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
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