LFR fuel overview and perspectives

Transcription

IWINRH Pisa, April 2012
Politecnico di Milano, 19 dicembre 2007
LFR fuel overview and
perspectives
Dario Manara, Rudy Konings, Philippe Raison
European Commission
Joint Research Centre
Institute for transuranium materials (ITU)
P.O. Box 2340
76125 Karlsruhe
Germany
Generation IV overall
overall mission
–Significant advances in:
•Sustainability
•Safety and reliability
•Proliferation and physical protection
•Economics
–Competitive in various markets
–Designed for different applications:
Electricity, Hydrogen, Clean water,
Heat
Argentina
Brazil
US
UK
Switzerland
Generation IV
International
Forum (GIF)
Canada
Euratom
France
S. Africa
Korea
Japan
Criteria for fuel materials
• Low neutron capture cross section of nonnon-fissile
elements + good irradiation behaviour
• High fissile density
• No chemical reaction with cladding or coolant
• Favorable physical properties, especially thermal
conductivity and melting point (together
(together give the
margin to melting)
melting)
• High mechanical stability (isotropic
(isotropic expansion,
stable against radiation)
radiation)
• High thermal stability (no
(no phase transitions, no
dissociation))
dissociation
• Compatibility with reprocessing methods.
NUCLEAR FUEL OPTIONS
• MOX
•
•
•
•
Metal fuel
Nitride fuel
Carbide fuel
INCLUDING INERT MATRIX fuel and minor
actinide--containing fuel.
actinide
• Coated particle fuel for high temperature reactors
• Molten salt fuel
Oxide and “Advanced” Nuclear Fuels
OXIDES: MORE STABLE AT ROOM T; EASIER TO PREPARE
OXIDES
METALS, CARBIDES, NITRIDES:
NITRIDES
POSSIBLE OPTION AS GEN IV NUCLEAR FUEL THANKS TO:
• HIGHER FUEL DENSITY
U
UO2
UC
UN
•HIGHER MARGIN-TO-MELTING
INTEGRAL
Melting
point (K)
1388
3130
2780
3123
Density
-3
(g cm )
19.05
10.95
13.63
14.32
U-density
-3
(g cm )
19.05
9.6
12.97
13.53
50
∫ λ (T )dT
Top
40
Î/W m -1 K-1
CIM =
Tmelt
U
30
UN
20
UC
10
UO2
0
300
500
700
900
T/K
1100
1300
GIV - MATERIALS
Fuel performance indicators
LFR SYSTEMS CONSIDERED
SSTAR
ELSY
MYRRHA
Nitrides, metals
MOX (30(30-35% PuO2)
MOX, (nitrides)
Schematic Diagram of The Laser Flash Measurements of
Irradiated Fuels
Fiber Optic
1. Step: HF induction
furnace is heating up the
sample.
Glove BOX
Mirror With
Field Stop
Diaphragm
Manipulators
Water Cooled
Vacuum Chamber
Telescope
4. Step: the temperature
wave reaches the back
sample surface
generating a temperature
increase.
2. Step: laser shot is fired
towards the sample front
face.
Support
Plate
HF-Power Supply
Sample
HF-Heater
γ-Shielding
Laser power
monitor
Pulsed Nd-YAG Laser
(0.1-1.0 ms, 10J)
Dichroic
InGaAs PD
Mirror
u
3. Step: the temperature
wave generated by the
laser pulse is moving
through the sample
towards the back surface.
Fiber Optic
Motorized Filter
Wheel System
Si PD Logarithmic
Amplifiers
Personal Computer
CW Nd-YAG Laser
Beam Mixer
Data processing
according
to the general integral
of the heat transport
equation
DTmax
Transient Recorder
(14bit, 1MHz)
5. Step: the increasing
temperature thermogram
is measured by the highly
sensitive fast pyrometer.
Thermal conductivity of irradiated UO2
Thermal diffusivity at 490K, m2 s-1 (x 10-6)
102 GWd/t LWR UO2
2.0
Fresh fuel
1.8
At end of life
(no out-of pile auto-irradiation)
1.0
Degradation
by in-pile
burn-up
degradation
by out-of-pile
auto-irradiation
end of life
(model prediction)
0.8
After storage
0.6
0.0
recovery by
out-of-pile
annealing
Annealed at 590 K
Annealed at 725 K
0.2
0.4
0.6
0.8
1.0
Radial position (r/r0)
The white circles along the radius
indicate the spots for thermal
diffusivity measurements by Laser
flash.
Predicted and measured thermal diffusivity. After
annealing the diffusivity converges to the
predicted values.
OXIDE FUEL
Rather low thermal conductivity, high emissivity
High vapour pressure. Non- stoichiometry.
Well established
U(
U(Pu
Pu)O
)O2
UNCERTAIN
UO2+x
OBSCURE
D.Manara et al., J. Nucl.
Mater. 342 (2005), 148.
After: C. Guéneau et al., J. Nucl. Mater. 304 (2002),
161.
After: Kato et al., JNM 2008
Oxygen potential of (U,Pu)O2
U4+ → U6+
Pu4+
U4+ → U3+
Pu4+ → Pu3+
The situation is even more complex in the
presence of MA:
NpO2, AmO2-x and CmO2-x have even higher
oxygen potential.
Experimental data + CALPHAD
UO2±x and PuO2-x
Guéneau
Guéneau et al. JNM 2011
High oxygen potential ⇒ O2 losses before melting
Cf. well known systems like CeO2!!!
THE EXPERIMENTALIST’S STRUGGLE FOR EQUILIBRIUM...
N. Dupin
In
F. De Bruycker et al.
JNM 2011
⇒UO2 melts quasiquasicongruently under an
inert atmosphere, PuO2
melts the closest to
congruently under an
oxidising atmosphere.
The UU-Pu
Pu--O system
At 3000 K
Experimental data with HUGE
uncertainty ≈ 350 K – O2 losses
very important!
FUNDAMENTAL FOR THE COMPREHENSION OF ININ-PILE NUCLEAR FUEL BEHAVIOUR!!!
More research ongoing on chemical analysis of melted MOX samples: O, Pu distribution
Similar research on (U, Th
Th),
), (U, Am) MOX + minor actinide fuel
F. De Bruycker et al. JNM 2011, C. Guéneau et al. JNM 2011
Fast Reactor (U,Pu
(U,Pu)O
)O2 fuel
Source: Olander
Mixed oxide (MOX) fuel fabrication methods
Source: IAEA-Technical Report Series 415
NITRIDES
PN2 extremely high.
Metal de-mixing under irradiation (NIMPHE2 experience)
Quasi-metallic behaviour: low emissivity, high
conductivity.
Melting point: few experimental data, not always
accurate.
?
Melting point UN measured under at least 2.5 bar N2:
at 1atm, decomposition around 3000 K.
Melting behaviour: almost unknown.
After: Tagawa, JNM 51 (1974), 78.
Phase diagrams Nitrides
Source: Massalski
(U,Pu)N fuel
PuO2
UO2
Graphite
Blending
Compaction
MO2(cr) + 2C(cr) → M(cr) + CO(g)
M(cr
M(cr)) + ½N2(g) → MN(cr
MN(cr))
Carbothermic Reduction
Milling
Additives
Pressing
Sintering
Grinding
Fast Reactor (U, Pu)N fuel
• 4 at% burnup
• 710 W/m
• He- or Na- bonded
• 85% TD (initial)
• No restructuring at
same linear heat as
oxides (not true in
NIMPHE 2)
Porosity 40%
Porosity 10%
Source: Tanaka et al.
Fast reactor metallic fuel
• Alpha
Alpha--Uranium is not suited (swelling)
• Stabilisation with Zr (cf. EBR II experience).
• Lower smeared density (< 80% TD) and larger pellet
pellet--cladding
gap to accommodate swelling (about 30% volume increase).
• NaNa-bonded
Pseudo-binary U0.8Pu0.2-Zr
U-15Pu15Pu-12Zr
Source: Kittel et al.
•2.4 at% burnup
•460 W/m
•Na
Na--bonded
Fast reactor fuels: overview
•
Oxide fuel
– Low thermal conductivity, high fuel temperature, restructuring, Pu
redistribution.
– Extensively studied.
•
Nitride fuel
– Decomposition before melting; phase diagram poorly known.
– Am vaporisation
– 15N enrichment to avoid 14C production
•
Metal fuel
– Pyrophoric, needs purified atmosphere
– Low melting T; huge expansion
– Am vaporisation
Carbide fuel
– Pyrophoric, needs purified atmosphere
– Not compatible with aqueous reprocessing
– Metastability
•
Fast reactor fuels: perspectives
•
Oxide fuel
– Rich experience.
•
Nitride fuel
– Excellent CIM and fissile nuclide density.
– Need to be better studied.
– Optimize fabrication.
•
Metal fuel
– Maximum fissile nuclide density and efficiency.
•
Carbide fuel
– Fair experience
– Oxidation issue
– Difficult recycling: more suited for VHTR fuel.
THANKS:
- EC FP7 EUROTRANS + FF-BRIDGE + SEARCH
- Prof. L. LUZZI (POLITECNICO DI MILANO)
- Dr. M. TARANTINO and N. FORGIONE (Università
(Università di Pisa)
THANK YOU FOR YOUR ATTENTION
Mixed oxide (MOX) fuel fabrication methods
• OCOM (Siemens)
Optimised Comilling
• COCA (COGEMA)
Cogranulation Cadarache
• MIMAS (BN, COGEMA) Micronised Master Blend
• SBR (BNFL)
Short Binderless Route

LFR fuel overview and perspectives

Transcription

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