Xenon effects

In Fig. 1 we show the xenon effective potentials and their lowest eigenfunctions for / = 0 and 1. Both effective potentials become strongly repulsive in the inner core region to mimic the orthogonality constraints on the true orbitals. 

For the Ve-U2 +xt contribution, we have performed a one-electron ab initio calculation where the two Li+ cores and the electron-xenon effects have been replaced by semilocal pseudopotentials [22]. 

Xenon override capability Because the steam void reactivity effect is large compared with xenon reactivity, the BWR core has the excellent capability of overriding the xenon effect, thereby increasing power after a power decrease. 

The total or sum (679 inhours) represents the reactivity status of the operating pile with te.mperature and xenon effects at their eouilibri jm values all fut ore reactivity changes add to or subtract from this 679 inho ur base. 

H Describe the rod motion which would be required near the beginning of core life following the below changes. Include the approximate times until equilibrium conditions would be established. Consider xenon effects only. 

The one-time presence of superheavy elements in meteorites has been inferred from the anomalous xenon effect. The ratios of xenon isotopes measured in some meteorites are very different from those found in terrestrial xenon. This was thought to be due to the former presence of Pu which had produced fission-product xenon as it decayed out. This theory was confirmed in part recently when xenon isotope ratios from Pu were measured and were found to be identical with ratios from one group of meteorites, the achondrites. On the other hand, the chondrite meteorites still do not fit. It had been shown that an element heavier than Cf was needed to give the required ratio, ° and Anders and Heymann and Dakowski suggested independently that extinct superheavy elements could be the cause. Rao indicated that excess Kr could be explained similarly. Schramm has calculated that if fission of a superheavy element is the cause, its half-life would lie in the surprisingly narrow range of 1.6 x lO" —6.8 x 10 yr. 

The mass-133 chain represents a fission reactor problem. Iodine-133 with a 21-hour half-life decays to 5-day xenon-133, which has a high cross section for thermal neutrons. This was discovered when the first Hanford reactors unexpectedly shut down after a few hours operation. Fortunately, these reactors were built with provision for the extra fuel that could override the xenon effect. However, when a reactor is shut down, the xenon-133 grows in from its 1-133 parent. Unless it is started up again in a few hours, several days must pass before the Xe-133 has decayed enough to allow restart. 

The physical properties of argon, krypton, and xenon are frequendy selected as standard substances to which the properties of other substances are compared. Examples are the dipole moments, nonspherical shapes, quantum mechanical effects, etc. The principle of corresponding states asserts that the reduced properties of all substances are similar. The reduced properties are dimensionless ratios such as the ratio of a material s temperature to its critical... 

Account must be taken in design and operation of the requirements for the production and consumption of xenon-135 [14995-12-17, Xe, the daughter of iodine-135 [14834-68-5] Xenon-135 has an enormous thermal neutron cross section, around 2.7 x 10 cm (2.7 x 10 bams). Its reactivity effect is constant when a reactor is operating steadily, but if the reactor shuts down and the neutron flux is reduced, xenon-135 builds up and may prevent immediate restart of the reactor. 

Fig. 5. Effect of uv exposure on nylon-6,6 yam tenacity and whiteness with and without copper salt and alkah haUde in polymer scoured 210-denier 34-filament yams exposed in Xenon-arc Ci65 Weather-Ometer using radiation intensity of 0.55 W/m at a wavelength of 340 nm. Exposure from 0 to 800...

In other applications of CT, orally administered barium sulfate or a water-soluble iodinated CM is used to opacify the GI tract. Xenon, atomic number 54, exhibits similar x-ray absorption properties to those of iodine. It rapidly diffuses across the blood brain barrier after inhalation to saturate different tissues of brain as a function of its lipid solubility. In preliminary investigations (99), xenon gas inhalation prior to brain CT has provided useful information for evaluations of local cerebral blood flow and cerebral tissue abnormalities. Xenon exhibits an anesthetic effect at high concentrations but otherwise is free of physiological effects because of its nonreactive nature. 

Xenon difluoride [4, 5, 7, 8,10] is a white crystalline material obtained through the combination of fluorine and xenon m the presence of light The reagent is commercially available and possesses a relatively long shelf-life when stored cold (freezer) Xenon difluoride is very effective for small-scale fluormation of alkenes and activated nucleophilic substrates. The reactions are usually conducted between 0 °C and room temperature in chloroform or methylene chloride solutions Hydrogen fluoride catalysis is sometimes helpful Xenon difluoride reacts in a manner that usually involves some complexation between the substrate and reagent followed by the formation of radical and radical cation intermediates... 

Xenon difluoride may be used as the pure reagent or as a graphi te intercalate for the effective fluonnation of polynuclear aromatics [86 87] (equations 49 and 50)... 

Xenon difluoride [55], xenon difluoride complexed with dialkyl sulfides [59], and xenon difluoride intercalated with graphite [90] are all effective reagents for the fluonnalion of acids, enolates, or enols (Table 2)... 

Calculate the ratio of the number of electrons in a neutral xenon atom to the number in a neutral neon atom. Compare this number to the ratio of the atomic volumes of these two elements. On the basis of these two ratios, discuss the effects of electron-electron repulsions and electron-nuclear attractions on atomic size. 

Yamakura T, Harris RA Effects of gaseous anesthetics nitrous oxide and xenon on ligand-gated ion channels comparison with isoflurane and ethanol. Anesthesiology 93 1093-1101,2000... 

L. M. Schwartz, R. L. Walswofhry 2001, (Tortuosity measurement and the effects of finite pulse widths on xenon gas diffusion NMR studies of porous media), Mag. Reson. Imag. 19, 345. 

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