Reprocessing Issues of Fuels for GenIV · 2011-02-18 · Reprocessing Issues of Fuels for GenIV...

Nuclear Energy Division

RadioChemistry & Processes Department ACTINET-I3 plenary meeting

February 2011

Reprocessing Issues

of Fuels for GenIV

[email protected]

mailto:[email protected]



February 2011

Outline

• Introduction

• Reprocessing issues

– MOX, MA oxide fuels

– Carbide

– Nitride

– Metal

– Fundamental actinide chemistry

– Other issues

• Conclusions



February 2011

Why a reprocessing?

• 1) The energetic challenge – Energy needs will double

– Mitigating the Global Climate Change Low-carbon energy

•2) Nuclear energy can help to

meet the future energy

challenge

–Low-carbon energy

–Efficiency for electricity base-

production

–Available ressources and world-

around dispersed

But…



February 2011

What about the sustainability?

• Uranium ressources

– Limited at a reasonable price (130$/kg U)

• 5,5 Mt identified

• 7,5 Mt estimated

– Ressources ~1 century

• Global efficiency is currently very low: < 1%

– Driver for recycling

• Need for increasing the sustainability

– By better consuming natural ressources

– By increasing the global lifetime

• Require shifting towards fast neutron reactors 0

40

80

120

160

200

Gen 1 Gen 2 Gen 3 Gen4

To

nn

es

Un

at/

GW

e-a

n

sans recyclage

avec recyclage

UNGG PWR EPR

160

U n

at

(t)

/ G

We.y

ear

200

50

120

80

40

SFR

With

recycling

1t/yr of 238U is sufficient to produce 1 GWe



February 2011

What is the current status of the actinides recycling ?

• Major actinides (U,Pu) recycling:

– Still represent 96% of spent fuel and can be used to produce energy ( waste)

– Pu (and U) recycling is an industrial reality since more than 50 y.

• Example of French experience:

– UP1 plant (Marcoule, 1958-1997), UP2-400 (La Hague, 1976-1994), UP2-800 (La Hague, 1994-) and UP3 plants (La Hague, 1990-)

– 23500 t NUGC, 24000 t UOX, 72 t MOX PWR, 27 t MOX SFR already reprocessed in France …

• In France, this strategic choice is stated in the Waste Management Act of 28th June 2006

• What about the minor actinides recycling?

– Main contributors to the long-term radiotoxicity of HLW

– waste toxicity and lifetime

– waste burden towards future generations

uranium

plutonium

PF

Ultimate waste regarding French

Law (28th June 2006)

FP 4%

U 95%

Pu 1%



February 2011

Saving the "repository" ressource by recycling MA

Due to interim storage time

Due to Am partitioning

Due to Cm partitioning

• Cost excavated volume heat power

• Repository volumes : reduction up to a

factor of 8

• Repository = ressource to save



February 2011

The rationale of the future nuclear fuel cycles

7

Gen. II & III

1950 1970 1990 2010 2030 2050 2070 2090

Gen. IV

…+ MA recycling

Pu-monorecycling

Pu-multi-recycling Pu-mono-recycling

- PWR reactors (N4 to EPR)

- Pu-recycling in MOX fuel

- from PUREX to COEXTM Pu multi-recycling

- Fast-Reactors (SFR)

- COEXTM process

-Pu multi-recycling

Pu+MA multi-recycling

- Fast Reactors (SFR)

- GANEX, SANEX, EXAm processes

- Pu multi-recycling

- MA burning

Gen. IV

Main incentives

- Ressource savings

- Waste conditioning

- Towards a more

proliferation-resistant

process: COEXTM

Main incentives

- Ressource savings

- Energetic independence

- Economic stability

Main incentives

- Waste decrease,

- disposal ressource optimisation

- Public acceptance



February 2011

The fuels that can face the GenIV fuel cycles

• MOX, FR MOX and other Oxide fuel

– With or withour MA,

– homogenous or heterogeneous (blanket)

– With or without inert matrix (CERCER – CERMET, transmutation fuel)

• Metal

– a good option for SFR fuel, in the US

– a large experimental program in the US National Labs

• Carbide

– a good option for SFR fuel, “almost” reference option for GFR fuel

– France (limited) and India (large) experience on UPuC

– no MA-UPuC experiment so far ?

– pyrophoricity of divided material, fabrication and reprocessing in safe industrial conditions ?

• Nitride

– a good experience in Japan, France and US

– a complicated fabrication process, N15 enrichment

– stability of Am nitride compounds as function of temperature ?



February 2011

The reprocessing issues



February 2011

The different strategies

PUREX

U Product

Pu Product

U, Np , Pu, Am , Cm

U

Np

PUREX

U Product

Pu Product

U, Np , Pu, Am , Cm

U

Np

PUREX

U Product

Pu Product

U, Np , Pu, Am , Cm

U

Np

LWRs LWRs LWRs Fuel COEX

U Product

UPu Product

U, Np , Pu, Am , Cm

U

UPu

Np

Am , Cm Am Am Am

An(III) + Ln(III)

co - extraction

An(III)/Ln(III)

separation Am , Cm

An(III) + Ln(III)

co - extraction

An(III)/Ln(III)

separation Am

An(III) + Ln(III)

co - extraction

An(III)/Ln(III)

separation Am

An(III) + Ln(III)

co - extraction

An(III)/Ln(III)

separation Am

(DIAMEX) (r-SANEX)

Am ,Cm Am Am Am

Am selective

extraction

(EXAm)

Ganex 1

Ganex 2

U

Pu Np Am Cm

Am Cm

Am Cm

A(III) selective

Stripping

(i-SANEX)

A(III) selective

Extraction

(1c-SANEX)

Am Cm



February 2011

Various types of processes under study

UREX USA

TRPO CHINA

DIDPA JAPAN

TRUEX USA

UNEX USA

CYANEX USA

TALSPEAK USA

SETFICS JAPAN



February 2011

MOX

• What characterizes the SFR MOX Fuel at the reprocessing

Fuel Characteristics LWR MOX RNR

UOX MOX

Composition before. irr. UO2 enrichi (U,Pu)O2 (U,Pu)O2235U: 3 - 4,5% Pu: 3 - 8,5% Pu: 13 - 20%

Metallic Materials Assembly 270 pins 200-300 pins

Cladding Zircaloy Zircaloy Stainless steel

Others materials Nozzles, grids, …

SNP, nozzles,

wrapper,

spacewire, …

Ø pins (mm) 11 à 12 11 à 12 6 à 8

Irradiation BU (MWd/t) 33000/60000 33000/45000 80000/120000

Average

temperature (°C)850-1300°C) 850-1300°C 1700

Thermal power Cooling 1 year 10 25 40

(KW)

Composition after irr. Plutonium 1 1 - 5 8 - 15

Minors Act. 0,03 - 0,1 0,55 0,5

FP 3,5 5 8 - 12

Nobles metals 0,4 0,9 2 - 3

Solubility

Criticality

Corrosion Fe, Cr, ...

Pu-PF compounds

Glasses Incorporation

Technology

LWR SFR



February 2011

MOX

Dissolution

• Mechanisms of oxides dissolution

– Reasons for kinetics limitations at

high Pu content

• Kinetic rate law of dissolution

• Nature and precipitation of newly-

formed phases in the dissolution

solutions

– Nature, properties, thermodynamics

of phases

Separation processes

• High Pu loading

• Radiolysis, hydrolysis

Manageable

COEX, GANEX…



February 2011

Inert matrix MA bearing oxide fuel

• UO2 !

• MgO – Head end Treatment

• Not major difficulty.

– Dissolution • Very good dissolution: the MgO matrix is soluble in nitric acid with fast

dissolution kinetics, Mg is not involved in precipitation.

– PUREX Extraction • Mg is not extracted by the TBP ligand and remains in the HAFP raffinate: no

problem.

– MA Partitioning • Mg is not extracted by the DMDOHEMA and the SANEX ligand and remains in

the raffinate with the light FP elements: no problem.

– F.P. Concentration • Mg is not known as being involved in precipitation during FP concentration.

– WASTE !!!!! • Mg is not known for generating troubles during the vitrification process, but MgO

content is limited to a low part (1 to 7.5 % weight) of matrix glass composition to prevent the degradation of the lixiviation resistance of the matrix. Production of a huge amount of high active glass containers

– MgO separation • No process is known.

• Such a process should generate less high active waste



February 2011

Inert matrix MA bearing oxide fuel

• Mo – Head end Treatment

• Not majordifficulty.

– Dissolution • Mo is soluble in nitric acid. But with high Molybdenum concentrations, formation of

Mo containing precipitates will occur over the time, including actinides.

– PUREX Extraction • Mo is not extracted by the TBP ligand and remains in the HAFP raffinate

– MA Partitioning • Mo is extracted by the diamide.

• oxalic acid was identified as the best complexing agent.

• Too much oxalic acid in solution induces precipitation of fission products lanthanides and actinides elements.

– F.P. Concentration • Mo precipitates, trapping actinides.

• dilution of the high active raffinate is the only solution

• reduces the capacity of the vitrification workshop downstream, increasing the amount of water and acid to be evaporated during calcination and vitrification.

– WASTE • Mo increases the corrosion rates of the vitrification pot and gas treatment columns.

• lead to the production of a huge amount of high active glass containers

– Mo separation • Acheivable (see DIAMEX-SANEX/HDEHP CEA Process)

• However, the Mo recovered is far from being clean – a lot of work to be done



February 2011

Carbide fuel

• Aqueous reprocessing

– If pre-treatment

• Oxydation (or “nitridation” - K. Ananthasivan et al. /J. Nucl. Mat. 228 (1996) 18)

of the fuel prior dissolution to remove carbon

• No big issues identified (but almost no experience with MA

containing fueL…)

– Impact of organic species if direct dissolution

• Pyroreprocessing

– A few studies

• Cladding behaviour?

– SiC

– Cladding/fuel separation? Hansen, W. N. "Reprocessing of uranium carbide by molten salt electrolysis,«

USAEC - ATOMICS INTERNATIONAL - NAA, 1963, NAA-SR-7660.



February 2011

Nitride Fuel

• Aqueous reprocessing

– No big issues

– Dissolution easy

– Management of N15

– Pretreatment?

• Voloxidation and N15 trapping

• Other routes?

• Pyroreprocessing

– Studied in Japan

– Minor modifications of the metallic fuel pyro

reprocessing



February 2011

Metallic Fuel

• Pyroreprocessing would be the reference

route

– Scientific faisibility not fully demonstrated

– Far from technological maturity

– but an impressive work done in Korea and Japan the

last 5 years

– Homogeneous recycling



February 2011

Key scientific issues related to actinides recycling

• Current and future recycling processes still require long-

running R&D effort

– To optimise the running process: adaptation to new fuel types,

increase efficiency and safety, …etc APPLIED R&D

• Beyond the specific process developments, generic

scientific areas are of great interest FUNDAMENTAL R&D:

– Basic actinide science (5f chemistry, coordination, …)

– Thermodynamics and kinetics in aqueous/organic phase (speciation, deviation from ideality, physical aggregation, interface …)

– Radiolysis and irradiation effects (molecules stabilities, transient

species, degradation products…)

– Chemical engineering and development of efficient extracting

devices (hydrodynamics, scaling approach …)

– From molecular modeling towards process modeling (towards multi-

scale / multi-physics modeling …)

– Analytical developments to acquire relevant experimental data.

• A challenging R&D field ranging from fundamental

chemistry to chemical engineering and process design



February 2011

Upscaling the molecular processes to the process modeling

ps ns µs ms nuclei and

electrons Atoms

Molecules

and ions

Ions within

continuum

solvent

Continuous

distribution c(r),

v(r), r(r)

Mean distribution on

the whole geometry

CP-MD Classical

MD

Hydrodynamic

(Fick, Navier-

Stokes, PNP)

Macroscopic

Hydrodynamic

Brownian

description

Molecular modeling Chemical engineering modeling Bridge the gap

New field of interest: coupling the different modeling-scale deriving some of the chemical

engineering models parameters from lower scale calculations.

Increase the physical-consistency, limit the empirical parameters,

Example: assessing

the activity

coefficients from MD

calculations through

BIMSA models



February 2011

More economic and political issues

If MA recycling:

important MA inventory in the cycle Specific Biological protection

(potential) increase of the Dose to the workers

Specific plant design

High cost!

Impacting the science:

Avoid any MA powders to limit the contamination of the hot cells

New fabrication processes Co-precipitation co-conversion, sol-gel…



February 2011

Conclusion

• In most of the cases the issues are on the head-end steps – dissolution – High Pu content, Mo precipitates, N15 trapping…

• Once the dissolution liquor obtained, the “classic” PUREX (or COEX) followed by a partitioning process will work in most of the cases – High Pu loading to be managed

• In the case of transmutation fuels with inert matrix, in addition to the HES, the waste management is also an issue – The best matrix: UO2!

– Develop specific separation processes for MgO, Mo?

• Potentialities of Pyroprocesses for metal, nitride, carbide,



February 2011

Thank you for your attention

11thIEMPT, San Francisco, 1-4 November 2010 S.Bourg 23



February 2011

0

0,05

0,1

0,15

0,2

0,25

0,3

0,35

0,4

0,45

Np 237 Am 241 Am 243 Cm 244

Fission/capture

REL

RNR

0,00

1,00

2,00

3,00

4,00

5,00

6,00

238Pu 239Pu 240Pu 241Pu 242Pu

Fission/capture

REL

RNR

Why could fast neutrons increase nuclear sustainability ?

• Interest of fast neutron spectrum

– Promote the neutron capture of 238U to produce Pu isotopes

– Promote the fission of Pu isotopes

to avoid the formation of higher

actinides

• Fast neutron spectrum reactors

– Could be operated with the

accumulated stockpile of Pu from

PWR and

• Potential use of stockpile of

Udepleted, Ureprocessed

• Theoretically, no need for

additional natural ressources

(Unatural)

– Require the multi-recycling of Pu

• Fast neutron reactors also open

the door to minor actinides

recycling

Pu

MA

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Reprocessing Issues of Fuels for GenIV · 2011-02-18 · Reprocessing Issues of Fuels for GenIV...

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