thorium molten salts, theory and practice paul madden (oxford, uk) & mathieu salanne &...
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Thorium molten salts, theory and practice
Paul Madden (Oxford, UK)& Mathieu Salanne & Maximilien Levesque (UPMC, France)
Euratom Project, 13 Groups Molten Salt Fast Reactor
WP2: MSFR whole system
Thermal power (MWth) 3000
Electric power (MWe) 1500
Fuel Molten salt LiF-ThF4-233UF4 initial composition (mol%) with 77.5 % LiF
or LiF-ThF4-(Pu-MA)F3
Fertile Blanket Molten salt LiF-ThF4 initial composition (mol%) (77.5%-22.5%)
Melting point (°C) 565
Input/output operating temp. (°C) 625-775
Fuel Salt Volume (m3) 18 9 out of the core 9 in the core
Blanket Salt Volume (m3) 7.3
Total fuel salt cycle in the system 3.9 s
Physical Separation Gas Reprocessing Unit
through bubbling extraction Extract Kr, Xe, He and
particles in suspension
Chemical Separation Pyrochemical Reprocessing
Unit Located on-site, but outside
the reactor vessel
Motivation Control physicochemical properties of the salt (control deposit, erosion and
corrosion phenomena's) Keep good neutronic properties
Fission products extraction
Discussion by Sylvie Delpech (Tuesday 4pm)
The complexity of the flow inside the cavity involves a coupled Thermal-Hydraulic & Neutronics approach:
Elsa Merle-Lucotte (Wednesday 10am)
Fluid velocity Temperature
Hence need various thermodynamic, transport and chemical properties of multi-component molten salts over a wide range of temperatures
e.g. Melting points, heat capacities, thermal conductivity......... chemical activity coefficients
Phase diagram of LiF:ThF4
Liquid
Physical properties
Formula Value at 700°C
Validity Range, °C
Density ρ (g/cm3) 4,094 – 8,82 ×10-4 (T(K)-1008) 4,1249 [620-850]
Kinematic Viscosity ν (m²/s)
5,54 ×10-8 exp{3689/T(K)} 2,46×10-6 [625-846]
Dynamic viscosity μ (Pa.s)
ρ (g/cm3)×5,54 ×10-5 exp{3689/T(K)} 10,1×10-3 [625-846]
Thermal Conductivity λ (W/m/K)
0,928 + 8,397×10-5×T(K) 1,0097 [618-747]
Calorific capacity Cp
(J/kg/K)
(-1,111 + 0,00278 × T(K)) × 103
1594 [594-634]
Physical properties for LiF-78%mol-ThF4-22%mol (ISTC Project No. #3749)
Hence need various thermodynamic, transport and chemical properties of multi-component molten salts over a wide range of temperatures and compositions
e.g. Solubilities, heat capacities, thermal conductivity......... chemical activities
Such datasets do not exist!!
Sub-binary systems
10
26 -28 June 2013, Grenoble
4th progress meeting - EVOL Project
• Phase transition points
• Enthalpy of mixing
• Li3ThF7 enthalpy of fusion
• ThF4 enthalpy of fusion
• Phase transition points (Barton et al.)
• No experimental data available on ThF4-PuF3 system.
• Phase diagram optimized based on similarity with ThF4-CeF3 system.
Experimental data:
Thermodynamic modelling of ternary system from data for binary subsystems e.g. by O. Beneš & R. Konings (ITU, Karlsruhe)
11
26 -28 June 2013, Grenoble
4th progress meeting - EVOL Project
LiF-ThF4-PuF3 ternary system
Tmin=818,14 K
LiF-ThF4-PuF3 (69.6-28.6-1.8)
Perform realistic Molecular Dynamics simulations, with polarizable, deformable ionic interaction models
model parameters from first-principles electronic structure calculations
-- i.e. predictive simulations (no experimental input)
A general methodology – applicable to a wide variety of ionic liquids
Approach via atomistic simulation
Liquid-vapour interface in LiF:ThF4
Output of simulations is a trajectory of the ions in the fluid in a given thermodynamic state
By averaging functions of positions and velocities can calculate observable properties – validate, predict, interpret
Molten LaCl3 (1300K) – diffraction structureX-rays(Okamoto)
EXAFS
Transport Properties of LiF:ThF4
Viscosity
Conductivity
Figure of Merit for heat transfer
Can link observable properties to underlying atomic scale structure - interpretation of different material behaviours
3LiF:BeF2 LiF:BeF2
BeF2 X-ray diffraction (Narten)Viscosity of LiF:BeF2 mixtures
Increase cell voltage-> deposition of M3+
Separability of fission products
Activity coefficients
LiCl/KCl “solvent”
Thermodynamic Activity Coeff.
ΔGtot
“Transmutation” by changing the interaction potential U(λ)
Transmutation of U3+ into Sc3+
99.9% separability requires ΔE = 0.149 V
Conclusion: the modelling methodology is generally applicable, capable of predicting material properties and of helping to interpret material behaviour
the accuracy has been validated on molten salts of interest