Current status of R&D on MSR fuel salt reprocessing

1. Current status of R&D on MSR fuel salt reprocessing by Jan Uhlíř AER working group F2 meeting, Liblice, Czech Republic, March 25-27, 2008

2. Historical background MSRE and MSBR programs in ORNL in 1960s and 1970s • Reactor chemistry was intensively studied in ORNL, liquid (molten salt) fuels were prepared and studies of MSR fuel “on-line” reprocessing were launched, although the reprocessing was newer realized neither in pilot scale. • However, chemistry of fluoride molten salts of uranium, protactinium, thorium and rare elements was deeply investigated. • Huge amount of physical – chemical data of possible MSR fuel salts was measured. (In addition to LiF – BeF2 also the salts containing fluorides of Zr, Na, K, and U, Th, Pu, Pa and some others.)

3. Fuel cycle of MSRE a MSBR • Gas extraction from molten salt medium (He bubbling method) • Fused salt fluoride volatilization technique (U separation) • Molten salt / liquid metal reductive extraction (Metal transfer process)

4. MSRE: Gas extraction from molten salt • Separation of Kr, Xe na d some noble metals (Nb, Mo, Ru, Sb, Te) from fuel circuit of MSRE • He or Ar sparging (bubbling) in the fuel pump (impeller). Gases were cleaned-up in the charcoal trap

5. MSRE: Uranium separation(Fused salt volatilization technique) In 1968, the original fissile material - 235U was changed for 233U. Uranium was extracted in the form of uranium hexafluoride by sparging the salt with fluorine gas UF4 + F2 UF6 • Continuous fluorination reactor with frozen walls was designed and manufactured

6. Fused salt volatilization technique

7. MSBR: Molten salt / liquid metal reductive extraction(Metal transfer process) Principle: MXn + nLi(Bi)  M(Bi) + nLiX Distribution coefficient: DM = XM / XMXn

8. Molten salt / Liquid metal extraction Separation of protactinium and lanthanides from the fuel circuit (extraction from fuel salt and from LiCl)

9. U and Pa extraction

10. Molten salt / liquid metal reductive extraction Rare earth (lanthanides) separation

11. Conceptual flow-sheet of MSBR fuel processing (ORNL)

12. Current status in R&D of MSR fuel reprocessing technology Original separation techniques studied proposed by ORNL have been replenished by electrochemical separation methods. • Gas extraction method (He – bubbling) – no experimental activity • Fused salt volatilization – no direct experimental activity, but the Fluoride Volatility Method is under development in NRI Řež plc • Molten salt / Liquid metal extraction (Metal transfer process) – active development of the process in CEA Marcoule, but the choice of carrier salts and studied actinides has no direct link to MSR (no FLIBE, no Pa no Th) • Electrochemical separation methods – main present-day studied pyrochemical methods in several institutions, but the main activities are focused to chloride molten salts. Study of fluoride systems is limited to CNRS, CEA, EDF and NRI in EU and RRC-KI in Russia, beryllium containing salts are studied only in NRI and RRC-KI • Flow-sheeting research – CNRS and EDF for TMSR and AMSTER, NRI for SPHINX and RRC-KI for MOSART

13. MSR carrier molten salt for fuel circuit and for use during the MSR fuel reprocessing: • 7LiF-BeF2 eutectic (FLIBE) – a reference fuel salt carrier (MSRE, MSBR) • 7LiF-BeF2 with addition of NaF proposed for MSR – An-burners • 7LiF-ThF4 (salt proposed for TMSR) Alternative proposals: • Fluoride salts containing ZrF4 and/or RbF Carriers proposed for use during electrochemical reprocessing (not used in MSR fuel circuit): • LiF-NaF-KF eutectic (FLINAK), LiF-NaF, LiF-CaF2 • Chloride salts (containing LiCl, LiCl-NaCl etc.) Chlorides are sometimes proposed for MSR system working in fast spectrum.

14. Present day and planned national activities in MSR fuel salt reprocessing France CNRS – main nowadays activities: • Electrochemical studies in LiF-CaF2 using active electrodes • Studies of gas extraction process • Electrochemical studies LiF-ThF4 system - main future plans: • Electrochemical studies with active electrodes • Extraction of fission products by oxide precipitation in chloride media • Extraction of actinides and lanthanides by electrolysis using inert or liquid electrodes and LiF-ThF4 and LiF-CaF2-ThF4 systems EDF – main nowadays activities and future plans: • Corrosion studies in molten fluoride systems LiF-NaF, LiF-CaF2, LiF-AlF3 • Fuel cycle simulation

15. Present day and planned national activities in MSR fuel salt reprocessing – cont.1 France CEA – main nowadays activities: • Optimization studies of the salt treatment process scheme • Bibliographic and thermodynamic evaluation of the MSBR salt treatment process • Development of a reprocessing code coupled to the neutron code • Simulation of MSR reprocessing unit - main future plans: • Coupling of the neutron code and a reprocessing code • Modeling of the reprocessing unit • Modeling of the reactor core behavior • Simulation of MSR reprocessing unit Italy ENEA – main nowadays activities and future plans: • Development of electrochemical facility PYREL for electrolysis in chloride and fluoride systems • System studies in the area of MSR waste management technology

16. Present day and planned national activities in MSR fuel salt reprocessing – cont.2 Czech Republic NRI – main nowadays activities and future plans: • Electrochemical separation studies in LiF-BeF2, LiF-NaF-BeF2, LiF-NaF-KF and LiF-CaF2 systems • Design and calculation of MSR An-burner and MSR Th-breeder fuel reprocessing flow-sheets Slovakia VÚJE – main nowadays activities and future plans: • Physical-chemical studies of fluoride, oxofluorides and oxides of lanthanides in molten fluoride systems (the studies are performed in the collaboration between VUJE and the Slovak Technical University in Bratislava)

17. Present day and planned national activities in MSR fuel salt reprocessing – cont.3 EC-EURATOM JRC-ITU – main nowadays activities and future plans: • There is no present activity in MSR fuel cycle technology development, but there are future plans to build “fluoride laboratory” for R&D of actinide / fission product electrochemical separation studies Russian Federation RRC-KI in collaboration with other Russian institution - main nowadays activities and future plans: • There were broad activity of RRC-KI and other Russian institutions in the frame of ISTC 1606 project. Now a new project (ISTC 3749) enabling continuation of this activity was approved and is ready to be launched. The ISTC 1606 project covered as R&D of MSR (MOSART) fuel salt clean-up technology including the theoretical as experimental studies of molten salt / liquid metal extraction, electrochemical separation, material corrosion studies etc.

18. Present-day activities in flow-sheeting MOSART SPHINX TMSR