Mechanical Behavior and Degradation of Advanced Nuclear Fuel and Structural Materials: Fuels & Claddings II
Sponsored by: TMS Structural Materials Division, TMS: Mechanical Behavior of Materials Committee, TMS: Nuclear Materials Committee
Program Organizers: Dong Liu, University of Oxford; Peng Xu, Idaho National Laboratory; Simon Middleburgh, Bangor University; Christian Deck, General Atomics; Erofili Kardoulaki, Los Alamos National Laboratory; Robert Ritchie, University of California, Berkeley
Thursday 2:00 PM
March 3, 2022
Room: 204A
Location: Anaheim Convention Center
Session Chair: Simon Middleburgh, Bangor University ; Peng Xu, INL
2:00 PM
Microscale Thermal Conductivity and Residual Stress Measurements in TRISO Particle Coatings: Alexander Leide1; Miriam Mowat2; James Pomeroy1; Roland Simon2; Mark Davies3; Dave Goddard4; Martin Kuball1; Dong Liu1; 1University of Bristol; 2Thermap Solutions; 3Ultra Safe Nuclear Corporation; 4National Nuclear Laboratory
Tristructural isotropic (TRISO) nuclear fuel particles consist of a central fuel kernel and a series of pyrolytic carbon and silicon carbide coatings to create a multi-layer sphere approximately 1 mm in diameter. These coatings are typically only tens of microns thick, making measuring their properties challenging using conventional methods. Thermal conductivity of individual TRISO coating layers has been measured at room and elevated temperatures using time domain thermoreflectance (TDTR) with ~5 µm spatial resolution on polished cross sections. Similar measurements in the frequency domain (FDTR) probe millimetre scale heat transfer, giving information on the thermal barrier resistance of coating layer interfaces in complete TRISO particles. Additionally, residual stress measurements have been made in the coating layers of TRISO particles using a ring-core focussed ion beam milling technique, finding tensile hoop stress in PyC and compressive hoop stress in SiC, of similar magnitude to those predicted to arise during operation.
2:20 PM
Mesoscale Modeling of the Relationships between Microstructure and Mechanical Properties in the Porous Pyrocarbon Buffer Layer for TRISO Particle Fuel: Mohammed Gomaa Abdoelatef1; Claire Griesbach2; Kumar Sridharan2; Ramathasan Thevamaran2; Gerczak Tyler3; Wen Jiang4; karim Ahmed1; 1Texas A&M University; 2University of Wisconsin; 3Oak Ridge National Laboratory; 4Idaho National Laboratory
TRISO particle fuel is a leading nuclear fuel for several advanced reactors. TRISO exhibit high performance but occasionally fail because of the fracture and degradation of the porous pyrocarbon buffer layer. A combined phase-field and finite-element mesoscale modeling approach has been developed to correlate microstructure and mechanical properties of this buffer layer. 3D experimental characterization and atomistic scale modeling were utilized to both inform and validate the mesoscale model. The model accounts for the change of the layer’s elastic and fracture properties with microstructure, temperature, and irradiation conditions. The modeling results demonstrate a strong dependence of the mechanical properties on the fraction, size, and morphology of pores in the buffer layer. Parametric studies and sensitivity analysis were employed to assess uncertainty. This work is a part of our combined experimental and computational multiscale effort for quantifying and correlating buffer microstructure with mechanical properties towards a more robust TRISO fuel particle.
2:40 PM Cancelled
Effect of Nb Alloying and Thermo-mechanical Processing on the Anisotropic Biaxial Creep Behavior of Zircaloy Cladding: Mahmoud Hawary1; K. Murty1; 1North Carolina State University
ZIRLO® and HANA-4 are Nb-containing Zircaloys, which have been developed to enhance the degradation characteristics of the radioactive nuclear fuel cladding tubes in light water reactors. These two alloys are alloyed with different weight% of Nb and used in nuclear reactors as thin-walled tubes following cold work and stress relief. In this work, the anisotropic biaxial creep of ZIRLO® is compared to HANA-4 in the as-received (CWSR) and recrystallized conditions. A quantitative description of the creep anisotropy is evaluated using EBSD to generate crystallite orientation distribution functions (CODF). The biaxial creep tests were conducted using internally pressurized tubing superimposed with axial load under varied hoop-to-axial stress ratios of 0 to 2. Anisotropy parameters (R and P) are evaluated using the modified Hill criterion for anisotropic materials. Creep loci are constructed at a constant energy of dissipation that deviated from isotropy. This work is supported by NSF grant #CMMI-1727237.
3:00 PM
Size-dependent Radiation Damage Mechanisms in Nanowires and Nanoporous Structures: Daniel Vizoso1; Maria Kosmidou2; T. John Balk2; Khalid Hattar3; Chaitanya Deo1; Remi Dingreville3; 1Georgia Institute of Technology; 2University of Kentucky; 3Sandia National Laboratories
This presentation details the origins and size effects of the radiation-damage mechanisms in nanowires and nanoporous structures in model FCC (gold) and BCC (niobium) nanostructures using accelerated multi-cascade atomistic simulations and in-situ ion irradiation transmission electron microscopy experiments. We will discuss three different size-dependent mechanisms of damage accumulation in irradiated nanostructures: the sputtering of very small nanowires, the formation and accumulation of point defects/dislocation loops in larger nanowires, and a FCC to HCP phase transformation for a narrow range of wire diameters in the case of gold nanowires. The details of size-effects in nanowires at the transition from defect accumulation to a saturation and annihilation mechanism and how it impacts nanoporous structures will be highlighted. Taken together, our results shed light on the compounded, size-dependent mechanisms leading to the radiation resistance of nanowires and nanoporous structures. SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525.
3:20 PM Break
3:40 PM
Investigation of Elemental Segregation and Precipitation in Ion-irradiated Advance Austenitic Alloy A709 Using Advance Techniques: Dominic Piedmont1; Xiang Liu2; Hyosim Kim3; Frank Garner4; Lin Shao4; T.-L. Sham5; James Stubbins1; 1University of Illinois at Urbana-Champaign; 2Zhejiang University; 3Los Alamos National Laboratory; 4Texas A&M University; 5Argonne National Laboratory
A709, an advanced austenitic alloy, has been down-selected for the next generation reactors for structural applications because of its high-temperature strength, corrosion resistance, and creep properties. Previous studies investigated the microstructural evolution at low doses and swelling behavior at high doses. This work quantifies the dose dependence of elemental segregation and precipitation behavior at high doses, using Atom Probe Tomography (APT), to link other microstructural changes, like void swelling and formation of network dislocations, to be observed with High Energy Diffraction Microscopy (HEDM). Samples were investigated after ion-irradiation by 3.5 MeV Fe2+ ions at an irradiation temperature of 575°C to peak dpa of 100, 200, and 400. This work addresses the need to accurately measure compositional differences of the matrix at different doses with atomistic resolution; critical to understanding the radiation-induced segregation and precipitation of A709 at the mesoscale. Potential interconnection between elemental segregation and void swelling is investigated.