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[en] When steam is introduced into the pool of water by means of a pipe, DCC of steam in water occurs. In general, DCC consists of four different regions. The first region in the process of condensation is the steam plume. This region occurs at the steam pipe (or nozzle) exit through which the steam is introduced into the pool of water. The outer surface of the steam plume is the steam-water interface. The hot water layer is also named bulk water. And the pool water us a single-phase area of water at certain temperature. When the steam jet is condensed in a pool, the plume modes due to DCC can be classified into three main patters: chugging: jetting: and bubbling. These modes can be shown in condensation regime map. In the view point of the engineering, the pool mixing analysis related to DCC is also very important. In this paper, the characteristics of the steam plume jet in water will be reviewed more detail in the following sections
[en] The PANACH three dimensional calculation code developed from tests on a small scale model and validated from full scale measurement campaigns, was used to estimate a three dimensional statistic of plumes. As it is not possible with the calculation times to make a calculation for each radio sondage, a classification method was adopted. This method developed by the French National Meteorological Office is based on a double classification comprising basic classes in which the plumes are assumed to be dynamically similar and a sub-classification to take better account of the true moisture profiles. This statistical method was then applied to the case of 2 or 4 1300 MWe units fitted with natural draught cooling towers of the wet, dry or wet-dry types
[fr]Le code de calcul tridimensionnel PANACH apres avoir ete mis au point a partir d'essais sur modele reduit et valide a partir de campagnes de mesures en nature a ete utilise pour estimer une statistique tridimensionnelle de panaches. Les temps de calcul ne permettant pas d'effectuer un calcul pour chaque radiosondage, une methode de classification a ete adoptee. Cette methode developpee par la meteorologie Nationale est basee sur une double classification comprenant des classes de bases dans lesquelles les panaches sont supposes dynamiquement semblables et une sous-classification pour mieux tenir compte des profils reels d'humidite. Cette methode statistique a ensuite ete appliquee au cas de 2 ou 4 tranches de 1300 MWe equipees d'aerorefrigerants a tirage naturel de types humide, sec et humide-sec
[en] In the 2008 E-Area Performance Assessment (PA), each final disposal limit was constructed as the product of a preliminary disposal limit and a plume interaction factor. The following mathematical development demonstrates that performance objectives are generally expected to be satisfied with high confidence under practical PA scenarios using this method. However, radionuclides that experience significant decay between a disposal unit and the 100-meter boundary, such as H-3 and Sr-90, can challenge performance objectives, depending on the disposed-of waste composition, facility geometry, and the significance of the plume interaction factor. Pros and cons of analyzing single disposal units or multiple disposal units as a group in the preliminary disposal limits analysis are also identified.
[en] Highlights: • Extensions of Taylor’s theory of dispersion are compatible with the far-field growth rate of scalar plumes in grid turbulence. • Similar extensions apply very well to plume growth data in uniformly sheared turbulence. • The far–field approximation does not need to be satisfied in a strict sense. - Abstract: Taylor’s theory of dispersion was extended to produce estimates of the far–field growth rate of the plume of a passive scalar in grid turbulence (GT) and in uniformly sheared flow (USF), both of which evolve in the streamwise direction. Expressions for the evolution of the plume width relative to the integral length scale of turbulence were also derived. The predictions of plume growth rate were tested against available data in both of these types of flows and were found to be accurate in an extensive region of USF and compatible with an extrapolated trend in GT, in which the available data did not extend very far from the scalar source. Although in both cases the measured half-width of the plume was comparable in magnitude to the streamwise integral length scale of the turbulence, the far–field approximation seemed to hold.
[en] The spiral galaxy NGC 1433 is a prototypical ringed, barred galaxy which possesses plumes or island enhancements located just off the leading ends of the bar. These features have been identified in 16 other barred spirals, although in terms of contrast and strength of the enhancements NGC 1433 appears to be unique. The origin of the plumes is still uncertain, but theoretical evidence suggests that they are secondary compressions close to CR, possibly related to arm-doubling just outside of inner second harmonic resonance