ERMSAR 2012, Cologne March 21 – 23, 2012
Institut de Radioprotection et de Sûreté Nucléaire (IRSN), Cadarache, FranceInstitute of Nuclear Technology and Energy Systems, (IKE) Stuttgart University, GermanyRoyal Institute of Technology (KTH), Stockholm, Sweden
Contact : [email protected], [email protected] [email protected]
Investigation of Multidimensional Effects during Debris Cooling
G. Repetto, T. Garcin (IRSN), M. Rashid *, R. Kulenovic (IKE), Weimin Ma, Liangxing Li (KTH)
* presenter
ERMSAR 2012, Cologne March 21 – 23, 2012
Experiments Parameters
POMECO KTH
DEBRIS IKE
PRELUDE IRSN
Reflooding From Bottom-Top and dry-out
Bottom- and Top-flooding, dry-out
Bottom-flooding
Temperature (K) Up to 775 Up to 800 Up to 1300
Pressure (MPa) 0.1 0.1 to 0.5 0,1
Water temperature (K)
293 (room temp) 40 to 120 (Subcooling)
293 (room temperature)
Water inlet velocity (m3/h/m2)
Gravity driven with downcomer
1 to 36 2, 5, 10, 20
Heating process Internal heaters Induction Induction
Power maintained during quench (0 to 300W/kg)
Geometry
Debris mass 1 : FL 2 : HT
1 2 3 4
5kg 24kg 57kg 58kg
Diameter/height (mm)
1 : Ø90/635
2 :200×200/620
1 : Ø125/640
2 : Ø150/640
1 : Ø110/100 2 : Ø180/200 3 : Ø170/500 4 : Ø290/250
Particle diameter (mm)
0.2 to 12 both multi-size spheres / irregular shape
3 to 6 + mixtures (2, 3, 6) and irregular shape
Stainless steel : 1, 2, 3, 4, 8 + mixtures + non homogeneous size
bypass by
pass
37kg, 60kg
Debris bed coolability plays an important role in the termination and stabilization of a severe accident. Towards the quantitative understanding of debris bed coolability, many experiments (IKE-IRSN-KTH) have been conducted to investigate two-phase flow and heat transfer in particle beds
Introduction
2
The table summarizes briefly, some conditions of those experiments related to coolability of debris beds: POMECO at Stockholm, DEBRIS at Stuttgart, PRELUDE at Cadarache.
ERMSAR 2012, Cologne March 21 – 23, 2012 3
POMECO-FL POMECO-HT
PRELUDE-HTDEBRIS
Reflooding Facilities
Water tank
Test section
Outlet steam line
ERMSAR 2012, Cologne March 21 – 23, 2012 4
Instrumentation : reflooding tests
170 mm
50mm
150 mm150 mm150 mm
Water injection
Overflow line
Water storage
tank(Bottom-Flooding)
Ceramic cylinderQuartz glass
External
Mid radius
Central
PRELUDE-HTDEBRIS
In PRELUDE, simultaneous measurements of steam flow rate, and pressure drop across the bed provide complementary data that allow “cross-checking” and contribute to improve our understanding of quenching of a particle bed
Thermocouples inside the debris bed, in different (axial and radial) locations allow a fine view of the different phases of the transient and are useful to follow the quench front propagation.
ERMSAR 2012, Cologne March 21 – 23, 2012 5
DEBRIS Experiments
Boiling / Dryout Experiments with down comer installation in the center of the bed
a) a) Closed down comer (top-flooding)
b) b) Open down comer (bottom-flooding / natural circulation)
c) c) Perforated down comer (lateral flow of water to the bed)
(a)(a) (b)(b) (c)(c)
ceramic balls
“debris”
water pool
down comer
ERMSAR 2012, Cologne March 21 – 23, 2012 6
Polydispersed particle bed, System pressure 1, 3 and 5 bar
- no qualitative effect on pressure drop behavior- no qualitative effect on pressure drop behavior
- higher vapor density and small change in latent heat- higher vapor density and small change in latent heat
- higher DHF increased coolability- higher DHF increased coolability
Lateral-flooding may lead to steam flow into the down comer
DEBRIS Experiments
ERMSAR 2012, Cologne March 21 – 23, 2012 7
DEBRIS Quenching Experiments
Polydispersed particle bed, bed height 640 mm
Top-flooding, initial maximum bed temperature 432 °C
Two distinct quenching phases realized
ERMSAR 2012, Cologne March 21 – 23, 2012 8
DEBRIS Quenching Experiments
Polydispersed particle bed, initial maximum bed temperature 631 °C
Water supplied to the bottom of the bed from an overlying water
tank at a height of ~ 950 mm
Near wall thermocouples indicate faster quench front progression
-75 0 75 -75 0 75 -75 0 75
Radius [mm]
Be
d H
eig
ht
[mm
]
Temperature °C
ERMSAR 2012, Cologne March 21 – 23, 2012
DEBRIS Experiments- Summary
Boiling and dryout experiments with water have been performed in
volumetrically heated debris bed varying the
- flow conditions (top- and bottom-flooding) and system pressures (1, 3 and 5 - flow conditions (top- and bottom-flooding) and system pressures (1, 3 and 5 bar)bar)
and measuring
- pressure gradient along bed height, temperature distribution and dryout heat - pressure gradient along bed height, temperature distribution and dryout heat fluxflux
Quenching experiments at different flow conditions (top- and bottom-flooding) and
initial superheating temperatures at ambient pressure
- quench time and the behaviour of quench front progression- quench time and the behaviour of quench front progression
Air / Water cold experiments
- single - and two - phase pressure drop measurements- single - and two - phase pressure drop measurements
9
ERMSAR 2012, Cologne March 21 – 23, 2012
Almost 1000°C during the reflooding phase
Those results qualified PRELUDE HT facility
Water velocity = 2 m/h at 870°C
0
200
400
600
800
1000
2600 2650 2700 2750 2800 2850 2900 2950 3000 3050 3100 3150 3200 3250 3300
Tem
pera
ture
(°C)
0
2
4
6
8
10
12
14
16
Steam
flow
rat
e (g/
s)
TN_0_87_348 (°C) TN_10_46_311 (°C) TN_10_6_314 (°C) TN_55_87_271 (°C) TN_55_6_273 (°C)TN_100_7_282 (°C) TN_100_46_281 (°C) TN_100_87_280 (°C) TN_155_6_366 (°C) TN_155_42_364 (°C)TN_155_87_365 (°C) TN_175A_5_207 (°C) TN_175B_46_226 (°C) TN_175A_46_317 (°C) TN_175B_5_344 (°C)TN_195_87_263 (°C) TN_195_46_269 (°C) TN_195_5_270 (°C) Debit Vapeur (g/ s)
Test 111 : Reflooding at 900°C , P = 300 w/kg - 2mm particles - Q = 2 m/h
This test corresponds to the worst thermal hydraulics conditions for the outlet steam line :
- HT for the debris ( 860-990°C)
- High power deposition (300 W/kg)
- Low flow rate (2 m/h)
First example : B2 mm
Results PRELUDE HT (1/5)
10
The PRELUDE facility, in operation since mid of 2009, has been modified in 2011 to increase the performance regarding the power deposition and the initial temperature of the debris bed up to 1000°C.
ERMSAR 2012, Cologne March 21 – 23, 2012
with higher water velocily = 5 m/h at 900°C
Second example : B4 mm
0
100
200
300
400
500
600
700
800
900
1000
2750 2775 2800 2825 2850 2875 2900 2925 2950 2975 3000 3025 3050 3075 3100
Time (s)
Tem
per
ature
(°C)
0
5
10
15
20
25
30
35
40
45
50
Wat
er a
nd s
team
flow
rat
e (g
/s)
TN_0_0_322 (°C) TN_10_85_325 (°C) TN_10_40_324 (°C) TN_10_0_323 (°C) TN_45_85_328 (°C)TN_45_0_326 (°C) TN_45_40_327 (°C) TN_100_0_329 (°C) TN_100_40_330 (°C) TN_100_85_331 (°C)TN_155_45_392 (°C) TN_155_0_332 (°C) TN_175_85_390 (°C) TN_175_40_338 (°C) TN_155_85_399 (°C)TN_175_0_391 (°C) TN_195_0_393 (°C) TN_195_40_400 (°C) debit Corriolis (g/ s) Debit Vapeur (g/ s)
0 mm45 mm 100 mm 155 mm 195 mm
250 s
175 mm
220 s
0
5
10
15
20
25
30
35
40
0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300
Stea
m F
low
rat
e (g
)
0
500
1000
1500
2000
2500
3000
3500
4000
Stea
m P
roduct
ion (g)
Debit Vapeur (g/ s) E126 Debit vap. (g/ s) essai 80 Cumul vap. Essai 80 Cumul Vapeur (g) E126
Test 126 : 900°C
Test 80 : 700°C
Results PRELUDE HT (2/5)
11
While the general behavior of the reflooding is not strongly changed by the increase of temperature, the experiment performed at 900°C has shown the highest water/steam conversion factor never reached up to now (> 90%), even more that was foreseen by the pre-calculation.
Higher peak steam flow rate in the short term and reflooding longer in long term (more important stored energy) with a higher total steam production
ERMSAR 2012, Cologne March 21 – 23, 2012
y = 0,9405x - 2656
y = 1,6846x - 4761,6
y = 1,0985x - 3099,5
0
20
40
60
80
100
120
140
160
180
200
220
2800 2850 2900 2950 3000 3050
Quenching time (s)
Leve
l (m
m)
Central location
Liquid from pressure
Mid radius location
External location
Reflooding duration : 220 s
Quench Front Velocity : 5,6 m/ h
Quench Front Velocity : 3,4 m/ h
Quench Front Velocity : 4,0 m/ h
Results PRELUDE HT (3/5)
12
Illustration of the quench front propagation (timing for quenching identified when thermocouples reached the saturation conditions). The existence of a quasi steady propagation of the quench front is verified for most of the tests. The faster quench front velocity in the periphery versus the centre outlines the 2D behaviour of the reflooding process.
Comparaison with DEBRIS tests regarding the Quench front propagation
ERMSAR 2012, Cologne March 21 – 23, 2012
0
100
200
300
400
500
600
700
800
900
1000
1950 2000 2050 2100 2150 2200 2250 2300 2350 2400
Tem
pera
ture
(°C)
0
5
10
15
20
25
30
35
40
Wat
er/s
team
flow
rat
e (g
/s)
0 mm55 mm 100 mm
155 mm 195 mm175 mm
Water flow rate
0 2 m/h 5 m/h 10 m/h 20 m/h 50 m/h
900
800
700
600
500
400
300
200
100
Billes de Ø2 mm
Test 90Test 93Test 94
Test 95
Test 87Test 88
Test 91 Test 92Test 96
Test 89
Test 107
Test 108 Test 109
Test 113
Test 118
Test 112
Test 110
Test 111
Test 114
Test 115
Test 117
Test 116FLUIDISATION Tests 2011 :
12Tests 2010 : 10
Test 117
The impact of the bypass which could change T/H conditions for the fluidisation will be studied in the beginning of 2012, using a larger PRELUDE test section
Nevertheless, those results give preliminary information of their impacts on the PEARL tests matrix
The fluidisation domain has been estimated for various particles size : B4, B2 et B1 as function of the thermal hydraulics conditions (T, Q)
22 tests with Ø2mm diameter
Results PRELUDE HT (4/5)
13
When the steam produced during the reflooding create drag force higher to gravitational force of the debris, fluidisation phenomenon could occure and was observed in PRELUDE experiments
ERMSAR 2012, Cologne March 21 – 23, 2012
0
5
10
15
20
25
0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360 380 400 420 440
Time (s)
Stea
m fl
ow r
ate
(g/s
)
0
500
1000
1500
2000
2500
3000
3500
4000
Stea
m P
rodu
ctio
n (g)
Test 107 Test 108 Test 116 Test 114 Test 115 Test 117
850°C/190 W/kg
850°C/300 w/kg
750°C/190 W/kg
750°C/190 W/kg
900°C/0 w/kg
420°C/190 W/kg
0
2
4
6
8
10
12
14
16
0 30 60 90 120 150 180 210 240 270 300 330 360 390 420 450 480 510 540 570 600 630 660
Time (s)
Stea
m fl
ow r
ate
(g)
0
500
1000
1500
2000
2500
3000
3500
4000
Stea
m P
rodu
ctio
n (g)
Test 91 Test 112 Test 109 Test 110 Test 111
850°C/300 w/kg
750°C/190 W/kg
720°C/190 W/kg
420°C/70 W/kg
850°C/190 W/kg
with injection flow rate 2 m/h with injection flow rate 5 m/h
Effect of temperature and power deposition
Results PRELUDE HT (5/5)
14
The effect of the initial debris temperature has shown an impact on the peak of the steam flow rate during the first stage of the reflooding whereas the(specific power maintained during the transient) has a stronger impact during the second stage of the reflooding and consequently on the duration of the complete quenching of the debris bed , which is in agreement with the more important stored energy
ERMSAR 2012, Cologne March 21 – 23, 2012
While the general behavior of the reflooding is not strongly changed, the High
Temperature Tests in PRELUDE HT, up to 900°C, outlined very high
water/steam conversion factor during the first stage of the Reflooding
The impact of the power deposition, which simulated the residual neutron
power has a stronger impact during the end of the transient
Simultaneous measurements of steam flow rate, temperature evolution and
pressure drop across the bed provide complementary data that allow “cross-
checking” and contribute to improve our understanding of quenching of a
particle bed with bottom cooling injection
Regarding Fluidisation, the open questions are the probability to occur in the
Reactor case, according to the thermal hydraulics in the partially degraded
core, the heat transfers which could increase the efficiency of the Reflooding.
Conclusion in PRELUDE
15
ERMSAR 2012, Cologne March 21 – 23, 2012
Objective: To study the friction laws and dryout heat flux of particulate
beds packed with non-spherical particles
16
Bed Particles Facility Bed shape ε Test Focus
1
Cylinders:
3 x 3 / mm
(diameter x length)
POMECO-FL
Cylindrical:
90 x 635 / mm
(diameter x length)
0.34 Single-phase flow Effective diameter
2
Cylinders:
3 x 3 / mm
(diameter x length)
POMECO-HT
Cuboidal:
200 x 200 x 620 /mm
(L x W x H)
0.34
Two-phase flow:
top-flooding
&bottom fed
Dryout heat flux
POMECO Experiments
ERMSAR 2012, Cologne March 21 – 23, 2012
mmdd sdeq 6.2
mmSA
Vd
vp
psd 3
66
1–Hu & Theofaneous model
2–Schulenberg & Műller model
3–Reed model 4–Lipinski model
1–Lipinski model
2–Reed model
POMECO-FL POMECO-HT
Single phase flow test Top flooding test Bottom fed tests
Results POMECO
17
ERMSAR 2012, Cologne March 21 – 23, 2012
The tests on the POMECO-FL facility show that for a particulate bed packed
with non-spherical particles such as cylinders, the effective particle diameter
can be represented by the equivalent diameter of the particles, which is the
product of Sauter mean diameter and the shape factor.
Given the diameter obtained from the test on POMECO-FL facility, the dry-out
heat flux obtained in POMECO-HT test is well predicted by the Reed’s model
for a top-flooding bed.
The bottom injection improves the dry-out heat flux significantly and the
prediction of the Reed model is more conservative with increasing flow rate of
the bottom injection.
18
Conclusion in POMECO
ERMSAR 2012, Cologne March 21 – 23, 2012
Future Work
19
2D quenching experiments with down comer installation in the center of the
bed
The PRELUDE results will be extended in 2012 with reflooding experiments of
heterogeneous porous media (mixture of particles of different diameter, non
spherical particles) in the larger test section (PRELUDE 2D including a
bypass) and different mode of water injection to prepare PEARL experiments,
in a the largest Debris Bed and very challenging configuration never
performed up to now
Benchmark reflooding experiments at IKE-DEBRIS and IRSN-PRELUDE
Investigation of friction laws with Air / Water cold experiments at IKE-DEBRIS
ERMSAR 2012, Cologne March 21 – 23, 2012
• The European Research Project on Severe Accidents SARNET: Severe Accident Research NETwork of Excellence)
Acknowledgement:
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Thank you for your attention