Capture Ratios

For the start-up of a reactor, its core is allowed to heat up by withdrawal of the control rods until the recapture ratio is slightly greater than f.O. When the optimum operating temperature is reached, the control rods are inserted until the capture ratio is exactly f, and the reaction proceeds at a steady rate. For the shutdown of a reactor, its control rods are fully inserted, reducing the recapture ratio to nearly zero. 

Table XIII. Capture Ratios in the Solvolysis of 18a in Binary Solvent Mixtures at 35 ° C (77, 78)...

Solvolysis reactions of vinylic substrates in binary protic solvents are numerous (69), but in the majority of cases, the distribution of the two products is not useful for evaluating the relative reactivities of the two solvents. The main reason is that the vinyl ethers formed in H20-R0H mixtures, the vinyl formates, and sometimes the vinyl acetates formed in HCOOH-AcOH or AcOH-H20 mixtures are frequently unstable under the solvolytic conditions. Their hydrolysis to the ketones will give erroneous capture ratios. In addition, in most cases the nature of the product-forming intermediate is not clear and it is frequently the ion pair. 

Fig. 2. Variation of capture ratio with square of impact parameter for linear HCI target rotators distributed at temperatures = 500 and 1000°K 50 collisions were studied per point, (a) V = 10 cm/sec. (b) d = 5.5 x 10 cm/sec. (c) v = 10 cm/sec.

Figure 4 shows calculated plots of the capture ratio as a function of impact parameter for a dipolar symmetric top molecule in collision with an ion. The molecule is CHgCN and the ion has the mass of the parent ion CH3CN+. The very large effect of the dipole on capture is clearly apparent when comparison is made with the Langevin prediction for a molecule with the polarizability of CH3CN. On the other hand, as for HCI, the effectiveness of... 

Fig. 4. Variation of capture ratio with square impact parameter for CHgCN+ -f CHgCN system. The symmetric top target rotators are distributed at temperature Tr = 500° K. Bars indicate variation of calculation with different random number sets.

Numerical cross sections for such reactions can be obtained by calculating the fraction of hindered collisions from plots of ion-dipole orientation angle and then multiplying this fraction by the capture ratio. The product, an eflective reaction ratio, is then integrated over impact parameters to give the reaction cross section. 

Transmutation. Recycling actinides to the LWRs will decrease the average material neutron multiplication factor by only 0.8 percent, provided that they are of high purity [C2], Recycling to LMFBRs, however, will be preferred. There will be less neutron capture in impurities, such as lanthanides, and the average fission-to-capture ratio of the actinides should be higher in a fast spectrum than in a thermal one. 

For the ZEPP system presented in Fig. 2.7 the allowable installed costs for the capture plant have been estimated to be in between 80 and 120M for a 1.4GWthermai input natural gas combined cycle (NGCC) plant. To meet the cost targets, an ITM based ZEPP power plant should have an electric efficiency of at least 52%. Capture ratios (carbon captured/carbon fed to the process) of 100% result in plant efficiencies lower than 50%. Capture ratios of the order of 85% are accompanied with plant efficiencies of about 52%. The allowable installed costs window is satisfied when the oxygen flux is at least 20 ml/cm min and the costs of the ITM tubes should be less than 1,500 /m. This clearly sets the targets for materials and turbine development in order for the system to be economically viable within the capture cost boundary conditions. 

Mesonic atoms can be regarded as new types of nuclear probes in material science dealing with chemical aspects. In this section, capture ratio problems in binary systems as well as X-ray intensity patterns in mesonic transitions are briefly described. 

Coulomb capture or atomic capture ratio is an important parameter. The capture ratio A(Zj, Zj) is defined by ... 

The capture ratio of the muon has been measured for chlorides as shown in Fig. 14. Fermi and Teller assumed that the capture probability is proportional to the energy loss of the muon (or pion) near the corresponding atomic species. This leads to a relation between the capture ratio and Z as follows ... 

Therefore, efforts to improve agreement between the theoretical and experimental capture ratios have been extended by several authors. Daniel et al. proposed the following relation ... 

Fig. 14. Capture ratio and atomic number. The Fermi-Teller s Z-law is indicated by a broken line...

Chemical effects on the muon capture ratio have been studied in several target systems. As this review paper does not aim at providing a complete bibliography on... 

Some uses of mesonic X-rays for analytical purposes have been published". However, only in a system in which the capture ratio is well known, would a quantitative determination be practical. 

The flume experiment made it clear that CPOM was captured behind the crest of ripple by separation vortex, and was deposited. The CPOM particles transported to the rearward of crest of ripple is presented by the accumulation of supplied number density particle velocity Ug and capture ratio iff. The supplied number density and particle velocity are written as follows (Ashida Michiue 1972). 

As a result of all the improvements, the K-Mg30 sorbent had substantially lower steam consumption for the regeneration resulting in a steam/C02 ratio of 1.6 at the test conditions used. Consequently, the efficiency penalty was reduced almost 50% from 13% points (K-Mg70) to about 7.6% points (K-Mg30) for a 95% CO2 capture ratio in an NGCC [31]. 

Unfortunately, at the moment, there is not any work available in literature on the economic assessment of SER therefore, the evaluation and comparison can only be performed in terms of efficiencies and carbon capture ratio. 

To summarize the situation at present, the nonclassical norbomyl cation seems to be the species observed in superacid media, but the reservation has been expressed that the species observed may not be the same as the intermediate in solvolytic reactions, in which much of the electrophilicity of the cationic center may be attenuated by solvation. The cationic intermediate generated in solvolysis reactions may also be the nonclassical ion, but the observable properties of rapid solvolysis, high exo/endo capture ratio, and high exo/endo rate ratio are not sufficient to require this conclusion. Similar properties can be shown to obtain in model systems that surely react through intermediates in which bridging is absent. 

Numerous models have been proposed for describing the formation of exotic atoms via Coulomb capture. The muons in atoms do reach the atomic ground state (as opposed to hadronic atoms), and the lack of strong interaction effects makes them good probes to study Coulomb capture. One of the most important experimental methods is measuring Coulomb capture ratios. In a mixture of two elemental gases (e.g., N2 + O2) or in binary compounds, one can determine the amount of muons captured in the different elements by summing up the amplitudes of the muonic Lyman series, the (n p —> Is) transitions. 

Net atomic charges have been obtained from atomic Coulomb capture ratios of pions in 3-BN by applying the modified mesomolecular model, which accounts forthe Auger process in the cascade transitions from mesomolecular to atomic orbitals. The resultant atomic charges are +0.48 for the boron and -0.48 for the nitrogen atom [16]. 

Measurements were made of (dysprosium disadvantage factor), poz (ratio of epi- to subcadmium capture ratio in Th), and 6 (ratio of fission in Th to fission in U). The techniques used in measuring C and p were reported elsewhere and will not be reported here. Of more interest is a new technique of measuring the fSst fission ratio. 

In Table I, a comparison of calculated and measured central reactivity worths is presented in units of Ih/kg using the conversion factor 1% Ak/k = 949.67 Ih for eff - 0 00358. The calculated reactivity worths using the GAM data tapes for Fe, Cr, Ni, Al, and C are given In the parentheses in Table I. Experimental and calculated central fission and capture ratios for various materials relative to the fission rate are also presented in Table I. 

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