Natural circulation capacity is one of the important indicators to evaluate the performance and safety level of marine nuclear reactors. Affected by ocean conditions, marine nuclear power plants will generate complex ship motions. These kinds of ship motions can change the spatial position of the reactor system and cause the thermal parameters fluctuation, which affects the natural circulation operation stability of marine nuclear reactor. In this paper, the effects of rolling motion conditions on the flow instability characteristics of natural circulation (NC) in rod bundle channel is studied experimentally. A 3×3 rod bundle channel is used as the testing section. The experimental system pressure range is 0.2 to 0.6 MPa, and the range of inlet subcooling is 10 to 70℃. The ranges of rolling motion amplitude and period are 10 to 20° and 10 to 30s, respectively. Two typical two-phase flow instabilities in rod bundle channel under rolling condition are found in experiments: (a) the trough-type oscillation caused by the vapor generation at the minimum point of flow fluctuation and (b) the compound oscillation formed by the superposition of the trough-type oscillation and DWO~I~. The determination method, classification criterion and evolution law of two-phase NC flow instabilities are obtained. Experimental results show that the rolling motion can reduce the threshold heating power of trough-type oscillation and cause the occurrence of NC flow instability in advance. But the rolling motion cannot affect the dimensionless boundary of DWO~I~ in rod bundle channel. 


Study on Natural Circulation Flow Instabilities in Rod Bundle Channel Under Rolling Condition

Division / Sponsors: 
Power Division & Nuclear Engineering Division (NED)

Power Conference
Paper Proceedings: https://asmedigitalcollection.asme.org/POWER/POWER2020/volume/83747

International Conference on Nuclear Engineering
Paper Proceedings: https://asmedigitalcollection.asme.org/ICONE/ICONE2020/volume/83761

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