Waste Salt Minim imiza zatio ion durin ing g Pyropro oprocess - PowerPoint PPT Presentation

The 10th IEPT, Oct. 6-10, Mito, Japan Part rtitio itionin ing g of Fissio ion Product ducts and Waste Salt Minim imiza zatio ion durin ing g Pyropro oprocess 2008. 10. 8. Eung Ho Kim, G-I Park, I-T Kim, H.Lee and S-W.Park KAERI 1

Backgrounds  Next generation nuclear fuel cycles ○ Reduction of environmental hazard by selectively recovering a long-lived nuclide and transmuting it ○ Minimization of the waste volume to be eventually disposed of  Basic strategy for partitioning ○ Classify and optimize waste streams arising when treating spent fuel ○ Minimize waste volumes resulting from each waste stream Little information on a strategy for waste minimization in pyroprocess  Strategy for optimization of waste streams and waste minimization ○ Pyro-partitioning of fission products being performed in KAERI ○ Strategy requested for optimizing waste streams and minimizing waste amounts ○ Reduction of HLW generating from each waste stream -Converting HLW to LLW through an increase of DF or SF ○ Candidate wasteforms for consolidation of waste salts from a pyroprocess 2

A Strategy for Efficient Management of Spent Fuel in Korea Sodium-Cooled Fast Reactor Pu ( SFR ) TRU (0.9%) MA Recovered / (0.1%) Transmute I, Tc (0.1%) FP Reuse Disposal Facility (D/F) Cs, Sr Recovered / Dispose of LLW (0.3%) Stored Burn-up 100 % U Storage/Reuse Uranium (95.6%) Dispose of LLW / HLW CANDU Reducing FP HLW by 235 U = 0.9% (3%) converting to LLW and disposal Hull Reuse Fresh Fuel Spent Fuel (100 % Uranium) FP: Rare earth, Noble metal, Volatile / Semi-volatile Fission Products KAERI’s waste management strategy: directed to minimize HLW amounts 3

A Flow Diagram of Pyroprocess being Developed by KAERI Optimizing waste streams and evaluating a strategy for minimization of wastes Environment Waste form Off-gas treatment Spent Metallic Fuel (?) Xe, Kr, 3 H, I, Tc, etc U 3 O 8 SFR UO 2 (TRU+FP) U+TRU+ Oxide RE Electro- TRU fuel Decladding & Electrolytic refining fabrication reduction Vol-oxidation U +TRU + LiCl-KCl- FP(RE) LiCl- PWR RECl 3 (AnCl 3 ) CsCl/SrCl 2 Spent Oxide fuel Air Anode Cathode Processor Sludgy Hulls (Salt Vaporization) (NM) U Waste salt Treatment Metallic Waste Form Fab. recovery Recycle to SFR / CANDU or Store as LLW Metallic Ceramic Waste form Waste forms -Cs/Sr -RE with An 4

Fission Products Release with Voloxidation Conditions Standard Advanced Flow sheet for capturing fission gases Nuclides voloxidation voloxidation* Remarks (500 o C) (1200 o C) HT I Cs,Rb,Cd Tc, Ru,C-14 Advanced Kr / Xe <30% 100% Conversion Trapping Trapping Trapping Voloxidizer Unit Unit Unit Unit H 100% 100% ~1200 o C Fly ash Filter Ca-based filter CuO Ag-X I-129: long- 1,000 o C 600 o C 400 o C 150 o C vacuum I <10% 100% lived nuclide Tc-99: long- Tc <1% 92% lived nuclide C-14: long- HTO Kr/Xe C <10% 100% HEPA lived nuclide Trapping Trapping Filter Unit Unit Highly Vent radioactive, Molecular Solid Adsorbent Cs <1% 98% RT high decay -80 o C Sieve, RT heat nuclide Ru <1% 98% Noble metal Challenges Mo <1% 62% Noble metal Rh <1% 83% Noble metal  DF > 10 4 to minimize the impact to the environment Rb <1% 96% Further development of trapping technologies and conditions * INL hot experimental data in I-NERI program of INL-KAERI  Optimization of waste forms for consolidation of Advantages several absorbents  Minimize influence of fission products on the  Minimization of waste amounts issued from capturing down-stream process conditions fission gases  Recover and store fission products separately 5

Treatment of Hull Objective:  Experimentally recover higher than 99% fissile material during air-voloxidation process  Look for a promising way enabling a conversion of hull to LLW  Strip residual fissile materials from the contaminated hull  Classify the hull as LLW → Challenge !! Promising technology (Rinsing Mechanism) Fabrication of LLW metallic Waste (Zr - 8SS 1) ) LiCl + KCl ZrCl 4 LiCl + KCl Hull contaminated AnCl 3 , RECl 3 , Regeneration of Salt with actinide CsCl, SrCl 2 NMO+ZrO 2 Actinides Rare earth and I/II groups Noble metals 4UO 2 + 3ZrCl 4 + Zr = 4UCl 3 + 4ZrO 2 RE 2 O 3 + ZrCl 4 = RECl 3 + ZrO 2  Not chlorinated 4PuO 2 + 3ZrCl 4 + Zr = 4PuCl 3 + 4ZrO 2 Cs 2 O + ZrCl 4 = CsCl + ZrO 2  Co-precipitated with ZrO 2 4AmO 2 +3 ZrCl 4 + Zr = 4AmCl 3 + 4ZrO 2 SrO + ZrCl 4 = SrCl 2 + ZrO 2 Steven M. Frank, et al., “ Immobilization of Technetium and other Fission Products from Processed Spent Nuclear Fuel 1) into a Metallic Waste Form”, 2008 IPRC, Aug 24 -27, 2008 Jeju Island, Korea 6

Waste Salt Treatment Technologies  Developing technologies to recycle waste salts to process units, not by releasing to repository -Salt cooling technologies: Czochlarski, Zone freezing, Layer crystallization -Precipitation technology: oxidation-precipitation using air PWR   Spent Fuel U U, TRU, FPs U, TRU, FPs Electrorefining (Drawdown) Voloxidation Electrolytic Reduction (Metal) (Oxides) TRU Strategy LiCl Waste (Sr/Cs) LiCl+KCl Waste (RE / An) Minimize Salt Cs/Sr : Salt refining RE : Oxidation waste salt (Crystallization) by adopting Regeneration Distillation & a recycling Condensation (FPs Removal & Residual Salt RE technology w/ Cs & Sr Oxides Salt Recycle)   LiCl Recycle LiCl/KCl Recycle Develop Solidifying Agent Final Waste Forms high- High-integrity Disposal integrity Solidifying Solidification wasteforms Agent Pretreatment : Waste from unit process 7

Recovery of Purified LiCl Salt from a Waste Salt Cooled wall Crystal layer Salt LiCl LiCl Czochlarski Layer Crystallization  To concentrate Cs and Sr to eutectic point by cooling method  To theoretically recover 99wt% LiCl of LiCl from a waste salt  To evaluate and select which technology is more preferable and effective for scale-up and practical use. Zone Freezing 8

Zone Freezing Technology for Recovery of LiCl Salt Experimentally 1.0 recycle 90% of LiCl * Diameter : 44mm(LiCl=200g) * Diameter : 44mm(LiCl=200g) (contaminated with * initial weight : 2wt% (CsCl=1wt%, SrCl 2 =1wt%) * Initial weight : 2wt% (CsCl=1%, SrCl 2 =1%) a small amount of * temperature : 660 o C * Temperature : 660 o C 0.8 *1.67 mm/Hr impurity) * 1.67 mm/Hr CsCl ; k=0.0101 / SrCl 2 ; k=0.0116 CsCl k=0.0101 SrCl 2 k=0.0116 90% *2.8mm/Hr 0.6 * 2.8mm/Hr C h /C o CsCl ; k=0.0224 / SrCl 2 ; k=0.0184 O CsCl k=0.0224 SrCl 2 k=0.0184 h /C  C 0.4 Cs/Sr separation efficiency : 90%(90% recovery of LiCl) 0.2 Fabricated to a final 10% Cs/Sr separation efficiency : 95%(80%recovery of LiCl) wasteform (contaminated with 0.0 0.0 0.2 0.4 0.6 0.8 1 90% of initial impurity h/H [-] amount) h/ho (or weight ratio) [-] 9

LiCl-KCl Waste Salt Recycle Possible to recycle all most of eutectic salts to electrorefiner and to minimize waste salt to be disposed of  REE are precipitated as oxide or oxychloride forms metal ingot Electro-refining pure LiCl/KCl REUSE condensation 3+ 3+ U TRU LiCl/KCl pure LiCl/KCl LiCl/KCl vapor Pure salt phase waste Vacuum Distillation 2) 1) & Precipitation Oxidation/Dechlorination O 2 Phase Precipitate phase RE oxide Final separation RE/TRU Oxychloride Waste (or oxide) form + Salt residue RECl 3 + 0.5O 2 → REOCl + Cl 2 1) or RECl 3 +O 2 → REO 2 + 1.5Cl 2 REOCl + 0.25O 2 → 0.5 RE 2 O 3 + 0.5Cl 2 2) 10

Wasteforms Waste LiCl from Electro-reduction Waste LiCl-KCl from Electro-refining Recycle of clean salt Melt Crystallization Oxide precipitation Concentrated residual salt Oxide precipitates Cs & Sr REE Solidification Candidate wasteform for consolidation Candidate wasteform for REE / An oxides of waste salt [LiCl residual salt]  BSG, SynRoc, Pyrochlore and etc  Incorporation of Cl into a wasteform - Mineral-based wasteform  Monazite-based wasteform [KAERI] sodalite, apatite, spodiosite, wadalite - Reliable host matrix for α -radionuclide - phosphate-based glass - Reasonable processing condition  Not incorporation of Cl [KAERI] - Waste loading & Chemical durability - Radiation stability - SAP-based wasteform [SAP: xSiO 2 -yAl 2 O 3 -zP 2 O 5 ] 11

A Flowsheet for Wasteforms Fabrication Fabrication of Final Ceramic Waste Forms Gelling Agent (Si, Al, P)  Two different waste streams : LiCl salt residue and RE oxides Gellation &  Each waste can be treated by using the same solidification Aging (70 o C) equipment, but at different processing conditions. Drying (100 o C) Solidification of Solidification of Heat (600 o C) LiCl Salt Residue RE Oxides Treatment Salt Residue RE Oxides Reaction Agent (with Cs/Sr) SAP matrix (NH 4 H 2 PO 4 ) Mixing & Rxn Preparation (650 o C) of SAP matrix Glass Frit Glass Frit Heat Treatment (≈ 1,000 o C) Final Waste Form Monazite SAP Waste Form Waste Form 12