June 19, 2013

Bong Yoo/Didier De Bruyn

SCK-CEN

byoo@sckcen.be

Copyright © 2013

SCK•CEN

SILER International Workshop-Rome, Italy

Seismic Isolation of Reactor Assembly

for a fixed base ADS Reactor Building

Contents

Introduction

MYRRHA Design Revision 1.2

Interface Components

Approach

Seismic Isolation of Reactor Assembly Only

Input motions

Modeling

Seismic Responses

Issues

Conclusion

© SCK•CEN

3

Vertical Section in Reactor Building

Horizontal section 90m x 49m

Vertical section 64.8m

(-26.5m underground, 38.3m above ground)

t

t

f

f

g

g

LINAC Reactor

Vessel

FRS

Bedrock

Soil Layers/rock

g

Fixed Reactor

Foundation

Reactor

Vessel

Interface systems

for Reactor Assembly Isolation

Soil Structure Interaction(SSI)

Ground Level

Artificial Time History

DGRS

ZPA PGA

Reactor

Building

-beam line coupling joint

-upper beam tube

-spallation target assembly

-RVAC pipings

-joint cover of seismic gap

-pipe joint on Rx cover

-foundation and isolation slab(pedestal)

-fail safe system

-radiation effect

g

f

ADS RB and RA Seismic Isolation Procedure

© SCK•CEN

ADS RB SYSTEM MODELING

-Isolator model

-Soil model

-RB model

(EA)

ADS DATA INPUT

(SCK•CEN)

Define

-EDRS, ATH

-Soil/Rock data(SCK•CEN)

Seismic responses

-FRS

-Displacement

SSI

FEM

2D RB isolation

Simple 2-DOF

2D RA isolation

with Fixed RB

Seismic responses

-spectral acceleration

-Displacement

Define Input Motion

-FRS at RV support

-ISOLATOR(HDRB)

(SCK•CEN)

Define

-ISOLATOR

(HDRB, LRB)

Comparison of seismic

responses

-relative displacement

-shear strain

-spectral acceleration

6

Expansion Joint for Beam Line for RB and RA Isolation for ADS

(BOA’s design)

EXP J

RA Isolation

RB Isolation

H. Saugnac, CDT WP2, October 14&15 2010

Beam Line in Containment Boundary

4.3 m

10 m

2 m

5.7 m

Interfaces on Reactor Cover and RVAC system

© SCK•CEN

Reactor Cover

Main dimensions

Height: 2m

Outer diameter: 9.5m

Material

AISI 316L

Concrete

Weight

About 338ton

© SCK•CEN

IVFHM(2)

PHX(4)

Pump(2)

Fuel transfer channel(2)

Wet-sipping device(2)

Safety valve(2) Recovery channel(2)

Si-doping channel(2)

LBE-conditioning inlet(2)

LBE-conditioning

Outlet(2)

Cover gas conditioning system inlet(2, outside)/outlet(2, inside)

Interconnection Systems for Isolation of Reactor Assembly

© SCK•CEN

Isolated nonisolated size remarks

1 Spallation target(1) Beam tube OD ~88mm, thk1.375 Vacuum, 450~500°c

*T91/SS316L

2 Si-doping channel(2) Piping, ducts,

electrical cables and trays

OD1010, box type duct

*thk4.78

*10barg, 80°c

SS316L

3 PHX(4) Pipings for Feed Water

and Steam lines

OD200(FW)

OD510(SL)

29barg, 230°c

16barg, 200°c, SS316L

4 Pump(2) electrical cables No outlet pipings

5 IVFHM(2) Flex electrical cables No connecting pipes

6 LBE-conditioning inlet(2)/outlet(2) pipings OD300(outlet), eliptical

OD100(inlet)

20barg, 350°c

12barg, 550°c, SS316L

7 Cover gas conditioning system

inlet(2)/outlet(2)

pipings OD300(out/inlet) 6barg, 350°C or

1barg, 550°C, SS316L

8 Fuel transfer channel(2) Flex inter tubes OD420 SS316L

9 Wet-sipping device(2) Flex inter tubes OD300 SS316L

10 Pressure Relief System(2) OD600 6barg, 550°c, SS316L

11 Above core structure(2) IPS cables (isotope rabbit

system)

No connecting pipes

12 CR/SR/IPS Flex electrical cables No connecting pipes

13 RVAC 4 piping groups 160 pipes (40x4=160)

OD110, *thk7.11 RV support recomm,

SS316 or 304

Note: These are preliminary design data (* assumed).

Approach

Input motions as FRS at Reactor Vessel Support

Design of isolator and arrangement of isolation

system for Reactor Assembly

Modeling of isolation system and Reactor

Assembly

Linear theory of SI

2 DOF System

Simplified Mode superposition analysis

Relative displacements

Acceleration responses

Interfaces

Connecting systems and pipings on Reactor Cover

RVAC Pipings

Some issues

Fail-safe system and gap joint cover

© SCK•CEN

Seismic Isolation of RA (2D RA isolation with Fixed RB)

Input motions at Reactor Vessel support

Frequencies of fixed RB for rock and site specific soils

Horizontal frequency : rock 3.6-4.6Hz / soil 1.1-1.4Hz

Vertical frequency : rock 8.8Hz / soil 2.5Hz

Determination of isolator: HDRB

Determination of Isolation frequency

isolation frequency of RV: 0.5Hz 0.47Hz

Fundamental horizontal frequency of RV: 3.71Hz

Vertical frequency of RV: 6.59Hz

© SCK•CEN

Seismic Isolation for Reactor Assembly

Free surface of LBE

- Cold LBE height: 500mm

- Hot LBE height: 2,500mm

from top of Reactor

Cover(Other dimension is

not correct)

RVAC System gap(without SI)

- 500mm to cover reactor core

with LBE if RV leaked

Seismic Isolators(HDRB)

FRS at Reactor Vessel Support for DBE for Fixed Base RB

© SCK•CEN

Spectral Accelerations in X horizontal direction

- 0.3g at 0.47Hz with 10% damping ratio

- 0.43g at 0.6Hz with 10% damping ratio

- 1.03g at 3.71Hz of RV with 4%

FRS at Reactor Vessel Support for BDBE for Fixed Base

© SCK•CEN

Spectral Accelerations in X horizontal direction

- 0.9g at 0.47Hz with 10% damping ratio

- 1.2g at 0.6Hz with 10% damping ratio

- 3.6g at 3.71Hz with 4%

FRS at Reactor Vessel Support for DBE with HDRB SI Reactor Building

© SCK•CEN

ZPA in horizontal direction

- 0.2g with 10% damping ratio in x-horiz

In vertical direction

- 0.5g ZPA

- 1.0~1.4g in frequency range of at 1.2Hz~3.5Hz

with 10% HDRB

© SCK•CEN

FRS at Reactor Vessel Support for BDBE with HDRB SI Reactor Building

ZPA in horizontal direction

- 0.6~0.62g with 10% HDRB

In vertical direction

- 1.35g ZPA

- 2.0~4.2g in frequency range of at 1.2Hz~4.2Hz

with 10% HDRB

18

Mass of Reactor Assembly (Reactor Vessel, LBE and Reactor Internals)

Total mass of RA=5700 ton including LBE 435 ton

HDRB Isolator Characteristics for RA SI

HDRB SI-N/290 (FIP):

Rubber shear modulus G=1.4GPa

Diameter 1050cm, total Rubber thickness 290mm

Max/min vertical load of HDRB isolator

HDRB SI-N/290 (FIP): 15100/2307kN

Characteristics of Isolator

Horizontal stiffnees: Kh=4.18kN/mm

Damping: 10%

Vertical stiffness: Kv=4229kN/mm

Damping: 4%

Isolator Arrangement for RA SI

With first trial of isolation frequency f’iso=0.5Hz

Number of isolators

using K’=(2 π * fiso)2 *M

Total mass of RV including LBE: 5700Ton(LBE 4350Ton)

Number of isolators, n=K’/Kh =13.5, use n=12

Isolation frequency, fiso=0.47Hz

Put an isolator in every 30° apart(about 3m) under RV

support

some of the physical and mechanical characteristics

of the three standard rubber compounds

(FIP Elastomeric isolators)

Typical hysteretic curve of an elastomeric isolator

achieved during dynamic tests with increasing shear

strain amplitude

Dynamic characteristics of HDRB Isolator

Mean variation in dynamic shear modulus (Gdm)

as a function of the shear strain

Mean variation of the equivalent viscous damping

coefficient as a function of the shear strain

Dynamic characteristics of HDRB Isolator

Analysis

Simple isolator model

Linear spring-damper system

Simple 2-DOF system model of RA

Linear Mode superposition analysis

Relative displacement between Reactor Pit wall

and RV

Base shear coefficient(Acceleration)

Analysis

- Relative displacement at isolated base

|Vb|max = SA(ωb*, βb*)/ ωb*2 where SA(ωb*, βb*) spectral acceleration

at ωb* : modified isolation frequency, and βb* : modified isolation damping ratio.

- Relative displacement at structure (interstory drift) :negligible

|Vs|max = εSA(ωb*, βb*)/ ωb*2 where ε = (ωb/ ωs)2, ωb= (kb/M)1/2 = ωb*, ωs = (ks/m)1/2 = ωs/(1-γ)1/2.

ωb: isolated frequency, ωs: structural frequency,

kb: stiffness of isolation system, ks: stiffness of structure,

M = m+ mb total mass, m: structure mass, mb: isolated base mass, γ = m/M mass ratio.

- Base shear coefficient Cs

Cs = | ks*Vs/m | =SA(ωb, βb)[1+(1-γ)ε]1/2

where the second term is negligible.

- Reduction in base shear

RF = SA(ωb, βb)/ SA(ωs, βs)

Relative displacements for SI of RA

fiso=0.47Hz with 10% HDRB

- Relative displacement 34.2cm for DBE

- Relative displacement 100cm for BDBE

fiso=0.7Hz with 10% HDRB

- Relative displacement 24cm for DBE

- Relative displacement 74cm for BDBE

Note; FEM analysis results of SI of RB

with fiso=0.47Hz and 10% HDRB

- Relative displ 26cm for DBE

- Relative displ 78cm for BDBE

- ZPA 0.2g in horizontal direction for DBE

- ZPA 0.6g in horizontal direction for BDBE

- ZPA 0.45g in vertical direction for DBE

- ZPA 1.35g in horizontal direction for DBE

ZPA at Fiso=0.47Hz with 10% HDRB

- 0.3g for DBE

- 0.88g for BDBE

Reduction in shear with 10% HDRB

- RF= 1/3~1/5 for DBE and BDBE

Accelerations for SI of RA

Issues

Large Seismic gap with RA SI

Need complex flexible joints for interconnection

systems above Reactor Cover

Increase size of containment boundary

Make difficult to meet safety requirement of cooling of

ADS reactor in severe accidents when leakage of LBE

inventory to Reactor Pit due to RV failure

Need to cover reactor core with LBE coolant to keep

natural circulation as well as cool RV by RVAC (Reactor

Vessel Auxiliary Cooling) system

Repair and Maintenance of isolators inside

containment boundary

Radiation effect on isolators

Amplification of responses in vertical direction with

2D horizontal SI of RB

© SCK•CEN

Seismic Isolation for Reactor Vessel and Interfaces (RVAC Pipings)

Seismic gap:

500+1000=1500mm

- With 1500mm seismic gap expected, difficult to implement

for LBE to cover reactor core for cooling

when leakage of LBE inventory from RV failure

Conclusions

© SCK•CEN

SI frequency of RA with 10% HDRB is determined as 0.47Hz

Relative displacement for RA SI using FRS at Reactor Vessel Support for

fixed base ADS RB as input motions.

Max displacement is 34.2cm, shear strain 118% for DBE(0.3g)

Max displacement is 100cm for BDBE(0.9g)

ZPA of SI of ADS RA are

0.3g for DBE, 0.88g for BDBE

To reduce relative displacement, SI frequency of RA is proposed to be 0.7Hz:

Max displ 24cm(83%<100%) for DBE, 78cm for BDBE

Adversly amplifying ZPA to 0.48g

Comparison of seismic responses at RA between RA SI and RB SI shows in

good agreement in Rel displ(34.2cm/26cm) and ZPA(0.3g/0.2g).

Seismic gap of RA SI would not meet the safety req’t to cover reactor core as

well as to cool RV in RV failure

Future Study

Interfaces

Flexible Joints

Beam Tube and Spallation Target

Connecting pipings and cables on Reactor Cover

Change cooling system from RVAC system Pipings to

direct water cooling

Fail-safe system and gap joint cover

Fender system to reduce impacts

Need to further study on Vertical RA SI or 3D RB SI .

To reduce vertical acceleration responses as well.

© SCK•CEN

MYRRHA: EXPERIMENTAL ACCELERATOR DRIVEN SYSTEM

A pan-European, innovative and unique facility

Time horizon: full operation ~ 2023

Costs: ~ EUR 960 million

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SCK•CEN

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Centre d'Etude de l'Energie Nucléaire

Stichting van Openbaar Nut

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