ThEC 2018 – October 29-31, 2018, Brussels, Belgium Sylvie Delpech, IPNO, CNRS

Institut de Physique Nucléaire - CNRS/IN2P3 Univ. Paris Sud, Université Paris Saclay, 91406 Orsay, France

DRF-IRFU-DPhN-LEARN, Saclay, France

LPSC-IN2P3-CNRS, UGA, Grenoble INP, Grenoble, France

PRINCIPLE AND EVALUATION OF MOLTEN SALT REACTOR REPROCESSING

S. Delpech, G. Duran-Klie, D. Rodrigues

A. Marchix, M. Dieuaide, A. Letourneau

E. Merle, J. Martinet, M. Allibert, D. Heuer

ThEC 2018 – October 29-31, 2018, Brussels, Belgium Sylvie Delpech, IPNO, CNRS

LIQUID 1 LIQUID 2

SOLID GAS

Metal deposition on solid or liquid cathod.

Oxide précipitation

Gas formation by electrolysis or reaction with an oxidizing gas : F2

or Cl2

Gas formation by electrolysis or reaction with an oxidizing gas : F2

or Cl2

Reductive extraction using a liquid metal

Separation principles

ThEC 2018 – October 29-31, 2018, Brussels, Belgium Sylvie Delpech, IPNO, CNRS

Controlled by the redox system UF4/UF3

Controlled by the redox system F2/F-

Controlled by the redox system LiF/LiBi

Core

Fluorination

Reductive extraction

Redox potential domains in the fuel salt

MSFR concept: fuel salt LiF-ThF4-UF4

ThEC 2018 – October 29-31, 2018, Brussels, Belgium Sylvie Delpech, IPNO, CNRS

Controlled by the redox system UF4/UF3

Controlled by the redox system F2/F-

Controlled by the redox system LiF/LiBi

Core

Fluorination

Reductive extraction

Redox potential domains in the fuel salt Example of uranium

MSFR concept: fuel salt LiF-ThF4-UF4

ThEC 2018 – October 29-31, 2018, Brussels, Belgium Sylvie Delpech, IPNO, CNRS

Controlled by the redox system UF4/UF3

Controlled by the redox system F2/F-

Controlled by the redox system LiF/LiBi

Core

Fluorination

Reductive extraction

Redox potential domains in the fuel salt Example of cesium

MSFR concept: fuel salt LiF-ThF4-UF4

ThEC 2018 – October 29-31, 2018, Brussels, Belgium Sylvie Delpech, IPNO, CNRS

∆𝐸𝑠𝑜𝑙𝑣𝑎𝑡𝑎𝑡𝑖𝑜𝑛 = 𝐸° − 𝑘 ∗ 𝑙𝑜𝑔 𝜸 𝑅𝑒𝑑 + 𝑘 ∗ 𝑙𝑜𝑔 𝜸 𝑂𝑥

Redox potential domains in the fuel salt Solvation effect

Solvation of Ox

Solvation of Red

Solvation

ThEC 2018 – October 29-31, 2018, Brussels, Belgium Sylvie Delpech, IPNO, CNRS

∆𝐸𝑠𝑜𝑙𝑣𝑎𝑡𝑎𝑡𝑖𝑜𝑛 = 𝐸° − 𝑘 ∗ 𝑙𝑜𝑔 𝜸 𝑅𝑒𝑑 + 𝑘 ∗ 𝑙𝑜𝑔 𝜸 𝑂𝑥

Redox potential domains in the fuel salt Solvation effect

Solvation of Ox

Solvation of Red

Solvation

Activity coefficients

ThEC 2018 – October 29-31, 2018, Brussels, Belgium Sylvie Delpech, IPNO, CNRS

Reprocessing scheme

ThEC 2018 – October 29-31, 2018, Brussels, Belgium Sylvie Delpech, IPNO, CNRS

• ORNL concept (tested with MSRE

reactor)

• Extraction of U, Np, Tc, I, Ru, Mo,

Te, Pu…

• Separation in gaseous phase using

NaF traps at different

temperatures.

First step: fluorination

Example: UF4 + F2 (g) UF6 (g)

ThEC 2018 – October 29-31, 2018, Brussels, Belgium Sylvie Delpech, IPNO, CNRS

Reprocessing scheme

ThEC 2018 – October 29-31, 2018, Brussels, Belgium Sylvie Delpech, IPNO, CNRS

Reductive extraction process

Li

LiF MFx

M

Bi

LiF-ThF4

MFx + xLiBi xLiF + MBi

No miscible phases

ThEC 2018 – October 29-31, 2018, Brussels, Belgium Sylvie Delpech, IPNO, CNRS

Reductive extraction process Redox properties of Ln and An – LiF-ThF4 - 600°C - LM= Bi – R = Li

Why is it interesting to use a liquid metal ?

ThEC 2018 – October 29-31, 2018, Brussels, Belgium Sylvie Delpech, IPNO, CNRS

)()(

)()(log

4

3.2E

)(

)(loglog

3.2*)(

101

1

)()(

)()(

/LM

/

LiLix

LiFLiFx

F

RTEwith

M

MF

n

n

RT

zFEEy

MFnMn

MnMFEff

LiLiF

z

MS

LMMMFLM

yz

z

z

Efficiency depends on two adjustable parameters :

Concentration of Li in the liquid metal

Phases volume (or mole) ratio

Reductive extraction process Analytical model of An/Ln extraction efficiency

ThEC 2018 – October 29-31, 2018, Brussels, Belgium Sylvie Delpech, IPNO, CNRS

- Good selectivity - Extraction of Ln requires high volume of liquid metal and several stages.

Reductive extraction process Analytical model of An/Ln extraction efficiency

Influence of phases volume ratio

ThEC 2018 – October 29-31, 2018, Brussels, Belgium Sylvie Delpech, IPNO, CNRS

• Bi-Li (10 mol%) // LiF-ThF4-UF4-NdF3 ( 77-23-0,2-0,1 mol%)

Extraction efficiency stable after 100 minutes. Low efficiencies. Thorium is also reduced in Bi but its solubility is very low (< 0.2 mol%). Low extraction due to the formation of Bi-Th intermetallic compound which blocks the interface. Need to improve technology.

Reductive extraction process Experimental tests

ThEC 2018 – October 29-31, 2018, Brussels, Belgium Sylvie Delpech, IPNO, CNRS

• Multi-stages extraction

Limitation of extraction by a low kinetic

Reductive extraction process Experimental tests - Multistages

ThEC 2018 – October 29-31, 2018, Brussels, Belgium Sylvie Delpech, IPNO, CNRS

Reprocessing scheme

ThEC 2018 – October 29-31, 2018, Brussels, Belgium Sylvie Delpech, IPNO, CNRS

LiCl-KCl (58.8-41.2 mol%) at 450°C

Lanthanide oxide precipitation in a chloride salt

ThEC 2018 – October 29-31, 2018, Brussels, Belgium Sylvie Delpech, IPNO, CNRS

LiCl-KCl (58.8-41.2 mol%) at 450°C

Oxide donors usually used for the precipitation: Li2O Li2O + 2Cl- 2LiCl + O2-

Li2CO3 Li2CO3 + 2Cl- 2LiCl + CO2(g) + O2- ……

Modification of the molten salt composition

Use of a gas (water) for the precipitation: H2O H2O(g) + 2Cl- 2HCl(g) + O2-

No modification of the molten salt composition

Lanthanide oxide precipitation in a chloride salt

ThEC 2018 – October 29-31, 2018, Brussels, Belgium Sylvie Delpech, IPNO, CNRS

Lanthanide oxide precipitation in a chloride salt Experimental device

ThEC 2018 – October 29-31, 2018, Brussels, Belgium Sylvie Delpech, IPNO, CNRS

Description of the chemical plant

40 L: initial inventory

ThEC 2018 – October 29-31, 2018, Brussels, Belgium Sylvie Delpech, IPNO, CNRS

Cooling phase

ThEC 2018 – October 29-31, 2018, Brussels, Belgium Sylvie Delpech, IPNO, CNRS

One day in the cooling zone: - limits the evolution of the inventories in the different stages of the chemical plant.

This is of importance to allow a good performance of the chemical processes. - allows to reduce the total decay heat of the salt by a factor eight and the total

activity by a factor four. - allows to eliminate the most energetic gamma of the spectrum

Cooling phase

ThEC 2018 – October 29-31, 2018, Brussels, Belgium Sylvie Delpech, IPNO, CNRS

Description of the chemical plant

40 L: initial inventory

ThEC 2018 – October 29-31, 2018, Brussels, Belgium Sylvie Delpech, IPNO, CNRS

Determination of the transfer coefficients

ThEC 2018 – October 29-31, 2018, Brussels, Belgium Sylvie Delpech, IPNO, CNRS

Decay heat in the chemical plant

ThEC 2018 – October 29-31, 2018, Brussels, Belgium Sylvie Delpech, IPNO, CNRS

Shielding requirements in the most critical part of the plant

ThEC 2018 – October 29-31, 2018, Brussels, Belgium Sylvie Delpech, IPNO, CNRS

Thank you for your attention