Particle packing fraction

The RCSS has several design limits. These include limits on fast neutron fluence to the graphite components, peak graphite stress limits, fuel particle packing fraction limits, metallic component temperature limits, including control rods, and core shutdown margin limits. These limits are ... 

Updated neutronics analyses were performed at SNL to better match the reference AHTR geometry and fliel/coolant fractions. As before, the fuel type was TRISO-coated particle fuel with a particle packing fraction of 30% in the fuel compacts. All of the calculations were performed with 1200 K neutron cross-sections, and the thermal scattering function, S(a,P), was also used at 1200 K for the carbon in the fuel compacts and prismatic matrix. 

Z, Z and Z represent the Young s modulus or tensile strengths of the composite, matrix and fiber, respectively, A is twice the fiber aspect ratio (I and d are the fiber length and diameter, respectively), r/j accounts for the relative moduli of the fiber and matrix, Vf is the fiber volume fraction, fy depends upon the particle packing fraction, and is the maximum packing fraction of the reinforcement. 

A pebble as used in the HTR-10 contains about 12,000 parficles. The fuel zone is a ball of binding graphite matrix in a particle packing fraction of about 10%. The fuel zone measured in a diameter of 50 mm is wrapped by a fuel-free layer of graphite with a thickness of 5 mm, resulting in an overall diameter of 60 mm for the pebble. The heavy metal loading of each pebble is around 7 g. 

Polynomial vs. Krieger-Dougherty equations for relative viscosity variations with respect to maximum particle packing fraction. 

This fitted the data well up to volume fractions of 0.55 and was so successful that theoretical considerations were tested against it. However, as the volume fraction increased further, particle-particle contacts increased until the suspension became immobile, giving three-dimensional contact throughout the system flow became impossible and the viscosity tended to infinity (Fig. 2). The point at which this occurs is the maximum packing fraction, w, which varies according to the shear rate and the different types of packings. An empirical equation that takes the above situation into account is given by [23] ... 

FIG. 4 Nomialized concentration distribution of a 0.1 molar 1 1 electrolyte in an uncharged cylindrical pore of radius five times the diameter of the ions. The dashed line, solid up-triangles, and solid down-triangles are the neutral solvent particles, cations, and anions, respectively, in an SPM model with 0.3 solvent packing fraction. The open symbols are for the cations and anions in the RPM model. 

We have assumed that a random packed structure is more likely at high rates with a distribution of floe sizes. The volume fraction of floes will depend upon the floe packing fraction, giving rise to a floe diameter 2af with particles per floe ... 

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