Adapting standards to the site – Example of Seismic Base Isolation

Atom for the Future – Paris – 13, 16 October 2014 1 / 30

Atoms for the Future

October 13-16, 2014

Adapting standards to the site

Example of Seismic Base

Isolation

Emmanuel VIALLET – EDF

Adapting standards to the site – Example of Seismic Base Isolation

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Outline

Cruas NPP presentation Decision making and plant overview

Seismic Base Isolation : Design Principles and dynamic behavior

Seismic Base Isolation : Construction CW and components

Seismic Base Isolation : In-operation and ageing Monitoring and replacement

Experience feed-back from other nuclear facilities

Conclusion

Adapting standards to the site – Example of Seismic Base Isolation

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Introduction : Standard design principle

French approach : Propose a standard design that can be built on multiple sites Structures, systems and components are identical

Positive impact on cost, construction schedule (series effect)

Increased seismic level

Increased Soil stiffness

Adapting standards to the site – Example of Seismic Base Isolation

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Outline

Cruas NPP presentation Decision making and plant overview

Seismic Base Isolation : Design Principles and dynamic behavior

Seismic Base Isolation : Construction CW and components

Seismic Base Isolation : In-operation and ageing Monitoring and replacement

Experience feed-back from other nuclear facilities

Conclusion

Adapting standards to the site – Example of Seismic Base Isolation

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X

Cruas NPP presentation - Decision making

Fessenheim Chinon

Tricastin

St - Laurent

Cruas

Chinon Chinon

Tricastin Tricastin

Gravelines

Dampierre Dampierre Dampierre St - Laurent St - Laurent

Bugey Le Blayais

Chooz

Civaux

Chooz Chooz

Flamanville

Nogent

Golfech

Paluel Penly

Belleville

St - Alban

Flamanville Flamanville

Nogent Nogent

Golfech Golfech

Belleville Belleville

St - St -

900 MWe

1450 MWe

1300 MWe

900 MWe

1450 MWe

1300 MWe

900 MWe

1450 MWe

1300 MWe

EPR

Cattenom

French 900 MW Standard Design 0.2g seismic ground motion (DBE)

Except for Cruas-Meysse NPP 0.3g (SSE)

2 options Adapt the standard design (option 1) More reinforcement in CW structures

More supports on piping systems

Equipment re-qualification

…

Keep the standard design (option 2) Build the plant on a seismic isolation

system

After discussions Option 2 was selected The extra-cost of additional excavation,

concrete and pads represents a small fraction of the cost of option 1

Adapting standards to the site – Example of Seismic Base Isolation

Atom for the Future – Paris – 13, 16 October 2014 6 / 30

Cruas NPP presentation Plant overview

Upper Raft Isolation System Lower Raft

Adapting standards to the site – Example of Seismic Base Isolation

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Cruas NPP presentation Plant overview

Views of Cruas-Meysse NPP foundation system

Adapting standards to the site – Example of Seismic Base Isolation

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Outline

Cruas NPP presentation Decision making and plant overview

Seismic Base Isolation : Design Principles and dynamic behavior

Seismic Base Isolation : Construction CW and components

Seismic Base Isolation : In-operation and ageing Monitoring and replacement

Experience feed-back from other nuclear facilities

Conclusion

Adapting standards to the site – Example of Seismic Base Isolation

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Seismic Base Isolation - Principle

Base isolation effect on a reactor building

~ 4 Hz ~2 Hz ~ 1Hz

Accelerations and displacements given for 0.1g ground acceleration

Adapting standards to the site – Example of Seismic Base Isolation

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0,01

0,1

1

0,1 1 10 100

Pseu

do

accélé

rati

on

, g

Fréquency, Hz

Seismic Base Isolation - Design considerations

EDF 900MW standard design

spectrum

CRUAS original site specific SSE

spectrum

0.2 g

1 Hz

Standard design

Impact on floor response spectra

Selected frequency

900 MW standard design: 0.2g, without seismic isolation

Cruas-Meysse: 0.3g, with seismic isolation

NB : For complex “3D” structures, attention should be paid to 3D effects on FRS (vertical-horizontal coupling)

Adapting standards to the site – Example of Seismic Base Isolation

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Seismic Base Isolation - Design considerations

Differential displacements: 50 mm

Steel / polychloroprene rubber pad

NB :

In 1978, in France, elastomer bearings pad had been used for 30 years, with an excellent experience feedback.

In Europe, around 50 000 road or rail bridges are placed on such pads.

Adapting standards to the site – Example of Seismic Base Isolation

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Outline

Cruas NPP presentation Decision making and plant overview

Seismic Base Isolation : Design Principles and dynamic behavior

Seismic Base Isolation : Construction CW and components

Seismic Base Isolation : In-operation and ageing Monitoring and replacement

Experience feed-back from other nuclear facilities

Conclusion

Adapting standards to the site – Example of Seismic Base Isolation

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Seismic Base Isolation Construction considerations

A common raft for 2 units

Dead load is evenly distributed on supports

Implemented by Freyssinet

Adapting standards to the site – Example of Seismic Base Isolation

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Seismic Base Isolation Construction considerations

Necessary flexibility of piping systems

Adapting standards to the site – Example of Seismic Base Isolation

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Outline

Cruas NPP presentation Decision making and plant overview

Seismic Base Isolation : Design Principles and dynamic behavior

Seismic Base Isolation : Construction CW and components

Seismic Base Isolation : In-operation and ageing Monitoring and replacement

Experience feed-back from other nuclear facilities

Conclusion

Adapting standards to the site – Example of Seismic Base Isolation

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Seismic Base Isolation In-operation and ageing considerations

Ageing of elastomer pads

Samples of elastomer pads are shelved in situ and periodically tested

In 2005, as compared to the construction time, the stiffness increase is 37%, against 30% expected from ageing tests carried out in the 70’s This evolution is covered by design parameters

NB : Ageing effects on G Anticipated : Go x1.3 after 20 years ; < G0 x1.5 after 60 years Design margin: Go x 2.25 (the design is still OK up to f = f0 x1.5)

Adapting standards to the site – Example of Seismic Base Isolation

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Seismic Base Isolation In-operation and ageing considerations

Monitoring system

- Settlement, - Pedestal verticality, - Differential displacements are monitored

Seasonal differential displacement

Adapting standards to the site – Example of Seismic Base Isolation

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Seismic Base Isolation In-operation and ageing considerations

1

2

3 4

6

5

The demonstration that anti-seismic pads can be

changed has been performed in 1993,

following French Safety Authority request

Adapting standards to the site – Example of Seismic Base Isolation

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Outline

Cruas NPP presentation Decision making and plant overview

Seismic Base Isolation : Design Principles and dynamic behavior

Seismic Base Isolation : Construction CW and components

Seismic Base Isolation : In-operation and ageing Monitoring and replacement

Experience feed-back from other nuclear facilities

Conclusion

Adapting standards to the site – Example of Seismic Base Isolation

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Koeberg NPP South-Africa 1984-1985

Design similar to Cruas NPP

Rubber bearings (coupled with friction plates in Koeberg)

EDF Spie-Batignolles patent

PGA: 0.3 g Frequency: 0.75 Hz Pad size: 700x700x130 mm

Adapting standards to the site – Example of Seismic Base Isolation

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Koeberg NPP South-Africa 1984-1985

Tests of the Koeberg NPP bearing system on the CEA shaking table, Saclay

Adapting standards to the site – Example of Seismic Base Isolation

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La Hague (Areva) spent fuel pools

Operation: 1985 PGA: 0.2 g Frequency: 0.85 Hz Pad size: 700x700x147 mm

Adapting standards to the site – Example of Seismic Base Isolation

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Georges Besse II enrichment facility Built in Tricastin, France (Areva)

Testing facility

Decision made by Areva for investment protection

Operation: 2010 PGA: 0.3 g Pad size: Ø500x400 mm

Adapting standards to the site – Example of Seismic Base Isolation

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Jules Horowitz research Reactor Under construction in CEA Cadarache, France

PGA: 0.32 g Frequency: 0.60 Hz Pad size: 900x900x181 mm

Adapting standards to the site – Example of Seismic Base Isolation

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PGA: 0.32 g Frequency: 0.55 Hz Pad size: 900x900x181 mm

ITER International Thermonuclear Experimental Reactor Under construction in Cadarache, France

Adapting standards to the site – Example of Seismic Base Isolation

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GEN 4 opportunities: ASTRID - Advanced Sodium Technological Reactor for Industrial Demonstration Under conceptual design (CEA Marcoule, France)

Adapting standards to the site – Example of Seismic Base Isolation

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Outline

Cruas NPP presentation Decision making and plant overview

Seismic Base Isolation : Design Principles and dynamic behavior

Seismic Base Isolation : Construction CW and components

Seismic Base Isolation : In-operation and ageing Monitoring and replacement

Experience feed-back from other nuclear facilities

Conclusion

Adapting standards to the site – Example of Seismic Base Isolation

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Conclusion

In order to adapt standard design to specific (high seismic area), French approach is to build facilities on seismic isolation systems (laminated polychloroprene rubber bearings)

Aging of those systems (steel / neoprene pads), with more than 30 years of experience feedback now, is consistent with predictions

This technology can be regarded as mature and is supported by European Standards that address design and construction as well as manufacturing and maintenance - EN 1998 (Eurocode 8) - EN 1337, Structural bearings - EN 15129, Anti-seismic devices

It is expected that it will play an increasing role in seismic safety of nuclear facilities

Adapting standards to the site – Example of Seismic Base Isolation

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Conclusion

A synthesis of the French practice and experience on seismic isolation of nuclear facilities is available under the title

French Experience and Practice of Seismically Isolated Nuclear Facilities

It was jointly prepared by operators, designers and manufacturers and is under publication by AFCEN (*)

This document is also intended to be appended to an IAEA TECDOC under preparation on the subject

(*) FRENCH ASSOCIATION FOR DESIGN, CONSTRUCTION AND IN-SERVICE INSPECTION RULES FOR NUCLEAR ISLAND COMPONENTS

Adapting standards to the site – Example of Seismic Base Isolation

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Thank you for your attention !