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ERMSAR 2012, Cologne March 21 – 23, 2012 1
The Experimental Results of LIVE-L8B: Debris Melting Process in a Simulated PWR Lower Head
X. Gaus-Liu, A. Miassoedov, T. Cron,
S. Schmidt-Stiefel, T. Wenz
Karlsruhe Institute of Technology (KIT), Germany
ERMSAR 2012, Cologne March 21 – 23, 2012 2
Outline
Objectives
LIVE-3D test facility
Test definitions
Test results: – dry-out debris bed temperature
– debris melting process
– Steady-state melt pool and crust behaviour
Conclusion
ERMSAR 2012, Cologne March 21 – 23, 2012 3
Objectives
Dry-out debris bed temperature distribution in large-scale semispherical geometry → the position of the initiation of melting
Debris bed melting process after liquid melt relocation in the lower plenum→ penetration depth of a liquid melt jet, melt pool progression, melt temperature development
TH steady-state melt behaviour
ERMSAR 2012, Cologne March 21 – 23, 2012 4
LIVE 3D test facility
1:5 scaled 3D PWR lower head,
external cooling and top cooling
temperature profiles, heat flux distribution, crust analysis: growth rate, composition, heat conductivity
simulant: 20% NaNO3- 80-mol% KNO3
284,4
200
250
300
350
0% 10% 20% 30% 40% 50%
mole % NaNO3
tem
pe
ratu
re [
°C]
liquidius
solidius
vessel cooling
wall inner and outer therm ocouples
crust detection system
m elt pouring
cam era observation
heating system
ERMSAR 2012, Cologne March 21 – 23, 2012 5
Melt temperature measurements
MT10MT16MT20
MT4
MT12
MT8MT2
MT6
MT14 MT18
MT22MT28MT36 MT32 MT24 MT26 MT30 MT34
CT21-27
CT31-37
CT41-47
MT
40 -
49
MT
50 -
60 HT00i
HT0i
HT1i
HT2i
HT3i
HT4i
HT6i
HT5i
ERMSAR 2012, Cologne March 21 – 23, 2012 6
LIVE L8B test definition 50% of the total 355 kg simulant
material prepared as debris bed and preheated in the test vessel, the other 50% prepared as liquid melt and poured in the vessel afterwards;
debris porosity 50%, particle size 3-16 mm
21 kW homogenous heat input after pouring
water cooling short before melt pouring
ERMSAR 2012, Cologne March 21 – 23, 2012 7
Experimental data of debris bed dry-out temperature
57,0
89,5
73,3
89,5
89,5
171171
171
106
106
155
155
122
122
138
138
57,0
89,5
73,3
89,5
89,5
171171
171
106
106
155
155
122
122
138
138
57,0
89,5
73,3
89,5
89,5
171171
171
106
106
155
155
122
122
138
138
57,0
89,5
73,3
89,5
89,5
171171
171
106
106
155
155
122
122
138
138
57,0
89,5
73,3
89,5
89,5
171171
171
106
106
155
155
122
122
138
138
57,0
89,5
73,3
89,5
89,5
171171
171
106
106
155
155
122
122
138
138
57,0
89,5
73,3
89,5
89,5
171171
171
106
106
155
155
122
122
138
138
57,0
89,5
73,3
89,5
89,5
171171
171
106
106
155
155
122
122
138
138
57,0
89,5
73,3
89,5
89,5
171171
171
106
106
155
155
122
122
138
138
57,0
89,5
73,3
89,5
89,5
171171
171
106
106
155
155
122
122
138
138
57,0
89,5
73,3
89,5
89,5
171171
171
106
106
155
155
122
122
138
138
57,0
89,5
73,3
89,5
89,5
171171
171
106
106
155
155
122
122
138
138
57,0
89,5
73,3
89,5
89,5
171171
171
106
106
155
155
122
122
138
138
57,0
89,5
73,3
89,5
89,5
171171
171
106
106
155
155
122
122
138
138
57,0
89,5
73,3
89,5
89,5
171171
171
106
106
155
155
122
122
138
138
57,0
89,5
73,3
89,5
89,5
171171
171
106
106
155
155
122
122
138
138
57,0
89,5
73,3
89,5
89,5
171171
171
106
106
155
155
122
122
138
138
57,0
89,5
73,3
89,5
89,5
171171
171
106
106
155
155
122
122
138
138
57,0
89,5
73,3
89,5
89,5
171171
171
106
106
155
155
122
122
138
138
0 100 200 300 4000
50
100
150
200
250
300
350
he
igh
t (m
m)
radius (mm)
57,0
73,3
89,5
106
122
138
155
171
ERMSAR 2012, Cologne March 21 – 23, 2012 8
Debris melting process-melt pool formation
Melt pool formed initially at the top region;
Till 1500 s downwards extension;
Thereafter sideward's extension.
0 100 200 300 400
0
50
100
150
200
250
300
350
400
1500s
2000s
he
igh
t (m
m)
radius (mm)
0 100 200 300 4000
50
100
150
200
250
300
350
400
he
igh
t (m
m)
radius (mm)
0 100 200 300 400
0
50
100
150
200
250
300
350
400
steady state
5000sh
eig
ht
(mm
)
radius (mm)
0 100 200 300 400
0
50
100
150
200
250
300
350
400
he
igh
t (m
m)
radius (mm)
60
224
284
0 100 200 300 400
0
50
100
150
200
250
300
350
400
1000s
he
igh
t (m
m)
radius (mm)
400s
0 100 200 300 4000
50
100
150
200
250
300
350
400
he
igh
t (m
m)
radius (mm)
ERMSAR 2012, Cologne March 21 – 23, 2012 9
Fraction of liquid melt during melting process
1500s
400s
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0 5000 10000 15000 20000
time, s
fra
ctio
n o
f liq
uid
me
lt
ERMSAR 2012, Cologne March 21 – 23, 2012 10
Debris melting process- initial melt temperature
0 500 1000 1500 2000 2500 3000 3500 4000 4500 50000
50
100
150
200
250
300
350
400
300 mm height 400 mm heightm
elt
tem
pera
ture
, [°
C]
time [s]86000 86500 87000 87500 88000 88500 89000 89500 90000 90500 910000
50
100
150
200
250
300
350
400
me
lt te
mp
era
ture
, [°
C]
Time [s]
300 mm height 400 mm height
with
debris melting processwithout
debris melting process
ERMSAR 2012, Cologne March 21 – 23, 2012 11
Penetration of melt jet and crust structure
crust at upper part
crust at bottom
ERMSAR 2012, Cologne March 21 – 23, 2012 12
Final crust thickness
0
100
200
300
400
500
600
0 100 200 300 400 500 600
radius, mm
vess
el h
eigh
t, m
m
from temperature measurement
post-test crust profile
vessel wall
The determination of pool/crust boundary according to the melt temperature measurement is precise;
Final crust volume fraction 10.6 %
Final crust mass fraction 8.3 %
The difference comes from the loose debris layer at bottom
ERMSAR 2012, Cologne March 21 – 23, 2012 13
Steady-state melt temperature
260
280
300
320
340
360
150 200 250 300 350 400 450
vessel height, mm
mel
t tem
pera
ture
, °C
L8B-with debris melting
L10-without debris melting
L8B steady-state melt temperature distribution is comparable with tests without the process
L8B crust at bottom is thicker than the crust formed without debris melting
ERMSAR 2012, Cologne March 21 – 23, 2012 14
Steady state heat transfer characteristics
83 % of the heat transferred through the vessel wall
qmax/qmean = 2
Nudn=202
Rai =4.3 x1013
0
5000
10000
15000
20000
25000
30000
0 20 40 60 80
polar angle, °
he
at
flux,
W/m
²
ERMSAR 2012, Cologne March 21 – 23, 2012 15
Conclusion- 1
In a dry-out debris bed with volumetric heat release the highest temperature locates in the middle-upper region in the debris bed;
After melt relocation, a melt pool in a debris bed is formed initially at the top region;
A part of the relocated liquid melt freezes in the debris bed firstly;
The relocated melt jet penetrates in the debris bed easier sidewards than downwards;
During the melting process, the melt pool enlarges its boundary mainly downwards at the beginning, then sidewards;
ERMSAR 2012, Cologne March 21 – 23, 2012 16
Conclusion- 2
Melt pool temperature remains low during the debris melting process;
Steady-state melt temperature after debris melting process is comparable with the one without the melting process.
ERMSAR 2012, Cologne March 21 – 23, 2012 17
Thank you for your attentionThank you for your attention
