Experimental evaluation of methodologies for single transient cavitation bubble generation in liquids

Single bubble dynamics are of fundamental importance for understanding the underlying mechanisms in liquid–vapor transition phenomenon known as cavitation. In the past years, numerous studies were published and results were extrapolated from one technique to another and further on to “real-world” cavitation. In the present paper, we highlight the issues of using various experimental approaches to study the cavitation bubble phenomenon and its effects. We scrutinize the transients bubble generation mechanisms behind tension-based and energy deposition-based techniques and overview the physics behind the bubble production. Four vapor bubble generation methods, which are most commonly used in single bubble research, are directly compared in this study: the pulsed laser technique, a high- and low-voltage spark discharge and the tube arrest method. Important modifications to the experimental techniques are implemented, demonstrating improvement of the bubble production range, control and repeatability. Results are compared to other similar techniques from the literature, and an extensive report on the topic is given in the scope of this work. Simple-to-implement techniques are presented and categorized herein, in order to help with future experimental design. Repeatability and sphericity of the produced bubbles are examined, as well as a comprehensive overview on the subject, listing the bubble production range and highlighting the attributes and limitation for the transient cavitation bubble techniques. Graphic abstract

A new non-diffusional gas bubble production route in used nuclear fuel: implications for fission gas release, cladding corrosion, and next generation fuel design

“Phase” map showing Noble metal phase particle (orange) and U fuel fragments (green and yellow) ejected into Zr cladding (red and blue) as a result of Xe bubble rupture.

A Critical Experimental Study of Bubble Effect in the Process of Spent Fuel Dissolving

The influence of gas introduction on the critical safety of the nuclear fuel system under the condition of cold condition, given reactor material and geometry structure is studied. Refer to bubble effect test experiment on nuclear critical safety test device (YSR) and considering solid-liquid two-phase nuclear fuel system with uranyl nitrate solution - uranium dioxide fuel element as the experimental platform, the dynamic process of the real behavior of bubbles in uranyl nitrate solution has been simulated in the quasi-static way by replacing bubble generator with aluminous bubble simulation elements. Bubble effect is the reactivity change caused by the change of volume of solution, neutron leakage and absorption property in the nuclear fuel system due to the bubbles generated in the solution. In the dissolving process of spent fuel, oxygen or nitrogen are usually added to accelerate the dissolution of fuel element shear section, and some other bubble production are also caused by the heat released during the dissolution process. Here, the bubble production caused by the heat is omitted and only artificial gas introduction is considered in my study. When there are enough bubbles in the uranium solution system, the volume of the solution will increase, which will inevitably influence the absorption and leakage property of the neutrons, and further influence the reactivity of the nuclear fuel system. The corresponding relationship between the bubble-intake rate and the bubble equivalent diameter, arising velocity and bubble share is determined through fluid dynamics modeling to manufacture the aluminous bubble simulation elements. The theoretical calculation by MONK9A and the critical experimental measurements are also compared and analyzed in this paper. The results showed that the reactivity caused by bubbles was negative, and the greater the intake rate, the greater the negative effect. Meanwhile the theoretical calculated value was in good agreement with the experimental value and the maximum deviation was 63.4 pcm.