Core true absorption

Figure9.8 The absorbance of 1.05 x 10 M pinacyanol chloride at 610.0 min pH 9.59 sodium borate buffer (I = 0.1) at 50 °C vs. dodecanoate concentration. The absorption spectrum of pinacyanol chloride in aqueous solution of anionic soaps changes sharply to one characteristic of its solutions in organic solvents within a small range of soap concentration (X ax 610 nm). This effect is attributed to the formation of micelles, in whose hydrocarbon-like layers or cores the dye is solubilized. The concentration of soap at which this spectral change occurs is taken as the cmc. The use of dyes for the determination of cmc values may lead to micelle formation at a concentration below the true cmc. In practice, the method gives only a rough approximation of the cmc. (Adapted, with some modifications, from Corrin et al., 1946.)...

When comparing these results with observations it should be kept in mind that the line strengths in some cases are sensitive to, for example, the density distribution of the ejecta. This is especially true for the Na I, Mg I], and [Si I] lines, for which the ionization is dominated by photoionization by diffuse UV emission, mainly from O I recombination lines. This is sensitive to both the density and to resonance line blocking in the UV. At epochs less than -450 days the density in the core can be so high that forbidden lines like the [O I] and [Si I] lines are optically thick, resulting in P-Cygni type absorptions also for these lines. 

The fact that the same parameter T appears in both distributions given in (4.196) is a direct consequence of the assumption that the medium in question is a purely scattering material. We know, however, that many media of practical importance to reactor technology possess appreciable absorption cross sections. This is especially true, of course, for media comprising the core of thermal reactors. In these situations the results (4.196) are not generally valid, and some modification must be made in... 

The boundary conditions used assume that the fast flux has the same value on the core side of the core-tank wall as on the blanket side the same is also true of the slow flux. It is also specified that the fast flux and slow flux become zero at some extrapolated reactor radius. At the coretank wall, the net fast-neutron current on the blanket side is assumed equal to that on the core side, while the net slow-neutron current on the core side is assumed equal to the flux rate of neutron absorptions in the core tank plus the net slow-neutron current on the blanket side. 

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