Natural Circ. Data, Methods by Adv. Water-Cooled Nuclear Powerplant Designs (IAEA

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So the effectiveness of systems with natural circulation is not primarily a question of high driving forces but of the proper design. Normally a simple calculation is sufficient for the designer to calculate the driving forces in a balance with flow resistances. It is not necessary to know each detail of the flow fields like degree of turbulence, exact velocity profiles in different regions of the circuit or the exact form and flow velocity of a raising plume in a pool. Rough calculations normally are sufficient to decide whether a system using natural circulation is properly designed or not.

The function characteristics and coolant flow transient of core make-up water tank, accumulator and automatic depressurization system can be tested using NPIC core make-up water tank experiment facility to simulate a small LOCA. 4. CONCLUSIONS Several conclusions can be drawn from the survey of experimental data and the identification of needs; they are listed below: a) The development and validation of CFD codes increased the requirements on the quality and details of experimental data. g. led to a new instrumentation like tomography of two-phase flows to get knowledge about the spatial distribution of different fluids or phase.

The heated water flows up through the riser to the upper plenum where a liquid-vapor interphase exists. The water exits this plenum through an outer volume in contact with the steam generator. The steam generator has two coils, once through, secondary inside. The sub-cooled water flows down through a downcomer or cold leg to the lower plenum. Natural circulation flow may be regulated by a valve in the cold leg and a bypass to the bottom of the riser. This rig was constructed according to ASME for the following primary parameters: 150 bar and 340°C.