Nitride Fuel and Pyrochemical Process Nitride Fuel and Pyrochemical Process Developments for Developments for
Transmutation of Minor ActinidesTransmutation of Minor Actinidesin JAERIin 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
OECD/NEA 8th Information Exchange Meeting on Actinide and Fission Product Partitioning & Transmutation, Las Vegas, USA, 9-11 Nov. 2004
>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
Content
OECD/NEA 8th Information Exchange Meeting on Actinide and Fission Product Partitioning & Transmutation, Las Vegas, USA, 9-11 Nov. 2004
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
> Experiments on MA nitride: Limitation in facility, apparatus, handling, material amount, High purity inert atmosphere required
> We have studied on: Fuel fabrication technology Property measurements Irradiation behavior Pyrochemical process
OECD/NEA 8th Information Exchange Meeting on Actinide and Fission Product Partitioning & Transmutation, Las Vegas, USA, 9-11 Nov. 2004
PROMINENT program
Pyrochemical ProcessTechnology
Fuel IrradiationExperiment
Nitride Fuel Cycle
Fuel Fabrication
Reprocessing Pu/MA burning
Fuel FabricationTechnology
Fuel PropertyMeasurement
Research areas in PROMINENT program
> JAERI, Osaka Univ, MMC, NDC, JAPC
> Started Nov. 2002, five year program
> Development and demonstration of elemental technology
for nitride fuel cycle in laboratory scale
PROMINENT:
Property Measurements,
Pyrochemical Process and
Irradiation Experiments Needed
for Nitride Fuel Cycle Technology.
OECD/NEA 8th Information Exchange Meeting on Actinide and Fission Product Partitioning & Transmutation, Las Vegas, USA, 9-11 Nov. 2004
Fabrication of MA nitrides (1)
243Am2O3, (240Pu,244Cm)O2, ZrO2
amorphous carbon
> Starting materials
> Fabrication method
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
(Pu,Am,Cm)N
(Pu,Am,Cm,Zr)N
Process temperature and CO gas release
> Pu+Am+Cm+(Zr) nitrides
30~40 mg scale
OECD/NEA 8th Information Exchange Meeting on Actinide and Fission Product Partitioning & Transmutation, Las Vegas, USA, 9-11 Nov. 2004
Fabrication of MA nitrides (2)
Expected product
Pu/Am/Cm/Zr molar ratio
C/O molar ratio
Mixture weight (mg)
(Pu,Am,Cm)N (Pu,Am,Cm,Zr)N
31.40 37.58
0.45 /0.34 /0.21 /0 0.14 /0.10 /0.06 /0.70
1.32.0
Composition of the oxides and carbon mixtures
OECD/NEA 8th Information Exchange Meeting on Actinide and Fission Product Partitioning & Transmutation, Las Vegas, USA, 9-11 Nov. 2004
Fabrication of MA nitrides (3)
(Pu,Am,Cm)N
(Pu,Am,Cm,Zr)N
XRD profiles of products
> (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
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
OECD/NEA 8th Information Exchange Meeting on Actinide and Fission Product Partitioning & Transmutation, Las Vegas, USA, 9-11 Nov. 2004
AmN Am(OH)3 Am2O3
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
Weight gain of AmN, (Am,Zr)Nand (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
Property measurements (2) Evaporation behavior
> Am has high vapor pressure
> Evaporation behavior of AmN &
(Am,Zr)N in He gas flowAmN = Am(g) + 1/2N2
> Evaporation rate constant, k (s-1)
v = -(dN/dt) = kN
> AmN retained the phase while heating,
no metallic phase
> Selective evaporation of AmN on (Am,Zr)N
change in composition
> k of AmN in (Am,Zr)N depressedArrhenius’ plots of k
OECD/NEA 8th Information Exchange Meeting on Actinide and Fission Product Partitioning & Transmutation, Las Vegas, USA, 9-11 Nov. 2004
Property measurements (3) New apparatus
> Apparatus for thermal property measurements installed
> Thermal diffusivity ~ laser flash method sample diameter 3~5 mm installed in Ar atmosphere
> Specific heat capacity ~ drop calorimeter sample sealed in Pt capsule
> Designed for nitrides and small sized samples
> 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
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
Schematic diagram of pyrochemicalprocess for nitride fuel
> Pu in Pu-Cd alloy converted to PuN
> Experiments on Am-containing nitride
will start soon at “TRU-HITEC”
OECD/NEA 8th Information Exchange Meeting on Actinide and Fission Product Partitioning & Transmutation, Las Vegas, USA, 9-11 Nov. 2004
Nitridation of Pu in Pu-Cd alloy
(a) N2 bubbling process
Cd
N2 gas
Pu-Cd
PuN
Furnace
(b) Nitridation-distillation combined process
> 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
Pu: 99% recovery
PuN with high purity obtained
Pu-Cd (12wt% Pu) Recovered PuN
Crucible
N2 gas
Pu-Cd melt
PuN
LiCl-KCl
723K
973K
OECD/NEA 8th Information Exchange Meeting on Actinide and Fission Product Partitioning & Transmutation, Las Vegas, USA, 9-11 Nov. 2004
Irradiation test ongoing
(Pu,Zr)N
PuN+TiN
> (Pu,Zr)N & PuN+TiN pellets
Pu: 20wt%, He-bond
> Irradiation ongoing at JMTR
Linear power: ~40kW/m
Target burnup: 20 at% of Pu
> Basic irradiation behavior of
U-free nitride fuel
Irradiation: May 2002 ~ Nov. 2004
PIE: Apr. 2005 ~
Irradiation test schedule> 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
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
> Pu nitridation in Pu-Cd alloy investigated
AmN was chemically and thermodynamically stabilized
by formation of solid solution with ZrN.
Simultaneous nitridation-distillation process yielded high purity PuN.
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