recent experience with soil- structure interaction

AECL - OFFICIAL USE ONLY / À USAGE EXCLUSIF - EACL

Recent Experience with Soil-

Structure Interaction

Analyses for Nuclear

Facilities

Tarek Aziz, Richard Chen, Wei Liu, Sudip Adhikari,

George Stoynov and Qinhua Huang

Recent Experience with Soil-

Structure Interaction

Analyses for Nuclear

Facilities

Tarek Aziz, Richard Chen, Wei Liu, Sudip Adhikari,

George Stoynov and Qinhua Huang

Dr. Tarek Aziz

Principal Civil Engineer

Atomic Energy of Canada

Outline

• CANDU 6 Background

• Recent SSI models for life Extension and New Builds

(comparison of SSI models)

• Ground Motions Developed/Used and SSI Key

Assumptions

• Approach for Floor Response Spectra FRS Generation

• Comparison of SSI Models and Results (Stick models

versus HF models)

• Recent Case Studies CANDU 6 and Others

• Conclusions and current SSI Issues

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Operating CANDU 6 Plants…Operating CANDU 6 Plants…

UNRESTRICTED / ILLIMITÉ 3

Qinshan 1/2 Cernavoda Embalse

Gentilly 2 Point Lepreau Wolsong 1/2/3/4

Reactor Assembly…Reactor Assembly…

• Low pressure and low temperature Calandria houses the reactor assembly

• Calandria is set in a light water-filled, concrete, shielding vault

• Fuel channels and moderator are contained in Calandria

• End-shields are filled with light water and steel balls


1 CALANDRIA

2 CALANDRIA END SHIELD

3 SHUT-OFF AND CONTROL

RODS

4 POISON INJECTION

5 FUEL CHANNEL

ASSEMBLIES

6 FEEDER PIPES

7 VAULT

Refuelling System…Refuelling System…


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Key Components…Key Components…

Fuel bundle

Calandria tube

Fuel channelFuel channel Calandria and HTS SystemCalandria and HTS System

Calandria (Reactor Core)Calandria (Reactor Core)

Fuelling MachineFuelling Machine

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CANDU 6 plantCANDU 6 plant

Qinshan Phase III, ChinaQinshan Phase III, China

Case Study # 1

CANDU 6 Reactor Building on a Rock

Site


Background

• FRS produced for the Reactor Building (RB) using

conventional methods show a significant “g” level in

particular at high frequency content.

• In order to minimize the impact of this significant

increase on the reference CANDU plant design, the

SASSI computer code accounting for ground motion

incoherence and travelling wave effects is used.

• The objective is to define realistic seismic demands for

the Reactor Building.

• The incoherency and travelling wave effects

implemented for rock sites tend to filter out the high

frequency content of the input motion and result in a

reduction in seismic demands.


HF Model Details


2008 UHS Mean Ground Motions

used


0.010

0.100

1.000

0.1 1.0 10.0 100.0

AC

CE

LE

RA

TIO

N (

g)

FREQUENCY (HZ)

G2 - 5% Damped Ground Response Spectra Comparison

Atkinson Nov. 2008 report - 0.0001 P.A. Mean UHS

Motion 1


-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

TIME (SECONDS)

SIMULATED GROUND ACCELERATION (MOTION-1)

_1

Motion 2


-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

TIME (SECONDS)


_1

Motion 3


-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

TIME (SECONDS)


_1

Incoherency and Travelling wave

Effects at Top of RB Mat


0

0.5

1

1.5

2

2.5

3

0.1 1 10 100

5% FRS Node - 05018 (130 )in B/D (1/X) Direction

G2 HF Surface model COH

G2 HF Surface model INCOHWP




0

0.5

1

1.5

2

2.5

3

0.1 1 10 100

5% FRS Node - 05018 (130 )in A/C (3/Y) Direction






0

0.5

1

1.5

2

2.5

3

0.1 1 10 100

5% FRS Node - 05018 (130 )in VERTICAL (2/Z) Direction




Effects at Boiler Box


0

0.5

1

1.5

2

2.5

3

0.1 1 10 100

5% FRS Node - 05046 (500 )in B/D (1/X) Direction






0

0.5

1

1.5

2

2.5

3

0.1 1 10 100

5% FRS Node - 05046 (500 )in A/C (3/Y) Direction






0

0.5

1

1.5

2

2.5

3

0.1 1 10 100

5% FRS Node - 05046 (500 )in VERTICAL (2/Z) Direction



Case Study # 2

CANDU 6 Reactor Building on a

Soil Site


Soil Profile


SASSI Model


Acceleration Comparison


Case Study # 3 Reactor Building


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Ground Motion 1 (Horizontal X)


33

R/B Stick Model

33


34

1st

Mode of R/B Stick Model with

Fixed Base

34

F1= 6.531 Hz

Y Direction

Kajima F1=6.2

Hz (Y-Direction)


2nd

Mode of R/B Stick Model with

Fixed Base

35

F2= 7.021 Hz

X Direction

Kajima F2=7.3

Hz (X-Direction)

Site Soil Profile and Properties

• Soil profile with shear wave velocity, layer thickness, density, and

Poisson’s ratios as follows


Depth

(m)

Layer Thickness

(m)

Mass Density

(ton/m3) Poisson's Ratio

Shear Wave Velocity

(m/s)

Shear Modulus

(kN/m2)

0 ~ 6 6.0 1.8639 0.35 272 1.37899E+05

6 ~ 13 7.0 1.8639 0.35 229 9.77448E+04

13 ~ 20 7.0 1.8639 0.35 261 1.26971E+05

20 ~ 26 6.0 1.8639 0.35 281 1.47175E+05

26 ~ 33 7.0 1.8639 0.35 308 1.76817E+05

33 ~ 41 8.0 1.8639 0.35 344 2.20566E+05

41 ~ 50 9.0 1.8639 0.35 417 3.24112E+05

50 ~ 60 10.0 1.8639 0.35 482 4.33029E+05

Analysis Models

• Stick Model

–Check Overall Structural Stability (overturning and sliding)

–Check overall concrete shear capacity of C/S and I/S

• 3D FE Model

–Check strength of the C/S

–Check Strength of the I/S

–Check strength of the UJE support Column


R/B 3D ANSYS FE Model


R/B 3D ANSYS FE Model (cont.)


R/B 3D ANSYS FE Model – I/S


R/B 3D ANSYS FE Model – S/C


Structure Assessment Based on

3D FEA Model Data

Selected Critical Locations


Critical Locations for Assessment


Sample Results

• Section Check:


Result of axial

force plus bending

recent experience with soil- structure interaction

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