2010. 6

Do-Hee AhnDo-Hee Ahn

The Korean Strategy for Nuclear

Fuel Cycle

The Korean Strategy for Nuclear

Fuel Cycle

Table of ContentsTable of Contents

2

Ⅰ

Ⅱ

III

Spent Fuel Management

Recent Pyroprocessing Research Activity

Summary

II-1. Electrolytic ReductionII-2. ElectrorefiningII-3. ElectrowinningII-4. Waste Salt Treatment

Spent Nuclear FuelSpent Nuclear FuelSpent Nuclear FuelSpent Nuclear Fuel

3

AttributeAttribute

High radioactivity and heat : emits about 12 kW/ton after 1 yr coolingHigh radioactivity and heat : emits about 12 kW/ton after 1 yr cooling

High radiotoxicity : 300,000 yrs will be taken to be natural uranium level High radiotoxicity : 300,000 yrs will be taken to be natural uranium level

Energy resource : contains 1% Pu and 93% UraniumEnergy resource : contains 1% Pu and 93% Uranium

Annual Spent Fuel Generation 700t/yr

CANDUCANDU PWRPWR

Projection of Spent Fuel Generation

20 t/yr, unit 16 units 320 t/yr

95 t/yr,unit 4 units 380 t/yr 11,500 톤 /년700 톤 /년

0

10

20

30

40

50

60

70

80

90

2005 2015 2025 2035 2045 2055 2065 2075 2085 2095

Year

Ac

cum

ula

ted

SF

Ari

sin

gs

(ktH

M)

PWR

CANDU

0

10

20

30

40

50

60

70

80

90

2005 2015 2025 2035 2045 2055 2065 2075 2085 2095

Year

Ac

cum

ula

ted

SF

Ari

sin

gs

(ktH

M)

PWR

CANDUS

pen

t F

uel

Acc

um

ula

tio

n (

ktH

M)

10,0761 t, 2009

Status of Spent Fuel StorageStatus of Spent Fuel StorageStatus of Spent Fuel StorageStatus of Spent Fuel Storage

4

NPPSites

Kori

Yonggwang

Ulchin

Wolsong

Total

Storage Capacity(MTU)

2,253

2,686

1,642

5,980

12,561

CumulativeAmount(MTU)

1,762

1,704

1,401

5,894

10,761

Year of Saturation

2016

2016

2008

2009

As of end of 2009

Storage Capacity(MTU)

2,253

3,528

2,326

9,155

17,262

Year of Saturation

Expansion Plan

2016

2021

2018

2017

On-site SF storage limit will be reached from 2016On-site SF storage limit will be reached from 2016

Decision making process for interim SF storageDecision making process for interim SF storage

Korean, Innovative, Environment-Friendly, and Proliferation-Resistant System for the 21st C (KIEP-21)

Benefits Saves disposal space by a factor of 100

Shortens the management period to a fewhundred years

Increases U utilization by a factor of 100

Ensures intrinsic proliferation resistance

Promising Fuel Cycle Concept (KIEP-21)Promising Fuel Cycle Concept (KIEP-21)Promising Fuel Cycle Concept (KIEP-21)Promising Fuel Cycle Concept (KIEP-21)

FR Closed Fuel Cycle Volume Reduction

GEN-IVFR(SFR)

PWR

CANDU

FR Metal Fuel(U-TRU-Zr)

(Cs, Sr)Decay Storage

DisposalDisposal

S/G

IHTS Piping

Secondary EM Pump

Reactor Core

Primary Pump

Reactor Vessel

IHX

DHX

Reactor Head

Containment Vessel

S/G

IHTS Piping

Secondary EM Pump

Reactor Core

Primary Pump

Reactor Vessel

IHX

DHX

Reactor Head

Containment Vessel

Recycling

Wastes

Pyroprocess

Dupic

Flow Diagram of Pyroprocessing (KAERI)Flow Diagram of Pyroprocessing (KAERI)Flow Diagram of Pyroprocessing (KAERI)Flow Diagram of Pyroprocessing (KAERI)

6

TRU fuelfabrication

Decladding & Voloxidation Electrolyticreduction Electrorefining

Electrowinning

Molten saltwaste treatment

Uraniumrecovery

Recycleor LLW

Recycleor treatment

Cladding material

Low level waste

Off-gastreatment

Sodium-cooledfast reactor

Fission gas

Air

U3O8+(TRU+FP)oxide

(U+TRU+FP)metal

PWR spent fuel

TRU : Transuranic elementsNM : Noble metal elementsFP : Fission products

TRU fuelfabrication

Decladding & Voloxidation Electrolyticreduction Electrorefining

Electrowinning

Molten saltwaste treatment

Uraniumrecovery

Recycleor LLW

Recycleor treatment

Cladding material

Low level waste

Off-gastreatment

Sodium-cooledfast reactor

Fission gas

Air

U3O8+(TRU+FP)oxide

(U+TRU+FP)metal

PWR spent fuel

TRU : Transuranic elementsNM : Noble metal elementsFP : Fission products

R&D Issues of PyroprocessingR&D Issues of PyroprocessingR&D Issues of PyroprocessingR&D Issues of Pyroprocessing

7

Purposes Increase throughput Simple and easy remote operability Enhance interconnection between unit processes Reduce waste volume

Improvement High performance electrolytic reduction process Graphite cathode employment to recover U in electrorefining system Application of residual actinides recovery (RAR) system Crystallization method applied to recover pure salt from waste mixture

Spent Fuel Voloxidation Electroreduction Electrorefinning Electrowining Fuel Fabrication SFR

HM

Electrolytic Reduction Process – Flow DiagramElectrolytic Reduction Process – Flow Diagram

Pre-treatment

Electrolytic Reducer(650 oC, 120 kW)

Electro-refining

Waste Salt Treatment

Cathode Processor(725 oC, 120 kW)

UO2

MS + Cs, SrMS: LiCl-Li2O molten salt

Metal U

Metal U+ MS + Cs, Sr

LiCl

Electrode Handling Apparatuses

8

Development of Electrolytic Reduction ProcessDevelopment of Electrolytic Reduction Process

Bench Scale ER(~g UO2/batch)

Lab. Scale ER(~20 kg UO2/batch)

Eng. Scale ER(~50 kg UO2/batch)

Year 2008→ Change of Ceramic Cathode Basket to Metal Cathode Basket

Year 2009→ Successful Demonstration of Lab-scale Electrolytic Reducer

Year 2010→ Construction of Eng-scale ER focusing on the High Speed Reduction

9

Electrorefining System – Flow Diagram Electrorefining System – Flow Diagram

CERS (Continuous Electrorefining System)CERS (Continuous Electrorefining System)

Continuous electrorefinerContinuous

electrorefiner

Continuous recovery

Continuous recovery

Uranium depositUranium deposit Uranium depositUranium deposit

Salt recycleSalt recycle

Salt distillerSalt distiller

Melting furnaceMelting furnace

Electro-reducer

UCl3UCl3

U chlorinatorU chlorinator

Impure U mixtureImpure U mixture

ElectrowinnerResidual saltResidual salt

22.5 kg UCl3/batch

Height: 2 m

OD: 0.9 m

50 kg U/day

Height: 2.3 m

OD: 1.2 m

71.43 kg U-deposit/batch

Height: 2.7 m

OD: 0.9 m

50 kg U/day

Height: 2.7 m

OD: 4.9 m

10

Development of Electrorefining ProcessDevelopment of Electrorefining Process

HTER Design (~20 kg U/batch)

HTER Construction/Test(~20 kg U/day)

Eng.-Scale HTER(~50 kg U/day)

Year 2008→ Lab. Scale HTER Design Electrohydrodynamic Anal. Cu-recovery Test

Year 2009→ Construction of Electrorefiner Design of Eng. Scale Melting Furn.

Year 2010→ Construction of Eng.-scale HTER System

Double layer cathode

167

mm

167

mm

Outer layer

Inner layer

Back side ofouter layer

Double layer cathode module

11

Electrowinning Process – Flow DiagramElectrowinning Process – Flow Diagram

Cd

TRU/U/RE/Cd- HM>10wt%- RE/TRU<0.25

Saltpurification RE

Salt from electrorefiner

RE/Salt(TRU<100ppm)

MetalFuel

FuelFabrication

TRUProduct

TRU/U/RE/Salt- Pu/U>3.0

RE/TRU/Salt

Cleaned saltTo electrorefiner

TRU/U/RE(Cd<50ppm)

Salt To electrorefiner

Cd-TRUDistillation

Residual ActinideRecovery

LCCElectrowinning

12

LCC assembly tests 8.4wt% U/Cd deposition by mesh-type LCC assembly (manual operation) Set-up of mesh-type LCC assembly to be installed in PRIDE (pneumatic operation)

LCC assembly tests 8.4wt% U/Cd deposition by mesh-type LCC assembly (manual operation) Set-up of mesh-type LCC assembly to be installed in PRIDE (pneumatic operation)

(a) paddle

(b) harrow

Fig. LCC deposition results using Paddle and Harrow (U dendrite growth at salt-Cd interface)

0 1 2 3 4 5 6 7 8-1.65

-1.60

-1.55

-1.50

-1.45

-1.40

-1.35

Vo

ltag

e(V

. vs

. A

g/L

iCl-

KC

l-1

% A

gC

l)

Passed Electric Charge(Ah)

0rpm 100rpm-paddle 200rpm-harrow

50 mA/cm2

U solubility in Cd

[ 5 wt%U/Cd )

Paddle Harrow

[Mesh]

Fig. LCC deposition result using Mesh(No U dendrite growth at salt-Cd interface)

Clean Cd surface

U deposits

0 2 4 6 8 10-2.3

-2.2

-2.1

-2.0

-1.9

-1.8

-1.7

-1.6

-1.5

C

ath

od

e V

olta

ge

(V.

vs.

Ag

/LiC

l-K

Cl-

1%

Ag

Cl)

Passed Electric Charge (Ah)

100 mA/cm2

U solubility in Cd

[ 8.4 wt%U/Cd )

Mesh-type LCC by pneumatic operation

Development of Lab-scale LCC ElectrowinnersDevelopment of Lab-scale LCC Electrowinners

13

Development of Drawdown(RAR) SystemDevelopment of Drawdown(RAR) System

Target concentration of residual actinides in a spent LiCl-KCl salt : < 0.01 wt% (100 ppm)

(1) Recovery of Ans & REs by LCC electrolysis (2) Oxidation of parts of codeposited REs using CdCl2

Features & Progress of RAR Study:

- Same equipment using a LCC electrowinning can be used for a RAR operation.

- RAR process has merits such as a compact equipment and a simple process application compared to a

counter current multi-staged reductive extraction.

- Experimental results show that the residual concentration of uranium can be reduced to a value of less than

100 ppm.

- Design of PRIDE-RAR equipment: 50 kg-salt/10 kg-LCC capacity & remote operation by MSM

[LCC Assembly]

[EW&RAR Reactor]

[Electrorefining & Electrowinning Schematic]

2Ce(-U-Cd) + 3CdCl2 2CeCl3 + 3Cd + 2(-U-Cd)

CdCl2CeCl3

Time intervals

Time intervals

Timeintervals

Timeintervals

(Interval: 30 mins)

14

Computational Model for LCC ElectrowinnerComputational Model for LCC Electrowinner

Simplified model development Half cell one-step reduction reaction:

An3+ + 3e- Ano

Electro-transport is controlled by reduction potential and activation polarization (Butler-Volmer kinetics)

Diffusion limited mass transfer at LiCl-KCl/Cd interface

- Linear concentration gradient at diffusion boundary layer:

Electric field analysis Overall cell voltage drop

CFD based model approach

Cdc

Cdbi

CdsiCd

iiSaltc

saltsi

saltbisalt

iii

CCFDn

CCFDni

,,,,

0 200 400 600 8000

2

4

6

8

10

12

-2.5

-2.0

-1.5

-1.0Applied current denisity: 10mA/cm2

(i0=0.1mA/cm2 )

U Np Pu Am La Ce Pr Nd Gd Y

Cu

rre

nt

de

nsi

ty (

A/c

m2 )

Deposition time (hours)

Cathode potential

Ca

tho

de

po

ten

tial(

V v

s. A

g/A

gC

l)

00.000

0.001

0.002

0.003

0.004

0.005

-2.5

-2.0

-1.5

-1.0

Applied current denisity: 10mA/cm2

(i0=0.1mA/cm2 )

U Np Pu Am La Ce Pr Nd Gd Y

Co

nce

ntr

atio

n in

LC

C(m

ol/c

m3 )

Deposition time (hours)

Cathode potential

C

ath

od

e p

ote

ntia

l(V

vs.

Ag

/Ag

Cl)

Partial current behavior of multi component simulation

(Iapp=10 mA/cm2)

Diffusion controlled electro-transport model

Deposition behavior of multi component simulation

(Iapp=10 mA/cm2)

Electric field pattern & current stream in molten-salt

region (Iapp=10 mA/cm2)

CathodeAnodeohmCell EE

LCC

Cathode

15

Waste Salt Treatment – Flow DiagramWaste Salt Treatment – Flow Diagram

Electrorefining (Drawdown)Electrorefining (Drawdown)

PWR Spent Fuel

VoloxidationU, TRU, FPs U, TRU, FPs

(Oxides)(Oxides)

LiCl Waste (Sr/Cs)

LiCl Recycle

U, TRU, FPs U, TRU, FPs

(Metal)(Metal)

LiCl-KCl Recycle

RE Oxides

LiCl+KCl Waste (RE)

RE : Oxidation

Residual SaltCs & Sr/Ba

Disposal

Solidifying Solidifying Agent Agent High-integrity

Solidification

Waste Salt

minimization(FPs Removal &

Salt Recycle)

<Waste from unit process><Waste from unit process>

Electrolytic ReductionElectrolytic Reduction

Cs/Sr : Salt refining (Crystallization)

Distillation &Condensation

UU

TRUTRU

FinalWasteForm I

FinalWasteForm II

SolidificationSolidification

Characterizationof Waste FormsCharacterizationof Waste Forms

Solidifying Solidifying Agent Agent

16

Waste salt minimizationWaste salt minimization

Lab-scale LiCl waste salt treatmentLab-scale LiCl waste salt treatment

Salt crystal

Crystallization Melting of crystal

▶ Reuse of LiCl waste salt by separation (or

concentration) of Cs/Sr/Ba using layer

crystallization process

▶ About 85-90 % LiCl salt reuse rate

→ 85-90 % FPs separation efficiency

Lab-scale eutectic salt treatmentLab-scale eutectic salt treatment

▶ Oxidative precipitation : separation of RE FPs by oxygen sparing process (←1st pure salt recovery)

▶ Vacuum dis./cond. : distillation /condensation of residual salt from precipitation phase(← 2nd pure salt recovery)

▶Total eutectic salt reuse rate : > 97%

Oxidative precipitationOxidative precipitation

Vacuum distillation/condensationVacuum distillation/condensation

Pure salt phase

Precipitation phase

Condensed Pure salt

Remaining RE oxides

Wasteform Fabrication of Residual WasteWasteform Fabrication of Residual Waste

Lab-scale wasteform fabricationLab-scale wasteform fabrication Eng.-scale waste salt treatment apparatusEng.-scale waste salt treatment apparatus

SAP wasteform

(FPs concentrated

LiCl)

ZIT wasteform

(RE oxides)

Waste loading ~25wt% 25wt%~

Durability

(g/m2day)

wasteform: ~10-2

Cs/Sr: ~10-3

Wasteform: ~10-3

REE: ~10-6

Density

(g/cm3)~2.4 ~4.3

Remark

~1/3 volume reduction

*Compared with zeolite method

Low temperature

processing & high waste

loading

(~1100℃)

Wasteform fabrication

20kg-waste/2 weeks

80kg-waste form

W2.0 X H2.5 X L5.0m

Distillation/condensation

8kg/batch

W2.0 X H2 X L1.5m

Process Layout in PRIDEProcess Layout in PRIDE

19

SummarySummary

Based on the national long-term R&D program, the pyroprocessing technology will be developed to achieve the milestones.

Research activities on lab-scale unit processes will be kept on in terms of throughput, remote operability, process optimization, waste minimization, and so on.

20 kg/batch scale experiments have been successfully conducted.

Eng. scale unit processes have been designed based on the lab-scale research activity. An inactive engineering-scale integrated pyroprocess (PRIDE) facility with a capacity of 10 tons-U per year is planned to be constructed by the end of 2011.

PRIDE should be open for international collaboration. KAERI welcomes collaboration for development of pyroprocessing technology.

Based on the national long-term R&D program, the pyroprocessing technology will be developed to achieve the milestones.

Research activities on lab-scale unit processes will be kept on in terms of throughput, remote operability, process optimization, waste minimization, and so on.

20 kg/batch scale experiments have been successfully conducted.

Eng. scale unit processes have been designed based on the lab-scale research activity. An inactive engineering-scale integrated pyroprocess (PRIDE) facility with a capacity of 10 tons-U per year is planned to be constructed by the end of 2011.

PRIDE should be open for international collaboration. KAERI welcomes collaboration for development of pyroprocessing technology.

20