As revealed by Fukushima Daiichi nuclear disaster, countermeasures against severe accidents in nuclear power plants are an urgent need. In particular, from the viewpoint of protecting containment and suppressing diffusion of the radioactive materials, it is most important to install filtered venting devices to release high pressure contaminated gas to the atmosphere with elimination radioactive materials in the gas.

A Multi Venturi Scrubber System (MVSS) is one of the filtered venting devices, and used in European reactors [1, 2]. One of the main components of the MVSS is a Venturi Scrubber (VS). It is considered that a dispersed or dispersed annular flow is formed in the VS by a self-priming phenomena. In the self-priming phenomena, the liquid was suctioned from a surrounding region of the VS to the inside of the VS. And a part of the radioactive materials are eliminated through the gas-liquid interface of the dispersed or annular dispersed flow. Therefore, to consider the MVSS operation characteristics, it is important whether to occur the self-priming or not and the liquid flow rate of the self-priming of the VS.

The objective of this paper is to understand the self-priming phenomena of the VS for the filtered venting. And theoretical analysis and experiment were conducted. By comparing these results, we discussed about the mechanism of the self-priming phenomena. As results, the self-priming phenomena in the VS was confirmed and, at a high gas flow rate, the suspension of the self-priming is confirmed experimentally and theoretically.

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