Search

Hydrogen gas leaks at high pressures pose a significant risk of self-ignition, potentially leading to flames without an ignition source and secondary damage such as fires and explosions. The rapid spread of hydrogen enhances the likelihood of such incidents. This study examined how a porous structure with narrow channels installed at the vent tube outlet affects the behavior of hydrogen flames. Experiments were conducted at the ejection burst pressure at which self-ignition occurs. The effects of porous structures on self-ignition were investigated using three design parameters: porosity, pattern, and length. The experimental results confirmed the existence of the maximum burst pressure capable of quenching the structure, defined as P critical. The quenching types were defined based on the behavior of a flame at the tube exit, considering the pressure difference between P critical and the burst pressure and the quenching types were determined for all structures at their respective burst pressures. The burst pressure capable of quenching increased as the length of the porous structures increased, a general effect attributed to the increased internal wetted area as the length increased. The influence of porosity was examined through experiments on honeycomb channel structures designed with four different porosities. The quenching possibility increased as the porosity decreased, but the effect was insignificant below a specific porosity threshold. The effect of the pattern was explored through experiments on honeycomb and lattice structures designed with similar porosities. Even at shorter lengths, the structure with the Octet truss lattice pattern exhibited the best quenching performance at all experimental burst pressures. Hence, the increase in the wetted area of the structure and the influence of the pattern are crucial factors in quenching. • Quench the flame from self-ignition of high-pressure hydrogen at the tube outlet. • Identify P c r i t i c a l for various porous structures through experiments. • Define quenching types based on the pressure difference between P c r i t i c a l and P b. • Compare quenching trends based on porosity, length, and pattern of porous structure. • Increase in wetted area with structure length is effective for quenching. [ABSTRACT FROM AUTHOR]

Due to epitaxial strain, BiFeO 3 (BFO) thin films exhibit a morphotropic phase boundary with coexisting rhombohedral-like (R-like) and tetragonal-like (T-like) phases. The T-like phase, distinguished by its large c/a ratio and giant polarization, has garnered extensive interest. In this work, by quenching an epitaxial mixed-phase BFO thin film grown on a LaAlO 3 substrate, a pronounced transition from the R-like to the T-like phase is observed. This transition is concomitant with improved phase structure stability under the force field induced by an atomic force microscope tip. PeakForce Quantitative NanoMechanics mapping reveals that the T-like phase exhibits a higher Young's modulus than the R-like phase, signifying an overall enhancement in the mechanical hardness of the BFO film. This work introduces a simple but powerful approach to manipulating the fraction of the T-like phase in the mixed-phase BFO films, presenting prospects for enhancing their performance and expanding their application range in advanced techniques. [Display omitted] [ABSTRACT FROM AUTHOR]

• A multi-physics coupling model is proposed for the dry-wound insulation HTS coil; • The homogenization technique is used to reduce computational complexity; • The differences between the coupling model and the one-way model are compared; • The effects of heat source and contact behavior on the quench are discussed. The second-generation high-temperature superconducting (HTS) ReBa 2 Cu 3 O 7-x (ReBCO) coated conductors have emerged as promising candidates for the fabrication of high-field magnets. The accurate analysis of the multi-physics coupling behaviors is the key to superconducting coil design and quench protection. In this paper, an electromagnetic-thermal-mechanical model based on the T-A formulation with Neumann boundary condition is proposed to analyze the excitation-quench process of the coil. The results indicate that the strain and deflection angle by the coupling model are smaller or larger than those of the traditional one-way model, which is dependent on the excitation process. For the coupling model, the slower temperature rise and lower current shunt are obtained during quench. The influences of the position and energy of the heat pulse are discussed, and the contact behaviors of two different models are also presented. The coupling model can provide the theoretical guidance for superconducting coil design. [ABSTRACT FROM AUTHOR]

Gas explosion is a common serious accident in underground coal mines and industrial production processes. Porous media, due to its special cellular structure, has a significant effect on stopping the propagation of pressure and flame, which can effectively reduce the explosion hazard. In this study, the explosion suppression effect of Fe-Ni and Cu foams with different pore sizes (20 and 40 holes pores per inch (ppi)) was experimentally investigated and comparatively analyzed at opening blockage ratios (OBR) equal to 0.36, 0.64 and 0.84, respectively. The results demonstrate that Fe-Ni foam with 20ppi quenches the flame only under the OBR of 0.84, which indicates that the larger the OBR is, the better the explosion suppression effect is. However, under the OBR of 0.64, the porous media achieve an enhanced quenching efficiency and the shortest quenching time. In addition, when the vent area is relatively large, the obstacle effect of porous media is stronger than its pressure absorption capacity, thus leading to an increased pressure in the explosion area. The lowest peak overpressure attenuation rate, − 25.9%, is observed for 40ppi Fe-Ni foam under the OBR of 0.36. In general, the OBR is positively correlated with the depressurization capacity. Among all the cases used in this study, the 20ppi Cu foam boasts the highest upstream and downstream peak overpressure attenuation rates under three OBRs, 0.86%, and 6.33%, respectively. [ABSTRACT FROM AUTHOR]

• We simulated the RBHT re-flooding experiment using the multi-channel models of RELAP5 and COSINE. • We verify the accuracy of the COSINE program in calculating the re-flooding phase. COSINE predicts the quenching time slightly earlier than the RELAP5 calculations and the experimental values of the RBHT, and the simulations are more conservative. • We analyzed the effects of system pressure, coolant subcooling, heating rod power and re-flooding rate on the thermal-hydraulic characteristics of the core during the re-flooding phase. • We derived the optimal re-flooding rate interval of 0.099–0.105 m/s based on the analysis of the effect of re-submergence rate on the peak cladding temperature and quench time. There are four main stages in PWR Loss of Coolant Accident (LOCA): blowdown, re-irrigation, re-flooding and long-term cooling. The re-flooding stage is a critical phase to avoid core meltdown and achieve long-term cooling. RBHT reflooding experiment was simulated with the RELAP5 and COSINE program respectively. Thermal-hydraulic characteristics in re-flooding phase were analyzed using multi-channel model. Quench time is mainly influenced by system pressure and coolant subcooling. Later quench will result in a higher cladding temperature. Comparatively, the peak cladding temperature is less affected by the power of the heating rod and the re-flooding rate, which fluctuates within 7 %. The higher re-flooding rate allows quenching to occur as fast as possible and improves cooling efficiency. However, higher coolant sub-cooling and re-flooding rates may cause greater thermal stresses on the core and endanger core integrity. Based on the analysis of the re-flooding rate on the peak cladding temperature and quench time, the optimal re-flooding rate interval of 0.099–0.105 m/s was obtained. [ABSTRACT FROM AUTHOR]

The present work investigated the microstructure and mechanical properties of TiC x -Cu cermets before and after thermal shock tests. Thermal shock temperature was from 800 °C to 1200 °C and number of cycles was from 1 to 20. The results indicated that TiC x -Cu cermets with co-continuous structure exhibited a stable and excellent thermal shock resistance. When quenched at 1000 °C for 1 cycle, the residual flexural strength of the cermet increased to 882 MPa, which was 10.1% higher than that without thermal shock. After 20 cycles of thermal shock, the residual flexural strength still maintain 760 MPa. When quenched at 800 °C and 1200 °C, the strengths of cermet decreased correspondingly, which were caused by the thermal mismatch between metal and ceramics and effusion of Cu or collapses of oxide layer, respectively. Herein, the recrystallization and refinement of metal phase grains caused during the thermal shock process, resulting in the superior thermal shock performance of cermet. [Display omitted] [ABSTRACT FROM AUTHOR]

Interaction of human programmed death factor-1 (hPD-1) of T cells and one of its ligands hPD-L1 which is expressed on cancer cells suppresses effector T cell functions. Studies showed that the hPD-1/hPD-L1 pathway is associated with killing mechanisms of tumor cells evading the immune system. Immunotherapy based on the checkpoint inhibitor on hPD-1 has been an important approach to treat cancer; however, not all cancer cells over-express hPD-L1. Detection of hPD-L1 over-expression in cancer cells may be a key factor for deciding on whether immunotherapy should be conducted. In the present study, we produced recombinant hPD-1 using Escherichia coli , and created a fluorescent probe termed quenched hPD-1 (QPD-1) for the detection of hPD-L1. We found that hPD-1 can quench fluorescence of carboxytetramethylrhodamine labeled on its N-terminal and QPD-1 is a convenient tool to rapidly detect hPD-L1 with a limit of detection of 10 nM and detectable range of 10 nM–1000 nM. QPD-1 may also function as a probe to screen for hPD-L1 over-expressing tumor cells and promote appropriate medical procedure through tumor immunotherapy. [ABSTRACT FROM AUTHOR]

The intra-layer no-insulation (LNI) layer-wound REBCO coil has been widely studied for its excellent high thermal stability in the research of nuclear magnetic resonance superconducting magnets. Due to the complex structure of the LNI layer-wound coil and the numerous factors that affect thermal stability, its quench characteristics are not clear. In this paper, a numerical multiphysics coupling model is established to study the transient electromagnetic and thermal behaviors of the LNI layer-wound coil during quench. The results indicate that temperature follows the diffusion law, while the currents evolve through electrical connection and electromagnetic induction. Due to the high contact resistance, the azimuthal current and axial current vary almost in units of the entire coil layer. The direction of the radial current upstream of the turn where a quench occurs is positive due to the bypassing behavior, while the radial current direction is negative downstream. The insulation material inside the LNI layer-wound coil strongly affects the quench propagation. When its thickness decreases, the equivalent radial thermal conductivity increases, thereby increasing the quench propagation velocity and current peak, and shortening the duration of the current response during quench. [ABSTRACT FROM AUTHOR]

In order to overcome the severe degradation of widely-used Ni-based cathodes in solid oxide electrolysis cells (SOECs), Ni-free oxide cathodes have recently attracted much attention. In this study, CO 2 electrolysis mechanism at LSCM ((La 0.75 Sr 0.25) 0.97 Cr 0.5 Mn 0.5 O 3) and LSCM/GDC (Gd-doped CeO 2) porous cathodes of SOEC, which are promising oxide cathodes, is investigated through active sites imaging by oxygen isotope labeling combined with electrochemical measurements. CO 2 electrolysis supplied with C18O 2 and subsequent cell quenching is conducted at 1073 K using button cells with LSCM or LSCM/GDC cathodes. From the 18O distribution in the cross section of the cathodes, oxygen is incorporated into the GDC from the triple phase boundary or GDC surface for the LSCM/GDC cathode while oxygen incorporation from the LSCM surface to its bulk occurs at the LSCM cathode. The impedance spectra show that low-frequency component of the polarization resistance is approximately 5.6 times larger than high-frequency component for the LSCM/GDC whereas both components are comparative for the LSCM. These results indicate that surface processes are the dominant resistance compared to charge transfer process in the oxygen incorporation path into GDC. In the incorporation path into LSCM, however, the both processes cause major resistances. [Display omitted] • Active sites of LSCM/GDC and LSCM cathodes are first visualized in CO 2 electrolysis. • Oxygen isotope labeling and reaction quenching experiments are conducted. • Oxide ion incorporation into GDC and LSCM particles under biased condition is imaged. • Visualization and impedance spectra give insights into CO 2 reduction pathways. [ABSTRACT FROM AUTHOR]

The abnormal expression level of alkaline phosphatase (ALP) will lead to serious diseases. Therefore, a sensitive and rapid assay for ALP activity monitoring is of vital importance. In this work, a fluorescence turn-off approach for the detection of ALP is designed on the basis of nitrogen doped carbon dots (N-CDs), which were synthesized by one-step hydrothermal method and applied as signal readout. p -Nitrophenylphosphate (PNPP) can be hydrolyzed into p -nitrophenol (PNP) by ALP and their absorption peaks are different under alkaline conditions, so it was chosen as the ALP substrate. The absorption spectrum of PNP has good overlap with the excitation and emission spectra of N-CDs, thus the fluorescence of N-CDs can be effectively quenched by PNP via the inner filter effect (IFE). Consequently, quantitative detection of ALP is realized because the relative fluorescence intensity is linearly with the ALP activity in a wide range from 0.05 to 40 U L-1. The detection limit is 0.02 U L-1 (S/N = 3), which is much lower than the normal level of serum ALP in adults (about 40–190 U L-1). Moreover, the assay was successfully applied to evaluate ALP inhibitor efficiency and screen ALP inhibitors in drug discovery. It is also demonstrated that N-CDs possesses low cytotoxicity, excellent biocompatibility and photostability, and can be successfully applied in vivo fluorescence imaging, showing great potential in clinical applications. Image 1 • N-CDs with high quantum yield were firstly synthesized by one-step hydrothermal methods. • Fluorescence detection of ALP was proposed based on the inner filter effect (IFE) of N-CDs. • N-CDs with low toxicity were also utilized in vivo fluorescence imaging. [ABSTRACT FROM AUTHOR]

• Coolant injection through control rod guide tubes (CRGTs) was conceived to cool the debris bed in a BWR lower head. • COCOMO/RELAP5 coupled analyses were conducted to assess the CRGT cooling performance. • The nominal flowrate of coolant through the CRGTs of was predicted to be able to quench the oxidic debris bed. • The oxidation of metallic debris significantly impacted the quenching process at high temperature. Since the reactor pressure vessel (RPV) of a typical BWR features a lower head that is penetrated by a forest of control rod guide tubes (CRGTs), coolability of the debris bed formed in the lower head during a severe accident can be realized by coolant injection through the CRGTs (so-called "CRGT cooling"). This paper is concerned with performance assessment of such CRGT cooling system, whose heat removal capacity is determined by two mechanisms: (i) heat-up and boiling of coolant inside the CRGTs; and (ii) evaporation of coolant which reached the top of the debris bed from CRGTs (top flooding). For this purpose, analyses were accomplished by coupling the COCOMO and RELAP5 codes, which simulate the quenching process of the debris bed and the coolant flow inside the CRGTs, respectively. An analysis was first carried out for a unit cell with a single CRGT, whose decay heat removal was limited by heat conduction from debris to the CRGT wall. The simulation indicated that without top flooding, though the temperature of the unit cell was eventually stabilized by the cooling of the CRGT wall, remelting of metallic debris (Zr) in the peripheral region was unavoidable due to low conductivity of corium. Boiling in the CRGT was not only beneficial to heat transfer, but also contributing to a flat axial temperature profile. Given the nominal flowrate of the CRGT cooling, the coolant was not completely boiled off in the CRGT, and therefore the remaining liquid water at the outlet of the CRGT was available for top flooding of the debris bed. The subsequent simulation including the top flooding showed that the debris bed was rapidly quenched without any remelting. However, the top flooding may have a side effect which was Zr oxidation risk at high temperature, leading to production of reaction heat and H 2. Finally analyses were performed for prototypical cases for a reference Nordic BWR, and the results implied that the CRGT cooling could be used as a promising strategy for severe accident mitigation. It is critical that the debris bed is sufficiently cooled down during its formation so that the oxidation risk is eliminated when the CRGT cooling is applied. [ABSTRACT FROM AUTHOR]

Resistive type superconducting fault current limiter (R-SFCL) has always been a research hotspot. Due to its simple principle and structure, good current limiting effect and easy module, it has a promising prospect applied in power system. However, R-SFCL quenching is a complex process of multiple physical fields coupling, including current, magnetic field and temperature. In general, finite element software is used to accurately simulate the process of R-SFCL. In the simulation of complex power system, the coupling calculation method can increase the complexity, calculated amount and operation time of transient simulation, availability of which is low. The calculation method of fitting formula can't accurately reflect the change of resistance in the quenching process, which affects the accuracy of system simulation. According to experiments and simulations, it is found that once superconducting tape tends to completely quenching, the quenching resistance R of YBCO superconducting tape has a fixed relation with joule heat Q produced by quenching resistance when the refrigerating mode remains unchanged. Therefore a novel simplified modeling method based on R–Q curve of YBCO resistive type SFCL is proposed, which can be easily implemented in system simulation software such as MATLAB, PSCAD/EMTDC. This method is simple structure and based on experimental data which has the advantage of fast operation speed. The good simulation effect of the method is verified by quenching experiments. [ABSTRACT FROM AUTHOR]

Highlights • The quenching of molten materials in de-ionized water and seawater is studied. • No fragmentation in the case of molten copper owing to its high surface tension. • The quench of BTOP with small surface tension results in extensive fragmentation. • The quench in seawater yields debris of larger sizes with rough surfaces. • Intensive interactions between BTOP melts and seawater owing to the complex ions. Abstract The interaction of molten materials with coolant is of significant fundamental interest and is of paramount importance for nuclear safety and material processing as well. This study explores the quenching of melts of copper spheres and a eutectic mixture of bismuth trioxide and tungsten trioxide (BTOP) in de-ionized water and natural seawater through visualization using a high-speed video camera. The results show no fragmentation in the case of molten copper owing to its high surface tension, while the quench of BTOP in de-ionized water and seawater results in extensive fragmentation. The fragmentation in seawater is characterized by a greater fraction of larger debris than that in the de-ionized water. Moreover, the examination of the debris quenched in seawater using scanning electron microscopy reveals a rougher surface, which demonstrates intensive interactions between the BTOP melts and the seawater owing to the complex ions there. [ABSTRACT FROM AUTHOR]

• The ASTEC code v2.2b models for early-degradation phenomena and hot core quenching are validated against the experimental results of the QUENCH test-6 experiment. • The accuracy of the code is quantitatively evaluated by means of the Fast Fourier Transform Based Method (FFTBM). • An Uncertainty Quantification study is performed to characterize the uncertainty affecting the code results and, in addition, to provide important outcomes regarding the application of UQ to SA code simulations. Severe Accident (SA) integral codes, such as the Accident Source Term Evaluation Code (ASTEC) developed by IRSN, are used to simulate the phenomena occurring during accident progression in Nuclear Power Plants (NPPs) up to the source term evaluation. Code validation against experimental data is fundamental to carry out deterministic safety analysis and apply these codes to NPPs. In addition, in the Best Estimate Plus Uncertainty (BEPU) framework, the quantification of the results uncertainty is needed. In the framework of the IAEA CRP I31033 "Advancing the State-of-Practice in Uncertainty and Sensitivity Methodologies for Severe Accident Analysis in Water-Cooled Reactors", the QUENCH test-6 experiment, conducted at KIT, has been selected to develop an uncertainty analysis using the ASTEC v2.2b code. The accuracy of the best-estimate ASTEC simulation was evaluated with the Fast Fourier Transform Based Method (FFTBM) against the experimental data. Then, the uncertainty of the code results was quantified by using the probabilistic propagation of input uncertainties method, through the coupling of ASTEC with RAVEN (Risk Analysis and Virtual Environment). Beyond identifying the main sources of uncertainty affecting the simulated test, the outcomes of the work also include some general discussion on the uncertainty propagation in a SA sequence. [ABSTRACT FROM AUTHOR]

Highlights • The latest PEARL experiments were reproduced by the MEWA simulation. • Top quenching was predicted by the simulation which was not detected in the experiment. • Great impact of the oxidation of Zr on the quenching process was investigated. • Injection of water from the bottom concentrated in the bed center was an effective mitigation. • Embedding a bypass inside the bed can reduce oxidation of Zr by evacuating steam. Abstract This paper is concerned with the coolability of the heap-like debris beds formed in the cavity of a Nordic-type boiling water reactor (BWR) during a postulated severe accident. A numerical simulation using the MEWA code was performed to investigate the quenching process of the ex-vessel debris bed at post-dryout condition upon its formation. To qualify the simulation tool, the MEWA code was first employed to calculate the quenching tests recently conducted on the PEARL facility. Comparisons of the simulation results with the experimental measurements show a satisfactory agreement. The simulation for the debris bed of the reactor scale shows that the heap-like debris bed flooded from the top is quenched in a multi-dimensional manner. The upper region adjacent to the centerline of the bed is the most difficult for water to reach under the top-flooding condition, and thus is subject to a higher risk of remelting. The oxidation of the residual Zr in the corium has a great impact on the coolability of the debris bed due to (i) large amount of reaction heat and the subsequent positive temperature feedback, (ii) the local accumulation of the produced H 2 which may create a "steam starvation" condition and suppresses the oxidation. As possible mitigation measures of oxidation, the effects of bottom-flooding and bypass on quench were also investigated. It is predicted that the debris bed becomes more quenchable with water injected from the bottom, especially for the case with the floor partially flooded in the center. A bypass channel embedded in the center of the debris bed can also promote the quenching process by providing a preferential path for both steam escape and water inflow. [ABSTRACT FROM AUTHOR]

Highlights • Design of the DEMO toroidal field coil, based on CroCo HTS strands, is proposed. • Thermal-hydraulic analysis of the proposed design is performed. • Temperature margin and the maximum quench temperature is assessed. Abstract The new HTS design concept for the DEMO toroidal field (TF) coil, based on cross-conductor (CroCo) strands, has been proposed by Karlsruhe Institute of Technology (KIT). The coil is layer wound and consists of 12 layers with different jacket radial thickness grades. Two variants of the design are considered, namely Option 8 and 9 with one-in-hand and two-in-hand winding, respectively. The present work is focused on the thermal-hydraulic analysis of the conductors' design, which includes: (1) hydraulic analysis—calculation of the mass flow rates in each conductor at operating conditions during the dwell time; (2) heat removal analysis aimed at the assessment of the temperature margin at the expected nuclear heat load during the plasma burn; and (3) estimation of the maximum hot spot temperature in each conductor during quench. The analysis is performed using simplified models and the THEA code, and is aimed at verification if the proposed designs fulfill the design requirements for the temperature margin and for the hot spot temperature. [ABSTRACT FROM AUTHOR]

Abstract Calcium copper titanium oxide (CaCu 3 Ti 4 O 12, CCTO) ceramics were quenched in air and liquid nitrogen separately after being subjected to sintering in low vacuum and thermobaric treatment (TBT) at 9 GPa and 1000 °C for 10 min. The refined XRD patterns showed cubic body-centered perovskite-related structure of CaCu 3 Ti 4 O 12. TBT and quenching caused extra low-intensity peaks of TiO 2 and Cu. The grain size decreased significantly from ~ 100 µm to ~ 30 µm and the configuration of grain boundary became indistinguishable after the post-treatment. The big grain size contributed to the large dielectric constant of low vacuum-sintered CCTO. Two semicircles in the complex impedance spectra (Z* plots) can be observed in the temperature range of 291–450 K that corresponding to contributions of grain boundary and grain. An apparent decreasing of the large arc diameter at low frequency suggested a reduction of the grain boundary resistance R gb by TBT, which should be related with the conduction phase of Cu. The smaller difference between R gb and R g (grain resistance) led to weaker interfacial polarization and then smaller dielectric constant of TBT-treated CCTO ceramics than the low vacuum-sintered ones. [ABSTRACT FROM AUTHOR]

A novel electrochemiluminescence (ECL) signal-off strategy based on CuS in situ grown on reduced graphene oxide (CuS-rGO) quenching luminol/H 2 O 2 system was firstly proposed. Luminol was grafted on the surface of Au@Fe 3 O 4 -Cu 3 (PO 4 ) 2 nanoflowers (Luminol-Au@Fe 3 O 4 -Cu 3 (PO 4 ) 2 ) which exhibited excellent catalytic effect towards the reduction of H 2 O 2 to enhance the ECL intensity of luminol. Cu 3 (PO 4 ) 2 nanoflowers showed large surface area which can immobilize more Fe 3 O 4 and Au nanoparticles. The quenching mechanism of CuS-rGO was due to ECL resonance energy transfer (RET). The spectral overlap between fluorescence spectrum of Luminol-Au@Fe 3 O 4 -Cu 3 (PO 4 ) 2 and UV–vis absorption spectrum of CuS-rGO revealed that resonance energy transfer was possible. Au nanoparticles were immobilized on the surface of CuS-rGO to capture secondary antibodies. After a sandwich-type immunoreaction, a remarkable decrease of ECL signal was observed. Under the optimal conditions, the immunosensor showed excellent performance for N-terminal pro-brain natriuretic peptide (NT-proBNP) detection with a wide detection range from 0.5 pg mL −1 to 20 ng mL −1 and a low detection limit of 0.12 pg mL −1 (S/N = 3). The prepared NT-proBNP immunosensor displayed high sensitivity, excellent stability and good specificity. [ABSTRACT FROM AUTHOR]

Protecting the magnets in case of a quench is a challenge for the 16 T superconducting dipole magnets presently designed for the 100 TeV: Future Circular Collider (FCC). These magnets are driven to the foreseen technological limits in terms of critical current, mechanical strength and quench protection. The magnets are protected with CLIQ (Coupling-Loss Induced Quench) system, which is a recently developed quench protection method based on discharging a capacitor bank across part of the winding. The oscillation of the magnet currents and the dissipation of the high stored energy into the windings cause electrodynamic forces and thermal stresses, which may need to be considered in the magnet mechanical design. This paper focuses on mechanical stress analysis during a quench of the 16 T cos-θ and block type dipole magnets. A finite element model allowed studying the stress due to the non-uniform temperature and current distribution in the superconducting coils. Two different CLIQ configurations were considered for the cos-θ design and one for the block type magnet. The analyses of the mechanical behavior of two magnets during a quench without or with hot spot turn were separately carried out. The simulation results show that the stress related to a quench should be considered when designing a high field magnet. [ABSTRACT FROM AUTHOR]

The effect of local defects on the quench properties for YBCO tapes after applying bending strain was investigated at self-field in 77 K. The minimum quench energy (MQE) was related to the position of defects in the tape and the smallest MQE appears where the region of the defects existed in the position of the heater at the same transport current. The normal zone propagation velocity (NZPV) was related to the size and quantity of the regions of defects. The more defects were in the tape, the faster the normal-zone propagation velocity. [ABSTRACT FROM AUTHOR]

In order to study the heat transfer of water during film boiling, stable film boiling heat transfer experiments are conducted in a circular tube. As the temperature of the heater surface sharply increases in a short period of time when critical heat flux (CHF) occurs, hot-patch technology is adopted to prevent damage to the test section. A complete experimental design, including the experimental facility, test section, experimental procedures, and the measurement of parameters, is developed. Two experimental schemes are used for testing, namely the post-CHF test and the quench test, respectively. These two schemes have been verified to achieve stable film boiling and yield consistent results. The effect of various parameters, including heat flux, pressure, mass flow and inlet subcooling, on the heat transfer coefficient has been analyzed. The experimental parameters range from an inlet subcooling of 10–50 K, a pressure of 0.1–2.5 MPa, and a mass flux of 100–1000kg/m2s. Through the analysis of the distribution of heat transfer coefficient along the axial location, three distinct heat transfer regions can be identified. Combined with heat transfer characteristics, three types of flow are considered: smooth inverted annular flow, rough inverted annular flow and inverted slug flow. Most of the data in this study is concentrated in the first two regions, namely the inversed annular flow. The data obtained in these tests is expected to provide important information for the study of inverted annular flow. • Direct hot-patch technology is adopted to carry out film boiling experiments. • Two different experimental methods are used and consistent results are obtained. • Three regions are divided along the axial direction by heat transfer coefficient. • Effect of several parameters on heat transfer coefficient are discussed detailed. [ABSTRACT FROM AUTHOR]

This work addresses the development and fabrication of new bioactive glass composition based on SiO 2 -CaO-Na 2 O-P 2 O 5 system that can be melted at lower melting temperature (1377 °C and 1348 °C) than 1400 °C through melt-derived route. All BG compositions did not show significant differences on their particle size while retaining their amorphous structure. Formation of Si- O -Si (tetrahedral) functional group indicated that silicate based glass structure was established as discovered by Fourier transform infrared spectroscope (FTIR). Apatite formation was observed on bioactive glass surface though being fabricated at lower melting temperature upon soaking in Tris-buffer solution. Feature of carbonate (C-O) and P-O functional group was discovered from FTIR for all glass composition. Present of crystalline peaks was detected in X-ray diffraction (XRD) though fewer peaks were observed for glass fabricated at lower melting temperature. Morphology of apatite in crystal cluster form on the glass surface was identified through scanning electron microscope (SEM). [ABSTRACT FROM AUTHOR]

JT-60SA is a fusion experiment which is jointly constructed by Japan and Europe and which shall contribute to the early realization of fusion energy, by providing support to the operation of ITER, and by addressing key physics issues for ITER and DEMO. In order to achieve these goals, the existing JT-60U experiment will be upgraded to JT-60SA by using superconducting coils. The 18 TF coils of the JT-60SA device are provided by European industry and tested in a Cold Test Facility (CTF) at CEA Saclay. The first coils were tested at the nominal current of 25.7 kA and at a temperature between 5 K and 7.5 K. The main objective of these tests is to check the TF coils performances and hence mitigate the fabrication risks. These first tests allowed checking a certain number of performances of the first TF coils: DC/AC insulation, cooling down characterization, RRR of the conductor, pressure drop in the winding pack and temperature margin against a quench. This paper will give an overview of the main experimental results obtained during these tests. These results will be analyzed and discussed in the light of the expected TF coils performances. [ABSTRACT FROM AUTHOR]

Three alternative designs of the toroidal field (TF) coil were proposed for the European DEMO being developed under the Eurofusion Consortium. The most ambitious TF coil winding pack in terms of technological deviation from the ITER TF coil design and consequent potential cost saving, the so-called WP1, is based on the react&wind technology of Nb 3 Sn layer-wound flat multistage conductors. We present the thermal-hydraulic and quench propagation analyses for the WP1 proposed in 2015, in which the realistic magnetic field and nuclear heat load maps are taken into account. The aim of the analysis, performed using the Cryosoft software, is to assess the temperature margin at the end-of-burn conditions, as well as the hot-spot temperature that is expected in case of quench, and consequently to optimize the WP1 design from the thermal-hydraulic point of view. [ABSTRACT FROM AUTHOR]

We analyzed the linear energy transfer (LET; energy deposited onto the target per unit length) effects on the scintillation properties of Bi 4 Ge 3 O 12 (BGO) with an emphasis on the dynamical aspect. We irradiated BGO with 20 MeV H ± , 50 MeV He ± , and 220 MeV C 5+ . We observed that the rise and the decay of the scintillation temporal profiles are faster at higher LET. The faster decay at higher LET is attributed to the competition between the radiative transition of self-trapped excitons (STEs) localized at Bi 3+ ions and the quenching caused by the interaction between STEs. The faster rise can be explained in terms of the competition between the quenching caused by the interaction between excited states and the formation of the STEs. [ABSTRACT FROM AUTHOR]

The higher melting temperature and longer soaking time during conventional glass melting route promoted the search for alternative in developing new bioactive glass (BG) composition with improved in fabrication temperature and melting time. The current project involved fabrication of new BG compositions based on SiO 2 -CaO-Na 2 O-P 2 O 5 system via melt derived route. It was confirmed that all bioactive glass composition can be melted at temperature lower than 1400 °C. Formation of Si-O-Si (tetrahedral) functional group highlighted that silicate based glass was established as detected by Fourier transform infrared spectroscope (FTIR). BG bioactivity was performed by incubating the BG powder in Tris-buffer solution (pH 8) for 7, 14 and 21 days. In vitro test confirmed the apatite formation on the bioactive glass surface upon soaking in Tris-buffer solution with characteristic of carbonate group (C-O) and P-O band noticed from FTIR and present of crystalline peak observed in X-ray diffraction (XRD). Morphology of apatite formation on BG surface was observed using scanning electron microscope (SEM). [ABSTRACT FROM AUTHOR]

The as-quenched martensite crystal structure is widely accepted as body-centered tetragonal. The classical Honda & Nishiyama model, c/a = 1 + 0.045 wt%C, was obtained based only on the experimental results for steels containing more than 0.6 wt% of carbon. This model was used to predict that steels containing less than 0.6 wt% of carbon would follow the same relation. However, it was reported by Sherby that the steel with less than 0.6 wt% of carbon is body-centered cubic, and c/a ratio equals to 1. This debate is caused by highly overlapped martensite (002) and (200) peaks when the carbon content of steel is less than 0.6 wt%. In this paper, the martensite lattice parameters of the as-quenched steels with different carbon contents were measured using high-resolution X-ray diffractometer. Rietveld refinement was used to deconvolute overlapped martensite peaks. For the steel with less than 0.6 wt% of carbon, the structure is proved to be body-centered tetragonal. It was found that the relationship between c/a ratio and carbon content follows as c/a = 1 + 0.031 wt%C. [ABSTRACT FROM AUTHOR]

The Fukushima accidents have shown that further improvements of Severe Accident Management Guidelines (SAMGs) are still necessary. Hence, the enhancement of severe accident codes and their validation based on integral experiments is pursued worldwide. In particular, the capabilities of the European integral severe accident ASTECV2.1 code are being extended within the CESAM project through the improvement of physical models, code numerics and an extensive code validation. Among the different strategies encompassed in the plant SAMGs, one of the most important ones to prevent core damage is the injection of water into the overheated core (reflooding). However, under certain conditions, reflooding may trigger a sharp hydrogen generation that may jeopardize the containment. Within this work, ASTECV2.1 models describing the early in-vessel phase of the severe accident and its termination by core reflooding are validated against data from the QUENCH test facility. The QUENCH-08, involving the injection of 15 g/s (about 0.6 g/s/rod) of saturated steam at a bundle temperature of 2073 K, has been selected for this comparison. Results show that ASTECV2.1 is able to reproduce the experimental temperatures and oxide thicknesses at representative bundle locations. The predicted total hydrogen generation (76 g) is similar to the experimental one (84 g). In addition, the choices of an axial mesh size lower than 55 mm and of an external electrical resistance of a 7 mΩ/rod have been justified with parametric analyses. Finally, new modelling options are introduced to overcome some discrepancies present in the reference case and to cancel the effect of the external electrical resistance in the QUENCH model. Results show that the predicted hydrogen generation during quenching (38 g) is closer to the experimental one (37 g) than the reference case, giving a better reproduction of the radial temperature gradient within the hottest zone. [ABSTRACT FROM AUTHOR]

Quench is a widely used technique in organic synthesis or inorganic material treatment but only limited studies have been performed on aluminosilicate. In this work, the quench effect on the textural properties and surface functional groups has been studied by the functionalization of a waste-derived aluminosilicate material. The porous structure has been changed in the presence of a quench reagent. We consider that this difference originated due to the prevention of replacement of potassium atoms in surface ion-exchange sites by hydrogen atoms. Surface characterization including SEM, XPS and FTIR further confirmed the preservation of Si O K functional groups. Meanwhile, due to the differences between the electronegativities of potassium atoms and hydrogen atoms the ion-exchange ability for heavy metals of the quenched samples was significantly enhanced and this has been validated by adsorption experiments with various kinds of metals. The mass balance for leaching calcium and potassium atoms also revealed that the enhanced ion-exchange capacity was caused by the improved liberation of potassium and calcium atoms from the aluminosilicate network. Moreover, the leaching test for metal doped material shows a limited amount of metal leaching under acidic conditions, indicating the potential application of this material in industrial wastewater treatment or catalysis applications. [ABSTRACT FROM AUTHOR]

A large-scale bundle experiment with silver-indium-cadmium absorber rod in the QUENCH facility as well as a series of small-scale single absorber rod tests with prototypical materials have been conducted. A variety of parameters like temperature history, initial contact between cladding and guide tube and possibility of inner oxidation of the guide tube was investigated in the single-rod tests. Different failure modes from local melt-through to explosive failure were observed depending on the sample type. No interaction between Ag-In-Cd melt and stainless steel was seen up to 1750 K, near to the melting temperature of the steel. The cladding did not balloon before failure. Metallographic post-test analysis identified various phases formed during the high-temperature interactions between the involved materials. Furthermore, solidus and liquidus temperatures of the Ag-In-Cd alloy were determined accurately by DSC. [ABSTRACT FROM AUTHOR]

• The behavior of B136Y3 (FeCrAl) cladding to LOCA-type conditions was evaluated. • Hydrogen release was significantly lower than a similar test with Zr-based cladding. • Thermocouple sheaths reacting with the FeCrAl led to significant cladding oxidation. • CTE mismatch was attributed to occasional cladding fracture events during quench. The QUENCH-19 experiment was a first-of-its-kind full-bundle test simulating accident conditions followed by water quench on accident-tolerant fuel (ATF) cladding. A type of FeCrAl(Y) alloy, B136Y3, was developed at Oak Ridge National Laboratory and tested at the Karlsruhe Institute of Technology using Kanthal APM corner rods, a shroud, and Kanthal AF spacer grids. Testing conditions were similar to those in QUENCH-15—which tested ZIRLO cladding behavior—so that B136Y3 and ZIRLO cladding could be compared. QUENCH-19 consisted of an initial pre-oxidation heating followed by a transient. Then, a maximum power hold, which was not present in QUENCH-15, was executed to extend the heating period for the FeCrAl(Y) rods. Finally, a rapid water quench was executed that was similar to emergency core coolant system (ECCS) actuation. Compared with the ZIRLO rods in QUENCH-15, the bundle in QUENCH-19 released significantly less H 2 (9.2 g vs. 47.6 g) and achieved a much lower maximum temperature (1455°C vs. 1880°C). Furthermore, no breakaway oxidation was observed in QUENCH-19. Metallographic mounts revealed that despite the symmetry of the setup, at elevations near the maximum temperature, cladding and thermocouples were heavily damaged, substantial melting and oxidation occurred, and the cladding underwent chemical interaction with the thermocouple sheaths. Additionally, the ZrO 2 spacers detrimentally interacted with the cladding, leading to mixed oxide debris and the full destruction of some rods. Additional failure was found in certain cooler rods that may have risen due to the high thermal expansion coefficient of FeCrAl alloys. This paper presents an analysis of this work, which suggests that FeCrAl cladding can chemically survive anticipated loss-of-coolant accident events followed by rapid ECCS quench if the correct geometry and core design are present. [ABSTRACT FROM AUTHOR]

The recent experimental campaign, carried out in the upgraded SULTAN facility and supported by EUROfusion, investigated quench propagation in high field, sub-size HTS Cable-In-Conduit Conductors. The available experimental data consist of voltage, jacket and helium temperatures measured along the length of the conductors. In this work, the analysis of experimental data is carried out, focusing on the normal zone propagation velocity and the hotspot temperature reached during the quench. The validation of one-dimensional (1D) thermal-hydraulic and electric numerical models implemented in the H4C code is presented, showing very good agreement between experimental and computed results, both in terms of global and local quantities. The validated tool is then used to assess the impact on the hotspot measured in SULTAN and that reached in a uniform magnetic field configuration, showing that SULTAN measurements provide conservative assessments. The tool is then used to simulate a quench in a real-case scenario, i.e., the EU DEMO Central Solenoid operation, showing that a conventional quench detection strategy based on voltage measurements should suffice, leading to hotspot temperature around 250 K. • The analysis of the experimental results of the quench tests on HTS conductors is presented. • Calibration and validation of numerical model implemented in the H4C code is carried out. • The model shows that a conventional detection strategy could be viable for the EU DEMO CS. • The SULTAN quench tests provide conservative results in terms of hotspot temperature. [ABSTRACT FROM AUTHOR]

• Development of simplified 1-D quench propagation model for fusion LTS magnet featuring cable-in-conduit conductors. • Application to JT-60SA toroidal field coil and its pressure relief system. • Comparison of simulations results with the SuperMagnet code. • Analyses of the simplified model accuracy, limitations and potential interest for fast assessment of magnet safety during pre-design studies. A simplified thermal hydraulic tool dedicated to quench propagation in superconducting magnets was developed. It models 1-D flow and heat transfers in cable-in-conduit conductor coupled with a helium hydraulic network. The model relies on assumptions saving computational resources for engineering design purposes and system performances assessment. It can simulate the quench development for both the early stage before primary quench detection as well as for the current discharge stage. The code robustness and accuracy are investigated on quench simulations of JT-60SA toroidal field coil in nominal tokamak conditions. Furthermore, a comparison with the widely used SuperMagnet code depicting consistent results confirms the simplified assumptions. A simplified thermal hydraulic tool dedicated to quench propagation in superconducting magnets was developed. It models 1-D flow and heat transfers in cable-in-conduit conductor coupled with a helium hydraulic network. The model relies on assumptions saving computational resources for engineering design purposes and system performances assessment. It can simulate the quench development for both the early stage before primary quench detection as well as for the current discharge stage. The code robustness and accuracy are investigated on quench simulations of JT-60SA toroidal field coil in nominal tokamak conditions. Furthermore, a comparison with the widely used SuperMagnet code depicting consistent results confirms the simplified assumptions. [ABSTRACT FROM AUTHOR]

Iron coke is an emerging alternative material for iron-making blast furnaces. To massively produce iron coke, the industrial-scale gas heat carrier pyrolyser is a suitable reactor, but the present pyrolysis technology requires further improvements to lower energy consumption and CO 2 emission. In this study, a transient 3D CFD model is developed to describe the thermochemical behaviours in the industrial-scale pyrolyser. Meanwhile, a DEM model is used to simulate the packing status evolution of ellipsoidal iron-coke hot briquettes in the pyrolyser chamber, which is input as the simulation conditions in the CFD model. The numerical model is validated against the lab-scale and pilot-scale experimental data. The integrated numerical model is then employed to illustrate heating and quenching processes using the recycled pyrolysis gas as the heat carrier. A new concept that utilises recycled pyrolysis gas to quench the hot briquette after pyrolysis inside the chamber is proposed and examined by the numerical model. In addition, the structure optimisation, i.e., adjustment of the gas inlets' layout, is conducted and numerically examined. The simulation results indicate that the present structure of the pyrolyser has some non-uniform temperature zones, such as the upper bed and near-wall areas where the heat is not effectively transferred to the bed like other zones. 10 h of pyrolysis could effectively pyrolysis iron-coke hot briquettes in the chamber, but for the quenching process, 10 h is not able to fully cool down the briquette bed to room temperature. The design of the upper inlet layout could significantly improve the heating and pyrolysis efficiency. It can shorten 14% heating time in comparison with the original lower inlet layout. [Display omitted] • A comprehensive 3D transient CFD model is developed to study ICHB pyrolysis. • The ICHB heating and quenching in an industrial-scale pyrolyser are modelled. • The impacts of gas inlets' layout adjustment on pyrolysis performance are examined. • The design of the upper inlet layout significantly improves pyrolysis efficiency. • 14% heating time is shortened in comparison with the original lower inlet layout. [ABSTRACT FROM AUTHOR]

• The delamination is analyzed in an epoxy-impregnated pancake coil during a quench. • The localized high-temperature gradients lead to delamination inside the coil. • The delamination propagation is mainly determined by shear stress. For the epoxy-impregnated high-temperature superconducting (HTS) REBa 2 Cu 3 O 7-x (REBCO) magnets, the quench cannot be still avoided in the operation, which may induce the mechanical damage of the magnets and even burning out. In this research, an electromagnetic-thermo-mechanical coupling model is proposed to explore the delamination mechanisms of an epoxy-impregnated REBCO pancake coil during a quench, and thereinto, a cohesive zone model (CZM) based on the mixed-mode traction-separation law is used to simulate the onset and growth of the delamination. The numerical results indicate that the delamination of the coil is mainly concentrated in the quenching turns. The reason is that localized high-temperature gradients are generated in these turns due to the large temperature increase during a quench, and thus the accumulated stress induced by the thermal mismatch stress locally leads to the cracking of the interface between the superconducting layer and Hastelloy substrate. Meanwhile, the delamination onset of the coil is predicted by mixed-mode delamination according to the quadratic failure criterion, and the delamination propagation is mainly determined by shear stress. Up to now, the delamination mechanisms of the epoxy-impregnated pancake coil during a quench are clarified in detail, which is different from those during cooling down. To further understand the delamination behaviors of the epoxy-impregnated pancake coil during a quench, the effects of the location and height of the heater, and the thickness of the epoxy resin on the interface delamination failure are discussed in the paper. [ABSTRACT FROM AUTHOR]

This work investigated the quenching effect of ferrocenecarboxylic acid (Fc-COOH) on the bovine serum albumin-stabilized Au nanoclusters-triethylamine (Au 25 -Et 3 N) electrochemiluminescence (ECL) system. Based on the annihilation between the oxidation product of Fc (Fc + ) and Et 3 N radical, a quenching-based sandwich-configuration ECL biosensor was established for sensitive and specific detection of concanavalin A (ConA). Au 25 with strong initial ECL signal were modified onto the glassy carbon electrode (GCE) for immobilizing glucose oxidase (GOD). With the further immobilization of target ConA, the quenching probe of GOD@Fc-COOH-PtPd nanocubes were incubated onto the electrode through a specific carbohydrate-ConA interaction, thus achieving a sandwich structure. The resulting ECL biosensor showed a wide linear range from 0.004 ng/mL to 90 ng/mL and a low detection limit of 0.001 ng/mL (S/N = 3) for ConA detection. The integration of Fc-COOH with Au 25 -Et 3 N system would hold a great promise in bioanalysis. [ABSTRACT FROM AUTHOR]

The effective removal of tar is one of the main obstacles to the large-scale industrialization of biomass gasification process. In this research, a quench coupled with adsorption technology (QCAT) has been developed and patented to ease this barrier, which contained the quench column, the 1 st adsorption column and the 2 nd adsorption column. For this research, an analysis method of light and medium biomass gas tar was established to determine the light PAH tar (2-4 ring) and light aromatic tar (1 ring) compounds as well as their concentrations; the removal performance and the mechanism of the real tar which produced by the gasification were researched. The results showed that the quench column was used to remove the heavy tar; the 1 st adsorption column was able to remove pyridine and the light PAH aromatic tar (2-4 ring) without naphthalene; the 2 nd adsorption column was used to remove the light aromatic tar (1 ring) as well as naphthalene. The tar removal rates of the light aromatic tar and light PAH tar were almost 99.9% in the effective time of the experiment. The outlet gas of the 2 nd adsorption column reached application requirement. [ABSTRACT FROM AUTHOR]

A large amount of energy is stored in ITER superconducting magnet system. Faults which initiate a discharge are typically mitigated to quickly transfer away the stored magnetic energy for dissipation through a bank of resistors. In an extreme unlikely occurrence, an unmitigated fault event represents a potentially severe discharge of energy into the coils and the surrounding structure. A new simulation tool has been developed for the detailed study of these unmitigated fault events. The tool integrates: the propagation of multiple quench fronts initiated by an initial fault or by subsequent coil heating; the 3D convection and conduction of heat through the magnet structure; the 3D conduction of current and Ohmic heating both along the conductor and via alternate pathways generated by arcing or material melt. Arcs linking broken sections of conductor or separate turns are simulated with a new unconstrained arc model to balance electrical current paths and heat generation within the arc column in the multi-physics model. The influence under the high Lorenz forces present is taken into account. Simulation results for an unmitigated fault in a poloidal field coil are presented. [ABSTRACT FROM AUTHOR]

The combination of advances in Computational Fluid Dynamics (CFD) reactive flow predictions together with mature, robust optimization techniques provides the opportunity to evolve promising design development methods. A quench conversion reactor concept has been chosen to perform a CFD-based multi-objective optimization on the basis of an optimization concept for turbulent, reactive flows using a Multi-Objective Genetic Algorithm (MOGA-II). The study includes the pre-optimization of the numerical setup as well as the reduction of a detailed chemical mechanism to reduce computation time and also fit the specific quench concept syngas and reaction conditions. Geometric and process parameters have been defined as control parameters to maximize the H 2 /CO ratio in the syngas and minimize the corresponding exit temperature. To achieve this, three cases with different optimization strategies, including a Pareto optimization, are investigated and discussed. Optimized, feasible design options for the quench reactor were obtained. [ABSTRACT FROM AUTHOR]

Syntheses downstream of coal gasifiers face specific requirements regarding syngas quality. High syngas H 2 /CO ratios are a typical requirement. A new quench concept for entrained-flow gasifiers has been developed in order to increase the H 2 /CO ratio within the quench vessel and thereby minimize efforts in the subsequent catalytic water–gas shift reaction (WGSR). To achieve this target, steam instead of water will be injected into the quench chamber to realize CO conversion via homogeneous WGSR. The concept allows a flexible mode of operation, such as full or partial water quenching with subsequent waste heat utilization for high and medium-pressure steam production. This allows self-sufficiency in terms of steam and additionally offers the potential to increase the overall plant efficiency. To test the concept, three different syngases from various feedstock and two inlet design configurations will be investigated using CFD and compared to one other. The numerical setup has been validated against gasification reactor measurements and simulation, respectively. A sensitivity analysis shows the performance and flexibility of the proposed concept. [ABSTRACT FROM AUTHOR]

Air ingress is a potential risk in some low probable situations of severe accidents in a nuclear power plant. Air is a highly oxidizing atmosphere that can lead to an enhanced Zr-based cladding oxidation and core degradation affecting the release of fission products. This is particularly true speaking about ruthenium release, due to its high radiotoxicity and its ability to form highly volatile oxides in a significant manner in presence of air. The oxygen affinity is decreasing from the Zircaloy cladding, fuel and ruthenium inclusions. It is consequently of great need to understand the phenomena governing cladding oxidation by air as a prerequisite for the source term issues in such scenarios. In the past years, many works have been done on cladding oxidation by air under severe accident conditions. This paper with in addition the paper “Cladding oxidation during air ingress – Part I: Synthesis of experimental results” of this journal issue aim at assessing the state of the art on this phenomenon. In this paper, the modelling of air ingress phenomena in the main severe accident codes (ASTEC, ATHLET-CD, MAAP, MELCOR, RELAP/SCDAPSIM, SOCRAT) is described in details, as well as the validation against the integral experiments QUENCH-10, QUENCH-16 and PARAMETER-SF4. A full review of cladding oxidation by air is thus established. [ABSTRACT FROM AUTHOR]

Loss-of-Coolant-Accident (LOCA) is a design basis accident that is considered in safety analyses for LWR. This paper discusses crack formation in one-side oxidized Zircaloy-4 cladding with LOCA oxidation quench experimental data. Two types of test pins were used in these experiments. One consisted of a Zircaloy-4 cladding tube and alumina pellets. Another comprised a Zircaloy-4 cladding tube alone. The experimental results showed that the fracture load in the latter cases was larger by about 1000 N, and cracks in the oxide layer were clearly observed in the former cases but not in the latter cases. This trend suggested that the order of cracks formed in cladding during LOCA quench conditions should be, first in the α-Zr(O) layer, and then in the oxide, finally in the prior-β layer when the fracture of cladding occurs. The formation of cracks in the oxide was considered to be related to the maximum thermal stress generated in the cladding during quench. RANNS computation suggested that the maximum radial temperature difference in the former case tended to be larger than that in the latter case, and the radial temperature difference increases considerably with off-center pellets, which might also affect crack formation. [ABSTRACT FROM AUTHOR]

Tar removal is one of the major limitations to the large-scale industrialization of biomass gasification technology. Quench Coupled with ABsorption Technology (QCABT) has been developed and patented to alleviate this obstacle. Cyclohexane and n-dodecane were used as the simulated light and heavy tars, respectively, and their removal performance and the mechanism of their removal by QCABT were evaluated. The results show that modified diesel is the preferred cyclohexane absorbent because of the resulting high removal rate. The concentration of n-dodecane can be reduced to about 15% in the quench scrubber, and is decreased to less than 1% in the absorber. QCABT exhibits both cooling and absorption effects in the quench scrubber upon the removal of cyclohexane, providing a total removal efficiency of 98%. The quenching temperature plays a dominant role in n-dodecane removal, and exhibits a beneficial linear relationship based on the Antoine equation. The mass ratio of the absorbent to the coolant couples the activities of the quench scrubber and the absorber. Varying tar sampling concentrations change the tar loading distributions in the quench scrubber and the absorber. The modified diesel can be regenerated effectively after being purged for 125 min at 50 °C. [ABSTRACT FROM AUTHOR]

Following a postulated severe accident, the temperature of fuel pins of light water reactor escalates because of decay heat and devoid of coolant. The presence of steam inside the core causes exothermic oxidation of the cladding surface at elevated temperatures. The in-vessel injection system of severe accident management guidelines injects the cold water inside the hot uncovered core to arrest the escalation of temperature rise and terminate the accident progression. However, the heated clad may be subjected to thermal shock during the quenching process, which inevitably assists in the failure and fragmentation of the severely oxidised fuel pins column. In this paper, the effect of thermal quenching shock on the severely oxidised fuel pins column during the reflooding of the hot uncovered core is studied experimentally. A 2ˣ2 square lattice arrangement of zircaloy-4 clads is used for experiments. First, the clads are oxidised in the presence of steam in the temperature range of 1100–1250 °C, and then the test-section is flooded with water at ambient temperature from its bottom. The violent heat transfer between the clad and cold water has been observed during the reflooding. Furthermore, the clad has failed with a circumferential crack at multiple locations along the clad length during this period; however, longitudinal cracks are not observed on the clad surface. The scanning electron micrographs of the clad samples show a significant oxide layer over the clad surface. At the same time, energy dispersive x-ray spectroscopy reveals significant oxygen diffusion inside the zirconium metal matrix, particularly near the outer tube surface. Additional experiments are performed to study the clad failure mechanism during the reflooding of the severely oxidised clad. The set of experiments reveals that the clad fails under the thermal quench shock (>7.41 °C/s) for severely oxidised cladding (ECR>25%) at an average temperature above 1100 °C. The failed clad is likely to create debris. The average quench front velocity is 0.6 cm/s while the reflood velocity is 1.13 cm/s. Quench velocity below the reflood velocity indicates excessive water evaporation and dispersed type flow ahead of the quench front. The total analytical H 2 generated before reflooding is 3.75 g. [ABSTRACT FROM AUTHOR]

Bond graphs are widely used in the modelling of various systems. In this work, we are exploring the idea of using bond graphs to model the event of 'Quench' in a superconducting magnet. Quench is the event where a portion of the magnet turns normal, i.e. resistive. This starts Joule heating at that spot, and the stored energy of the magnet will be deposited at that point. This can lead to temperature rise and high voltage arcs. Here a bond graph model is proposed to study the electrical and thermal domain of the quench event. The model is further used to simulate the quench in a 6T superconducting solenoid magnet, and the results are compared with the results of a commercial quench solver. The results show close agreement with minor variations due to various assumptions taken in both cases. With the case successfully demonstrated, the model can be improved further to simulate more complex magnet systems and can provide a robust and fast method for quench simulation. [ABSTRACT FROM AUTHOR]

Twence is a waste processing and energy generation company located in the eastern part of the Netherlands. In the Twence plant waste is incinerated and in this process the waste is converted to valuable products like heat and power. In the flue gas produced from this Waste-To-Energy (WTE) plant a significant amount of CO 2 is released to the atmosphere. Recently a new innovative process developed by Procede Gas Treating B.V. has been commissioned at line 3 of the Twence plant. In this process CO 2 emitted to atmosphere, is scrubbed from the flue gas and this CO 2 is used for mineralization. The CO 2 is converted in an innovative new reactor configuration from sodium carbonate directly to sodium bicarbonate (SBC). The produced SBC slurry will directly be used at the WTE plant to purify the flue gas stream, before it is released to atmosphere. Due to the implementation of this process, which is unique in the world, the carbon footprint of the Twence installation is reduced. The new SBC plant produces 8,000 tons of sodium bicarbonate annually and to produce this amount of SBC 2,000 ton per year CO 2 is captured from the flue gas. [ABSTRACT FROM AUTHOR]

Superconducting fault current limiters (SFCLs) are increasingly implemented in the power grid as a protection of substation equipment from fault currents. Resistive SFCLs are compact and light, however they are passively triggered and thus may not be sufficiently sensitive to respond to faults in the distribution grid. Here, we explore the prospect of adding an active management feature to a traditional resistive SFCL. A flexible radio-frequency coil, which is an integral part of the switching structure, acts as a triggering device. We show that the application of a short, 10 ms, burst of ac magnetic field during the fault triggers a uniform quench of the wire and significantly reduces the reaction time of the wire at low currents. The ac field burst generates a high density of normal zones, which merge into a continuous resistive region at a rate much faster than that of sparse normal zones created by the transport current alone. [ABSTRACT FROM AUTHOR]

SST-1 TF power supply provides the direct current for the required magnetic field of TF coil. TF power supply includes transformer, 12-pulse converter, bus bar, water-cooled cable, protection and measuring equipments, and isolator, VME DAC system and GUI software. TF power supply is operated through GUI software built in TCL/Tk. VME DAC system monitors the parameters, provides On/Off commands, voltage and current references and initiates predefined reference to emergency shutdown. The emergency shutdown is hardwired to TF power supply from central control. During quench power supply converter opens DCCB and dump resistor is connected in the circuit and VME DAC system acquires bus bar voltage, dump voltage and dump current. Operation of TF power supply also requires monitoring of SCR and transformer temperature and water flow rate of water-cooled cable during high current long pulse shot. Before start up of TF power supply a quench simulation is performed to check the readiness of protection. This paper describes pre startup operation, normal shot operation, emergency and quench process, dynamic control and complete shutdown operation of TF power supply. [ABSTRACT FROM AUTHOR]

Energy transfer dynamics in dimeric photosystem II (PSII) complexes isolated from four diatoms, Chaetoceros gracilis , Cyclotella meneghiniana , Thalassiosira pseudonana , and Phaeodactylum tricornutum , are examined. Time-resolved fluorescence measurements were conducted in the range of 0–80 ns. Delayed fluorescence spectra showed a clear difference between PSII monomer and PSII dimer isolated from the four diatoms. The difference can be interpreted as reflecting suppressed energy transfer between PSII monomers in the PSII dimer for efficient energy trapping at the reaction center. The observation was especially prominent in C. gracilis and T. pseudonana . The pathways seem to be suppressed under a low pH condition in isolated PSII complexes from C. gracilis , and excitation energy may be quenched with fucoxanthin chlorophyll a/c -binding protein (FCP) that was closely associated with PSII in C. gracilis . The energy transfer between PSII monomers in the PSII dimer may play a role in excitation energy regulation in diatoms. [ABSTRACT FROM AUTHOR]

For measuring a sample stored for a long period of time using liquid scintillation counting (LSC), it is necessary to study the long-term stability of the sample. The effect of sample stability on the determination of radioactivity for 241 Am, 90 Sr/ 90 Y, 137 Cs, 147 Pm, 237 Np/ 233 Pa, and 3 H by LSC has been investigated. The variation of quench level over time can be an indication of sample stability. If the variation in a sample is little, the effect of sample stability on the determination of the above radionuclides can be neglected. Otherwise, the sample stability will have impact not only on the counting efficiency (especially for low energy β emitters), but also on the results of α/β discrimination. For studying the stability of a sample, special attention should be paid to the radionuclides with chemical form apt to be adsorbed, because the quench level of a sample cannot be reflected by the quench index SQP(E) alone when significant physical quench exists. Shaking a sample stored for a long period of time and checking the LSC spectra can give the information on physical quench in the sample. In the range of this study, OptiPhase Hisafe 3 has much better quench resistance than Ultima Gold AB. [ABSTRACT FROM AUTHOR]