Homogeneous reactors, biological

The choice of an adequate DO concentration. The desired DO concentration is a compromize between economy demands and hydraulic and biological demands. Moreover, in a non-homogeneous reactor a proper spatial distribution has to be determined. 

The biological hazards associated with a homogeneous reactor are due chiefly to the radioactive rare earths, alkaline earths, and iodine [2]. The importance, as a biological hazard, of any one of these groups or nuclides within the group depends on assumptions made in describing exposure conditions however, contributes a major fraction of the radiation hazards for any set of conditions. While the accumulation of hazardous materials such as rare earths and alkaline earths will be controlled by the processing methods to be described, less is known about the chemistry of... 

Introduction. The removal of iodine from the fuel solution of a homogeneous reactor is desirable from the standpoint of minimizing the biological hazard and neutron poisoning due to iodine and reducing the production of gaseous xenon and its associated problems. Iodine will also... 

E. D. Arnold and A. T. Gresky, Relative Biological Hazards of Radiations Expected in Homogeneous Reactors TBR and HPR, US.A.EC Report ORNL-1982, Oak Ridge National Laboratory, 1955. 

By far the most efficient catalysts are enzymes, which regulate most biological reactions. Biological catalysts are without question the most important catalysts (to us) because without them life would be impossible. Enzymes are proteins that may be either isolated molecules in solution (homogeneous) or molecules bound to large macromolecules or to a cell wall (heterogeneous). We have not yet learned how to create catalysts with nearly the efficiency and selectivity of nature s enzyme catalysts. We will consider biological reactors at the end of this chapter as the example of the most efficient chemical reactor possible. 

Figure 4.1. Heterogeneous biological processes utilizing a biological film (a biodisk reactor). A group of disks is fastened to a horizontal shaft. Each disk supports the growth of the desired culture. The disks are turned through the liquid and gas phases. Mass transport is subject to the same limitations as given in Fig. 2.3 for pseudo-homogeneous processes. With the biodisk, however, step 4 (limitation in the solid phase) becomes significant. (From Moser, 1981.)...

Early chapters focused on homogeneous and heterogeneous reactions, since these are the two major systems with which practicing engineers are concerned. However, there are also many important biological/biochemical reactors, and systems. This has become a major growth industry for engineers. 

The radioactive inventories of the biological shields of the Finnish nuclear reactors have been estimated in a straightforward, but approximate way. The present knowledge on the compositions of the bioshield materials may be satisfactory mainly because of the measurements described in this report. A few checks against other studies indicate that no significant elements have been overlooked. However, the actual water content in the activated regions of the bioshields and the homogeneity of the materials are still uncertain. 

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