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Nitride Fuel and Pyrochemical Process Developments for Transmutation of Minor Actinides in JAERI

Nitride Fuel and Pyrochemical Process Developments for Transmutation of Minor Actinides in JAERI. Masahide Takano, Mitsuo Akabori, Kazuo Minato, Yasuo Arai Japan Atomic Energy Research Institute.

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Nitride Fuel and Pyrochemical Process Developments for Transmutation of Minor Actinides in JAERI

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  1. Nitride Fuel and Pyrochemical Process Developments for Transmutation of Minor Actinides in JAERI Masahide Takano, Mitsuo Akabori, Kazuo Minato, Yasuo Arai Japan Atomic Energy Research Institute OECD/NEA 8th Information Exchange Meeting on Actinide and Fission Product Partitioning & Transmutation, Las Vegas, USA, 9-11 Nov. 2004

  2. Content >Background >PROMINENT program >Fabrication of MA nitrides Carbothermic synthesis of (Pu,Am,Cm)N & (Pu,Am,Cm,Zr)N >Property Measurements of MA nitrides Hydrolysis & Evaporation behavior of AmN & (Am,Zr)N >Pyrochemical process Pu nitridation in Pu-Cd alloy >Irradiation test (Pu,Zr)N & PuN+TiN >Conclusion OECD/NEA 8th Information Exchange Meeting on Actinide and Fission Product Partitioning & Transmutation, Las Vegas, USA, 9-11 Nov. 2004

  3. Nitride fuel cycle - background > JAERI has proposed double strata fuel cycle for MA transmutation, based on U-free nitride fuel, ADS, and pyrochemical reprocessing. > Expected on nitride fuel: Good thermal properties, Mutual solubility among MA nitrides, High heavy metal density > We have studied on: Fuel fabrication technology Property measurements Irradiation behavior Pyrochemical process > Experiments on MA nitride: Limitation in facility, apparatus, handling, material amount, High purity inert atmosphere required OECD/NEA 8th Information Exchange Meeting on Actinide and Fission Product Partitioning & Transmutation, Las Vegas, USA, 9-11 Nov. 2004

  4. Fuel Fabrication Nitride Fuel Cycle Pu/MA burning Reprocessing Fuel Fabrication Technology Fuel Property Measurement Pyrochemical Process Technology Fuel Irradiation Experiment PROMINENT program > Started Nov. 2002, five year program > Development and demonstration of elemental technology for nitride fuel cycle in laboratory scale > JAERI, Osaka Univ, MMC, NDC, JAPC PROMINENT: Property Measurements, Pyrochemical Process and Irradiation Experiments Needed for Nitride Fuel Cycle Technology. Research areas in PROMINENT program OECD/NEA 8th Information Exchange Meeting on Actinide and Fission Product Partitioning & Transmutation, Las Vegas, USA, 9-11 Nov. 2004

  5. Fabrication of MA nitrides (1) (Pu,Am,Cm)N > Pu+Am+Cm+(Zr) nitrides 30~40 mg scale > Starting materials 243Am2O3, (240Pu,244Cm)O2, ZrO2 amorphous carbon > Fabrication method (Pu,Am,Cm,Zr)N Carbothermic reduction of oxides mixture MOx + xC + 1/2N2 MN + xCO Nitridation: N2 1300 ºC Decarburization: N2+4%H2 1500 ºC > Analyses X-ray diffraction N,O,C analyses Process temperature and CO gas release OECD/NEA 8th Information Exchange Meeting on Actinide and Fission Product Partitioning & Transmutation, Las Vegas, USA, 9-11 Nov. 2004

  6. Fabrication of MA nitrides (2) Composition of the oxides and carbon mixtures Expected product (Pu,Am,Cm)N (Pu,Am,Cm,Zr)N Mixture weight (mg) 31.40 37.58 Pu/Am/Cm/Zr molar ratio 0.45 /0.34 /0.21 /0 0.14 /0.10 /0.06 /0.70 C/O molar ratio 2.0 1.3 OECD/NEA 8th Information Exchange Meeting on Actinide and Fission Product Partitioning & Transmutation, Las Vegas, USA, 9-11 Nov. 2004

  7. Fabrication of MA nitrides (3) > (Pu,Am,Cm)N Single phase solid solution 0.4956nm (0.4960 nm by Vegard’s law) No oxide phase Low carbon content (<0.05 wt%) (Pu,Am,Cm,Zr)N > (Pu,Am,Cm,Zr)N Double phases with NaCl structure different (Pu,Am,Cm)/Zr ratio Low oxygen content (0.15 wt%) High carbon content (1.3 wt%) remained as carbonitride (Pu,Am,Cm)N XRD profiles of products OECD/NEA 8th Information Exchange Meeting on Actinide and Fission Product Partitioning & Transmutation, Las Vegas, USA, 9-11 Nov. 2004

  8. Property measurements (1) Hydrolytic behavior > MA nitrides are reactive with moisture > Hydrolysis of AmN and (Am,Zr)N observed in ambient air > AmN reacted with moisture to form Am(OH)3 > (Am0.1Zr0.9)N retained the phase over 1000h AmN Am(OH)3 Am2O3 Weight gain of AmN, (Am,Zr)N and (Dy,Zr)N in air and moist N2 OECD/NEA 8th Information Exchange Meeting on Actinide and Fission Product Partitioning & Transmutation, Las Vegas, USA, 9-11 Nov. 2004

  9. Property measurements (2) Evaporation behavior > Am has high vapor pressure > Evaporation behavior of AmN & (Am,Zr)N in He gas flow AmN = Am(g) + 1/2N2 > Evaporation rate constant, k (s-1) v = -(dN/dt) = kN > AmN retained the phase while heating, no metallic phase Arrhenius’ plots of k > k of AmN in (Am,Zr)N depressed > Selective evaporation of AmN on (Am,Zr)N change in composition OECD/NEA 8th Information Exchange Meeting on Actinide and Fission Product Partitioning & Transmutation, Las Vegas, USA, 9-11 Nov. 2004

  10. Property measurements (3) New apparatus > Apparatus for thermal property measurements installed > Designed for nitrides and small sized samples > Thermal diffusivity ~ laser flash method sample diameter 3~5 mm installed in Ar atmosphere > Specific heat capacity ~ drop calorimeter sample sealed in Pt capsule > Thermal expansion ~ high temp. XRD installed in Ar atmosphere OECD/NEA 8th Information Exchange Meeting on Actinide and Fission Product Partitioning & Transmutation, Las Vegas, USA, 9-11 Nov. 2004

  11. Pyrochemical process of nitride fuel > Anodic dissolution of PuN in LiCl-KCl eutectic salt examined > Recovery of Pu into liquid Cd cathode demonstrated with high current efficiency > Pu in Pu-Cd alloy converted to PuN > Experiments on Am-containing nitride will start soon at “TRU-HITEC” Schematic diagram of pyrochemical process for nitride fuel OECD/NEA 8th Information Exchange Meeting on Actinide and Fission Product Partitioning & Transmutation, Las Vegas, USA, 9-11 Nov. 2004

  12. N2 gas Crucible LiCl-KCl Pu-Cd melt 723K PuN N2 gas Furnace Cd Pu-Cd PuN Nitridation of Pu in Pu-Cd alloy > N2 bubbling process U in U-Cd: 100% recovery Pu in Pu-Cd: only 10% recovery decrease in Pu activity in Pu-Cd > Nitridation-distillation combined process (a) N2 bubbling process Pu: 99% recovery PuN with high purity obtained 973K Pu-Cd (12wt% Pu) Recovered PuN (b) Nitridation-distillation combined process OECD/NEA 8th Information Exchange Meeting on Actinide and Fission Product Partitioning & Transmutation, Las Vegas, USA, 9-11 Nov. 2004

  13. Irradiation test schedule Irradiation: May 2002 ~ Nov. 2004 PIE: Apr. 2005 ~ Irradiation test ongoing > Basic irradiation behavior of U-free nitride fuel (Pu,Zr)N > (Pu,Zr)N & PuN+TiN pellets Pu: 20wt%, He-bond > Irradiation ongoing at JMTR PuN+TiN Linear power: ~40kW/m Target burnup: 20 at% of Pu > Irradiation of (Pu,Np,Zr)N pellet scheduled at JOYO with JNC OECD/NEA 8th Information Exchange Meeting on Actinide and Fission Product Partitioning & Transmutation, Las Vegas, USA, 9-11 Nov. 2004

  14. Concluding remarks > (Pu,Am,Cm)N and (Pu,Am,Cm,Zr)N synthesized by carbothermic reduction of the oxides Mutual solubility among PuN-AmN-CmN was demonstrated. > Hydrolysis and evaporation behavior of AmN and (Am,Zr)N studied AmN was chemically and thermodynamically stabilized by formation of solid solution with ZrN. > Pu nitridation in Pu-Cd alloy investigated Simultaneous nitridation-distillation process yielded high purity PuN. OECD/NEA 8th Information Exchange Meeting on Actinide and Fission Product Partitioning & Transmutation, Las Vegas, USA, 9-11 Nov. 2004

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