The Korean Strategy for Nuclear
Fuel Cycle
2010. 6
Do-Hee Ahn
Table of Contents
Ⅰ
Spent Fuel Management
Ⅱ
Recent Pyroprocessing Research Activity
II-1.
II-2.
II-3.
II-4.
III
1
Electrolytic Reduction
Electrorefining
Electrowinning
Waste Salt Treatment
Summary
Spent Nuclear Fuel
Attribute
 High 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
 Energy resource : contains 1% Pu and 93% Uranium
 Annual Spent Fuel Generation 700t/yr
 Projection of Spent Fuel Generation
CANDU

95 t/yr,unit
 4 units
 380 t/yr
PWR

20 t/yr, unit
 16 units
 320 t/yr
Accumulated
SF Arisings (ktHM)
(ktHM)
Spent Fuel Accumulation
90
80
70
60
50
PWR
40
30
10,0761 t, 2009
20
CANDU
10
0
2005 2015
2035
700 2025
톤/년
2045 2055
Year
2
2065 2075 톤/년
2085 2095
11,500
Status of Spent Fuel Storage
 On-site SF storage limit will be reached from 2016
 Decision making process for interim SF storage
As of end of 2009
3
Expansion Plan
NPP
Sites
Cumulative
Amount
(MTU)
Storage
Capacity
(MTU)
Year of
Saturation
Storage
Capacity
(MTU)
Year of
Saturation
Kori
1,762
2,253
2016
2,253
2016
Yonggwang
1,704
2,686
2016
3,528
2021
Ulchin
1,401
1,642
2008
2,326
2018
Wolsong
5,894
5,980
2009
9,155
2017
Total
10,761
12,561
17,262
Promising Fuel Cycle Concept (KIEP-21)
Korean, Innovative, Environment-Friendly, and Proliferation-Resistant System for the 21st C (KIEP-21)
Volume Reduction
FR Closed Fuel Cycle
Recycling
Pyroprocess
FR Metal Fuel
(U-TRU-Zr)
Secondary
EM Pump
IHTS Piping
Reactor Head
S/G
DHX
IHX
PWR
Primary Pump
Reactor Core
Containment Vessel
Reactor Vessel
Dupic
Wastes
(Cs, Sr)
Decay Storage
GEN-IV
FR(SFR)
Benefits
CANDU
 Saves disposal space by a factor of 100
 Shortens the management period to a few
hundred years
Disposal
 Increases U utilization by a factor of 100
 Ensures intrinsic proliferation resistance
Flow Diagram of Pyroprocessing (KAERI)
Electrowinning
Off-gas
treatment
TRU fuel
fabrication
Fission gas
PWR spent fuel
Electrolytic
reduction
Decladding & Voloxidation
U3O8+
(TRU+FP)
oxide
Electrorefining
Sodium-cooled
fast reactor
(U+TRU+FP)
metal
Air
Molten salt
waste treatment
Uranium
recovery
Recycle
or treatment
Recycle
or LLW
Cladding material
Low level waste
TRU : Transuranic elements
NM : Noble metal elements
FP : Fission products
5
R&D Issues of Pyroprocessing
 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
HM
6
Voloxidation Electroreduction Electrorefinning Electrowining Fuel Fabrication
SFR
Electrolytic Reduction Process – Flow Diagram
Pretreatment
Electrolytic Reducer
(650 oC, 120 kW)
UO2
Metal U
+ MS
+ Cs, Sr
Cathode Processor
(725 oC, 120 kW)
Electrorefining
Metal U
Electrode Handling Apparatuses
MS: LiCl-Li2O molten salt
7
LiCl
MS + Cs, Sr
Waste Salt Treatment
Development of Electrolytic Reduction Process
Bench Scale ER
(~g UO2/batch)
Lab. Scale ER
(~20 kg UO2/batch)
Year 2008
→ Change of Ceramic
Cathode Basket to
Metal Cathode Basket
Year 2009
→ Successful Demonstration
of Lab-scale Electrolytic
Reducer
8
Eng. Scale ER
(~50 kg UO2/batch)
Year 2010
→ Construction of Eng-scale
ER focusing on the High
Speed Reduction
Electrorefining System – Flow Diagram
22.5 kg UCl3/batch
Height: 2 m
OD: 0.9 m
CERS (Continuous Electrorefining System)
71.43 kg U-deposit/batch
U chlorinator
Salt recycle
OD: 0.9 m
UCl3
Electroreducer
Height: 2.7 m
Uranium deposit
Salt distiller Uranium deposit
Impure U mixture
Continuous
electrorefiner
Melting furnace
Continuous
recovery
50 kg U/day
50 kg U/day
Height: 2.3 m
OD: 1.2 m
9
Height: 2.7 m
Residual salt
Electrowinner
OD: 4.9 m
Development of Electrorefining Process
HTER Design
(~20 kg U/batch)
HTER Construction/Test
(~20 kg U/day)
Eng.-Scale HTER
(~50 kg U/day)
167 mm
Double layer cathode
Inner layer
Outer layer
Back side of
outer layer
Double layer cathode
module
Year 2008
→ Lab. Scale HTER Design
Electrohydrodynamic Anal.
Cu-recovery Test
10
Year 2009
→ Construction of Electrorefiner
Design of Eng. Scale Melting Furn.
Year 2010
→ Construction of Eng.-scale
HTER System
Electrowinning Process – Flow Diagram
Salt To
electrorefiner
Cleaned salt
To electrorefiner
Residual Actinide
Recovery
LCC
Electrowinning
Salt from
electrorefiner
TRU/U/RE/Salt
- Pu/U>3.0
RE/
TRU/
Salt
Cd
RE/Salt
(TRU<100ppm)
Salt
purification
TRU/U/RE/Cd
- HM>10wt%
- RE/TRU<0.25
Cd-TRU
Distillation
TRU/U/RE
(Cd<50ppm)
11
TRU
Product
Fuel
Fabrication
Metal
Fuel
RE
Development of Lab-scale LCC Electrowinners
 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)
[Mesh]
Paddle
Harrow
[ 5 wt%U/Cd )
-1.35
0rpm
100rpm-paddle
200rpm-harrow
-1.40
-1.45
(a) paddle
-1.50
-1.55
-1.60
50 mA/cm
U solubility in Cd
2
-1.65
0
1
2
3
4
5
6
Passed Electric Charge(Ah)
7
8
(b) harrow
Fig. LCC deposition results using Paddle and Harrow
(U dendrite growth at salt-Cd interface)
12
Cathode Voltage(V. vs. Ag/LiCl-KCl-1% AgCl)
Voltage(V. vs. Ag/LiCl-KCl-1% AgCl)
Mesh-type LCC by pneumatic operation
[ 8.4 wt%U/Cd )
-1.5
2
100 mA/cm
-1.6
-1.7
-1.8
Clean Cd surface
-1.9
U deposits
-2.0
-2.1
-2.2
U solubility in Cd
-2.3
0
2
4
6
8
10
Passed Electric Charge (Ah)
Fig. LCC deposition result using Mesh
(No U dendrite growth at salt-Cd interface)
Development 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
2Ce(-U-Cd) + 3CdCl2  2CeCl3 + 3Cd + 2(-U-Cd)
[EW&RAR Reactor]
CeCl3
(Interval: 30 mins)
CdCl2
Time
intervals
[LCC Assembly]
[Electrorefining & Electrowinning Schematic]
13
Time
intervals
Computational Model for LCC Electrowinner
2
Current density (A/cm )
 Half cell one-step reduction reaction:
An3+ + 3e-  Ano
 Electro-transport is controlled by
reduction potential and activation
polarization (Butler-Volmer kinetics)
Diffusion controlled electrotransport model
cSalt
 ni FD
Cd
i
Electric field analysis
Cd
CiCd
, s  Ci ,b
Cd
c
 CFD based model approach
2
0
200
400
600
3
0.005
-1.0
Applied current denisity: 10mA/cm
2
(i0=0.1mA/cm )
0.004
2
Cathode potential
0.003
0.002
0.001
U
Np
Pu
Am -1.5
La
Ce
Pr
Nd
-2.0
Gd
Y
-2.5
0
Cathode
LCC
Deposition time (hours)
Deposition behavior of multi
component simulation
(Iapp=10 mA/cm2)
Electric field pattern &
current stream in molten-salt
region
(Iapp=10 mA/cm2)
14
-2.5
800
(Iapp=10 mA/cm2)
0.000
 Overall cell voltage drop
E Cell  Eohm  Anode Cathode
4
Partial current behavior of
multi component simulation
Cathode potential(V vs. Ag/AgCl)
salt
Cisalt
,b  Ci , s
Cathode potential
6
-1.0
U
Np
Pu
Am -1.5
La
Ce
Pr
Nd
Gd -2.0
Y
Deposition time (hours)
Concentration in LCC(mol/cm )
ii  ni FD
salt
i
8
0
 Diffusion limited mass transfer at LiClKCl/Cd interface
- Linear concentration gradient at
diffusion boundary layer:
2
Applied current denisity: 10mA/cm
2
(i0=0.1mA/cm )
10
Cathode potential(V vs. Ag/AgCl)
12
Simplified model development
Waste Salt Treatment – Flow Diagram
PWR
Spent Fuel


Voloxidation
U, TRU, FPs
(Oxides)
Waste Salt
minimization
U
U, TRU, FPs
Electrolytic Reduction
Electrorefining (Drawdown)
(Metal)
LiCl Waste (Sr/Cs)
LiCl+KCl Waste (RE)
Cs/Sr : Salt refining
(Crystallization)
RE : Oxidation
<Waste from unit process>
(FPs Removal &
Residual Salt
Cs & Sr/Ba
Salt Recycle)
RE
Oxides
 LiCl Recycle
High-integrity
Solidification
15
Solidifying
Agent
Distillation &
Condensation
 LiCl-KCl Recycle
Solidification
Final
Waste
Form I
Final
Waste
Form II
Disposal
Solidifying
Agent
Characterization
of Waste Forms
TRU
Waste salt minimization
Lab-scale LiCl waste salt treatment
Lab-scale eutectic salt treatment
Oxidative precipitation
Pure salt phase
Precipitation phase
Crystallization
Melting of crystal
Vacuum distillation/condensation
Condensed Pure salt
Remaining RE oxides
Salt
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
▶ 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%
Wasteform Fabrication of Residual Waste
Lab-scale wasteform fabrication
Eng.-scale waste salt treatment apparatus
Distillation/condensation
 8kg/batch
 W2.0 X H2 X L1.5m
SAP wasteform
ZIT wasteform
(FPs concentrated
LiCl)
(RE oxides)
Waste
loading
~25wt%
25wt%~
Durability
wasteform: ~10-2
Wasteform:
~10-3
(g/m2day)
Cs/Sr: ~10-3
Density
(g/cm3)
Remark
REE:
~10-6
~2.4
~4.3
~1/3 volume
reduction
Low
temperature
processing &
high waste
loading
*Compared with
zeolite method
(~1100℃)
Wasteform fabrication
 20kg-waste/2 weeks
 80kg-waste form
 W2.0 X H2.5 X L5.0m
Process Layout in PRIDE
18
Summary
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 labscale 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.
19