Article
Nuclear Science & Technology
Yan Xiang, Sachin Thakre, Weimin Ma, Sevostian Bechta
Summary: This study focuses on the formation and characteristics of debris during a severe accident in a light water reactor, analyzing the debris bed formed by a metal-rich corium jet falling into a water pool. Experimental results show the influence of parameters like superheat and subcooling on the characteristics of the debris bed, including configuration, porosity, particle morphology, and size distribution. Preliminary comparison between metallic and oxidic debris beds was also provided.
NUCLEAR ENGINEERING AND DESIGN
(2021)
Article
Nuclear Science & Technology
Seokgyu Jeong, Keun Sang Choi, Hwan Yeol Kim, Sang Mo An, Jaehoon Jung
Summary: This study analyzed the basic characteristics of non-explosive TROI particles and conducted single-and two-phase pressure drop experiments in the particle bed. The Ergun model with an effective diameter of 1 mm predicted single-phase pressure drop results accurately, while the Schmidt and Schulenberg & Muller models with effective diameters of 3 mm and 2 mm respectively predicted two-phase pressure drop results well. The effects of particle bed characteristics on pressure drop were also discussed, and a modified pressure drop model reflecting the measured porosity was proposed.
NUCLEAR ENGINEERING AND DESIGN
(2022)
Article
Nuclear Science & Technology
Mayank Modak, Vishal V. Nirgude, Hyun Sun Park, Yu Jung Choi, Mi Ro Seo
Summary: The coolability of relocated corium from the reactor vessel is a significant safety issue in severe accidents in light water reactors (LWRs). Failure in cooling and stabilizing the molten core can threaten the integrity of the containment boundary. A porous corium debris bed is expected to develop on the bottom of the flooded cavity, and the geometric configuration of the bed is important for accurate coolability assessment.
NUCLEAR ENGINEERING AND DESIGN
(2023)
Article
Engineering, Geological
Jianting Du, Jiantao Yu, Clarence Edward Choi
Summary: Submarine debris flows pose a threat to offshore development. Existing experimental studies do not accurately simulate actual bed conditions, and recent experiments have shown that bed roughness and permeability play an important role in flow dynamics.
Article
Mechanics
Walter Villanueva, Seyed Mohsen Hoseyni, Sevostian Bechta, Akitoshi Hotta
Summary: This paper presents an experimental program that investigates melt infiltration, solidification, remelting, and relocation in a particulate debris bed using the MRSPOD facility. The experiments reveal a non-linear kinetics of melt infiltration and complex infiltration process under similar test conditions.
Article
Nuclear Science & Technology
Hanbee Na, Dong Gu Kang, Sukyoung Pak, Hee Joon Lee
Summary: An analytical model was developed to study concrete ablation during ex-vessel cooling, evaluating the effectiveness and pressure requirements for ex-vessel cooling in the reactor cavity of Westinghouse nuclear power plants.
ANNALS OF NUCLEAR ENERGY
(2021)
Article
Geosciences, Multidisciplinary
Lonneke Roelofs, Eise W. Nota, Tom C. W. Flipsen, Pauline Colucci, Tjalling de Haas
Summary: A solid physical understanding of debris-flow erosion is crucial for hazard prediction and understanding landscape evolution. However, the effects of bed composition on erosion have not been well studied. In this study, we experimentally investigated the influence of bed composition on debris-flow erosion and found that water and clay content significantly affect erosion magnitude. Our results emphasize the importance of considering small variations in bed composition for accurately assessing debris-flow hazards.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Thermodynamics
Yan Xiang, Yucheng Deng, Di Fang, Disen Liang, Weimin Ma
Summary: A series of experiments was conducted to investigate the characteristics of metallic melt-water interactions. The results showed that water pool depth significantly influenced steam explosion and debris bed formation characteristics, and jet breakup length was sensitive to jet diameter and free fall height. Additionally, the features of metallic debris beds were compared with those of oxidic ones in terms of configuration, porosity, and particle morphology and size distribution.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2023)
Article
Environmental Sciences
LI Pu, WANG Jia-ding, HU Kai-heng, QIU Hai-jun, XIE Jia-lin
Summary: This study investigates the effects of discontinuous grading bed sediments on debris flow resistance forces and entrainment characteristics. A revised formula for calculating the debris flow entrainment rate is proposed.
JOURNAL OF MOUNTAIN SCIENCE
(2022)
Article
Nuclear Science & Technology
Yangli Chen, Huimin Zhang, Weimin Ma
Summary: The cornerstone of severe accident strategy of Nordic BWRs is to flood the reactor cavity for the long-term coolability of an ex-vessel debris bed. In this study, the coupling of MELCOR and COCOMO codes was used to analyze the quench process of an ex-vessel debris bed, showing that particle diameter and bed shape have significant effects on the quench front propagation. The coupled simulation predicts earlier cavity pool saturation and containment venting compared to standalone simulation.
ANNALS OF NUCLEAR ENERGY
(2022)
Article
Nuclear Science & Technology
Shengxing Yang, Houjun Gong, Yu Fang, Yuwen Hu, Yuanfeng Zan, Zumao Yang, Pengzhou Li
Summary: During severe accidents, a debris bed is formed after core meltdown and coolant interaction, which is crucial for melt retention in vessel and accident termination. Studying the drying characteristics of such particle beds can enhance the safety margin of the In-Vessel Retention (IVR) strategy.
PROGRESS IN NUCLEAR ENERGY
(2023)
Article
Nuclear Science & Technology
Seokgyu Jeong, Sang Mo An
Summary: To maintain the containment integrity of a nuclear power plant during severe accidents, a pre-flooding strategy is adopted to prevent the failure of the reactor cavity. The shape of the debris bed formed by molten corium released into the pre-flooded water pool plays a crucial role in removing heat from the bed and ensuring coolability. Various phenomena, such as free-fall & sedimentation, particle dispersion by steam spike and convection flow, and self-leveling, affect the debris bed shape.
NUCLEAR ENGINEERING AND DESIGN
(2023)
Article
Nuclear Science & Technology
Wanhong Wang, Yangli Chen, Weimin Ma
Summary: In Nordic BWRs, a flooded reactor cavity is used to receive corium in the event of vessel failure, with the aim of forming a coolable debris bed. Previous simulation studies used the MELCOR/COCOMO model for quenching ex-vessel debris beds, but were hindered by the slow computational cost of COCOMO. This study developed a surrogate model (SM) based on artificial neural networks (ANNs) to replace COCOMO, allowing for quick estimations of the quenching process. The coupled MELCOR/SM simulation was then used for integral severe accident analyses, showing similar trends to the MELCOR/COCOMO simulation in predicting containment pressure and pool temperature.
ANNALS OF NUCLEAR ENERGY
(2023)
Article
Thermodynamics
Yan Xiang, Disen Liang, Andrei Komlev, Di Fang, Yucheng Deng, Lu Zhao, Weimin Ma
Summary: During severe accidents in a light water reactor (LWR), the core melt (corium) can relocate to the lower head and cause the reactor pressure vessel (RPV) to fail. Fuel coolant interactions (FCI) occur when the reactor cavity is flooded with water, and the energetics of FCI and the coolability of resulting debris bed are crucial for reactor safety. This study aims to quantify the characteristics of a debris bed resulting from FCI using various materials, and high-speed photography was used to visualize the process. The comparative results provide insights into debris bed characteristics under different melt materials and compositions.
APPLIED THERMAL ENGINEERING
(2023)
Article
Nuclear Science & Technology
Chunming Teng, Bin Zhang, Jianqiang Shan
Summary: This paper conducted numerous experiments to study the debris bed relocation behavior and investigated the influence of different experimental factors on the process. The experimental data were used to further evaluate a semi-empirical onset model for predicting relocation, providing important references for CDA simulation analysis.
NUCLEAR ENGINEERING AND TECHNOLOGY
(2021)
Article
Nuclear Science & Technology
Orestes Castillo-Hernandez, P. E. Manuel Perdomo-Ojeda, C. R. Grantom, Pamela F. Nelson
Summary: Incorporating specified safety and production targets during the design phase can reduce costs and enhance the competitiveness of nuclear power plants. This paper presents two methods for proposing unavailability targets for nuclear reactor systems to optimize the design features. The methods are applied to a hypothetical facility, providing a basis for future work on estimating design alternatives affecting unavailabilities.
NUCLEAR ENGINEERING AND DESIGN
(2024)
Article
Nuclear Science & Technology
Qinjun Fu, Andre Bergeron, Philippe Fillion, Yohan Davit, Michel Quintard
Summary: In normal operating conditions, the flow within a pressurized water reactor (PWR) core primarily moves in the axial direction along the fuel rods. However, in accidents situations, transverse flows can have a significant impact on the thermal-hydraulic properties of the core. This study develops macroscopic pressure drop models for different flow directions and Reynolds numbers and validates them by comparing with existing system code results.
NUCLEAR ENGINEERING AND DESIGN
(2024)
Article
Nuclear Science & Technology
Xiang Chai, Xinyue Liu, Chaoran Guan, Tengfei Zhang, Xiaojing Liu
Summary: Micro nuclear reactors have gained attention for their high efficiency and long lifetime, making them suitable for remote and off-grid locations. This study examines the effects of burnable poisons on the performance of a micro nuclear reactor and improves the design for reactivity control. The computational results show that burnable poisons reduce excess reactivity and power peaking factor without significant impact on core lifetime.
NUCLEAR ENGINEERING AND DESIGN
(2024)
Article
Nuclear Science & Technology
Liwei Chen, Cong Zhou, Yu Wang, Yiran Zong, Tingting Lu, Chunhua Chen
Summary: This paper proposes an autonomous search method for leakage sources in nuclear emergency rescue based on the updated Infotaxis method. By considering factors such as radioactive decay and wet deposition, the method improves search efficiency and accuracy. Experimental results show that the method is particularly effective in searching for leakage sources under high emission rates and provides scientific information for early emergency response and consequence assessment.
NUCLEAR ENGINEERING AND DESIGN
(2024)
Article
Nuclear Science & Technology
Kirill S. Dolganov
Summary: This paper is the first part of a summary overview of IBRAE's work on the severe accident at Unit 1 of Fukushima Daiichi Nuclear Power Station. It focuses on the integral model of Unit 1 and its qualification with available data, including the comparison of simulation results with measurements for the initial phase of the accident. Important issues discussed include the direct modeling of isolation condenser performance and verification of the possibility to use an integral approach to estimate the nuclide inventory in the core.
NUCLEAR ENGINEERING AND DESIGN
(2024)
Article
Nuclear Science & Technology
F. Feria, C. Aguado, J. Benavides, J. Benavides, R. Canencia-Hernanz, M. Cristobal-Beneyto, J. Fernandez Garcia, H. Galan, C. Gonzalez, A. Hernandez-Avellaneda, L. E. Herranz, G. Jimenez, L. Martinez, J. C. Martinez-Murillo, A. Milena-Perez, A. Palacio Alonso, J. Penalva, R. Plaza, D. Perez-Gallego, L. Rey, N. Rodriguez-Villagra, J. Ruiz-Hervias, J. Saiz de Omenaca Tijero, P. Vinas-Pena
Summary: The Spanish R&D efforts in dry interim storage of spent nuclear fuel mainly focus on supporting safety under storage and transportation. Experimental and modelling activities are carried out to understand and predict the fuel response, with major outcomes being improvements in the characterization of dry stored fuel, essential for safety assessment of the back-end fuel cycle.
NUCLEAR ENGINEERING AND DESIGN
(2024)
Article
Nuclear Science & Technology
Ang Li, Yuqing Chen, Yuxian Rao, Qi Cai, Cong Wang
Summary: This paper focuses on the boiling heat transfer model of mini-channels casing-pipes once-through steam generator (MCOTSG). By calibrating and analyzing the different nucleate boiling heat transfer models based on steady state experimental results, the secondary loop heat transfer characteristics and overall operating characteristics of OTSG under feedwater flow rate reduction are simulated. The results can provide a basis for the safety analysis and optimal design of MCOTSG and small modular reactor under low flow rate conditions.
NUCLEAR ENGINEERING AND DESIGN
(2024)
Article
Nuclear Science & Technology
Shu Soma, Masahiro Ishigaki, Satoshi Abe, Yasuteru Sibamoto
Summary: In this paper, the analytical wall function approach was applied to analyze the condensation flow of steam/air mixtures, and good predictions were obtained through CFD analysis.
NUCLEAR ENGINEERING AND DESIGN
(2024)
Article
Nuclear Science & Technology
Jinho Song, Sungjoong Kim
Summary: In this study, a machine learning platform is proposed to assist operators in diagnosing the progression of severe accidents and predicting key parameters using long short term memory networks and MELCOR simulation data. The platform shows reasonable accuracy in predicting both similar and unseen test data, as well as lost signals and key parameters for accident management.
NUCLEAR ENGINEERING AND DESIGN
(2024)
Article
Nuclear Science & Technology
Liang Zhao, Zhengbai Chang, Chulin Mai, Hong Ran, Jin Jiang
Summary: This study investigates the dynamic characteristics, valve disc motion, and flow field of a nozzle check valve under different spring stiffness and fluid deceleration rates. Experimental tests and numerical simulations were performed to analyze the effects on various parameters during the dynamic closing process of the valve. The results provide insights for the optimization design of check valves and more accurate calculation of their dynamic characteristic curves.
NUCLEAR ENGINEERING AND DESIGN
(2024)
Article
Nuclear Science & Technology
Xun Lan, Yanbo Jiang, Dan Sun, Wenbo Liu, Wenjie Li
Summary: In this study, a three-dimensional phase-field model was developed to investigate the evolution of intergranular bubbles during irradiation. The study examined the dependency of bubble percolation on bubble shape, fission rate, and average grain size. The simulation results revealed the significant effects of these factors on the shape of GB bubbles, the percolation rate, and the connectivity threshold of GB bubbles.
NUCLEAR ENGINEERING AND DESIGN
(2024)
Article
Nuclear Science & Technology
J. M. S. Mendes, A. Heimlich, A. M. M. De Lima, F. C. Silva
Summary: An algorithm for solving the constitutive equations of the fourth-order Nodal Expansion Method (NEM) in parallel using GPU with quadratic transverse leakage has been proposed. The algorithm, implemented in CUDA language, showed comparable accuracy and reduced execution time compared to the CNFR code. This algorithm and the developed program have potential use in the optimization process of nuclear fuel reload patterns.
NUCLEAR ENGINEERING AND DESIGN
(2024)
Article
Nuclear Science & Technology
M. Jafari, H. Jafari, M. H. Choopan Dastjerdi, J. Mokhtari
Summary: This study investigates the ability of the PGNAA facility of the Isfahan MNSR reactor to measure boron concentration in solution samples. A measurement system model is developed using Monte Carlo calculation, and a cadmium sheet is used to reduce the effect of boron in the shield. The accuracy of the model is verified through experimental tests, resulting in a calibration curve.
NUCLEAR ENGINEERING AND DESIGN
(2024)
Article
Nuclear Science & Technology
Ibrahim Gad-el-Hak, Njuki Mureithi, Kostas Karazis, Brian Painter
Summary: This study investigates the risk of fluidelastic instability induced by degraded baffle-former bolts in a nuclear fuel assembly. Experimental results show that the stability threshold of the mock-up array strongly depends on the relative position of the jet flow with respect to the array centerline, and axial flow velocity also has a significant effect on the jet-induced instability.
NUCLEAR ENGINEERING AND DESIGN
(2024)
Article
Nuclear Science & Technology
Yuhang Niu, Scolaro Alessandro, Carlo Fiorina, Hao Qin, Gauthier Lazare, Yingwei Wu, Wenxi Tian, G. H. Su
Summary: This paper presents the incorporation of DNB prediction into the GeN-Foam code, which is based on OpenFOAM. The accuracy of GeN-Foam in modeling DNB conditions in PWR was assessed through validation against experimental data and other codes. The results show that GeN-Foam exhibits good performance in simulating two-phase flow boiling conditions and accurately predicts the occurrence of DNB.
NUCLEAR ENGINEERING AND DESIGN
(2024)