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Assessment of the depressurisation and mixing effects of two spray systems in the PANDA facility, part II – Simulations using GOTHIC8.3(QA)
Publicated to:Nuclear Engineering And Design. 403 - 2023-01-01 403(), DOI: 10.1016/j.nucengdes.2022.112120
Authors: Vázquez-Rodríguez, C; Andreani, M; Jiménez, G; Kapulla, R; Paranjape, S; Martín-Valdepeñas, JM; Paladino, D
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Abstract
The spray safety system is one of the most effective solutions to limit the pressure and temperature rise in the containment of a nuclear power plant during a design basis accident. However, its actuation under severe accident conditions may have either a positive effect on the hydrogen risk by mixing the containment atmosphere and avoiding high H2 local concentrations or a negative impact by condensing the steam and de-inerting the atmosphere. The experiments performed during the OECD/NEA HYMERES-2 Project aimed to extend the experimental database dedicated to assessing the capabilities of the codes used to optimise the operation of the safety systems. Specifically, the H2P5 series consisted of two experiments that compared the activation of a central full cone spraying nozzle (H2P5_2) with nine smaller spraying nozzles, eight equally distributed at 0.5 m from the metallic walls of PANDA (H2P5_1). The ninth nozzle was positioned in the vessel vertical axis for the latter configuration. These experiments created a demanding scenario for the computational codes, which need to consider three different fields: three components of the gas phase (air, helium, and steam), the dispersed liquid (droplets), and the continuous liquid accumulated on the walls and at the bottom of the PANDA vessel during the test. Furthermore, the proximity of the nozzles to the walls in H2P5_1 requires considering the strong interaction of the fluid with these metallic structures. In this work, the GOTHIC 3D models were able to qualitatively represent all the relevant phase change phenomena affecting the cooling effect of the spray and provided a reasonable qualitative representation of the depressurization behaviour observed during the experiments. However, the code overestimated the steam condensation on droplets. To achieve quantitative agreement between the experiments and computer models it was necessary to enhance the spatial distribution of the droplets (to compensate for anomalies due to a conical injection in a relatively coarse cartesian mesh) and to diminish the steam condensation on the droplets by decreasing the spray mass flow rate. Regarding the helium mixing, the simulations revealed a potential explanation for the faster mixing observed in the single nozzle (H2P5_2) experiment. Furthermore, the droplet diameter showed to be the parameter inducing the most significant variations in the mixing.
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Quality index
Bibliometric impact. Analysis of the contribution and dissemination channel
The work has been published in the journal Nuclear Engineering And Design due to its progression and the good impact it has achieved in recent years, according to the agency WoS (JCR), it has become a reference in its field. In the year of publication of the work, 2023, it was in position 9/40, thus managing to position itself as a Q1 (Primer Cuartil), in the category Nuclear Science & Technology.
From a relative perspective, and based on the normalized impact indicator calculated from the Field Citation Ratio (FCR) of the Dimensions source, it yields a value of: 1.91, which indicates that, compared to works in the same discipline and in the same year of publication, it ranks as a work cited above average. (source consulted: Dimensions Jul 2025)
Specifically, and according to different indexing agencies, this work has accumulated citations as of 2025-07-26, the following number of citations:
- Scopus: 5
Impact and social visibility
Leadership analysis of institutional authors
This work has been carried out with international collaboration, specifically with researchers from: Switzerland.
There is a significant leadership presence as some of the institution’s authors appear as the first or last signer, detailed as follows: First Author (VÁZQUEZ RODRÍGUEZ, CARLOS) .
the author responsible for correspondence tasks has been VÁZQUEZ RODRÍGUEZ, CARLOS.