High pressure natural convection loop

CAPCN resembles CAREM in the primary loop and steam generators, while the secondary loop is designed just to produce adequate boundary conditions for the heat exchanger. Water enters the heated section from the lower plenum. The nuclear core is reproduced by electric heaters. The heated water flows up through the riser to the upper plenum where a 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 subcooled 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 by pass to the bottom of the riser.

The secondary loop pressures and cold leg temperatures are controlled through feedback loops operating valves. The pump allows the regulation of the flow. The condenser is an air cooled type with flow control.

Both loops allow automatic control and can be pressurized by nitrogen injection.

This rig was constructed according to ASME for the following primary parameters: 150 bar and 340°C. The primary loop may operate in saturated or subcooled regimes, with a heating

power up to 300kW and different hydraulic resistance. The circuit configuration allows the study of stationary states similar to CAREM conditions of pressure, specific flow and enthalpy. Height was kept in a 1:1 scale.

Figure 4 shows a simplified diagram of the facility. A CAPCN general view is presented in Figure 5.

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FIG. 4. CAPCN simplified process and instrumentation diagram.

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FIG. 5. CAPCN general view.