Simulation of the TMI-2 Accident With ATHLET-CD and Analysis of the Late-Phase Modeling

2012 ◽  
Author(s):  
Mathias Hoffmann ◽  
Marco K. Koch
Keyword(s):  
Hydrogen Generation ◽  
Late Phase ◽  
Current Version ◽  
Molten Material ◽  
Plant Behavior ◽  
Accident Data ◽  
Core Components ◽  
Molten Materials ◽  
Two Phases ◽  
Reactor Pressure

This paper provides the results of a simulation of the TMI-2 accident with the current version of ATHLET-CD Mod. 2.2A as part of code validation activities at Ruhr-Universität Bochum (RUB). The calculated plant behavior during the first four phases of the accident is discussed and analyzed in comparison to available post-accident data and measurements. The calculation captures the plant response in terms of the thermal-hydraulics very well during the first two phases. However, during the reflooding of the degraded core some discrepancies between the calculation and TMI-2 data are identified. The code basically underestimates the hydrogen generation in this phase. Moreover, the debris bed and molten pool behavior during this phase cannot be simulated yet. An essential limitation of the current capabilities of the code in terms of the late-phase is the lack of models addressing the relocation of molten materials to the lower plenum of the reactor pressure vessel. Based on this analysis, the next steps needed to model the relocation of molten core components to the lower plenum are identified. These are the lateral leveling of accumulated molten material inside molten pools as well as the slumping to the lower plenum via different paths.

The Development of Candling Module Code in Module In-vessel Degraded Analysis Code MIDAC and the Relevant Calculation for CPR1000 During Large-Break LOCA

2016 ◽  
Vol 2 (2) ◽  
Author(s):  
Jun Wang ◽  
Yuqiao Fan ◽  
Yapei Zhang ◽  
Xinghe Ni ◽  
Wenxi Tian ◽  
...  
Keyword(s):  
Mass Distribution ◽  
Pressure Vessel ◽  
Hydrogen Generation ◽  
Peak Temperature ◽  
Severe Accident ◽  
Molten Material ◽  
Loss Of Coolant ◽  
Calculation Results ◽  
Relevant Calculation ◽  
Reactor Pressure

The occurrence of Fukushima has increased the focus on the development of severe accident codes and their applications. As a part of Chinese “National Major Projects,” a module in-vessel degraded analysis code (MIDAC) is currently being developed at Xi’an Jiaotong University. The developing situation of a candling module and relevant calculation for CPR1000 for large break loss of coolant analysis (LOCA) are presented in this paper. The candling module focuses on the melting, moving, and relocation of the melting core materials and necessary thermal hydraulic information. MIDAC’s LOCA accident calculation results of Chinese pressure reactor 1000 (CPR1000) cover the melting mass distribution, peak temperature, and hydrogen generation. The results have been compared with MAAP. Through comparison, the candling module of MIDAC proved to be able to predict the moving trend of the molten material mass relocation in the reactor pressure vessel.

scholarly journals Multi-Camera Based Setup for Geometrical Measurement of Free-Falling Molten Glass Gob

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1041
Author(s):  
Mazhar Hussain ◽  
Mattias O’Nils ◽  
Jan Lundgren
Keyword(s):  
Free Fall ◽  
Frame Rate ◽  
Geometrical Parameters ◽  
Contactless Method ◽  
Molten Material ◽  
Dynamic Changes ◽  
Direct Measurements ◽  
Molten Materials ◽  
Free Falling

High temperatures complicate the direct measurements needed for continuous characterization of the properties of molten materials such as glass. However, the assumption that geometrical changes when the molten material is in free-fall can be correlated with material characteristics such as viscosity opens the door to a highly accurate contactless method characterizing small dynamic changes. This paper proposes multi-camera setup to achieve accuracy close to the segmentation error associated with the resolution of the images. The experimental setup presented shows that the geometrical parameters can be characterized dynamically through the whole free-fall process at a frame rate of 600 frames per second. The results achieved show the proposed multi-camera setup is suitable for estimating the length of free-falling molten objects.

Evidence for the involvement of the optic nerve as a migration route for larvae in ocular toxocariasis of Mongolian gerbils

2003 ◽  
Vol 77 (4) ◽  
pp. 311-315 ◽  
Author(s):  
E. Hayashi ◽  
N. Akao ◽  
K. Fujita
Keyword(s):  
Optic Nerve ◽  
Late Phase ◽  
Toxocara Canis ◽  
Meriones Unguiculatus ◽  
Migration Route ◽  
Mongolian Gerbils ◽  
Ocular Toxocariasis ◽  
Optic Chiasma ◽  
Two Phases ◽  
The Brain

AbstractAlthough Toxocara canis, an important pathogen of ocular disease, tends to migrate to the eye, the precise migratory route has yet to be determined experimentally. Mongolian gerbils, Meriones unguiculatus, known as a useful animal model for human toxocariasis, were used to investigate the migration route toward the eyes. Infective larvae of T. canis were directly inoculated into the intracranial region. Haemorrhagic lesions or larvae were observed in 56.3% of cases. Histopathologically, a larva was observed in the optic nerve of gerbils 6 days after inoculation, and two larvae were found in the optic chiasma in the gerbils having a haemorrhage in the retina 9 days after inoculation. These results indicate that T. canis migrates from the brain to the eye through the optic nerve. Considering these data and previous studies showing that the ocular changes appear as early as 3 days of infection in the oral-administrated gerbils, there are two phases in the migration to the retina: a haematogenous early phase and an optic nerve route late phase.

scholarly journals Hydrogen Production Improvement on Water Decomposition Through Internal Interfacial Charge Transfer in M3(PO4)2-M2P2O7 Mixed-Phase Catalyst (M = Co, Ni, and Cu)

Catalysts ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 602
Author(s):  
Junyeong Kim ◽  
Jun Neoung Heo ◽  
Jeong Yeon Do ◽  
Seog Joon Yoon ◽  
Youngsoo Kim ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Visible Light ◽  
Water Splitting ◽  
Hydrogen Generation ◽  
Light Response ◽  
Mixed Phase ◽  
Interface Charge ◽  
Production Improvement ◽  
Active Metal ◽  
Two Phases

In this study, three types of Nasicon-type materials, Co3(PO4)2-CO2P2O7, Ni3(PO4)2-Ni2P2O7, and Cu3(PO4)2-Cu2P2O7, were synthesized as mixed-phase catalysts (MPCs) for evaluating their potential as new photocatalytic candidates (called Co3(PO4)2-CO2P2O7mpc, Ni3(PO4)2-Ni2P2O7mpc, and Cu3(PO4)2-Cu2P2O7mpc herein). Based on various physical properties, it was confirmed that there are two phases, M3(PO4)2 and M2P2O7, in which a similar phase equilibrium energy coexists. These colored powders showed UV and visible light responses suitable to our aim of developing 365-nm light-response photocatalysts for overall water-splitting. The photocatalytic performance of Ni2(PO4)3-Ni2P2O7 MPC showed negligible or no activity toward H2 evolution. However, Co2(PO4)3-Co2P2O7 MPC and Cu3(PO4)2-Cu2P2O7 MPC were determined as interesting materials because of their ability to absorb visible light within a suitable band. Moreover, an internal interface charge transfer was suggested to occur that would lower the recombination rate of electrons and holes. For Cu3(PO4)2-Cu2P2O7 MPC, the charge separation between the electron and hole was advantageously achieved, a water-splitting reaction was promoted, and hydrogen generation was considerably increased. The performance of a catalyst depended on the nature of the active metal added. In addition, the performance of the catalyst was improved when electrons migrated between the inter-phases despite the lack of a heterojunction with other crystals.

Bicarbonate modulation of glucose-9nduced biphasic insulin release by rat islets

1976 ◽  
Vol 231 (3) ◽  
pp. 713-721 ◽  
Author(s):  
JC Henquin ◽  
AE Lambert
Keyword(s):  
Insulin Release ◽  
Islet Cells ◽  
Pancreatic Beta Cell ◽  
Late Phase ◽  
Early Response ◽  
Rat Islets ◽  
Cell Functions ◽  
Biphasic Insulin Release ◽  
Two Phases

The role of HCO3 ions in pancreatic beta-cell functions was evaluated with isolated rat islets. The early phase of insulin release was absent when HCO3 ions were omitted from the medium prior to glucose stimuation, but was augmented if HCO3- withdrawal or reintroduction coincided with glucose increase. The inhibition of the late phase augmented as a function of the duration of HCO3- absence, and its reversibility upon readmission of the anion was delayed. Theophylline and cytochalasin B partially corrected the inhibition of the late phase but failed to restore a rapid response. In the presence of 5 mM NaHCO3, the early response was delayed but the total response was normal. In a HCO3--free medium, glucose oxidation and utilization and glucose transport in islet cells were unaltered. Uptake of calcium was reduced in the absence of HCO3 ions, but normal in 5 mM HCO3-. The results document the importance of HCO3- in insulin release and show that the two phases of glucose-induced secretion are differentially modified by its omission. Some of these findings may be explained by alterations in Ca++ uptake by islet cells. It is suggested that the mechanisms regulating insulin granule extrusion upon stimulation by glucose may be partially different for the two phases of release.

Inward rectification in Limulus ventral photoreceptors

1992 ◽  
Vol 8 (1) ◽  
pp. 19-25 ◽  
Author(s):  
Cynthia L. Phillips ◽  
Juan Bacigalupo ◽  
Peter M. O'Day
Keyword(s):  
Late Phase ◽  
Inward Rectifier ◽  
Inward Rectification ◽  
Voltage Range ◽  
Inward Current ◽  
Intracellular Ca ◽  
Dynamic Voltage ◽  
Inward Currents ◽  
Two Phases ◽  
Inwardly Rectifying

AbstractWe examined inward rectification in Limulus ventral photoreceptors using the two-microelectrode voltage clamp. Hyperpolarization in the dark induced an inward current whose magnitude was distinctly dependent on extracellular K+ concentration, [K+0]. The [K+0] dependence resembled the characteristic [K+0] dependence of other inward rectifiers. The inward current was not dependent on extracellular Ca2+ or Na+, and it was unaffected by intracellular injection of Cl−. The hyperpolarization induced currents had two phases, an early nearly instantaneous phase and a slowly developing late phase. The currents were sensitive to extracellular barium and cesium. In voltage-pulse experiments, the magnitudes of the inwardly rectifying currents were variable from cell to cell, with some cells exhibiting negligible inward currents. Large hyperpolarizations (to membrane potentials more negative than about – 140 mV) caused unstable inward current recordings, irreversible desensitization, and irreversible elevation of intracellular Ca2+ concentration. The inward rectifier provides negative feedback by tending to depolarize the cell (with inward current) in response to hyperpolarization. We suggest that the inward rectifier reduces the amount of hyperpolarization that would otherwise be generated by electrogenic processes. This feature would restrict the dynamic voltage range of the photoreceptors at very hyperpolarized potentials.

Retinoic acid and the late phase of neural induction

Development ◽  
1992 ◽  
Vol 116 (Supplement) ◽  
pp. 203-207 ◽  
Author(s):  
C. R. Sharpe
Keyword(s):  
Gene Expression ◽  
Retinoic Acid ◽  
Late Phase ◽  
Posterior Part ◽  
Neural Induction ◽  
The Difference ◽  
Two Phases ◽  
Basic Features ◽  
Anterior Posterior ◽  
Anterior Posterior Axis

Regional neural gene expression in Xenopus is the result of a number of processes that continue well beyond the end of gastrulation. By considering two of the basic features of neural induction, the duration of contact between mesoderm and ectoderm and the timing of neural competence, it has been possible to distinguish two phases in neural tissue formation. The late phase includes the period following gastrulation. A factor in determining regional neural gene expression is the difference in inducing ability of the mesoderm that develops during gastrulation along the anterior-posterior axis. The resulting ability to express regional neural genes is subsequently refined during the late phase by a signal that progresses from the posterior part of the embryo. Using a dorsal explant system, it is shown that this progressive signal can be mimicked by the addition of retinoic acid (RA). However, the observation that regions along the anterior-posterior axis respond in different ways to the addition of RA suggests that additional factors are also important in defining regional neural gene expression. One possibilty is that the expression of retinoic acid receptors along the axis may demarcate regions that respond to RA in particular ways.

scholarly journals α-Difluoromethylornithine-Induced Cytostasis is Reversed by Exogenous Polyamines, Not by Thymidine Supplementation

Biomolecules ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 707
Author(s):  
Mervi T. Hyvönen ◽  
Maxim Khomutov ◽  
Jouko Vepsäläinen ◽  
Alex R. Khomutov ◽  
Tuomo A. Keinänen
Keyword(s):  
Colorectal Cancer ◽  
Cancer Cells ◽  
Cell Lines ◽  
Late Phase ◽  
Eukaryotic Cells ◽  
Polyamine Biosynthesis ◽  
Colorectal Cancer Cells ◽  
Two Phases ◽  
Necessary And Sufficient ◽  
Ht 29

Polyamine spermidine is essential for the proliferation of eukaryotic cells. Administration of polyamine biosynthesis inhibitor α-difluoromethylornithine (DFMO) induces cytostasis that occurs in two phases; the early phase which can be reversed by spermidine, spermine, and some of their analogs, and the late phase which is characterized by practically complete depletion of cellular spermidine pool. The growth of cells at the late phase can be reversed by spermidine and by very few of its analogs, including (S)-1-methylspermidine. It was reported previously (Witherspoon et al. Cancer Discovery 3(9); 1072–81, 2013) that DFMO treatment leads to depletion of cellular thymidine pools, and that exogenous thymidine supplementation partially prevents DFMO-induced cytostasis without affecting intracellular polyamine pools in HT-29, SW480, and LoVo colorectal cancer cells. Here we show that thymidine did not prevent DFMO-induced cytostasis in DU145, LNCaP, MCF7, CaCo2, BT4C, SV40MES13, HepG2, HEK293, NIH3T3, ARPE19 or HT-29 cell lines, whereas administration of functionally active mimetic of spermidine, (S)-1-methylspermidine, did. Thus, the effect of thymidine seems to be specific only for certain cell lines. We conclude that decreased polyamine levels and possibly also distorted pools of folate-dependent metabolites mediate the anti-proliferative actions of DFMO. However, polyamines are necessary and sufficient to overcome DFMO-induced cytostasis, while thymidine is generally not.

scholarly journals Differential role of afferent and efferent renal nerves in the maintenance of early- and late-phase Dahl S hypertension

2016 ◽  
Vol 310 (3) ◽  
pp. R262-R267 ◽  
Author(s):  
Jason D. Foss ◽  
Gregory D. Fink ◽  
John W. Osborn
Keyword(s):  
Arterial Pressure ◽  
Renal Denervation ◽  
Antihypertensive Effect ◽  
Late Phase ◽  
Renal Nerves ◽  
Similar Degree ◽  
Sham Surgery ◽  
Selective Ablation ◽  
Two Phases

Clinical data suggest that renal denervation (RDNX) may be an effective treatment for human hypertension; however, it is unclear whether this therapeutic effect is due to ablation of afferent or efferent renal nerves. We have previously shown that RDNX lowers arterial pressure in hypertensive Dahl salt-sensitive (S) rats to a similar degree observed in clinical trials. In addition, we have recently developed a method for selective ablation of afferent renal nerves (renal-CAP). In the present study, we tested the hypothesis that the antihypertensive effect of RDNX in the Dahl S rat is due to ablation of afferent renal nerves by comparing the effect of complete RDNX to renal-CAP during two phases of hypertension in the Dahl S rat. In the early phase, rats underwent treatment after 3 wk of high-NaCl feeding when mean arterial pressure (MAP) was ∼140 mmHg. In the late phase, rats underwent treatment after 9 wk of high NaCl feeding, when MAP was ∼170 mmHg. RDNX reduced MAP ∼10 mmHg compared with sham surgery in both the early and late phase, whereas renal-CAP had no antihypertensive effect. These results suggest that, in the Dahl S rat, the antihypertensive effect of RDNX is not dependent on pretreatment arterial pressure, nor is it due to ablation of afferent renal nerves.

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