study on the in-core-instrumentation tube ejection failure

1

Subhead or Second Line

2015. 2. 17

Hwan Yeol Kim

Study on the in-core-instrumentation tube ejection failure at APR1400 lower

reactor vessel

Severe Accident & PHWR Safety Research Division


ICI Penetration for APR1400

2


ICI Penetration Failure

3

Penetration tube ejection & rupture

Penetration tube heat-up & rupture

Compare Pi and V

Severe Accident & PHWR Safety Research Division 4

Reaction

Melting

Specimen of Welding Material

(ENiCrFe-7)

75 mm

50 mm

Welding Erosion Test (1)

VESTA-S Test Facility


Welding Erosion Test (2)

5

Composition: SUS304 (Cr 19%, Ni 11%, Fe 70%) Mass: 2.2155 kg

Composition: Fe 46%, U 31%, Zr 16%, Cr 7%) Mass: 3.129 kg


ICI Penetration Failure Test (1)

Furnace vessel (VESTA )

Melt delivery channel

Interaction vessel

Melt crucible

Intermediate melt catcher

Plug & Puncher

Melt delivery channel

Melt crucible

Funnel

Test specimen

Ar or Air

Pressure boundary

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Penetration test specimen

Penetration test specimen

(DOOSAN Heavy Industries and Construction. Co., Ltd.)

K-type T/C: 33 ea.

C-type T/C: 1 ea.

C11, K11 : Melt temperature

P1-P11 : Penetration tube temperature

PW1-PW4 : Penetration weld temperature

RVH1-RVH7 : Reactor vessel hole temperature

RV1-RV10 : Reactor vessel temperature

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Melt Material Charging

8


0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 110000

250

500

750

1000

1250

1500

1750

2000

2250

2500

Pyromter

C-type TC

Power

Tem

pe

ratu

re (

oC

)

Time (sec)

0

20

40

60

80

100

120

140

160

180

200

Po

we

r (k

W)

0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 110000

250

500

750

1000

1250

1500

1750

2000

2250

2500

P1

P2

P3

P4

P5

P6

P7

P8

P9

P10

P11

PowerT

em

pe

ratu

re (

oC

)

Time (sec)

0

20

40

60

80

100

120

140

160

180

200

Po

we

r (k

W)

Melt Temp.

Penetration tube Temp.



c=0.73 for Molten pool debris bed of PWR

: Total thermal binding shear force

: Ejecting pressure force

Ejection criteria

TV

pFTp VF where,

Tube Ejection (Weld failure)

Failure Models & Calculations (1)



Tube Ejection

11

i

ou

t2

it2

oo

2i

2oi

thi

ln3

2

121

oflesser :0

r

rσ

νrνrr

rrEδ

Pδ

1. Free thermal expansion of tube and hole

2. Pressure expansion of tube

3. Total expansion of tube

4. Tube-hole radial gap at temperature and pressure

5. Tube-hole interface pressure

+ → 𝑔𝑎𝑝 − → 𝑖𝑛𝑡𝑒𝑟𝑓𝑎𝑐𝑒

6. Total thermal binding shear

7. Ejecting pressure force

8. Ejection criteria

: not a f (temp.), but a f (roughness)

- 0.27 for high-temperature, oxidized conditions

𝑓

- The pressure expansion of hole is negligibly small.

Required pressure to cause compression fai lure of the tube material

Required interfacial pressure to force the outer diameter of the tube to conform to the diameter of the hole after free expansion

K 294 ,Δ refrefttoo TTTαrrTTube:

K 294 ,Δ refrefhhhh TTTαrrTHole:

2i

2o

tioio

2Δ

rr

νrr

E

pr P

Tube:

Hole: 0Δ h Pr

PT rrr ooo ΔΔΔ Tube:

oohhi ΔΔ rrrrδ

0 :0 thi Pδ

n

n

lrπPfV

1

tothT Δ2

2oip rπpF

Tp VF


Molten Corium

Penetration tube

Reactor vessel wall

Thermocouple

Failure Models & Calculations (3) Experimental results

Temperature distribution



Tube Ejection

Input data

Obtained temperature profile

Pi=10 bar

Lt=180.6

76.2

76.3

Assumption

Pi=10 bar

Clearance gap size: same as normal operating condition

Top surface temp. up to 2600 oC while maintaining similar temp. profile


Tube Ejection (Weld failure)

: Total thermal binding shear force,

: Ejecting pressure force,

Ejection criteria

TV

pFTp VF where, 2

oi rp toth lrPf 2

Iteration start

Tube ejection

FP>VT

Simplified Flow Diagram

Weld fail ?

Y

N t = t + t

tothT lrPfV 22

oip rπpF

Pi=10 bar


Lt=180.6

Lt=Lt-Lt

Update

temperature

profile

Y


1200 1400 1600 1800 2000 2200 2400 2600

0

20

40

60

80

100

Forc

e(k

N)

Top surface temperature(C)

Ejecting pressure

Total binding shear force


Ejection

Tube Ejection


8

10

12

14

16

18

20

22

300 400 500 600 7000

20

40

60

80

100

Fo

rce(k

N)

Time(s)

Total tbinding shear force

Th

ickne

ss(m

m)

Thickness


Tube Ejection

Top surface temperature = 1950oC


ANSYS Analysis

17

Gap=0.0015 in

(0.0381 mm)

Partial Model Line

ICI Nozzle

RV Bottom Head

Displacement B.C.Detail “A”

RV

Nozzle

“A”

Gap Elements with

Friction Capability

Resultant Friction

Force

Melting Zone

Deformation of reactor vessel affects the gap. Clamping or non-clamping ICI nozzle depends on the location. Clearance gap size may change.


Concluding Remarks

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APR1400 ICI penetration tube failure study

Welding material erosion test at VESTA-S facility

ICI penetration tube failure test at VESTA facility

ICI penetration tube failure calculation with suggested model

Future work

Test with high heat flux and elevated pressure

Test under the external reactor vessel cooling condition

Analysis in case of clearance gap change

study on the in-core-instrumentation tube ejection failure

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