Investigation of fl ow regime in debris bed formation behavior with nonspherical particles

Songbai Cheng,Pengfeng Gong,Shixian Wang,Jinjiang Cui,Yujia Qian,Ting Zhang,Guangyu Jiang 한국원자력학회 2018 Nuclear Engineering and Technology Vol.50 No.1

It is important to clarify the characteristics of flow regimes underlying the debris bed formation behaviorthat might be encountered in core disruptive accidents of sodium-cooled fast reactors. Although in ourprevious publications, by applying dimensional analysis technique, an empirical model, with itsreasonability confirmed over a variety of parametric conditions, has been successfully developed topredict the regime transition and final bed geometry formed, so far this model is restricted to predictionsof debris mixtures composed of spherical particles. Focusing on this aspect, in this study a new series ofexperiments using nonspherical particles have been conducted. Based on the knowledge and data obtained,an extension scheme is suggested with the purpose of extending the base model to cover theparticle-shape influence. Through detailed analyses and given our current range of experimental conditions,it is found that, by coupling the base model with this scheme, respectable agreement betweenexperiments and model predictions for the regime transition can be achieved for both spherical andnonspherical particles. Knowledge and evidence from our work might be utilized for the futureimprovement of design of an in-vessel core catcher as well as the development and verification of sodium-cooled fast reactor severe accident analysis codes in China.

An experimental study on pool sloshing behavior with solid particles

Songbai Cheng,Shuo Li,Kejia Li,Ting Zhang 한국원자력학회 2019 Nuclear Engineering and Technology Vol.51 No.1

It is important to clarify the mechanisms of molten-fuel-pool sloshing behavior that might be encounteredduring a core disruptive accident of sodium-cooled fast reactors. In this study, motivated byacquiring some evidence for understanding the characteristics of this behavior at more realistic conditions,a number of experiments are newly performed by injecting nitrogen gas into a water pool with theaccumulation of solid particles. To achieve comprehensive understanding, various parameters includingparticle bed height, particle size, density, shape, gas pressure along with the gas-injection duration, wereemployed. It is found that due to the different interaction mechanisms between solid particles and thegas bubble injected, three kinds of regimes, termed respectively as the bubble-impulsion dominantregime, the transitional regime and the bed-inertia dominant regime, could be identified. The performedanalyses also suggest that under present conditions, all our experimental parameters employed can havenoticeable impact on the regime transition and resultant sloshing intensity (e.g. maximum elevation ofwater level at pool peripheries). Knowledge and fundamental data from this work will be used for thefuture verifications of fast reactor severe accident codes in China

Characteristics of Self-Leveling Behavior of Debris Beds in a Series of Experiments

Songbai Cheng,Hidemasa Yamano,Tohru Suzuki,Yoshiharu Tobita,Yuya Nakamura,Bin Zhang,Tatsuya Matsumoto,Koju Morita 한국원자력학회 2013 Nuclear Engineering and Technology Vol.45 No.3

During a hypothetical core-disruptive accident (CDA) in a sodium-cooled fast reactor (SFR), degraded core materials can form roughly conically-shaped debris beds over the core-support structure and/or in the lower inlet plenum of the reactor vessel from rapid quenching and fragmentation of the core material pool. However, coolant boiling may ultimately lead to leveling of the debris bed, which is crucial to the relocation of the molten core and heat-removal capability of the debris bed. To clarify the mechanisms underlying this self-leveling behavior, a large number of experiments were performed within a variety of conditions in recent years, under the constructive collaboration between the Japan Atomic Energy Agency (JAEA)and Kyushu University (Japan). The present contribution synthesizes and gives detailed comparative analyses of those experiments. Effects of various experimental parameters that may have potential influence on the leveling process, such as boiling mode, particle size, particle density, particle shape, bubbling rate, water depth and column geometry, were investigated, thus giving a large palette of favorable data for the better understanding of CDAs, and improved verifications of computer models developed in advanced fast reactor safety analysis codes.

CHARACTERISTICS OF SELF-LEVELING BEHAVIOR OF DEBRIS BEDS IN A SERIES OF EXPERIMENTS

Cheng, Songbai,Yamano, Hidemasa,Suzuki, TYohru,Tobita, Yoshiharu,Nakamura, Yuya,Zhang, Bin,Matsumoto, Tatsuya,Morita, Koji Korean Nuclear Society 2013 Nuclear Engineering and Technology Vol.45 No.3

During a hypothetical core-disruptive accident (CDA) in a sodium-cooled fast reactor (SFR), degraded core materials can form roughly conically-shaped debris beds over the core-support structure and/or in the lower inlet plenum of the reactor vessel from rapid quenching and fragmentation of the core material pool. However, coolant boiling may ultimately lead to leveling of the debris bed, which is crucial to the relocation of the molten core and heat-removal capability of the debris bed. To clarify the mechanisms underlying this self-leveling behavior, a large number of experiments were performed within a variety of conditions in recent years, under the constructive collaboration between the Japan Atomic Energy Agency (JAEA) and Kyushu University (Japan). The present contribution synthesizes and gives detailed comparative analyses of those experiments. Effects of various experimental parameters that may have potential influence on the leveling process, such as boiling mode, particle size, particle density, particle shape, bubbling rate, water depth and column geometry, were investigated, thus giving a large palette of favorable data for the better understanding of CDAs, and improved verifications of computer models developed in advanced fast reactor safety analysis codes.

Investigation of flow-regime characteristics in a sloshing pool with mixed-size solid particles

Cheng, Songbai,Jin, Wenhui,Qin, Yitong,Zeng, Xiangchu,Wen, Junlang Korean Nuclear Society 2020 Nuclear Engineering and Technology Vol.52 No.5

To ascertain the characteristics of pool sloshing behavior that might be encountered during a core disruptive accident of sodium-cooled fast reactors, in our earlier work several series of experiments were conducted under various scenarios including the condition with mono-sized solid particles. It is found that under the particle-bed condition, three typical flow regimes (namely the bubble-impulsion dominant regime, the transitional regime and the bed-inertia dominant regime) could be identified and a flow-regime model (base model) has been even successfully established to estimate the regime transition. In this study, aimed to further understand this behavior at more realistic particle-bed conditions, a series of simulated experiments is newly carried out using mixed-size particles. Through analyses, it is verified that for present scenario, by applying the area mean diameter, our previously-developed base model can provide the most appropriate predictive results among the various effective diameters. To predict the regime transition with a form of extension scheme, a correction factor which is based on the volume-mean diameter and the degree of convergence in particle-size distribution is suggested and validated. The conducted analyses in this work also indicate that under certain conditions, the potential separation between different particle components might exist during the sloshing process.

Distinctive Roles of Wnt Signaling in Chondrogenic Differentiation of BMSCs under Coupling of Pressure and Platelet-Rich Fibrin

Cheng Baixiang,Feng Fan,Shi Fan,Huang Jinmei,Zhang Songbai,Quan Yue,Tu Teng,Liu Yanli,Wang Junjun,Zhao Ying,Zhang Min 한국조직공학과 재생의학회 2022 조직공학과 재생의학 Vol.19 No.4

BACKGROUND: Although newly formed constructs of feasible pressure-preadjusted bone marrow mesenchymal stem cells (BMSCs) and platelet-rich fibrin (PRF) showed biomechanical flexibility and superior capacity for cartilage regeneration, it is still not very clear how BMSCs and seed cells feel mechanical stimuli and convert them into biological signals, and the difference in signal transduction underlying mechanical and chemical cues is also unclear. METHODS: To determine whether mechanical stimulation (hydrostatic pressure) and chemical cues (platelet-rich fibrin, PRF) activate canonical or noncanonical Wnt signaling in BMSCs, BMSCs cocultured with PRF were subjected to hydrostatic pressure loading, and the activation of the Wnt signaling molecules and expression of cartilage-associated proteins and genes were determined by western blotting and polymerase chain reaction (PCR). Inhibitors of canonical or noncanonical Wnt signaling, XVX-939 or L690,330, were adopted to investigate the role of Wnt signaling molecules in mechanically promoted chondrogenic differentiation of BMSCs. RESULTS: Hydrostatic pressure of 120 kPa activated both Wnt/b-catenin signaling and Wnt/Ca2? signaling, with the the maximum promotion effect at 60 min. PRF exerted no synergistic effect on Wnt/b-catenin signaling activation. However, the growth factors released by PRF might reverse the promotion effects of pressure on Wnt/Ca2? signaling. Real-time PCR and Western blotting results showed that pressure could activate the expression of Col-II, Sox9, and aggrecan in BMSCs cocultured with PRF. Blocking experiment found a positive role of Wnt/b-catenin signaling, and a negative role of Wnt/ Ca2? signaling in chondrogenic differentiation of the BMSCs. Mutual inhibition exists between canonical and noncanonical Wnt signaling in BMSCs under pressure. CONCLUSION: Wnt signaling participates in the pressure-promoted chondrogenesis of the BMSCs co-cultured with PRF, with canonical and noncanonical pathways playing distinct roles during the process.

Knowledge from recent investigations on sloshing motion in a liquid pool with solid particles for severe accident analyses of sodium-cooled fast reactor

Ruicong Xu,Songbai Cheng,Shuo Li,Hui Cheng 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.2

Investigations on the molten-pool sloshing behavior are of essential value for improving nuclear safetyevaluation of Core Disruptive Accidents (CDA) that would be possibly encountered for Sodium-cooledFast Reactors (SFR). This paper is aimed at synthesizing the knowledge from our recent studies onmolten-pool sloshing behavior with solid particles conducted at the Sun Yat-sen University. To bettervisualize and clarify the mechanism and characteristics of sloshing induced by local Fuel-CoolantInteraction (FCI), experiments were performed with various parameters by injecting nitrogen gas intoa 2-dimensional liquid pool with accumulated solid particles. It was confirmed that under differentparticle-bed conditions, three representative flow regimes (i.e. the bubble-impulsion dominant, transitional and bed-inertia dominant regimes) are identifiable. Aimed at predicting the regime transitionsduring sloshing process, a predictive empirical model along with a regime map was proposed on thebasis of experiments using single-sized spherical solid particles, and then was extended for coveringmore complex particle conditions (e.g. non-spherical, mixed-sized and mixed-density spherical particleconditions). To obtain more comprehensive understandings and verify the applicability and reliability ofthe predictive model under more realistic conditions (e.g. large-scale 3-dimensional condition), furtherexperimental and modeling studies are also being prepared under other more complicated actualconditions

Reference Intervals for Thyroid-Associated Hormones and the Prevalence of Thyroid Diseases in the Chinese Population

Zou Yutong,Wang Danchen,Cheng Xinqi,Ma Chaochao,Lin Songbai,Hu Yingying,Yu Songlin,Xia Liangyu,Li Honglei,Yin Yicong,Liu Huaicheng,Zhang Dianxi,Zhang Kui,Lian Xiaolan,Xu Tengda,Qiu Ling 대한진단검사의학회 2021 Annals of Laboratory Medicine Vol.41 No.1

Background: Thyroid diseases are highly prevalent worldwide, but their diagnosis remains a challenge. We established reference intervals (RIs) for thyroid-associated hormones and evaluated the prevalence of thyroid diseases in China. Methods: After excluding outliers based on the results of ultrasound screening, thyroid antibody tests, and the Tukey method, the medical records of 20,303 euthyroid adults, who visited the Department of Health Care at Peking Union Medical College Hospital from January 2014 to December 2018, were analyzed. Thyroid-associated hormones were measured by the Siemens Advia Centaur XP analyzer. The RIs for thyroid-associated hormones were calculated according to the CLSI C28-A3 guidelines, and were compared with the RIs provided by Siemens. The prevalence of thyroid diseases over the five years was evaluated and compared using the chi-square test. Results: The RIs for thyroid stimulating hormone (TSH), free thyroxine (FT4), free triiodothyronine (FT3), total thyroxine (TT4), and total triiodothyronine (TT3) were 0.71–4.92 mIU/L, 12.2–20.1 pmol/L, 3.9–6.0 pmol/L, 65.6–135.1 nmol/L, and 1.2–2.2 nmol/L, respectively. The RIs of all hormones except TT4 differed significantly between males and females. The RIs of TSH increased with increasing age. The prevalence of overt hypothyroidism, overt hyperthyroidism, subclinical hypothyroidism, and subclinical hyperthyroidism was 0.5% and 0.8%, 0.2% and 0.6%, 3.8% and 6.1%, and 3.3% and 4.7% in males and females, respectively, which differed from those provided by Siemens. Conclusions: Sex-specific RIs were established for thyroid-associated hormones, and the prevalence of thyroid diseases was determined in the Chinese population.