Overview of Cold Crucible Induction Melting of Corium

Overview of Cold Crucible Induction
Melting of Corium
Sevostian Bechta (KTH) and Dmitry Lopukh (SPbGETU «LETI»)
PLINIUS 2 International Seminar, Marseille, France, May 16th, 2014
Contents
 Motivation
 CCIM method: How it works?
 History of CCIM development and application to corium studies
 Examples of induction furnaces and experiments done so far
 What we need for large scale corium facility
 CCIM simulation
 Conclusive remarks
2
Motivation
 We need PLINIUS-2 furnace(s) for preparation of about 500 kg of
superheated metallic-oxidic corium melt and melt pouring as a
well controlled jet into a test section for FCI and MCCI studies
 Keeping in mind that prototypic corium melt, which is a mixture of
oxidic (UO2, ZrO2, …, SiO2, …) and metallic components (Zr, Fe,
…), is very high-temperature and reactive with all known crucible
materials, we cannot use traditional refractory or hot crucible
technologies
 Is CCIM one of the possible options for PLINIUS-2?
3
CCIM furnace: How it works?
 Combination of contact-free method of power
supply with non-polluting method of melt
Melt
retention
Crust
 Advantages:
(Garnissage)
- Volumetric power in the melt (but not uniform)
Cold crucible
- Melting all oxides (except pure Silica) and
reaching very high temperatures
Inductor
- Synthesis of ultrapure materials,
- Long term retention of high temperature and aggressive melts in
different atmospheres (including oxidizing ones)
- Compact design and cheap furnace disposal (important for
melting radioactive materials)
 Complexities:
CCIM ↔ IMCC ↔ Scull Melting
Cold crucible
-
Heating efficiency is sensitive to melt specific resistance (material and
temperature efects)
Inductor frequency should be adjusted for every combination of melt
composition and crucible diameter
4
Power profile is not uniform and start-up heating is necessary
History of CCIM
 Skull melt retention was originally proposed in
1905 for melting of metals Ref: [Bolton W.V. //
Z. Electrochemie,1905, vol. 11, p 45]
Examples of vitrification CCIMs
SPbGETU “Chamomile” and “Draining”
furnaces
 The method was combined with inductive
heating in 1931 [Siemens & Halske A.G.
German Patent 518499]
 Currently used in industrial scale for
manufacture of refractory oxides and reactive
glasses as well as for crystal growth
 Used in nuclear industry for radioactive waste
vitrification
Radon and DOE cold crucibles
 Used for production of fibers,
granules and spheres
from rocks and oxidic
materials by melt jet
dispersion
5
Corium CCIM facilities worldwide
6
Overview of corium CCIM facilities
Facility
Commiss
ioning
date
Research area
Melt mass,
kg
Inductor
frequency,
MHz
Installed
power,
kW
5
10
2
2
1.76
1.76
0.1
5.2
240
240
120
100
RASPLAV
facilities:
2
2C
3
4
1989
1993
1998
2004
COMETA
1998
Experiments with
model corium
~1-2
4.5
80
(output)
TROI
2000
FCI
50
~0.05
50
VESTA
2010
Melt/material
interactions,
phase diagrams,
melt properties
Melt-Structure
interaction (Ex.,
Jet impingement
from core
catcher, Melt/SM
interaction, RPV
vessel
penetration
failure)
400
0.1
450
Company
and contact
person
NITI, Russia.
Evgeny
Krushinov
[email protected]
UJV (Czech )
Dr Monika
Kiselova,
Monika.Kisel
[email protected]
KAERI,
(Korea)
Dr Hwan
Yeol KIM,
hykim1@kae
ri.re.kr
Operation features
Furnace
Melt
gas
composition
Oxidized
Air, N2,
corium,
He, Ar,
Sub oxidized
steam
corium,
and
Corium
mixtures with silica and
alumina
Air,
Oxide
nitrogen
mixtures
(UO2+FexOy,
CaO, ZrO2,
SiO2, Al2O3)
Air or
UO2-ZrO2 and
Air/N2
other oxides,
UO2-ZrO2-Fe,
Inert
Oxidised and
sub-oxidized
corium with
metal
Possible manipulations
with corium melt
Melt sampling, melt
pouring, zonal
crystallization, melt
quenching, VPA IMCC
Crucible shift against
inductor: 0-50 mm/min
(possibility of zonal
crystallization)
Well-designed melt jet
injection and jet
observation
Measurements: Melt jet
velocity, Void fraction,
Melt temperature
Dynamic pressure loads,
etc.
Melt delivery from the
furnace into the lower
experimental section
also equipped by
induction heating
7
Overview of corium CCIM facilities (2)
Facility
SICOPS
Commiss
ioning
date
Research area
2000
(A small
medium
frequency
melt facility
since 1992)
SOFI
Phase1
Phase 2
Jan –
2014
End of
2014
Melt mass,
kg
Inductor
frequency,
MHz
Installed
power,
kW
Company
and contact
person
1- and 2-D corium
interactions with
sacrificial or
protective
material, with
concretes
20 max
1-4
100
(output)
AREVA
(Germany)
Dr Gert
LANGROCK
gert.langroc
[email protected]
m
FCI of SFRs:
molten UO2
interaction with
Sodium including
fuel
fragmentation
aspects, debris
relocation
behavior and
morphological
characteristics of
generated debris
bed
50
0.002
50
200
0.1-0.2
200
IGCAR
(India)
Prof P.
Chellapandi
[email protected]
ov.in
Operation features
Furnace
Melt
gas
composition
Air, N2,
UO2 melts
Ar
and simulant
melts
Inert
UO2 melts
with steel
Possible manipulations
with corium melt
Simultaneous Interaction
of Molten Corium with
Protective and Sacrificial
Material
Melt pouring into lower
crucible for 2D tests
>In-sodium pressure
transducer
>Imaging of debris bed
with high power X-Ray
with flat panel detector
>Melt pouring into test
section using
combination of remotely
operated pneumatic
valves
8
Examples of CCIM facilities and experiments
Studies of Corium Melt Interactions with Structural Materials
(Vessel steel, Concretes, Refractory, Sacrificial Materials, etc.)
Immersed specimens
1D Downward Ablation
Sideward Ablation
Rasplav-2
SICOPS
Rasplav-2
SM after interaction
with metal corium
Rasplav-2
Vessel steel interaction
(simulation)
ZrO2 ceramic after interaction
with oxide corium
293
9
Examples of CCIM facilities and experiments (2)
SICOPS Studies of 2D MCCI: Conventional (b) and inverse (a) geometries
a
b
Ref: [J. J. FOIT, M. FISCHER, CH. JOURNEAU, G. LANGROCK Experiments on MCCI
with oxide and steel // 6th European Review Meeting on Severe Accident Research
(ERMSAR-2013), Avignon (France), Palais des Papes, 2-4 October, 2013]
10
Examples of CCIM facilities and experiments (3)
FCI and steam explosion studies
FCI in water: TROI
Ref: [JinHo Song, Current Progress of TROI Program, presentation at
KAERI-NITI Meeting, 10-11 April, 2006, St. Petersburg]
FCI in sodium: SOFI
Ref: [VENKATARAMAN NATARAJAN KARTHIK RAVICHANDRAN
Experimental and Analytical Simulation of MFCI during CDA in Sodium
Cooled Fast Reactor. Master of Science Thesis, CHALMERS UNIVERSITY
OF TECHNOLOGY, Göteborg, Sweden, 2011]
11
Examples of CCIM facilities and experiments (4)
Study of corium phase
diagrams at Rasplav-2
VPA IMCC method of liquidus
temperature determination
Corium samples preparation for solidus
measurements
Study of miscibility gap and determination
of tie lines
2350
2300
Tliq=2390 oC
Temperature, C
Melt equilibrium crystallization and
determination of solubility limit
Cord 37
Tmel
2250
2200
2150
2100
4745
4750
4755
4760
Time, s
12
Examples of CCIM facilities and experiments (5)
Study of corium phase diagrams at COMETA
 CCI melting in air or air/nitrogen mixture
 Observation and video recording of the melt surface to check the second liquid
 Quenched samples of melt by means of initially cold metallic rod
 Rapid or slow (zonal crystallization) cooling of ingot
 Systems studied: U-Zr-O, U-Fe-Zr-O, U-Fe-Zr-Si-Ca-O, U-Fe-Zr-Si-Ca-Al-O
1 melting chamber with
illuminators
2 supporting movable frame
3 cold crucible
4 inductor
5 high frequency generator
6 drive mechanism for moving
frame (2)
7 ball-&-screw couple of the
moving mechanism
8 ventilator of the gas –
purification system
9 filter
10 water-cooling system
11 aerosol sampler
12 radiation pyrometer or
videocamera
13 PC-based information and
measuring system.
Example of microstructures formed at different
cooling rates in the system of U-Fe-Zr-Si-Ca-Al-O
Ref.: [S. BAKARDJIEVA et al, Thermodynamic Data applied to Corium
Interactions for Improved Quality of Severe Accident Modelling in
SARNET2, to be published soon]
13
Examples of CCIM facilities and experiments (6)
Study of corium melt properties
Melt specific resistance versus
oxidation index of corium
7.5
Melt density: Comparison of NITI data
measured in CC with RRC KI data
measured in Tungsten crucibles
2700 K
7.0
2900 K
ln cm)-1
6.5
6.0
5.5
2
1
3100 K
5.0
2800 K
4.5
4.0
3000 K
3.5
3.0
30
40
50
60
70
80
90
100
110
120
Corium oxidation index, %
1 - Exp. Data of ISTC METCOR Project
2 – Beong Tae Mina, Seong Wan Hong et.al.
A Computational Analysis of the Cold Crucible
Melting of Corium. // Proceeding of ICAPP ’04,
Pittsburg, PA USA, June 13-17, 2004. Paper 4222.
RRC KI: Data of RASPLAV and MASCA projects
14
Examples of CCIM facilities and experiments (7)
Aerosol formation and transport & Fission product release from corium melt
FP simulants:
stable or radiolabeled
Sr, Ba, Ce, La, Mo, Ru …(simulated fissium)
Measurements and charactrization:
Mass and element specific release rates
Aerosol composition and morphology
Aerosol size distribution
 Transport and deposition phenomena
In past:
Experiments at NITI for FPRMP
and LPP projects of EU and
EVAN ISTC project
Currently:
Aerosol formation experiments
at UJV using COMETA facility
15
Features of large scale CCIM for PLINIUS-2
Melt jet initiation and control
Rotary furnace
Trough the bottom
Trough the side section
Used in conventional
induction furnaces with
refractory or hot crucibles
(e.g. in KTH)
TROI: with plunger
VESTA
SOFI
Rasplav-2 C
16
Features of large scale CCIM for PLINIUS-2 (2)
Melt jet initiation and control
Unpredicted release start,
unstable jet (UO2/ZrO2 corium)
Jet initiation and control by additional high
frequency inductor (molten glass)
SPbGETU “LETI” CCIM Laboratory
17
Features of large scale CCIM for PLINIUS-2 (3)
Melt mass and power increase
 Increase of melt mass of specific composition (i.e. increase of cold crucible
diameter) allows decrease of inductor frequency, which is quite favorable for
the induction furnace reliability
 Necessary space for power supply and cooling systems can be reduced, if the
decreased frequency will allow use of thyristor or transistor generator
 Different melt compositions for water/sodium FCI and MCCI experiments (i.e.
different specific resistances of melt) probably will require different inductor
frequencies
 It can be achieved by using different power suppliers or generator with
adjustable frequency or by a combined solution
 Design solutions should be supported by CCIM simulation
18
CCIM simulation: DYMELT code
 Developed in NIEFA (St Petersburg) by Dr S.
Calculation domain for
Smirnov
molten pool simulation
 DNS of non-steady-state convection of viscous
electro-conductive liquid volumetrically heated by
electromagnetic field
 Solution of magneto-hydrodynamic task
 Influence of cold crucible sections
 Consideration of two liquids in miscibility gap
 Consideration of gas phase
 Modeling of melt pouring
The code was verified against experimental data
measured in corium tests:
1 - Furnace lid
2 – Cold crucible
- Pool and jet surface temperatures and velocities
3 - Inductor
4 – Pool
- Integral parameters of CCIM (power in the melt, cold
5 - Bottom
crucible, inductor)
- Heat fluxes to cold crucible and bottom calorimeters
19
CCIM simulation: examples of results for single
liquid pool and melt jet release
Dynamics of molten glass jet
delivery from CCIM to a cask
Dynamics of natural convection
of single liquid corium pool
T, C
20
CCIM simulation: behavior of immiscible oxide
and metal melts within a stratified pool
MA-3: Power in the melt
Temperature and velocity vectors
Metal distribution after crystallization
Posttest ingot
Metal
inclusions
21
CCIM simulation: 2D-MCCI with gaseous
concrete decomposition products in the pool
Average gas velocity on Bottom and Concrete
wall – V = 0.04 m/s
Wall temteratures – 2100 C
Temperature
Initial melt temperature – 2277 C
Void
Inductor current – 266 A, as without gas
22
Conclusive remarks
 Successful experience of corium cold crucible furnaces operated in
different countries and organizations confirms that CCIM is one of the best
options for the new experimental platform at CEA
 Wide range of corium composition requested for PLINIUS-2 will probably
require variation of inductor current frequency
 Industrially produced power supplies have sufficient power in a wide
enough frequency range
 Challenging features of the new facility are associated not only with the
heating capacity but also with the quality of melt delivery into the test
section and furnace compatibility with sodium test section
 Pre-design, pre- and post-test IMCC simulations as well as supporting
experiments are necessary for successful application of this complex
melting technology
23
Acknowledgements
 Thanks to Dr Hwan Yeol Kim and Dr Seong-Wan Hong (KAERI), Prof
Perumal Chellapandi (IGCAR), Dr Gert Langrock and Manfred Fischer
(AREVA), Dr Monika Kiselova (UJV) for provided technical information
about CCIM facilities
 Thanks to many colleagues participated in design, construction,
commissioning and operation of different facilities as well as in the cold
crucible experiments
 Thanks to PLINIUS 2 International Seminar organizers for invitation to
present our experience
24