WiN Canada Conference 2013 Closing the CANDU Fuel Cycle with Modified PUREX Recycling CANDU Spent Fuel Authors Juhx Pellazar Jinah Kim Alexander Koven Sameena Mulam (Presenter) Marty Tzolov Leon Wu
Closing the CANDU Fuel Cycle with Modified PUREX Recycling CANDU Spent Fuel Need for Processing The Modified PUREX Process Benefits Future Work 1
Rationale for Processing Canada s radioactive nuclear used fuel inventory and the cost of managing it is a growing, long term concern How long before something is done about it? Nuclear Fuel Waste Inventory, 2010 and Projection to 2050 [1] 2
CANDU Fuel Fresh CANDU nuclear fuel consists of 88% uranium atoms (U), mostly U 238 Spent CANDU fuel with a burn up of 190MWh/kg U is composed of 0.57% fission products (FP)* Considered unusable waste BUT, processing it can unlock the carbon free energy in the 99.43% actinides, decrease stored waste and storage time *Hart D and Lush D (http://www.nwmo.ca/uploads_managed/mediafiles/645_ 4 4TheChemicalToxicityPotentialofCANDUSpentFuel.pdf) [2] 3
Research Objectives To design a process to convert spent fuel into: 1) Mixed Oxide Fuel (MOX) for CANDU 2) Metallic actinide for Fast Neutron Reactors (FNR) fuel replenishment To maximize the purity of the FP stream and the fuel streams 4
Need for PUREX Modifications Traditional PUREX Process Liquid liquid extraction using Tributyl Phosphate (TBP) Selective separation plus purification of U and Pu Large amounts of liquid waste No separation of long lived minor actinides (MA) from short lived FPs Limited recycling options for fuelling other reactors Modified PUREX Spent Process Fuel Liquid liquid extraction using TBP, plus Dissolution compatible in agents Acid Co extraction of Pu with U Extract Crystallization used to U & Pu decrease liquid load Fission Products & Minor Actinides Minor actinides and FPs separated Partition U & Pu Spent fuel recycled as U Pu metallic and MOX fuel 5
Need for PUREX Modifications Traditional PUREX Process Liquid liquid extraction using Tributyl Phosphate (TBP) Selective separation plus purification of U and Pu Large amounts of liquid waste No separation of long lived minor actinides (MA) from short lived FPs Limited recycling options for fuelling other reactors Modified PUREX Process Liquid liquid extraction using TBP, plus compatible agents Co extraction of Pu with U Crystallization used to decrease liquid load Separation of minor actinides and FPs Recycling of spent fuel as metallic and MOX fuel 6
CANDU Spent Fuel Bundle Feed Preparation Separation and Partitioning Fuel Preparation Metallic FNR Fuel Ln FP Mixed Oxide CANDU Fuel 7
CANDU Spent Fuel Bundle Preparation % Actinide of Feed Dissolution 99.43 % Separation and Partitioning Fuel Preparation Metallic FNR Fuel Ln FP Mixed Oxide CANDU Fuel 8
CANDU Spent Fuel Bundle Preparation U 69.52 % % Actinide of Feed Dissolution 99.43 % U Crystallization other Fuel Preparation Metallic FNR Fuel Ln FP Mixed Oxide CANDU Fuel 9
CANDU Spent Fuel Bundle Preparation U/Pu/Np 29.90 % U 69.52 % Extraction % Actinide of Feed Dissolution 99.43 % U Crystallization other MA/FP/Ln 0.01 % Fuel Preparation Metallic FNR Fuel Ln FP Mixed Oxide CANDU Fuel 10
CANDU Spent Fuel Bundle % Actinide of Feed MA 0.01 % Preparation U 69.52 % Dissolution 99.43 % U Crystallization U/Pu/Np 29.90 % Extraction other MA/FP/Ln MA MA/Ln SETFICS B SETFICS A TRUEX FP <0.01 % Ln <0.01 % Fuel Preparation Metallic FNR Fuel Ln FP Mixed Oxide CANDU Fuel 11
CANDU Spent Fuel Bundle % Actinide of Feed MA 0.01 % Preparation Dissolution U 69.52 % 99.43 % U Crystallization U/Pu/Np 29.90 % Extraction other MA/FP/Ln MA MA/Ln SETFICS B SETFICS A TRUEX FP <0.01 % Ln <0.01 % Oxidation Electrolytic Reduction Metallic FNR Fuel Ln FP Mixed Oxide CANDU Fuel 12
Overall Efficiency Metallic actinide stream <0.01% FP 99.99% Actinides Final FP stream 97.26% FP <0.01% Actinides 13
Waste Management Waste Type Waste Proposed Treatment Solid Zircaloy Fuel Cladding Reused as alloying material for FNR bundle High Level Liquid Waste Organic Aqueous Reused after alkaline washing Calcination and Ceramic immobilization Effluent Gases NO x Nitric acid formation with absorption column 14
Criticality Issues Subcritical limits were compared to the guidelines in the CNSC Guidance document GD 327, Guidance for Nuclear Criticality Safety, section 2.4.1. Parameter Subcritical Limit for Fissile Solute Concentration of fissile nuclide (g/l) 235 UO 2 (NO 3 ) 2 239 Pu(NO 3 ) 4 11.6 7.3 [3] 235 UO 2 (NO 3 ) 2 = 0.01 g/l 239 Pu(NO 3 ) 4 = 0.01 g/l 15
Benefits of Modified PUREX Recycle fuels from CANDU, FNR, LWR, etc. U crystallization leads to decreased liquid waste Depleted U can be used in FNRs Actinides separated from fission products Concentrated to ~1.21% fissile content, reused as fuel in CANDU Minimizes stored waste and storage time Proliferation mitigated by not separating Pu from U 16
Future Recommendations Strategically separate out already stable, valuable fission products (rhodium and ruthenium) Recycle waste streams and multiple cycles to increase recovery of all actinides Development of an implementation strategy Optimization of spent fuel storage times and volumes of used nuclear fuel constituents Transition plan for FNRs in Canada 17
Thank you 18
References [1] Low Level Radioactive Waste Management Office, "Inventory of Radioactive Waste in Canada," Government of Canada, Ottawa, 2012. [2] Hart D and Lush D, http://www.nwmo.ca/uploads_managed/mediafiles/645_4 4TheChemicalToxicityPotentialofCANDUSpentFuel.pdf [3] http://nuclearsafety.gc.ca/eng/lawsregs/guidancedocuments/published/html/gd327/ 19