French experience and practice of seismically isolated ... experience - II. From... · SILER International Workshop – 2013/06/18-19 – Rome | 1 French experience and practice of

| 1SILER International Workshop – 2013/06/18-19 – Rome

French experience and practice of seismically isolated nuclear facilities – From fabrication to construction

1 NUVIA Travaux Spéciaux, Lyon, France

2 EDF Nuclear Engineering Division SEPTEN, Lyon, France

3 AREVA Engineering & Projects, Lyon, France

Sébastien DIAZ & Micaël CONNESSON1, Frédéric ALLAIN2, Nadim MOUSSALLAM3, Ilie PETRE-LAZAR2


Introduction

Since recent events in KK and FKS, there is a global renewal of interest in seismic isolation technologies.The IAEA is preparing a TECDOC dedicated to the seismic isolation of nuclear facilities.For more than 30 years, seismic isolation technologies have beenused by operators of nuclear facilities in France (EDF, AREVA, CEA, I/O) to protect them against earthquake loading.To support the IAEA documentation effort and to share knowledge with other member countries, a synthesis of the French practice and experience is being jointly written by operators, designers and manufacturers.This presentation is an extract from this work. The full document will be published by AFCEN before the end of 2013.

Le Groupe NuviaIsolators are Safety Important Components 1ActivitésFabrication process 2Gamme de produitsSite installation 3

| 3SILER International Workshop – 2013/06/18-19 – Rome3




Isolators are Safety Important Components

Seismic isolation has two different sides: fabrication and installation which are both linkedIn both case, high quality level is required:

Fabrication can be easily mastered through industrial process

Site installation requires specific cares and critical issues need to be solved in a construction-wise way to ensure viable projects

QRA (Quality Related Activity) are identified regarding safety and declined in control plans to assess each steps. In France it is the used of the decree “INB” dated 8th February 2012 (previous decree of 10th August 1984) which complies to IAEA general safety requirements GS-R-3.QRA are defined during qualifications (tests on full-scale prototypes, full scale mock-up including sensitiveness of key parameters and failure mode). A non compliance to a QRA shall mean non conformity

1




Elastomeric Vulcanizing agent

Plasticizer Adds

Mixing

Raw materials mixed

Confection

Vulcanizing

Plates preparation

Plates Bonding agent

Plates prepared

Finishing Works

Calendaring

Protection agent

2Fabrication process – Elastomeric bearing

7

Elastomeric bearing


Important process points are identified and checked at each steps and are part of the QA process as described in EN 15129 and EN 1337-3.In addition QRA (Quality Related Activity) are identified regarding safety:

Mechanical properties respect

Homogeneous properties in the isolator (aging)

Typical deviations are ±20% to ±10% pending upon the properties and measurement methods

QRA are monitored and compared to criteria range determined during qualification through:Follow-up documents

Mechanical tests (rheology & mechanical properties of mixture)

Measurements (thickness, mass, pressure)

Monitoring (thermal gage inside each bearing)

QA & QC during production 2

8


Examples of QRA follow-up

QA & QC during production 2

9

Rheological test (torque vs time)Monitoring of the vulcanization duration and

temperature (different locations)

Mechanical rubber control (tensile test, hardness…) after each chemical modification step

Geometrical controlControl of elastomeric

layer thickness


ITT or prototype testsPre-series isolators produced to determine the production targets as ITT (Initial Type Test) in civil standard such EN 15129.

Static tests (compression and shear tests)

Dynamic tests (compression and shear tests)

Additional tests could be requested (in addition to qualification)

2

10

EUCentre (Pavia - Italy) testing Center

Static compression test


Production tests 2Factory Production Tests (FPC) are performed on the final product (the isolator)

Static tests (compression and shear tests)

Additional dynamic tests (compression and shear tests)

These tests required power-full equipment especially for dynamic test (few testing laboratory could comply the high frequency and distortion demand with heavy vertical loading)FPC frequency and distribution need to be adapted according to optimized safety approach:

20% is requested in EN 15129

Need to be balanced by depth QA control (i.e QRA approach)

and a construction-wize approach (cost and schedule for testing)

Adaptation such as increase of static test number may be proposed

11


Production tests 2Examples of testing rigs and facilities

12

NUVIA in-house static press

EUCentre (Pavia - Italy) testing Center

SMRMD shacking table (San Diego University - USA) testing Center

NIED ‘E-Defense’ shaking table (Miki city, Japan) Laboratory


QA/QC on the connection system 2Same approach for the connection to civil structureFor example, plates with welded shear studs :

Follow-up documents filled

Measurements (thickness, rectitude, coating…)

Tests on the welds of the connectors (traction and bending)

On-shop assembly

13




Main requirements on the isolation system

Site installation criteria often come along with fabrication requirements.BUT they are driven by the main construction erection sequence and methods. The schedule is the key and construction-wise solutions need to be found to ensure high quality and cost effective approach.The three main requirements are:

Ensure load transmission (horizontal shear and vertical loading)

Ensure vertical load homogeneity (as per assumed in the design)

Ensure interface management

3

15


Load transmission

During installation, the load path need to fulfill the design. The following items need to be specially taken into account:Vertical load transmission

Void under the isolator (bubbling)

Risk: hazardous settlement of the isolator

Criteria: void ratio <1% bubbling /m²

Parallelism between horizontal faces Geometrical tolerances

Risk: Isolator stiffness change (due to high ratio Kh/Kv)

Criteria: Flatness of 1.5mm/m

3

Bubbling effect under the bearing plate

KhKh

Kv Kv

16


Example of construction-wise solutions

Pre-commissioning of bearing plates and isolatorIndustrial methodology

Ensure QA control of sensitive operations on workshop

Monolithic sandwich assembly (same height)

Injection of a mortar layer (removable layer for replacement operations)

3

Assembly of bearing plates and isolator Injection of mortar under the isolator

17


Example of construction-wise solutionsCasting in two steps

3

STEP 1 : Bearing installationAdjustment of horizontality by the mean of 3 adjustable supports

Shuttering the top of the pedestal

STEP 2 : 1st stage grouting (studs sealing)Pouring of self-compacting concrete on 20cm

Horizontality control before concrete hardening

STEP 3 : 2nd stage groutingPouring of a 3cm-thick non-shrinkage mortar layer, without bubblesRemoving the formwork and concrete finishing

18



3

Self-compacting concrete Formwork for first concreting

19



3

Final grouting system Final grouting vacuum

20


Vertical load homogeneity 3

21

During installation, the vertical loading shall comply with the design which means to be as homogenous as possible. It is a key issue since it is directly linked to the construction method.Building construction solutions impacts are :

Construction methodology (casting method on shoring, on shoring + isolators…): Ability to tune the vertical loading (jacking of the upper raft + some levels) Loading transfer during the propping removal

Construction sequence (phasing of concrete pouring): Concrete creep / shrinkage Stiffness changes due to the structure erection itself

The construction methods need to take into account:the final loading of the isolators (load transfer) the final state of isolators (initial distortion due to shrinkage)


Interface 3

22

During installation, some interface between the isolation system and the other construction tasks need to be managed as assumed to be during design.

Interface with reinforcement:Plinth top head bursting reinforcementConnectors interface with reinforcement

Interface with othersAccessSequence of works (plinth casting delay…)

Pedestal reinforcement (additional bursting on plinth head)

Studs layout vs reinforcement


THANK YOU

23

Documents

French experience and practice of seismically isolated ... experience - II. From... · SILER International Workshop – 2013/06/18-19 – Rome | 1 French experience and practice of