| 1. |
- Zeng, Xiao, et al.
(författare)
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A scoping study on remelting process of a debris bed in the lower head of reactor pressure vessel
- 2023
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Ingår i: Annals of Nuclear Energy. - : Elsevier BV. - 0306-4549 .- 1873-2100. ; 189
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Tidskriftsartikel (refereegranskat)abstract
- Coolability and retention of core melt (corium) in the lower head of reactor pressure vessel (RPV) has been accepted as a severe accident management strategy to maintain the reactor pressure vessel (RPV) integrity of a light water reactor. To qualify the in-vessel melt retention strategy, lots of studies have been performed to investigate the natural convection heat transfer of a melt pool in the lower head. However, little work has been attributed to the precursory phase of the melt pool, i.e., the remelting process of a debris bed which is formed in the lower head at the very beginning of corium relocation from the core the lower head. The present study is motivated to conduct an experimental study on the debris remelting process. For this purpose, a dedicated test facility named COREM (COrium REMelting) is conceived and constructed, which features internal heating of electromagnetic induction and visualization of debris remelting dynamics. The test section is a semicircular vessel representing a slice of scaled-down RPV lower head, whose front and back walls are made of transparent tempered glass which facilitate visualization and induction heating of the debris bed. Fiber probes with multiple optical temperature sensors are mounted in the semicircular wall of the test section to measure its temperature distribution. In the scoping test, n-octanol and Wood's metal are selected as the simulant materials of metallic and oxidic components of corium, respectively, and their particles ware loaded in the test section to form a debris bed. This paper presents the first two scoping tests which have been performed with the COREM facility so far, under different mixing ratios of two debris materials. The measured data include the photography of debris remelting processes and the temperatures in the debris bed and the semicircular wall. Based on the temperature distributions, heat flux profile along the semicircular vessel wall is also estimated. The scoping tests well reproduce the dynamic process of debris remelting, with two distinct stages of fusion of n-octanol and Wood's metal, i.e., melting successively from low to high melting-point debris particles. During the remelting process, the vessel wall temperatures increase with the polar angle firstly and then decrease gradually, leading to the highest temperature appearing in the middle of the lower layer of the stratified molten pool which is finally formed.
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| 2. |
- Li, Huixiong, et al.
(författare)
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蒸汽-冷流体接触冷凝流动的数值模拟
- 2005
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Ingår i: Gongcheng Rewuli Xuebao. - Beijing, China. - 0253-231X. ; 26, s. 963-966
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Tidskriftsartikel (refereegranskat)abstract
- 介绍了关于蒸汽-冷流体直接接触冷凝流动与传热的数值计算模型与部分研究结果。用Level Set方法确定蒸汽-冷流体接触界面的位置和形状,建立了对蒸汽和冷流体普遍适用的动量、能量和质量守恒方程,在能量和质量寺恒方程中增加了部分项用于计算蒸汽冷凝所产生的影响。用有限差分法在交错网格上离散控制方程,用Runge-Kutta法-五阶WENO组合格式求解Level Set输运方程,用压力修正的迭代Projection方法求解动量方程,而用SIMPLE方法求解温度控制方程。对算例的计算结果表明,本文所建立的数值计算模型能反映物理现象的宏观特性。根据计算结果,分析了本文模型的优缺点,并指出了今后改进的方向。
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| 3. |
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| 4. |
- Li, Liangxing, et al.
(författare)
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Dynamic characteristics of molten droplets and hot particles falling in liquid pool
- 2010
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Ingår i: Frontiers of Energy and Power Engineering in China. - : Springer Science and Business Media LLC. - 1673-7393 .- 1673-7504. ; 4:2, s. 246-251
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Tidskriftsartikel (refereegranskat)abstract
- The dynamic characteristics of molten droplets and hot particles at the very beginning of their fall into coolant pools are presented. The falling course of a single droplet or a single hot particle was recorded by a high-speed camera and a curve of velocity vs. time was obtained. Emphasis was placed on the effects of the droplet's size and temperature, the coolant's temperature and properties, and the droplet's physical properties on the moving behavior. The results for the all cases showed that the velocity of a falling droplet/particle decreased rapidly but rebounded shortly, at the beginning of droplet/particle falling in the coolant. Following such a V-shaped evolution in velocity, the droplet/particle slows down gradually to a comparatively steady velocity. An increase in either coolant temperature or droplet temperature results in a larger velocity variation in the "J-region", but a smaller deceleration when it moves out of the "J-region". The elevated volatility of a coolant leads to a steeper deceleration in the "J-region" and beyond. The bigger size of a particle leads to a greater velocity variation in the "J-region" and terminal velocity. A high melting point and thermal conductivity as well as lower heat capacity contribute to dramatic variation in the "J-region" and low terminal velocity.
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| 5. |
- Li, Liangxing, et al.
(författare)
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Evaluation of the void fraction in the crescent-shape moderator cell of the CARR-CNS
- 2008
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Ingår i: Physica. B, Condensed matter. - : Elsevier BV. - 0921-4526 .- 1873-2135. ; 403:12, s. 2036-2042
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Tidskriftsartikel (refereegranskat)abstract
- The mathematical model developed in a previous paper is improved in the present paper for analyzing and evaluating the void fraction profiles in the crescent-shape moderator cell of the Cold Neutron Source (CNS) of the China Advanced Research Reactor (CARR) which is now under construction in the China Institute of Atomic Energy (CIAE). The model is then applied to the case of the CARR-CNS with liquid hydrogen as a moderator and the void fraction in the crescent-shape moderator cell of the CARR-CNS is evaluated. The calculation results show that the void fraction in the crescent-shape moderator cell less than 20%. The model and the calculation results will help to obtain insight of the mechanism that controls the void fraction distribution in the crescent-shape moderator cell, and provide theoretical supports for the moderator cell construction.
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| 6. |
- Li, Liangxing, et al.
(författare)
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Experimental investigation on the moving characteristics of molten metal droplets impacting coolant
- 2008
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Ingår i: Experimental Thermal and Fluid Science. - : Elsevier BV. - 0894-1777 .- 1879-2286. ; 32:4, s. 962-972
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Tidskriftsartikel (refereegranskat)abstract
- This paper reports the results of an experimental investigation on the moving characteristics of molten metal droplets impacting coolant free surface. A visualization experimental facility of molten fuel coolant interactions (MFCI) is designed and set up in the present study. The lead–bismuth (Pb–Bi) alloys are employed as the metal materials. An automatic control circuit is designed and applied to control the release of the molten droplets. High-speed camera is employed to record the movement of the molten metal droplets falling down and into a coolant pool. Based on the analysis of the experimental data, a so-called “J-region” of the droplet’s velocity–time curves was found and the melt droplet enters the “J-region” when it impacts the free water surface. In the “J-region”, the velocity of the melt droplet decreases rapidly and suddenly at first, and then increases again. The droplet gradually reaches a comparatively steady velocity when it leaves the “J-region”. The present study provides essential information for further study on the fragmentation behavior of high-temperature molten droplets in coolant.
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| 7. |
- Li, Liangxing, et al.
(författare)
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Study on void fraction distribution in the moderator cell of Cold Neutron Source systems in China Advanced Research Reactor
- 2007
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Ingår i: Physica. B, Condensed matter. - : Elsevier BV. - 0921-4526 .- 1873-2135. ; 393:1-2, s. 336-346
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Tidskriftsartikel (refereegranskat)abstract
- A physical model is developed for analyzing and evaluating the void fraction profiles in the moderator cell of the Cold Neutron Source (CNS) of the China Advanced Research Reactor (CARR), which is now constructing in the China Institute of Atomic Energy (CIAE). The results derived from the model are compared with the related experimental data and its propriety is verified. The model is then used to explore the influence of various factors, including the diameter of boiling vapor bubbles, liquid density, liquid viscosity and the total heating power acted on the moderator cell, on the void fraction profiles in the cell. The results calculated with the present model indicate that the void fraction in the moderator cell increases linearly with heating power, and increases with the liquid viscosity, but decreases as the size of bubbles increases, and increases linearly with heating power. For the case where hydrogen is being used as a moderator, calculation results show that the void fraction in the moderator cell may be less than 30%, which is the maximum void fraction permitted from the nuclear physics point of view. The model and the calculation results will help to obtain insight of the mechanism that controls the void fraction distribution in the moderator cell, and provide theoretical supports for the moderator cell design.
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| 8. |
- Li, Liangxing, et al.
(författare)
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冷中子源冷包截面含汽率数理模型探讨
- 2005
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Ingår i: Proceedings of the 11<sup>th</sup> Annual Meeting of Chinese Engineering Thermophysics.
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Konferensbidrag (refereegranskat)
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| 9. |
- Li, Liangxing, et al.
(författare)
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冷中子源冷包截面含汽率数理模型探讨
- 2007
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Ingår i: Gongcheng Rewuli Xuebao. - Beijing, China. - 0253-231X. ; 28, s. 64-67
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Tidskriftsartikel (refereegranskat)abstract
- 文章推导出一种计算冷包截面含汽率的数学模型;将模型计算结果与已知文献相关实验结果进行对比,验证了模型的正确性.利用该模型探讨了冷包截面含汽率的影响因素如气泡直径,工质液体的密度、粘性,加热功率等.模型计算表明:气泡直径越大,在同一截面高度处的截面含汽率越低;工质粘性越大,在同一截面高度处的截面含汽率越高.本文模型的计算结果能对冷包设计提供理论支持.
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| 10. |
- Li, Liangxing, et al.
(författare)
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熔融液滴与冷却剂相互作用实验中液滴释放控制机构的研制
- 2008
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Ingår i: Hedongli Gongcheng. - ChengDu, China. - 0258-0926. ; 29, s. 42-45
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Tidskriftsartikel (refereegranskat)abstract
- 在高温熔融液滴与冷却剂相互作用的实验中,熔融液滴的释放控制对整个实验起至关重要的作用。本文在以往实验机械控制装置的基础上,自主设计一个自动控制电路来代替人工机械操作,利用控制电路给电磁铁提供瞬时脉冲来控制液滴瞬时释放下落,简化实验的可持续性操作,提高实验的重复性、精确性和操作方便性。
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