• Nuclear Engineering and Technology
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• v.16 no.2
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• pp.70-79
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• 1984

With the help of the nuclear computational system for a large LMFBR (KAERI-26 group cross section library/1DX/2DB), the reactivity coefficients for the diagrid expansion and the pad expansion at the beginning of cycle of the equilibrium core of SUPER-PHENIX I are calculated and reviewed. the core is described using R-Z geometry model, and a two-dimensional multigroup diffusion theory is used. For reference cases, reactivity calculations for radial and axial uniform expansion are performed, and also calculated are reactivity variations due to changes in material density and core volume. The reactivity coefficient for the diagrid expansion is calculated to be -0.553pcm/mil. The temperature coefficient corresponding to the above value is -1.0766pcm/$^{\circ}C$ and is well in accord with the French datum of -1.09pcm/$^{\circ}C$ within 1.2% difference. With the use of 4he calculational method for the diagrid expansion effect, reactivity calculations for the pad expansion bringing about nonuniform expansion are performed, which show that the calculational method is very useful in the analysis of the pad expansion effect. The reactivity coefficients for the pad expansion are calculated to be -0.2743 pcm/mil and -0.2786pcm1mi1 for the averaged expansion model and for the integrated pancake model, respectively. Under the assumption of the free expanding core the temperature reactivity coefficients for each model are obtained to be -0.5766pcm/$^{\circ}C$ and -0.5858pcm/$^{\circ}C$, both of which agree with the French datum of -0.574pcm/$^{\circ}C$ within 2% difference.

• Journal of Environmental Science International
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• v.19 no.11
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• pp.1423-1436
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• 2010

The effects of meteorological and reclaiming conditions on the reduction of suspended particles are investigated using a computational fluid dynamics (CFD) model with the k-$\varepsilon$ turbulence closure scheme based on the renormalization group (RNG) theory. Twelve numerical experiments with different meteorological and reclaiming conditions are performed. For identifying the meteorological characteristics of the target area and providing the inflow conditions of the CFD model, the observed data from the automatic weather station (AWS) near the target area is analyzed. Complicated flow patterns such as flow distortion, horse-shoe vortex, recirculation zone, and channeling flow appeared due to the topography and buildings in the domain. Specially, the flow characteristics around the reclamation area are affected by the reclaiming height, reclaiming size and windbreak height. Reclaiming height affected the wind speed above the reclaiming area. Windbreak induces more complicated flow patterns around the reclaiming area as well as within the reclaiming area. In front of the windbreak, flow is distorted as it impinges on the windbreak. As a result, upward flow is generated there. Behind the windbreak, a secondary circulation, so called, a recirculation zone is generated and flow is reattached at the end of the recirculation zone (reattachment point). At the lower part of the recirculation zone, there is a reverse flow toward the windbreak. Flow passing to the reattachment point starts to be recovered. Total amounts of suspended particles are calculated using the frictional and threshold frictional velocities, erosion potential function, and the number of surface disturbance. In the case of a 10 m-reclaiming and northerly wind, the amount of suspended particles is largest. In the presence of 5 m windbreak, the friction velocity above the reclaiming area is largely reduced. As a result, the total amount of the suspended particles largely decreases, compared to the case with the same reclaiming and meteorological conditions except for the windbreak The calculated suspended particle amounts are used as the emission rate of the dispersion model simulations and the dispersion characteristics of the suspended particles are analyzed.