Effect of free falling condition on melt jet breakup length in partially flooded cavity

IF 1.9 3区工程技术 Q1 NUCLEAR SCIENCE & TECHNOLOGY

Nuclear Engineering and Design Pub Date : 2025-02-25 DOI:10.1016/j.nucengdes.2025.113923

Woo Hyun Jung , Hyun Sun Park

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Abstract

When a severe accident occurs and proceeds to the failure of the reactor pressure vessel, the fuel–coolant interaction commonly occurs under the partially flooded cavity. The jet acceleration and the air entrainment phenomena, which were caused by the existence of the air space, resulted in different jet breakup lengths compared to the fully flooded cavity condition. Since the jet breakup length is an important parameter regarding the debris bed coolability, its precise prediction has been a significant issue for decades. This study investigated the effect of the free fall on the jet breakup length by observing the Froude number change and the air cavity generation according to the free fall height. Therefore, the Saito correlation was re-expressed as a function of the falling height emphasizing the influence of the jet acceleration in the air. Also, the size prediction model for the air cavity was developed as a function of the volume and the velocity of the jet head (bulge) based on the energy conservation between the bulge and the air cavity. By calculating the actual jet breakup length (the breakup length only from a melt-water interaction) and comparing it with the literature data, the influence of the jet acceleration and the air entrainment was highlighted indicating the necessity of the elaborate observation of the melt jet at the air in the fuel–coolant interaction experiments.

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来源期刊

Nuclear Engineering and Design 工程技术-核科学技术

CiteScore

3.40

自引率

11.80%

发文量

377

审稿时长

5 months

期刊介绍： Nuclear Engineering and Design covers the wide range of disciplines involved in the engineering, design, safety and construction of nuclear fission reactors. The Editors welcome papers both on applied and innovative aspects and developments in nuclear science and technology. Fundamentals of Reactor Design include: • Thermal-Hydraulics and Core Physics • Safety Analysis, Risk Assessment (PSA) • Structural and Mechanical Engineering • Materials Science • Fuel Behavior and Design • Structural Plant Design • Engineering of Reactor Components • Experiments Aspects beyond fundamentals of Reactor Design covered: • Accident Mitigation Measures • Reactor Control Systems • Licensing Issues • Safeguard Engineering • Economy of Plants • Reprocessing / Waste Disposal • Applications of Nuclear Energy • Maintenance • Decommissioning Papers on new reactor ideas and developments (Generation IV reactors) such as inherently safe modular HTRs, High Performance LWRs/HWRs and LMFBs/GFR will be considered; Actinide Burners, Accelerator Driven Systems, Energy Amplifiers and other special designs of power and research reactors and their applications are also encouraged.