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Inactive experiments for advanced separation processes prior to high activity trials in ATALANTEJ. Duhamet, J.-Y. Lanoë, P. Rivalier, G. Borda
Introduction
The search for new hydrometallurgical processes for minor actinide separation has led the CEA to develop suitable apparatus for carrying out feasibility tests on representative aqueous solutions produced by the dissolution of irradiated nuclear fuels.Two major constraints had to be taken into account: on the one hand, the need to reduce the amount of effluents produced by the trials as much as possible, and on the other, the need to use laboratory apparatus whose results could reliably be extrapolated to industrial-scale equipment.
Several types of apparatus were developed or adapted to meet these criteria.
Conclusions
P1-03
Extraction apparatus developed to meet Atalante's needs
The approach adopted
Stockage solvant
COLONNE COUETTE 2type CBP
Lavage Ln 3BSCOLONNE COUETTE 3
type CBPDésextraction An 3BX
A/O=0,51
TPHQ: mL/h
Désextraction Zr,Fe3CXX
Acidif icationQ : mL/h]
Traitement soude
Désextraction8 ECLHA
3HAAECRANS
COLONNE COUETTE 1type CBP
Extraction-lavage 3AX+3AS
COLONNE COUETTE 4type CBP
Désextraction Ln 3CX
Lavage 3ASQ : mL/h[HNO3]
Charge aqueuse : 3AFQ : mL/h
[HNO3] : N
Charge aqueuse dedémarrage et de chasse
[HNO3] :
RaffinatQ : mL/h
Solvant recyclé 3AX
Solvant recyclé 3BSQ: mL/h
Sortie AnQ :mL/h
Désextraction AnQ : mL/h
Sortie LnQ :mL/h
Désextraction LnQ : mL/h[HNO3]
Sortie Ln
Légende
Analyse en ligne
Echantillonnage
Flux aqueux
Flux organiques
E 14P
ANL NdHellma
Densimètre Anton-Paar
ANL Nd tuyau
E 12
E 11
E 24
E 23
E 22
E 21
E 34
E 33
E 32
E 31
E 45
E 44
E 43
E 42
E 25P
E 35P
E 41P
3AP
3BSW 3BW 3CXW
3CW
SO3HAA
3HAAW3AW 3BP
3BXP3CLn
pH 1
pH 2(secours)
3CXXW
1 1
1
Pompe àengrenages
ou piston
Pompe àpiston C11/C12 Pompe à
piston C11/C12
pompe20 L
pompe
Pompe àengrenages
ou piston
Seringueplastique
1Pot type C11/C12
pompe
TPH
PompeSTEPDOS
PD 11
COM 6
HE BLNC 04
COM 8
HE BLNC 30
COM 9
HE BLNC 03
COM 10
HE BLNC 32
HNO3
Pompe àpiston C11/C12
COM 5
HE BLNC 31
Clapetanti-retour
ANLNd , FeT. Davin
E 13P
3AX
ANLNd, Fe
T. Davin
PD 17
PD 08
Péristaltique
PD 07
PD 01
ANLrefracto
COM 4
EA3BS
Several steps can be identified prior to high activity trials:- Apparatus design in consultation with the teams in charge of the high activity trials, so as to be fully aware of the special issues regarding its implementation in a shielded cell: bulk, ease of dismantling, limited accessibility, etc.- Follow-up of the apparatuses’ construction,- Individual checking of hydraulic operation with water, then with phases representative of those used in the separation processes- Implementation of separation processes coupling the different apparatus chosen under inactive conditions.
Results
From theoretical scheme to implementation of liquid/liquid extraction process
DIAMEX TRIALS IN COUETTE-TAYLOR COLUMNS
These trials in pulsed columns were also the opportunity to see that the breakdown of a vital element (in this case, the solvent pump) and its replacement in 3 hours, given the longer time imposed by the difficulties of working in a shielded cell, do not mean the trial has failed and that restarting following a suitable procedure enables a return to a state of equilibrium.The on-line spectrophotometry monitoring of the neodymium content of the back-extraction aqueous phase after restarting the solvent pump shows that equilibrium is recovered in less than 1.5 hour.
It was necessary to have columns with hydrophobized internal surfaces, in order to be able to function in continuous organic phase mode. A silanization treatment to the glass external cylinder was applied, and the stainless steel rotor was coated with a Teflon film.
Trials run for the whole process showed that precipitates appeared in the extraction column. Their analysis showed them to be lanthanide oxalates linked to the use of oxalic acid as a complexing agent. Overly weak acidity in the washing step caused these precipitates to appear. Analysis of the trial results enabled the modelling team to suggest a modified process flowchart.
DIAMEX TRIALS IN PULSED COLUMNS
Some column hydraulic malfunctions were identified, coming from wetting effects of the aqueous phase on the internal surfaces which very significantly reduced the interfacial exchange area. A hydrophobization treatment in situ for the columns has been used. The result obtained (showed that it was possible to establish a satisfying emulsion in the column.
Phase inversion on hydrophilic surfaces
Good hydrodynamic conditions with hydrophobic surfaces
Phase inversion on hydrophilic surfaces
Emulsion sticking to the walls of a non hydrophobized column
Emulsion in a hydrophobized column
These inactive trials, carried out in G1 facility, have demonstrated that it has been of primary importance to create a mock-up as representative as possible of the most significant apparatuses’ location as planned for the shielded line in order to identify implementation problems and find solutions more easily. It was also the opportunity to train the personnel in the implementation of the new separation processes in a less complex, more easily-understood environment.
Solvent
Feed
Extractioncolumm
Back extr.columm
Scrubcolumm
Solvent pump
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