CRISP Wokshop on Imaging with Neutrons, ILL 17 March 2014 INDUSTRIAL RESEARCH AT E.N.E.A. R. Coppola ENEA-Casaccia, Via Anguillarese 301, 00123 Roma, Italy
CURRENT ACTIVITIES SANS studies of high-dose irradiated steels, neutron diffraction characterization of plasma-facing components (EFDA, ITER) SANS studies of low-dose irradiated nuclear steels, textures in ODS materials (EERA JPNM) Neutron diffraction studies of fuel cell electrodes (Italian Ministry for Economic Dev., Ansaldo FC, SOFCPower) Participation in IAEA CRP’s for development of neutron techniques applied to energy research materials and in NeT – JRC Petten
TRIGA RC-1 – 1 MW at ENEA-Casaccia Specific applications - Radiography and Neutron Tomography - Material activation - Thermal cavity availability - Neutron Diffraction - Epithermal flow generation - Training for students and safety authority staff
Irradiated Structural Material Chemical compositions of the test alloys in wt.% Heat C Si Mn Cr Mo Ni B V W N Ta Fe EUROFER97 0.12 0.04 0.48 8.91 <0.001 0.02 < 0.001 nat B 0.2 1.08 0.02 0.14 Rest 806 ADS2 0.109 0.020 0.602 9.31 0.002 0.005 0.0082 nat B 0.190 1.27 0.021 0.055 Rest 826 ADS3 0.095 0.031 0.395 8.80 0.046 0.008 0.0083 10 B 0.193 1.125 0.028 0.088 Rest 825 ADS4 0.10 0.03 0.38 9.00 0.028 0.006 0.1160 10 B 0.197 1.06 0.025 0.08 Rest Heat Treatment: 1040 °C 30 min + 760 °C 90 min He Concentration Irradiation HFR-Petten up to < 10 ppm nat B <10 appm He 16.3 dpa at T = 250°C, 350°C, 450°C 82 ppm nat B ~80 appm He Neutron fluence rate: 83 ppm 10 B 1.42x10 18 m -2 s -1 (thermal); ~415 appm He 3.99 x10 18 m -2 s -1 (fast, >0.1 MeV) 1160 ppm 10 B ~5800 appm He Dr. M. Klimenkov KIT
Investigation of B doped alloys He bubbles in ADS3 (450°C), 415 appm He, 16 dpa Cuboidal helium bubbles decoration of grains boundaries and dislocations lines Dr. M. Klimenkov KIT
D22 measurements ( in coll. Dr. L. Porcar )
Best-fit distributions 400 and 5600 appm He Number (left) and volume (right) distribution functions obtained from SANS nuclear cross-sections of samples ADS4 B-alloyed Eurofer97 5600 appm helium neutron irradiated at 400 ° C to 16 dpa (red, volume fraction 0.038) and ADS3 B-alloyed Eurofer97 400 appm He neutron irradiated at 450 ° C to 16 dpa (blue, volume fraction 0.007).
SANS-TEM comparison ADS4 16 dpa 400°C 5600 appm He Black squares: SANS best-fit volume distribution (A. U.) R > 15 Å Blue rectangles: TEM histogram (Dr. M. Klimenkov )
H-loaded Zr-Nb 2.5 wt% tubes Axial H-free reference material H-loaded by cathodic charge + Radial 24 h 400°C in N 2 ( Nb hydrides ) provided by Dr. J. Santisteban - CNEA, in the frame of IAEA CRP
radially averaged SANS cross sections (cm -1 vs nm -1 ) of CNEA H-loaded and H-free Zr-Nb 2.5 wt % samples ( unpublished, coll. Dr. A. Heinemann, TUM )
2D SANS intensities at 20 m 12 Å (A.U.) of CNEA Zr-Nb tubes H-free H-loaded ( unpublished coll. Dr. A. Heinemann, TUM )
Best-fit and size distributions for the difference between CNEA H-loaded and H- free samples obtained by the B-spline method
Neutron diffraction studies of FC electrodes Scheme of a molten carbonate fuel cell, where the electrolyte is a combination of alkali carbonates, water is produced at the anode site and CO 2 is needed at the cathode site .
The potential of Neutron Diffraction • All components of the HTFC can be studied, both separately and as a whole • Observation of crystallographic (lattice) structure changes (not too localized – only for homogeneous effects) • Diagnostics under controlled environment (T & atmosphere not restrictive) • Penetration possible through several mm of shielding and containing material
NiCr/CeO 2 anodes Porous Ni-Cr (5 wt%) anodes (1 mm thick) were coated with CeO 2 protective layer obtained by sol-gel technique followed by heat treatment at 650°C under N 2 – H 2 5% Ni-Cr-Ce Ni-Cr The following samples were investigated by neutron diffraction ( no chance with grazing X-Rays! ): -N. 1: Uncoated NiCr substrate as a reference -N. 3: as N. 1 with standard CeO 2 deposition parameters -N. 3bis as N. 1 with optimised CeO 2 deposition parameters
NiCr/CeO 2 anodes: results NiCr CeO 2 NiO NiO mag. D20, in coll. J. Rodriguez-Carvajal, V. Nassif, L. Laversenne
NiCr/CeO 2 anodes: results Optimizing the CeO 2 deposition parameters the electrode as a whole can be accurately characterized at D20 : The following crystallographic phases were identified: NiCr 68.4%, CeO 2 6.3%, NiO (n.+m.) 25.3% Pathway towards in-situ measurements 1. Characterize as-received materials and define optimum measurement conditions OK 2. Analyze each treated (operated) material/component by ND analysis and compare whether the differences in crystallographic structure with the as-received sample (e.g. CeO 2 vs Ce 2 O 3 , hexagonal vs cubic lattice or different lattice spacing) can be understood 3. Prepare complete fuel cell for ND analysis (carry out poisoning, long term operation, accelerated testing protocol, etc.) 4. Carry out ND measurement (short spells only)
Degradation effects in HTFC Too many to mention! But which should be monitored in situ?
Residual stresses in Eurofer97 TBM welded mock- up’s (in collaboration with CEA) Scheme of the investigated Eurofer welded plate and a cross-sectional picture of the weld. The principal stress axes are the longitudinal direction (along the weld, in the plane of the plate), the transverse direction (the direction across the weld line, in the plane of the plate) and the normal direction (normal to the surface of the plate). The neutron diffraction measurements were carried out at mid-length of the plate, at different distances from the weld centre.
STRESSES IN WELDED EUROFER97 STEEL Longitudinal stresses in MPa (dots) determined by neutron diffraction as a function of the distance, in mm, from the weld centre (“ 0 ”) . For comparison, the longitudinal calculated stresses are shown, indicated by squares. Ref.: R. Coppola, O. Asserin, P. Aubert, C. Braham, A. Monnier, M. Valli, E. Diegele, JNM 417 (2011) 51
NUCLEAR AND MAGNETIC SANS I M + I N Nuclear and magnetic SANS cross-section d Q ( ) 2 2 2 ( ) dR N ( R ) V ( R ) F ( Q , R ) d 0 I N dQ d ( ddQ ) d ( ) nucl mag 2 2 R ( Q ) 1 ( ) / ( ) mag nucl dQ ( ) H = 1.4 T nucl Polarised SANS A A M N m n a) reference sample, b) irradiated sample
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