Current Status and Perspective of R&D－Element Separation－

Yasuji Morita

Nuclear Science and Engineering Center

Section of Nuclear Science Research

Japan Atomic Energy Agency

October 9-10, 2014International Symposium on

“Present Status and Future Perspective for Reducing Radioactive Wastes

～Aiming for Zero-Release～”

2

Two Types of Fuel Cycles for P and T TechnologyDouble-strata

PowerGeneration

Fuelfabrication

Dedicated Transmutation

by ADS

TransmutationCycle

Commercial Fuel Cycle

Fuel fabricationPower

Reactors(LWR and FR）

Transmutation

Homogeneous Recycle in FBR

Commercial FBR Cycle

Fuel fabrication

FR power plantwith transmutation

Reprocessing

Spent fuel

MA–bearing fuel

Pu,MA

Pu

Finaldisposal

Spent fuel

Spent fuel

・Transmutation cycle is attached to commercial cycle.

・ADS is used as dedicated transmutation system.・MA can be confined into a small cycle and transmuted efficiently.

・Transmutation cycle is attached to commercial cycle.

・ADS is used as dedicated transmutation system.・MA can be confined into a small cycle and transmuted efficiently.

・MA is transmuted by commercial FBRpower plants in a closed cycle

・MA is transmuted by commercial FBRpower plants in a closed cycle

FPFP

Reprocessing

Reprocessing

MA

MA–bearing fuel

PowerGeneration Transmutation

Finaldisposal

FP: Fission ProductMA: Minor Actinide (Np, Am, Cm)ADS: Accelerator-Driven System

Reprocessing in both system can acceptthe same separation technology.

High-level Liquid Waste -Start solution for MA separation-

3

PWR spent fuel：Initial enrichment 4.5%、Burn-up 45GWd/t、cooled for 5 yearsMA-recycle fast reactor spent fuel (FR-MA)：core fuel + axis blanket (69.4%：30.6%)

Core fuel：Initial composition Pu19.6%, MA0.92%、Burn-up 147.1GWd/t、cooled for 5 yearsBlanket fuel：Depleted uranium (0.3%)、Burn-up 21GWd/t （Average burn-up 108.5GWd/t）

FP

MA

Pu

U

Fig. Example of spent fuelcomposition

FP

Pu

U

MA

※ based on data in JAEA Review 2008-037 “Handbook on Process and Chemistry of Nuclear Fuel Reprocessing”.All figures were obtained per 1 ton of spent fuel.

Reprocessing（U, Pu recovery)

U, Pu 99.5%Np 95%

Kr, Xe 100%Br, I 99%removal

Normalized by 10GWd/t

Higher ratio of residual U in PWR. Higher ratio of MA and Pu in FR-MA

Fig. Example of elementcomposition after reprocessing

Ln：La～DyAm

Ru

Pu

U

Cm

Rh

Pd

Ba

Cs

Tc

Zr MoY

Sr

Higher ratio of Am-Cm and PGM (Ru, Rh, Pd） in FR-MA

CmAm

Sr+Y

Rh

Cs+Ba

Ln

Mole ratio

Heat emission ratio

Very high ratio of heat emission by Cm in FR-MA4

High-level Liquid Waste -Start solution for MA separation-

※ based on data in JAEA Review 2008-037 “Handbook onProcess and Chemistry of Nuclear Fuel Reprocessing”

FP:2.1kW, An:0.16kW, 計2.3kW

FP:3.1kW, An:3.8kW, 計6.9kW

per 1 ton of spent fuel

Element to be separated

5

１） Minor Actinides（MA）＝Np, Am, Cm- Long-lived nulides to be transmuted- Np can be separated together with U and Pu, andtherefore main MA to be separated from HLLW areAm and Cm.

- Am and Cm are stable in trivalent state (An(III)),and rare earths (RE) shows similar behavior.

Mole ratio of An(III) to RE is 0.025 in PWRand 0.136 in FR-MA

- In many cases, An(III) are separated by two steps.２） Heat emitters ＝Sr, Cs

- Most of the heat by FP are emitted by Sr and Cs.- Highly loaded waste form would be possible afterSr and Cs removal.

３） Platinum group metals (PGM)＝Ru, Rh, Pｄ- Valuable elements- They shows bad effect in vitrification

４） Long-lived fission products＝Tc- Tc can be separated with PGM in many cases.- to be transmuted, and also a valuable element

U

Other FP

U, Pu, Np

Sr, Cs

An(III)+RErecovery

Partial U separation

FP without RE

Sr-Cs sep.

IodineDissolution

Am Cm

Am/Cm sep.RE

Tc

PGM

Tc-PGM sep.

High-level liquid solution (HLLW)

U-Np-Pu separation

Example of separation process flow

An(III)/REseparation

MA Separation （An(III) Separation）

Separation Process for MA with an extractant, DIDPA or CMPO was tested withreal HLLW and the separation performance was confirmed in JAEA.

Both processes have, however, drawbacks to be overcome.DIDPA extraction : Nitric acid concentration of HLLW should be reduced, which results

in formation of precipitation. Waste generation by P atom.CMPO extraction : Huge volume of solution. Waste generation by P atom.

OP

HO

O

O

iso-C10H21

iso-C10H21

P

O

H2C C

O

N

i-C4H9

i-C4H9

C8H17

CMPO

DIDPA

Experimental apparatus in NUCEFfor tests of DIDPA extraction process

with real HLLW from LWR SF

New research and development① Application of some new extractants② Application of extraction chromatography 6

Experimental apparatus in CPF for testswith real HLLW from FR SF

Solvent extraction and Extraction chromatography

7

１） Solvent extraction : separation method using difference in distribution equilibriumbetween aqueous phase such as nitric acid solution and organic phase containingextractant(s) by each element

Advantage : Easy continuous operation giving high recovery with high purity. Muchexperience in nuclear industry.

Problem : Treatment of spent solvent. Scale of extractors. The third phase formation.2） Extraction chromatography : extraction between solution and adsorbent which is

impregnated with extractant(s).Advantage : No diluent. High separation factor. Compact apparatus.Problem : Less experience in nuclear industry. Difficulty in remote operation.

※ Problem of adsorbent swelling was solved by using porous silica particles.

Solvent Extraction Extraction chromatography

Porous silica particlescoated with organic

polymerSize : several tens m

Development of new extractants for An(III)+RE recovery

8

CC

O

O

OC

CH2

NN C12H25

H25C12

H2

C12H25

H25C12 CC

O

O

OC

CH2

NN C12H25

H25C12

H2

C12H25

H25C12

TDdDGA（dodecyl-DGA）

Requirements for An(III)+RE extractants・Extraction from the solution of high nitric acid

concentration to avoid precipitation・Effective extraction and back-extraction・Compound without P to avoid secondary waste

Tridentate DGA extractants are developed.・An(III) can be extracted from 1~3M nitric acid solution and

back-extracted with 0.1M nitric acid・Amide compound without P (CHON principle)・Soluble in n-dodecane・TDdDGA has high extraction capacity without formation of

the third ・ Acceptable durability against radiation

Status of TDdDGA extraction process development・Continuous extraction tests using simulated HLLW with Am

tracer gave the Am recovery of more than 99.99%.・Process simulation code was developed.・Optimization of process condition is underway.・Tests with real HLLW will be carried out as a next step.

DGA extractant is also applied to extraction chromatography.

Nitric acids (M)

Dis

tribu

tion

ratio

ofA

m(-

)

Easy back-extraction

Effectiveextraction

Malonamide

Present workTODGA

CMPO

An(III)／RE separation by solvent extraction

・Study on soft-donor extractants※soft-donor : nitrogen(N), sulfur(S)

hard-donor : oxygen(O)Soft-donor extractant gives higher distributionratio with An(III) than with RE.

→ Selective extraction of An(III)・Hybrid extractants which have both soft and hard

donor in the molecule are also studied.

In both DIDPA extraction and CMPO extraction, a complexing agent, DTPA, isused for An(III)／RE separation, which makes more stable complex with An(III).Problem ･Treatment of organic phase and aqueous solution including

complexing agent・Control of pH ・secondary waste

Separation by the combination of TDdDGA andDTPA is also examined and separation factor of9.4 between Am and RE was confirmed (figure)

Still in the stage of extractant selectionand basic data acquisition 9

TDｄDGA-DTPA

pH after back-extractionD

istri

butio

nra

tio(-

)

Separationfactor of 9.4

An(III)／RE separation by solvent extraction

10

Status of separation process development and the near future・Continue to obtain extraction data (extraction rate, extraction capacity, stability, etc.)・Process integration with An(III)+RE recovery.・After optimization of process condition and continuous extraction test with simulated

HLLW, tests with real HLLW will be performed.

pH

Dis

tribu

tion

ratio

TPDN■ Am● Eu

Organic phase：[TPDN] = 10 mM in nitrobenzeneAqueous phase： pH = 1.0 〜 4.8

TPDN

ADAAM(EH)

Multi-dentate N donorextractant, TPDN, provideAm/Eu separation（center figure)

Hybrid type extractants,ADAAM(EH) is being examinedand separation factor of morethan 20 was obtained betweenAm and Eu

Application of TPDN to extractionchromatography is also examined.

11

Adsorption/Elution assessmentMA can be adsorbed by adsorbents with CMPO and

TODGA from HLLW, and eluted with some FPs (Ln)MA can be adsorbed by adsorbents with R-BTP

(iHex-BTP) from HLLW, and eluted selectivelyMA can be adsorbed by adsorbents with HDEHP

and TOPEN from diluted HNO3 solution, and eluted selectively

0 2 4 6 8 10 12 14 16 18 20 22 24 26 280

0.5

1 Sr Pd Ru-106 Sb-125 Cs-137 Ce-144 Eu-155 Am-241 Cm-242 pH

C/C

0

Through Bed Volume

DV Feed 3M HNO3 H2O 50mM DTPA (pH=3)

3

1.5

pH

Chromatographic separation of real HLLW by the column with iHex-BTP/SiO2-P adsorbents

(FUGEN spent fuel test at TRP)

Chromatographic separation of real HLLW by the column with CMPO/SiO2-P adsorbents

(JOYO spent fuel test at CPF)

An(III)+Ln recovery

An(III) Separation by Extraction Chromatography

0.0

0.2

0.4

0.6

0.8

1.0

0 1 2 3 4 5 6 7 8 9 10 11 12

C/C

0

Sr YZr MoBa LaCe NdSm EuGd AmCm

DeadVol.

Feed 1 M HNO3 H2O

Through bed volume

Selective An(III)recovery

Y. Sano, et al., IOP Conf. Ser.: Mater. Sci. Eng. 9 012064 (2010)S. Watanabe, et al., Proc. of GLOBAL2011 (2011)

iHex-BTP

TOPEN

12

Durability of Adsorbents against Gamma Irradiation

Durability assessment Adsorbents with CMPO and TODGA have a similar durability Adsorbent with R-BTP is unstable in high HNO3 condition Adsorbents with R-BTP, HDEHP and TOPEN have a similar durability

in diluted HNO3 condition

Contact time : 180 min, Temp. : 25ºCAdsorption solution : [HNO3]=4.8M, [Eu(III)]=10mM

Contact time : 180 min, Temp. : 25ºCAdsorption solution : [HNO3]=2M, [U(IV)]=10mM

Distribution coefficient of Eu from 4.8M HNO3 by TODGA/SiO2-P adsorbents

Distribution coefficient of U from 2M HNO3 by iHex-BTP/SiO2-P adsorbents

10-1

100

101

102

103

0 1 2 3 4 5D

istri

butio

n co

effic

ient

(cm

3 /cm

3 )

ray dose (MGy)

0.01 M *

2 M

* [HNO3] at exposure

10-1

100

101

102

103

0 1 2 3 4 5

Dis

tribu

tion

coef

ficie

nt (c

m3 /c

m3 )

ray dose (MGy)

0.1 M *

4.8 M

* [HNO3] at exposure

Y. Koma, et al., Proc. of GLOBAL2009 (2009)

Separation of Fission Products

13

◎ Separation of Sr-Cs（1）Adsorption with inorganic ion exchangers

- Titanic acid for Sr and Zeolite (mordenite) for Cs.The adsorbents can be converted to a stable formby calcination.

- Experiments with real HLLW showed a good performancefor Sr-Cs recovery.

- Drawback : Reduction of acid concentration is required.

（２）Extraction chromatography- Crown-ether for Sr and Calix-crown for Cs.- Very small scale test with real HLLW was performed.- Drawback : High cost for extractants.

◎ Separation of Tc-PGM(Ru, Rh, Pｄ）- Adsorption method with active carbon was developed.- Precipitation method by denitration was tested with

real HLLW, and the recovery of Tc-PGM was confirmed.- Extraction with oxime for Pd separation and volatilization with electrochemical

oxidation for Ru separation were investigated.◎ Other elements

- Zr and Mo are separated by precipitation in DIDPA extraction.- Separation process for Zr-Mo by extraction with HDEHP was developed.

Very small scale test with realHLLW for Sr-Cs separation byextraction chromatography

Performance of eachseparation process wasconfirmed. Integration oftotal process is important.

Summary

14

In An(III) separation and FP separation, several methodshave been already confirmed to give good performance.

Methods to give better separation performance should beinvestigated.

High-level liquid solution from spent fuel of LWR and thesolution after U-Pu recovery from spent fuel of fast reactor,as a starting solution of An(III) separation, can be treated ina similar manner considering the difference in actinidecontent.

Integration of separation processes for An(III) and FP isimportant.

Together with the real HLLW tests, cold mock-up tests in anindustrial scale should be performed, and then it becomepossible to proceed to active tests in the industrial scale.