

2

3

4

5

6

7

Me

dia

n f

loo

r sp

ect

ral a

cce

lera

tion

(g

)

201

216

Seismic isolation: risk reduction

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Seismic isolation: cost

0 0.1 0.2 0.3 0.4Ra

0

0.25

0.5

0.75

1

Pro

ba

bili

ty o

f u

na

cce

pta

ble

pe

rfo

rma

nce

Model 2

Model 3

Model 4

0.047

0.12

0.017

0.51

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Seismic isolation: cost

The INL is a U.S. Department of Energy National Laboratory operated by Battelle Energy Alliance

INL/EXT-16-40122

Characterizing the Benefits of Seismic Isolation for Nuclear Structures: A Framework for Risk-Based Decision Making

INL Seismic Research Group

November 2016

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Risk‐based guidance for isolation

• Performance statements• Isolators suffer no damage in the DBE

• Confirm by production testing all isolators

• Isolated facility impacts surrounding structure • 1% NEP for DBE shaking; 10% NEP for BDBE shaking

• Isolators sustain gravity and earthquake induced axial loads at 90%‐ile BDBE displacement

• Confirm by prototype testing

• Safety‐critical umbilical lines sustain 90%‐ile BDBE displacement with 90% confidence

• Confirm by testing and/or analysis

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Risk‐based guidance for isolation

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Risk‐based guidance for isolation

• Isolation system and individual isolators– Capacity assumed fully correlated– Demand assumed fully correlated– Redundancy ignored– Lognormal distribution parameters– Variability small for high quality isolators

0 1 2 3 4 50

0.20.40.60.81

m

Pf

Withhardstop

0 1 2 3 4 50

0.2

0.4

0.6

0.81

m

Pf

Withouthardstop

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Risk‐based guidance for isolation

NA SU VO OR HA ID LA DC0

2

4

6

8

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Site

Annual frequency (x10‐6)

90% confidence/110% EDB GMRS displacement

95% confidence/110% EDB GMRS displacement

99% confidence/110% EDB GMRS displacement

90% confidence/125% EDB GMRS displacement

90% confidence/50% of 110% EDB GMRS displacement for DC

NA SUVO ORHA ID LA DC0

0.2

0.4

0.6

0.8

1

Site

Annual frequency (x10‐6)Without hard stop With hard stop

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Seismic isolation: SMRs and ARs

NuScale, 2016

www.generationmpower.com

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Acknowledgments

• US Nuclear Regulatory Commission– Dr. Jose Pires

– Mr. Ramon Gascot Lozada

• US Department of Energy– Justin Coleman, INL

– Dr. Robert Budnitz, LBNL

• Ms. Chingching Yu, UB

• Professors Manish Kumar2, IITGN and IITB

• Professor Yin‐Nan Huang, NTU

• Dr. Michael Constantinou, UB

• Dr. Annie Kammerer

• Dr. James Johnson

• Dr. Robert Kennedy

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