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Abstract. The characteristics of exposed built environments have a
significant effect on debris flow impacts on buildings, but knowledge about
their interactions is still limited. This paper presents a sensitivity
analysis on the peak impact forces on a whole building resulting from the
built environment parameters, including the orientation, opening scale of
the target building, and azimuthal angle and distance of surrounding
buildings. The impact forces were obtained from the monophasic viscous
debris flow with a synthetic and simplified hydrograph using the FLOW-3D
model, a computational fluid dynamics approach, verified through the
physical modeling results. The results show that the surrounding buildings'
properties have significant roles in determining the peak impact forces. A
shielding effect or canalization effect, which reduces or increases impact
forces, respectively, can be produced by changing the azimuth angle. A
deflection wall for building protection is recommended according to the
shielding effect. A narrowed flow path, determined by both the azimuth angle and distance, has a significant effect on the variation in impact forces. In
addition, it is concluded that a splitting wedge should be designed
following a criterion of avoiding the highest flow depth – the maximum
approaching angle – appearing near the longest wall element. The protruding parts caused by changing the building's orientation contribute to increasing
impact loads within a shielding area. A limited opening scale effect is
observed on the whole building if there is sufficient time for material
intrusion. The insights gained contribute to a better understanding of
building vulnerability indicators and local migration design against debris
flow hazard.

Many reactor safety simulation codes for nuclear power plants (NPPs) have been developed. However, it is very important to evaluate these codes by testing different accident scenarios in actual plant conditions. In reactor analysis, small break loss of coolant accident (SBLOCA) is an important safety issue. RELAP5-MV Visualized Modularization software is recognized as one of the best estimate transient simulation programs of light water reactors (LWR). RELAP5-MV has new options for improved modeling methods and interactive graphics display. Though the same models incorporated in RELAP5/MOD 4.0 are in RELAP5-MV, the significant difference of the latter is the interface for preparing the input deck. In this paper, RELAP5-MV is applied for the transient analysis of the primary system variation of thermal hydraulics parameters in primary loop under SBLOCA in AP1000 NPP. The upper limit of SBLOCA (10 inches) is simulated in the cold leg of the reactor and the calculations performed up to a transient time of 450,000.0 s. The results obtained from RELAP5-MV are in good agreement with those of NOTRUMP code obtained by Westinghouse when compared under the same conditions. It can be easily inferred that RELAP5-MV, in a similar manner to RELAP5/MOD4.0, is suitable for simulating a SBLOCA scenario.

CFD simulation for a PWR is an important part for the development of Numerical Virtual Reactor (NVR) in Harbin Engineering University of China. CFD simulation can provide the detailed information of the flow and heat transfer process in a PWR. However, a large number of narrow flow channels with numerous complex structures (mixing vanes, dimples, springs, etc.) are located in a typical PWR. To obtain a better CFD simulation, the challenges created by these structural features were analyzed and some quantitative regularity and estimation were given in this paper. It was found that both computing resources and time are in great need for the CFD simulation of a whole reactor. These challenges have to be resolved, so two schemes were designed to assist/realize the reduction of the simulation burden on resources and time. One scheme is used to predict the combined efficiency of the simulation conditions (configuration of computing resources and application of simulation schemes), so it can assist the better choice/decision of the combination of the simulation conditions. The other scheme is based on the suitable simplification and modification, and it can directly reduce great computing burden.

(1). Sen Dan: Development policies, plans and programmes of satellite communications in China. - 6 S.; (2). Gao Fuwen ; Li Weiwei ; Li Danian: PC-based audio/graphics/video image satellite communication education system and its applications. / Beijing Normal University. - 9 S.; (3). Xing Chunjie: Satellite tv education in China. - 5 S.; (4). Zhang Zhijian ; Ren Xianglin: The development of radio and television broadcasting service and satellite broadcasting in China. / The Ministry of Radio, Film and TV. - 4 S.; (5). Ma Junru: Satellite communications in China. Review and outlook. - 6 S.; (6). Hao Weimin: The application of satellite communications system in rural areas. - 2 S