Do-Hee Ahn The Korean Strategy for Nuclear Fuel Cycle

Table of Contents 1 Ⅰ Ⅱ III Spent Fuel Management Recent Pyroprocessing Research Activity Summary II-1. Electrolytic Reduction II-2. Electrorefining II-3. Electrowinning II-4. Waste Salt Treatment

Spent Nuclear Fuel 2 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 CANDU PWR  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 / 년 700 톤 / 년 Spent Fuel Accumulation (ktHM) 10,0761 t, 2009

Status of Spent Fuel Storage 3 NPP Sites Kori Yonggwang Ulchin Wolsong Total Storage Capacity (MTU) 2,253 2,686 1,642 5,980 12,561 Cumulative Amount (MTU) 1,762 1,704 1,401 5,894 10,761 Year of Saturation As of end of 2009 Storage Capacity (MTU) 2,253 3,528 2,326 9,155 17,262 Year of Saturation Expansion Plan  On-site SF storage limit will be reached from 2016  Decision making process for interim SF storage

Korean, Innovative, Environment-Friendly, and Proliferation-Resistant System for the 21 st C (KIEP-21) Benefits  Saves disposal space by a factor of 100  Shortens the management period to a few hundred years  Increases U utilization by a factor of 100  Ensures intrinsic proliferation resistance Promising Fuel Cycle Concept (KIEP-21) FR Closed Fuel Cycle Volume Reduction GEN-IV FR(SFR) PWR CANDU FR Metal Fuel (U-TRU-Zr) (Cs, Sr) Decay Storage Disposal Recycling Wastes Pyroprocess Dupic

Flow Diagram of Pyroprocessing (KAERI) 5

R&D Issues of Pyroprocessing 6  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

Electrolytic Reduction Process – Flow Diagram Pre- treatment Electrolytic Reducer (650 o C, 120 kW) Electro- refining Waste Salt Treatment Cathode Processor (725 o C, 120 kW) UO 2 MS + Cs, Sr MS: LiCl-Li 2 O molten salt Metal U Metal U + MS + Cs, Sr LiCl Electrode Handling Apparatuses 7

Development of Electrolytic Reduction Process Bench Scale ER (~g UO 2 /batch) Lab. Scale ER (~20 kg UO 2 /batch) Eng. Scale ER (~50 kg UO 2 /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 8

Electrorefining System – Flow Diagram CERS (Continuous Electrorefining System) Continuous electrorefiner Continuous recovery Uranium deposit Salt recycle Salt distiller Melting furnace Electro- reducer UCl 3 U chlorinator Impure U mixture Electrowinner Residual salt  22.5 kg UCl 3 /batch  Height: 2 m  OD: 0.9 m  50 kg U/day  Height: 2.3 m  OD: 1.2 m  kg U-deposit/batch  Height: 2.7 m  OD: 0.9 m  50 kg U/day  Height: 2.7 m  OD: 4.9 m 9

Development 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 Outer layer Inner layer Back side of outer layer Double layer cathode module 10

Electrowinning Process – Flow Diagram Cd TRU/U/RE/Cd - HM>10wt% - RE/TRU<0.25 Salt purification RE Salt from electrorefiner RE/Salt (TRU<100ppm) Metal Fuel Fabrication TRU Product TRU/U/RE/Salt - Pu/U>3.0 RE/ TRU/ Salt Cleaned salt To electrorefiner TRU/U/RE (Cd<50ppm) Salt To electrorefiner Cd-TRU Distillation Residual Actinide Recovery LCC Electrowinning 11

 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) [ 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 [ 8.4 wt%U/Cd ) Mesh-type LCC by pneumatic operation Development of Lab-scale LCC Electrowinners 12

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 CdCl 2  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) + 3CdCl 2  2CeCl 3 + 3Cd + 2(-U-Cd) CdCl 2 CeCl 3 Time intervals Time intervals (Interval: 30 mins) 13

Computational Model for LCC Electrowinner Simplified model development  Half cell one-step reduction reaction: An e -  An o  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 Partial current behavior of multi component simulation (I app =10 mA/cm 2 ) Diffusion controlled electro- transport model Deposition behavior of multi component simulation (I app =10 mA/cm 2 ) Electric field pattern & current stream in molten-salt region (I app =10 mA/cm 2 ) LCC Cathode 14

Waste Salt Treatment – Flow Diagram  Electrorefining (Drawdown) PWR Spent Fuel Voloxidation U, TRU, FPs (Oxides) LiCl Waste (Sr/Cs) LiCl Recycle   U, TRU, FPs (Metal) LiCl-KCl Recycle  RE Oxides LiCl+KCl Waste (RE) RE : Oxidation Residual Salt Cs & Sr/Ba Disposal Solidifying Agent High-integrity Solidification Waste Salt minimization (FPs Removal & Salt Recycle) Electrolytic Reduction Cs/Sr : Salt refining (Crystallization) Distillation & Condensation U TRU Final Waste Form I Final Waste Form II Solidification Characterization of Waste Forms Characterization of Waste Forms Solidifying Agent 15

Waste salt minimization Lab-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 % LiCl salt reuse rate → % FPs separation efficiency Lab-scale eutectic salt treatment ▶ Oxidative precipitation : separation of RE FPs by oxygen sparing process (←1 st pure salt recovery) ▶ Vacuum dis./cond. : distillation /condensation of residual salt from precipitation phase(← 2 nd pure salt recovery) ▶ Total eutectic salt reuse rate : > 97% Oxidative precipitation Vacuum distillation/condensation Pure salt phase Precipitation phase Condensed Pure salt Remaining RE oxides

Wasteform Fabrication of Residual Waste Lab-scale wasteform fabrication Eng.-scale waste salt treatment apparatus SAP wasteform (FPs concentrated LiCl) ZIT wasteform (RE oxides) Waste loading ~25wt%25wt%~ Durability (g/m 2 day) wasteform: ~10 -2 Cs/Sr: ~10 -3 Wasteform: ~10 -3 REE: ~10 -6 Density (g/cm 3 ) ~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 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 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  PRIDE should be open for international collaboration. KAERI welcomes collaboration for development of pyroprocessing technology. 19