Motivation
description
Transcript of Motivation
KIT – Universität des Landes Baden-Württemberg undnationales Forschungszentrum in der Helmholtz-Gemeinschaft
Karlsruhe Institute of Technology, Germany Institute for Nuclear and Energy Technologies
www.kit.edu
Ex-vessel Fuel Coolant Interaction Experimentin the DISCO Facility
Renaud Meignen (IRSN)Bruno Raverdy (IRSN)
Giancarlo Albrecht (KIT)Alexei Miassoedov (KIT)
17th International QUENCH WorkshopKarlsruhe, Germany, November 22-24, 2011
KIT-IKET2 R. Meignen, B. Raverdy (IRSN) , G. Albrecht, A. Miassoedov (KIT/IKET), | 17th International QUENCH Workshop, Karlsruhe, 2011
Experiment in the DISCO facility, similar to those made for Direct Containment Heating (DCH), but with water in the pit, that would give data for the validation of the codes in geometrical situation closer to the reactor ones than all other available data
No triggered steam explosion, only premixing stage is investigated (but possibility of spontaneous explosion)
Relevance for SARNET2 Ex-vessel Fuel Coolant Interaction (WP 7.1) and debris formation (WP
5.3) are two high-priority issues of SARNET2. Despite the importance of these issues, only a few experimental data are available for the qualification of codes.
Motivation
KIT-IKET3 R. Meignen, B. Raverdy (IRSN) , G. Albrecht, A. Miassoedov (KIT/IKET), | 17th International QUENCH Workshop, Karlsruhe, 2011
Available experimental data limited
Database for premixing modeling assessment for application of ex-vessel situation is very limited• Water subcooling (~50 K) • High temperature• High density• No way to assess the behavior with existing database• FARO L31 (ISPRA): 100 kg UO2/ZrO2 (gravity driven)• TROI-VISU (KAERI, SERENA): 15 kg UO2/ZrO2 (gravity driven)
Behavior is not as expected from “classical” FCI experiments Jet fragmentation with small fragments compared to TROI or FARO, even
at low melt vessel pressure Due to water inertia and small flow area around vessel
No escape for pressure Vapor film around the jet is unstable
Purpose is to check the code evaluation of fragmentation in more “reactor-like” configuration
KIT-IKET4 R. Meignen, B. Raverdy (IRSN) , G. Albrecht, A. Miassoedov (KIT/IKET), | 17th International QUENCH Workshop, Karlsruhe, 2011
Reason for experiment: evaluation of ex-vesselFCI in PWR’s at IRSN with MC3D
KIT-IKET5 R. Meignen, B. Raverdy (IRSN) , G. Albrecht, A. Miassoedov (KIT/IKET), | 17th International QUENCH Workshop, Karlsruhe, 2011
Investigating the fragmentation processes and subsequent phenomena occurring consecutively to the break of the vessel and melt ejection
Information will be useful for several SARNET2 WPs:
• Melt fragmentation processes for high velocity melt jets through a precise analysis of the size of the debris found (WP7.1, WP5.3)
• Pressurization of the pit and containment during the mixing (WP7.1)
• Debris bed characteristics important for coolability:shape, porosity, debris size distribution (WP5.3)
• Melt and water dispersion out of the pit during the process:initial conditions for MCCI (WP6)
• Oxidation of the iron to be compared with cases without water:impact of water on DCH (WP7.1)
• Hydrogen production and potential impact of water for combustion (WP7.2)
Major issues addressed in the experiment
KIT-IKET6 R. Meignen, B. Raverdy (IRSN) , G. Albrecht, A. Miassoedov (KIT/IKET), | 17th International QUENCH Workshop, Karlsruhe, 2011
Calculations with rough mesh
Strong interaction in most casesdue to Pit pressure > Vessel pressure
Water + melt flow back into the vessel
Not possible to pour all the corium
Weakest interaction for larger annular section
But very fast dispersion of melt
IRSN pre-test analysis for standardDISCO P’4 2D geometry
KIT-IKET7 R. Meignen, B. Raverdy (IRSN) , G. Albrecht, A. Miassoedov (KIT/IKET), | 17th International QUENCH Workshop, Karlsruhe, 2011
DISCO Test Facility
Tests with• Scale 1:18 (EPR)• Iron-alumina melt (2400 K)• Steam (10-20 bar)• Air-steam-hydrogen atmosphere• Production and combustion of hydrogen
Measurements of• Pressures (15)• Gas temperatures (22)• Hydrogen production and combustion (gas
samples)• Melt dispersal fractions• Video cameras (4)
Containment
RCS
RPV
Subcompartment
pit
KIT-IKET8 R. Meignen, B. Raverdy (IRSN) , G. Albrecht, A. Miassoedov (KIT/IKET), | 17th International QUENCH Workshop, Karlsruhe, 2011
Design of the DISCO-FCI experiment
Vmelt = 0.0026 m³
Vwater = 0.125 m³
Vw/Vm = 48
KIT-IKET9 R. Meignen, B. Raverdy (IRSN) , G. Albrecht, A. Miassoedov (KIT/IKET), | 17th International QUENCH Workshop, Karlsruhe, 2011
Geometry
No specific reference to a particular reactor, so simplifications for code calculations and analysis
• Symmetric reactor pit, no access: 2D calculations• Subcompartment without cover plates• Reactor pit circumferential exits (8) without main cooling
lines• Open flow paths from pit to containment• Height and diameter of the water pool in the cavity both
as high as possible to limit scaling effects: 540 mm• Distance between lower edge of the RPV and water
level: 20 mm• Temperature of the water: 85 °C
KIT-IKET10 R. Meignen, B. Raverdy (IRSN) , G. Albrecht, A. Miassoedov (KIT/IKET), | 17th International QUENCH Workshop, Karlsruhe, 2011
Geometry and initial conditions
CON: Volume m³ 13,88
CON: Height m 4.5
CON: Diameter m 2.17
Cavity: Volume m² 0.2034
Cavity: Height m 0.984
Cavity: Diameter m 0.540
Flow nozzles (8x cut out area) m² 0.0603
Flow area into con. (8 holes) m² 0.0688
CON: Pressure MPa 0.2
CON: Temperature °C 100
CON: Atmosphere - Air/Steam
RPV: Breach diameter mm 30
RPV: Driving pressure MPa 0.6
RPV: Amount of thermite kg 10.64
Water pool l / °C 125 / 85
KIT-IKET11 R. Meignen, B. Raverdy (IRSN) , G. Albrecht, A. Miassoedov (KIT/IKET), | 17th International QUENCH Workshop, Karlsruhe, 2011
- 5 pressure transducers at reactor pit, sampling rate >2 kHz
- 3 transducers below water level,range: 1.7, 3.5, 30 MPa
- 2 transducers above water level,range: 3.5, 3.5 MPa
- Thermocouples in containment, subcompartment, RCS and RPV
- Pre and post test analysis of gas samples in containment
- Collecting of the melt debris and sieve analysis
Facility instrumentation
KIT-IKET12 R. Meignen, B. Raverdy (IRSN) , G. Albrecht, A. Miassoedov (KIT/IKET), | 17th International QUENCH Workshop, Karlsruhe, 2011
Test procedure
Containment (steam, press, temp)
Loading steam accumulator
Water pool
Gas sample
Ignition (trigger: temp, press)
Steam valve open (1 s)
Melt plug (brass)
Discharge of melt increase temp, press hydrogen burning
Gas sample
Collecting of particles
KIT-IKET13 R. Meignen, B. Raverdy (IRSN) , G. Albrecht, A. Miassoedov (KIT/IKET), | 17th International QUENCH Workshop, Karlsruhe, 2011
Pressures Steam Accumulator and RPV
-6 -4 -2 0 2 4 6Time [s]
0
0.2
0.4
0.6
0.8
1
1.2P
ress
ure
[MP
a]
P4 RCS topP2 Steam Accu top
Valveopen
Valveclose
Nozzle open
KIT-IKET14 R. Meignen, B. Raverdy (IRSN) , G. Albrecht, A. Miassoedov (KIT/IKET), | 17th International QUENCH Workshop, Karlsruhe, 2011
Pressures Containment
0 2 4 6 8 10 12 14 16 18 20Time [s]
0.19
0.2
0.21
0.22
0.23
0.24
0.25P
ress
ure
[MP
a]
P7K Level B, Pos. 315°P5 Level A, Pos. 315°P6 Level A, Pos. 45°P7 Level B, Pos. 315°P8 Level C, Pos. 45°P9 Level B, Pos. 135°
KIT-IKET15 R. Meignen, B. Raverdy (IRSN) , G. Albrecht, A. Miassoedov (KIT/IKET), | 17th International QUENCH Workshop, Karlsruhe, 2011
Pressures Cavity
0 2 4 6 8 10 12 14 16 18 20Time [s]
0.1
0.15
0.2
0.25
0.3
0.35P
ress
ure
[MP
a]
P10 Cavity topP11 Cavity topP12 Cavity middleP13 Cavity middle
KIT-IKET16 R. Meignen, B. Raverdy (IRSN) , G. Albrecht, A. Miassoedov (KIT/IKET), | 17th International QUENCH Workshop, Karlsruhe, 2011
Pressures Cavity (short time line)
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Time [s]
0.16
0.2
0.24
0.28
0.32
Pre
ssur
e [M
Pa]
P10 Cavity topP11 Cavity topP12 Cavity middleP13 Cavity middle
KIT-IKET17 R. Meignen, B. Raverdy (IRSN) , G. Albrecht, A. Miassoedov (KIT/IKET), | 17th International QUENCH Workshop, Karlsruhe, 2011
Temperature Containment
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30Time [s]
80
90
100
110
120
130
140
150
160
Tem
pera
ture
[°C
]
KIT-IKET18 R. Meignen, B. Raverdy (IRSN) , G. Albrecht, A. Miassoedov (KIT/IKET), | 17th International QUENCH Workshop, Karlsruhe, 2011
Analysis of generated particles (distribution)
0.01 0.1 1 10Particle Size
0
100
200
300
50
150
250
350
Mas
s [g
]
KIT-IKET19 R. Meignen, B. Raverdy (IRSN) , G. Albrecht, A. Miassoedov (KIT/IKET), | 17th International QUENCH Workshop, Karlsruhe, 2011
Simplified vessel geometry but refined mesho High sensitivity of jet fragmentation when water contacts the jet
• Important work of analysis• Some 2D sloshing effect• 3D to be investigated
o Generally pressure in the pitreaches vessel pressure
• Strong interaction
IRSN preliminary post-test analysis
KIT-IKET20 R. Meignen, B. Raverdy (IRSN) , G. Albrecht, A. Miassoedov (KIT/IKET), | 17th International QUENCH Workshop, Karlsruhe, 2011
The experiment addresses SARP high priority issues
No experiment is known with pressure driven melt ejection in reactor geometry at accident conditions
Bridges the gap between DCH and ex-vessel FCI issues
Data will be used for code qualification
Analysis in the frame of SARNET2 WP7.1 and WP5.3 through post-test calculations
• MC3D (IRSN, CEA, …)• JEMI (IKE Stuttgart)
Conclusions