Experimental investigation of the inhibition effects of metal foam on condensation-induced water hammer in the offshore-based passive heat removal system

The offshore-based passive heat removal system (OBPHRS) for floating nuclear power platforms (FNPP) uses the marine environment as an infinite heat sink. However, the reverse flow of the cold sea can easily trigger the condensation-induced water hammer (CIWH) phenomenon, which can cause significant damage to the pipeline equipment and affect the system’s safety operation. In this paper, an experiment study was conducted to investigate the inhibition effects of metal foam on the CIWH phenomenon in the OBPHRS. The visual images show that the metal foam reduces the volume of isolated steam slugs and concentrates the capture positions near the water tank. Additionally, the metal foam diminishes the reverse flow effects of the cold water, leading to a significant decrease in temperature fluctuations during natural circulation. As a result of the reverse flow effects weakening, the CIWH phenomena in the pipe section near the pipe inlet are eliminated. The pressure peaks at the measuring points covered with the metal foam show a clear decrease in intensity. Furthermore, as the metal foam pore density increases, the pressure peak relief effects become more pronounced. The metal foam improves the flow rate of natural circulation, enhancing the residual heat removal capacity of the OBPHRS.