Li2TiO3 pebble beds constitutive equations of using standard three-axial tests: Implementation of the model in an FEM code

Atomistic Simulation of the Structural, Thermodynamic, and Elastic Properties of Li2TiO3

“…Finally, we provide a comparison between the elastic properties calculated here for Li 2 TiO 3 and those published for the other candidate ceramic breeder materials. For Li 4 SiO 4 the bulk, shear, and Young’s moduli (in x , y , and z ) were calculated using DFT, yielding values of 67.6, 49.8, and 108.2 GPa, 122.7 and 125.8 GPa, respectively, while the experimental study of Zaccari and Aquaro gave a value of 90 GPa for the Young’s modulus. The literature values for the bulk modulus of Li 2 O fall in the range 80.0–108 GPa, , while the isotropic Young’s modulus is 70.0 GPa and the shear modulus is 45.6 GPa .…”

“…6 There has been significant interest over the past decade in generating a complete database of relevant properties of these lithium ceramic materials. Despite this, for lithium metatitanate, there are still gaps in the database; some mechanical properties remain only partially known (in particular, the elastic moduli are either unknown or the data display a wide distribution 7,8 ), and tritium migration through the matrix is also poorly understood.…”

Thermal transient and the temperature profile in a HELICA mock-up simulated by a new finite element homogenous model

“…(1). The slip of the pebbles and the collapse of the bed are simulated by the Mohr-Coulomb yielding criterion, defined by a zero cohesion and a friction angle equal to 31.3 • [8].…”

“…The pebble bed temperature gradient is controlled by two external helium-cooled plates and provided with square cooling channels. The operating conditions of coolant are: helium at nominal flow rate of 8 g/s, inlet pressure of 1.5 MPa and inlet temperature of 250 • C. Inside the pebble bed a helium flow rate (purge gas) was regulated at 0.002 g/s (witch means to have velocity inside the bed lower than 0.01 m/s); the inlet pressure is equal to 0.05-0.1 MPa and the inlet temperature 50 • C [6][7][8][9].…”