Multigroup diffusion model

EXISTENCE THEOREMS AND SPECTRAL THEORY FOR THE MULTIGROUP DIFFUSION MODEL... 

D = Djh jc). Also, define two matrices of scalar functions hy A = (dj]c(r)) F = fjk T)). The differential equations of reactor kinetics for the multigroup diffusion model become (neglecting delayed neutrons)... 

The radiation-hydrodynamic simulation includes the Quotidien EOS [29] and Ion EOS based on the Cowan model [30], For the electron component, a set of fitting formulae derived from the numerical results from the Thomas-Fermi model and a semi-empirical bonding correction [31] are adopted. The effective Z-number of the partially ionized plasma is obtained from the average atom model. Radiation transport is treated by multigroup diffusion. 

Continuous models. The extension from the finite models of 2 to multigroup diffusion and transport theory models involving a continuum of possible positions and velocities, involves some very careful technical analysis. 

The second basically different approach to the multiregion problem is the two-group model. This model attempts to describe the distribution of neutrons in both space and energy by separating all neutrons into thermal neutrons and nonthermal (fast) neutrons. The spatial distribution of neutrons in each group is given by a one-velocity diffusion relation in much the same manner as in the multigroup treatment however, the... 

Neutronic characteristics of MSRs have been explored in the literature. Flow effects were considered when calculating the effective multiplication factor and fast neutron, thermal neutron, and delayed neutron precursor distribution of the liquid-fuel MSR based on the multigroup neutron diffusion equation and delayed neutron precursor conversation equation (Zhang et ah, 2009b Cheng and Dai, 2014 Zhou et ah, 2014). Spatial kinetic models were developed for better neutronic analysis of the MSRs (Zhang et ah, 2015 Zhuang et ah, 2014). 

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