Channel Box Research Articles

Performance evaluation of different new channel box photovoltaic thermal systems

Current research has highlighted three major gaps in the literature: (a) a rarity of studies on photovoltaic thermal systems with channel boxes, (b) a lack of data on pressure drop and surface temperature distribution in these systems, and (c) absence of analysis regarding the impact of materials (metals and polymers) used in photovoltaic thermal systems on performance, cost, payback time and weight. The novelty of this paper lies in addressing these gaps by studying a new channel-box photovoltaic thermal system, varying the number of channels and the height of the collectors that distribute water to these channels, in order to identify the most efficient design in terms of electrical, and thermal efficiency as well as pressure drop. In addition, the impact of different heat exchanger materials (metals and polymers) on the performance, cost, payback time, and weight of photovoltaic thermal systems was investigated. 3D numerical simulations were carried out using COMSOL Multiphysics software, based on the finite element method, and validated by outdoor experimental research. The results show that the photovoltaic thermal system 8 design performs best, with a total efficiency of 89.42%. In addition, the aluminum photovoltaic thermal system stands out as the most cost-effective option, with a payback time of 0.823 y (300 d) and annual savings of $459.262, while being 38% lighter than the copper system. Based on this study, it is recommended that the photovoltaic thermal system 8 be implemented because of its exceptional performance and ease of implementation.

Improved Analysis of the Short-Term Station Blackout Accidents of the Peach Bottom Unit-2 Reactor with ASTEC Including Radiological Impact and Statistical Analysis with JRODOS

After the severe accident at Fukushima, the importance of BWR design and related structures and their contribution to the severe accident progression has increased. Fuel channel boxes, absorber crosses, water rods, and smaller primary containment design of the BWR have been considered in the ASTEC code to increase the knowledge of BWR design and associated models. The previously developed ASTEC model for Peach Bottom Unit-2 was updated to include modern GE14 10x10 fuel assemblies with realistic fission product inventories. The CASMO5 code predicted the fission product inventory and burnup for GE14 10x10 fuel assemblies based on real plant data obtained from the ENRESA samples. First, a Short-Term Station Blackout (ST-SBO) analysis was performed to compare the impact of the old and new fuel assembly designs on the accident progression and radiological consequences. Second, a short-term station blackout with a stuck open safety relief valve (ST-SBO SOSRV) was considered for modern fuel assemblies. The actuation of the safety valve resulted in a much lower corium ejection and a longer transient to basemat failure in the cavity. The scatter of corium ejection amounts between the considered scenarios showed the importance of the design of the bottom head and the penetration points in BWRs. In both cases, failure of the drywell head flange and release of radionuclides to the environment occurred. Higher burnup and radionuclide inventory in the 10x10 assemblies resulted in a larger release compared to the previous design. Radiological analysis using JRODOS was performed for both cases and the maximum total effective gamma dose rate was estimated to be 67.89 mSv/h and 119.46 mSv/h for ST-SBO and ST-SBO SOSRV, respectively. The statistical analysis and the number of records in the considered cities around the Peach Bottom Plant showed the distribution over the region and the risk factors of the populated cities. The collaborative use of three codes in this study allows users to identify the fission product inventory with CASMO5 and investigation of the severe accident scenario with ASTEC and identifying radiological impact of the released radioactive isotopes to the environment with JRODOS code.

Computational Fluid Dynamics Analysis of an Open-Pool Nuclear Research Reactor Core for Fluid Flow Optimization Using a Channel Box

A channel box installation in the IEA-R1 research reactor core was numerically investigated to increase fluid flow in fuel assemblies (FAs) and side water channels (SWCs) between FAs by minimizing bypasses in specific regions of the reactor core, which is expected to reduce temperatures and oxidation effects in lateral fuel plates (LFPs). To achieve this objective, an isothermal three-dimensional computational fluid dynamics model was created using Ansys CFX to analyze fluid flow distribution in the Brazilian IEA-R1 research reactor core. All regions of the core and realistic boundary conditions were considered, and a detailed mesh convergence study is presented. Results comparing both scenarios are presented in the percentage of use of the primary circuit pump. It is indicated that 21.4% of fluid bypass to unnecessary regions can be avoided with the channel box installation, which leads to the total mass flow from the primary circuit for all FAs increasing from 68.9% (without a channel box) to 77.6% (with a channel box). For the SWCs, responsible for cooling LFPs, an increment from 9.7% to 22.4%, avoiding all nondesired cross three-dimensional effects, was observed, resulting in a more homogeneous fluid flow and vertical velocities. It was concluded that the installation of a channel box numerically indicates an expressive mass flow increase and homogeneous fluid flow distribution for flow dynamics in relevant regions. This gives greater confidence to believe that lower temperatures, and consequently oxidation effects in LFPs, can be expected with a channel box installation.

Drag coefficient of circular cylinder in axial flow of water for a wide range of length to diameter ratios

ABSTRACT An experimental campaign was conducted to determine drag coefficients of circular cylinders in axial flow of water for a wide range of length-to-diameter ratios (L/D) from 2 to 35. Drag force acting on the circular cylinders was acquired at a velocity of 2 to 6 m/s, which corresponds to the Reynolds numbers of 2.2 × 105 to 7.0 × 105. The experimental data were validated by analysis using the commercial CFD code, Star-CCM+. The measured drag coefficients increased monotonically as the L/D increased with the range of Reynolds numbers, and were almost constant regardless of the Reynolds number. The drag coefficient was decomposed by the term of form drag and skin friction. As the value of L/D increased, the drag coefficient increased due to the skin friction drag term. The drag coefficient correlation was proposed as a function of L/D. The predicted values were consistent with both the experimental data and numerical simulation results. Furthermore, this correlation was applied to a fuel assembly with a channel box, it was shown that the drag coefficient can be predicted for a wide range of Reynolds numbers by specifying an appropriate form drag term.

Temperature distribution modeling of PV and cooling water PV/T collectors through thin and thick cooling cross-fined channel box

Many aspects relating to thermal, economic, and reliability challenges are involved while designing a Photovoltaic/Thermal (PV/T) system under high performance. When compared to standard PV systems, PV/T systems are more effective in locations with high irradiance. To eliminate the excess heat from a PVT system, an optimal cooling system is necessary, resulting in improved the temperature of PV module which directly effect on the overall performance. The current study is focused on a new economic and essay construction thin and thick (3 mm and 15 mm) cooling cross-fined channel box that have covered modeled. In terms of cell temperature and output cooling water temperature, the effects of various irradiation levels and cooling water flow rates are examined. Software that is based on finite elements, the problem was solved numerically in a three-dimensional model using ANSYS (19.2). It has been discovered that when the cooling fluid flow rate increases, the average surface temperature distribution of PV/T system and outlet cooling water temperature are reduced for thin and thick box heat exchanger and ideal with a cooling fluid flow rate of 3 L/min. The average surface temperature and water-cooling temperature are 30.7 °C and 38.9 °C for thin box heat exchanger, respectively, whereas for thick box heat exchanger are 30.8 °C and 32.4 °C, respectively, under solar irradiance 1000 W/m2 and optimal flow rate.

Nonlinear behavior of cold-formed stainless steel built-up box sections under axial compression

Stainless steel is a highly versatile material, possessing a unique selection of properties that can be exploited in structural (load bearing) applications. In cold-formed steel structures, such as trusses, wall frames and portal frames, the use of built-up cold-formed stainless steel box sections as compression members are becoming popular. The AISI/ASCE Standard, SEI/ASCE-8–02 and AS/NZS do not include the design of stainless-steel built-up channels and very few experimental tests or finite element analyses have been reported in the literature for such face to-face cold-formed stainless-steel channel box sections. Thus, this paper presents a numerical investigation on the behavior of cold-formed stainless-steel built-up channel box sections. Three different grades of stainless steel i.e., duplex EN1.4462, ferritic EN1.4003 and austenitic EN1.4404 were considered. Effect of screw spacing on the axial strength of such built-up channel box sections was investigated. As expected, most of the short and intermediate columns failed by either local–global buckling interaction or just by local buckling, whereas the long columns, failed by global buckling. A comprehensive parametric study was carried out covering a wide range of slenderness and different cross-sectional geometries to assess the performance of the design guidelines by AISI and AS/NZS. In total, 180 finite element models were analyzed. From the results of the parametric study, it was found that the AISI and AS/NZS are conservative by around 15% for duplex grade (EN1.4462) of stainless-steel built-up box columns. However, for ferritic (EN1.4003) and austenitic (EN1.4404) grades of stainless-steel built-up box columns, the AISI and AS/NZS were conservative by only 5%.

Unraveling the Morphological Constraints on Roman Gold Mining Hydraulic Infrastructure in NW Spain. A UAV-Derived Photogrammetric and Multispectral Approach

The province of León preserves a unique hydraulic infrastructure 1200 km-long, used for the exploitation of auriferous deposits in Roman times. It represents the most extensive waterworks in Europe and is one of the best-preserved examples of mining heritage in Antiquity. In this work, three mining exploitation sectors (upper, middle, and lower) characterized by channels and leats developed in different geological materials were examined, using Unmanned Aerial Vehicles (UAVs). A multi-approach based on a comparison of photogrammetric and multispectral data improved the identification and description of the hydraulic network. Comparison with traditional orthoimages and LiDAR data suggests that UAV-derived multispectral images are of great interest in areas where these sets of data have low resolution or areas that are densely covered by vegetation. The results showed that the size of the channel box and its width were factors that do not depend exclusively on the available water resources, as previously suggested, but also on the geological and hydraulic conditioning factors that intervene in each sector. Additionally, the detailed study allowed the establishment of a water sheet maximum height that was much lower than previously thought. All in all, these inferences might help researchers develop new strategies for mapping the Roman mining infrastructure and establishing the importance of geological inheritance on the construction of the hydraulic system that led the Romans to the accomplishment of the largest mining infrastructure ever known in Europe.

Assessment of CASL VERA for BWR analysis and application to accident tolerant SiC/SiC channel box

Application of the Virtual Environment for Reactor Applications (VERA) to BWR analysis is assessed in this paper by comparing results to those calculated using other widely-used modeling tools, namely the U.S. Nuclear Regulatory Commission’s PARCS/PATHS and the Serpent Monte Carlo particle transport code. Additionally, VERA is used to calculate 3-D temperature and fast neutron flux distributions in silicon carbide (SiC) fiber-reinforced, SiC matrix composite (SiC/SiC) BWR channel boxes, which are being studied as an Accident Tolerant Fuel core structural material concept. The code-to-code comparisons were favorable, and the SiC/SiC channel box evaluation demonstrates the many advanced modeling features VERA provides while also highlighting the non-uniformity in fast neutron flux distributions that can play a role in potential SiC/SiC channel box deformation. Traditional BWR analysis tools do not have the calculation fidelity necessary for coupled assessment of flux and temperature gradients in a SiC/SiC channel box. VERA is a state-of-the-art modeling environment that was developed to increase the safety and economic competitiveness of nuclear power through improved modeling accuracy. While VERA has already been deployed in the nuclear industry for PWR applications, the current study is a vital initial step in the extensive development, validation, and verification that VERA must go through to be useful for BWR applications.

Development and validation of the eutectic reaction model in JUPITER code

The eutectic reaction model in JUPITER code was validated against two series of experimental tests that performed by JAEA. An experiment that aimed to evaluate the eutectic reaction between Zircaloy and Stainless steel, was simulated by JUPITER code to validate its reliability on predicting the binary eutectic reaction phenomenon. A comparison of the simulation and experimental results demonstrates good agreement on the increase rate of the solution depth at various temperature environments. Another series of tests which aimed to predict the eutectic reaction between the control rod blade and channel box in BWR, were simulated by JUPITER code to test its applicability on predicting the eutectic reaction between multiple mixture components. Although the deviation could not be completely eliminated, the reaction performance in the experiment was reasonably reproduced. As a result, it could be concluded that JUPITER code is feasible to predict the eutectic reaction behavior in nuclear severe accident.

Study on the optimal operation of urban combineddrainage channel box

This paper optimizes the operation mode of the combined drainage channel box sluice in H river basin of a city in south China to solve the problem of frequent sluice opening.Based on the InfoWorks ICM software, the hydraulic model of drainage system of the river basin was established, the measured rainfall and liquid level were screened, the model parameters were determined by using the rainfall data of medium and heavy rain, and the model was verified by using the rainfall data of heavy rain. The optimal liquid level is obtained by analyzing and comparing the simulation results. The simulation results are basically consistent with the actual precipitation.After optimization, the optimal liquid level of the combined drainage channel box sluice gate increased by 0.8m compared with the manually operated maximum liquid level. After the operation mode of sluice is optimized, the annual sluice opening times are reduced by 78%. After the experience, the InfoWorks ICM hydraulic model has high reliability, and the optimal sluice opening liquid level can be obtained through simulation analysis, which can more effectively prevent waterlogging and reduce river pollution.

Impact of control blade insertion on the deformation behavior of SiC-SiC channel boxes in BWRs

This article describes the analysis of distortion of a silicon carbide fiber-reinforced, silicon carbide matrix (SiC-SiC) composite channel box under in-reactor conditions of a boiling water reactor (BWR). The BWR core has significant gradients in the fast neutron flux across the channel box due to the presence of water rods within the fuel assemblies, and these gradients increase further with the insertion of control blades. As a result of the temperature and neutron flux dependent irradiation-induced swelling of SiC, the SiC-SiC composite channel box can undergo distortion. In this work, we evaluate the SiC-SiC channel box distortion for three different control blade positions. This analysis is based on the neutron flux and temperature distributions in the BWR core calculated using the neutronics code MPACT and thermal-hydraulics code CTF. This calculation is coupled through temperature feedback. Subsequently, we have performed structural analysis based on the calculated neutron flux and temperature distributions to determine the deformation and stress development in the channel box. The structural analysis was performed using the fuel performance modeling code BISON and the commercial finite element analysis software Abaqus. The results indicate that large gradients in fast neutron flux (up to 35–40% across a single axial level) will develop across the channel box. Due to these gradients, the channel box will undergo time-dependent bending for all the control blade positions in the assembly. The time-dependent bowing behavior is dominated by the transient swelling of SiC-SiC material under non-uniform neutron flux, and changes with variation in the control blade position. The bending will cause temporary interference between the channel box and control blade, and the interference is expected to be most severe for the fully inserted control blade position. The developed stresses due to differential swelling in the channel box exceed the proportional limit stress of the material, which may cause matrix microcracking in the channel box. However, the stresses remain below the tensile strength of the material, and therefore, development of a full, through-thickness crack in the channel box is not expected. Further work is recommended to explore and evaluate the mitigation strategies.

Mechanical and thermal properties of Zr-B and Fe-B alloys

ABSTRACT After the core meltdown in the Fukushima Daiichi (1F) nuclear power plant, various compounds in metal boride systems could potentially form as a result of the reactions between B4C (control material) and Fe, Zr alloys (control-blade sheaths, zircaloy claddings, channel box, etc.). Some previous studies have focused on the properties of intermetallic compounds of the Zr-B and Fe-B systems, such as ZrB2, FeB, and Fe2B. However, during the solidification of fuel debris, composites of these intermetallics rather than large chunks of single-phase intermetallics will form. This situation makes the understanding of the composition dependence of the mechanical and thermal properties of these metal borides a major task before debris retrieval takes place. In this study, we first investigated the temperature-dependent thermal conductivity of Fe-B and Zr-B eutectics from room temperature up to 900°C. We were then able to evaluate the composition-dependent indentation hardness of these metal borides at room temperature. Based on our experimental data, we concluded that the hardness and thermal conductivity of the Fe-B, Zr-B composites can be well estimated using the properties of the composites’ corresponding components, with Rule of Mixtures and Effective Medium Theory (EMT) calculations, respectively.

Development of Experimental Technology for Simulated Fuel-Assembly Heating to Address Core-Material-Relocation Behavior During Severe Accident

Abstract The authors are developing an experimental technology for simulating severe accident (SA) conditions using simulant fuel material (ZrO2) that would contribute, not only to Fukushima Daiichi (1 F) decommissioning, but also to enhance the safety of worldwide existing and future nuclear power plants through clarification of accident progression behavior. Nontransfer (NTR) type plasma, which has been in practical use with a large torch capacity as high as 2 MW, has the potential to heat subject materials to very high-temperatures without selecting the target to be heated. When simulating 1 F with SA code (Severe Core Damage Analysis Package (SCDAP), Methods for Estimation of Leakages and Consequences of Releases (MELCOR) and Modular Accident Analysis Program (MAAP)), the target of this core-material-melting and relocation (CMMR) experiment was to confirm that NTR plasma has a sufficient heating performance realizing large temperature gradients (>2000 K/m) expected under 1 F conditions. The authors selected NTR-type plasma-heating technology that has the advantage of continuous heating in addition to its high-temperature level. A prototype large-scale experiment (1 m × 0.3 m dia.), called CMMR-0, was conducted in 2016, in which a large temperature gradient was realized and basic characteristics of a heated test assembly were studied. However, the maximum temperature was limited in this test by the instability of the plasma torch under low-oxygen concentrations. It was clarified through this test that an improvement in plasma-heating technology was necessary to heat the large-scale test assembly. The CMMR-1/-2 experiments were carried out in 2017 with a test assembly similar to CMMR-0, applying the improved technology (higher heating power and controlled oxygen concentration). In these two tests, heating history was different, resulting in similar physical responses with more pronounced material melting and relocation in the CMMR-2 experiment. The CMMR-2 experiment was selected from the perspective of establishing an experimental technology. The CMMR-2 experiment adopted a 30-min heating period, wherein the power was increased to a level where a large temperature gradient was expected at the lower part of the core under actual 1 F accident conditions. Most of the control blade and channel box migrated from the original position. After heating, the simulated fuel assembly was measured by X-ray-computed tomography (CT) technology and by electron probe micro-analyzer (EPMA). CT pictures and elemental mapping demonstrated its excellent performance with rather good precision. Based on these results, an excellent perspective, in terms of applicability of the NTR-type plasma-heating technology to the SA experimental study, was obtained.

Resource theory of asymmetric distinguishability for quantum channels

This paper develops the resource theory of asymmetric distinguishability for quantum channels, generalizing the related resource theory for states [arXiv:1010.1030; arXiv:1905.11629]. The key constituents of the channel resource theory are quantum channel boxes, consisting of a pair of quantum channels, which can be manipulated for free by means of an arbitrary quantum superchannel (the most general physical transformation of a quantum channel). One main question of the resource theory is the approximate channel box transformation problem, in which the goal is to transform an initial channel box (or boxes) to a final channel box (or boxes), while allowing for an asymmetric error in the transformation. The channel resource theory is richer than its counterpart for states because there is a wider variety of ways in which this question can be framed, either in the one-shot or $n$-shot regimes, with the latter having parallel and sequential variants. As in our prior work [arXiv:1905.11629], we consider two special cases of the general channel box transformation problem, known as distinguishability distillation and dilution. For the one-shot case, we find that the optimal values of the various tasks are equal to the non-smooth or smooth channel min- or max-relative entropies, thus endowing all of these quantities with operational interpretations. In the asymptotic sequential setting, we prove that the exact distinguishability cost is equal to the channel max-relative entropy and the distillable distinguishability is equal to the amortized channel relative entropy of [arXiv:1808.01498]. This latter result can also be understood as a solution to Stein's lemma for quantum channels in the sequential setting. Finally, the theory simplifies significantly for environment-seizable and classical--quantum channel boxes.

Experimental study on local interfacial parameters in upward air-water bubbly flow in a vertical 6 × 6 rod bundle

This paper presents a complete database of the local two-phase flow parameters for upward adiabatic air-water two-phase flows in a vertical 6 × 6 rod bundle flow channel. A total of 16 flow conditions were selected and investigated at 16 measuring points in the octant triangular measuring region of a cross section at the position with height-to-diameter ratio of 149 (z/DH = 149) in the rod bundle experiment. The local void fraction, interfacial area concentration (IAC), bubble diameter and bubble velocity vector were measured by using the four-sensor optical probe measuring technique. In the measured cross-sectional distributions of local void fraction and IAC, both core-peaking and wall-peaking distribution shapes were observed and the distribution pattern trended to change from the core-peaking shape to the wall-peaking shape with the increase of superficial liquid velocity (〈jf〉) and the decrease of superficial gas velocity (〈jg〉). The radial distributions of local bubble diameter are nearly flat, which explains the similarity of the radial local void fraction and IAC distributions. The measured local bubble diameters increase with the increase of 〈jg〉 and the decrease of 〈jf〉. The bubbles move along the rod bundle flow channel with their velocity component in the main flow direction (vgz) showing a typical radial core-peaking profile and their velocity components in the cross section showing a significant movement from the central region to the channel box wall region especially under high superficial liquid velocities. The cross-sectional area-averaged results of the local parameters were obtained by a measuring-point-based graphical integration. The obtained area-averaged void fraction and IAC are compared with the predictions of the drift-flux model with its available 2 frequently-used distribution parameter and drift velocity correlations and the 2 recently-developed IAC correlations respectively. The applicability of the 2 drift-flux correlations and the 2 IAC correlations to the rod bundle flow channel is evaluated and analyzed.

Local measurements of upward air-water two-phase flows in a vertical 6×6 rod bundle

A 3 m high vertical rod bundle flow channel consisting of 6×6 rods with the rod diameter of 10 mm and the pitch of 16.7 mm and a channel box with the cross section of 100 mm × 100 mm was used to study the local two-phase flow characteristics under influences of the 36 rods and the channel box. The air and water were selected as the two-phase working fluids in the present experiments. A double-sensor probe installed at the axial position of z/DH = 149 and six evenly-installed differential pressure (DP) gauges measured the upward-moving two-phase flow in the rod bundle flow channel under the atmospheric condition. Since the local parameters of void fraction, interfacial area concentration (IAC), bubble diameter, and gas velocity are essential to know the internal structures of the two-phase flow, their data at 16 points within an octant symmetric triangular area of the flow channel cross section were collected by the double-sensor probe under various flow conditions in the experiments. The local measurements of double-sensor probe were found to agree well with the void fractions from the DP gauges and the superficial gas velocity from a gas flowmeter. Both the measured void fractions and IACs displayed a transition from radial wall-peaking profile to radial core-peaking profile in the low superficial liquid velocity flow conditions and pure radial wall-peaking profiles in the high superficial liquid velocity flow conditions. The measured Sauter mean diameters showed their radial wall-peaking profiles with the peaking degree decreasing with the increasing superficial gas velocity in both the low and high superficial liquid velocity flow conditions. The measured gas velocities in the main flow direction showed a transition from a radial nearly-flat profile or a radial mid-peaking profile to radial core-peaking profiles in the low and high superficial liquid velocity flow conditions. The area-averaged void fractions and IACs integrated from their measured local values were respectively compared with the predictions of existing drift-flux and IAC correlations. The comparison results showed that the drift-flux correlation of Ozaki et al. (2013) and the IAC correlation of Shen and Deng (2016) give the reasonable prediction and can be recommended for the predictions of the void fraction and the IAC respectively in the bubbly flows in the rod bundle flow channel.

Full-core analysis for FeCrAl enhanced accident tolerant fuel in boiling water reactors

The impact of replacing Zircaloy with FeCrAl, a candidate enhanced accident-tolerant fuel cladding material, was evaluated for 10 × 10 boiling water reactor fuel bundles. Results from a series of full-core parametric studies estimated that replacing UO2/Zircaloy with UO2/FeCrAl would require an average enrichment increase of 0.6% 235U throughout the fuel lattice with the cladding and channel box thicknesses halved and fuel pellet diameter increased. Full-core results indicated that UO2/FeCrAl models with these geometric/enrichment specifications matched the base UO2/Zircaloy cycle length of 527 effective full power days. Optimization studies of the full-core design established loading and control blade patterns for both Zircaloy and FeCrAl models. A side study was conducted modeling a hybrid fuel bundle consisting of FeCrAl cladding and a SiC/Ni/Cr channel box. By halving the cladding thickness, the enrichment level required was less than that of the Zircaloy base case design after performing loading pattern optimization of the hybrid bundle core. Lastly, the thermomechanical performance of a Zircaloy-cladded fuel rod was compared to that of a FeCrAl system. Results from this analysis show that, if starting from the same fuel-cladding gap thickness, a FeCrAl-clad fuel rod operates with a greater average fuel centerline temperature, comparable axial elongation and radial displacement, and longer time to gap closure compared to a Zircaloy-clad fuel rod. This fuel performance analysis was primarily based on the commercial Kanthal APMT FeCrAl alloy but also used available data for the C35M FeCrAl alloy developed at Oak Ridge National Laboratory.

On-Demand Coalescence and Splitting of Liquid Marbles and Their Bioapplications.

Coalescence and splitting of liquid marbles (LMs) are critical for the mixture of precise amount precursors and removal of the wastes in the microliter range. Here, the coalescence and splitting of LMs are realized by a simple gravity‐driven impact method and the two processes are systematically investigated to obtain the optimal parameters. The formation, coalescence, and splitting of LMs can be realized on‐demand with a designed channel box. By selecting the functional channels on the device, gravity‐based fusion and splitting of LMs are performed to mix medium/drugs and remove spent culture medium in a precise manner, thus ensuring that the microenvironment of the cells is maintained under optimal conditions. The LM‐based 3D stem cell spheroids are demonstrated to possess an approximately threefold of cell viability compared with the conventional spheroid obtained from nonadhesive plates. Delivery of the cell spheroid to a hydrophilic surface results in the in situ respreading of cells and gradual formation of typical 2D cell morphology, which offers the possibility for such spheroid‐based stem cell delivery in regenerative medicine.

Deformation analysis of SiC-SiC channel box for BWR applications

Silicon carbide fiber-reinforced silicon carbide matrix (SiC-SiC) composites are being considered as components in light water reactor cores to improve accident tolerance, including channel boxes and fuel cladding. In the nuclear reactor environment, core components like a channel box will be exposed to neutron and other radiation damage and temperature gradients. To ensure reliable and safe operation of a SiC-SiC channel box, it is important to assess its deformation behavior under in-reactor conditions including the expected neutron flux and temperature distributions. In particular, this work has evaluated the effect of non-uniform dimensional changes caused by spatially varying neutron flux and temperatures on the deformation behavior of the channel box over the course of one year. These analyses have been performed using the fuel performance modeling code BISON and the commercial finite element analysis code Abaqus, based on fast flux and temperature boundary conditions that have been calculated using the neutronics and thermal-hydraulics codes Serpent and CTF, respectively. The dependence of dimensions and thermophysical properties on fast flux and temperature has been incorporated into the material models. These initial results indicate significant bowing of the channel box with a lateral displacement greater than 6.5 mm. The channel box bowing behavior is time dependent and driven by the temperature dependence of the SiC irradiation-induced swelling and the neutron flux/fluence gradients. The bowing behavior gradually recovers during the course of the operating cycle as the swelling of the SiC-SiC material saturates. However, the bending relaxation due to temperature gradients does not fully recover and residual bending remains after the swelling saturates in the entire channel box.

Analisis Debit Limpas Drainase Akibat Pengaruh Perubahan Tata Guna Lahan di Daerah Kota Surabaya Barat

The drainage area of the secondary drainage system of the Gunungsari often occurs inundation or flood during rain. This is due to land use change, which was originally a water catchment area transformed into a densely populated area that resulted in disruption of soil absorption so that runoff becomes bigger. The analysis used in this thesis includes hydrological analysis, land use analysis, domestic discharge analysis, cumulative discharge analysis and hydraulics analysis. The hydrological analysis calculated the rainfall at return period of 2, 5, and 10 year with the Pearson Log distribution III, discharge calculation of the plan with the return period by means of the rational method and the method of coefficient value of land use (C) the land is then divided by the area of each sub das. The analysis of domestic waste was calculated from the total population prediction in the future and the water needs of the population. The cumulative discharge was total from domestic discharge and flood discharge of the return period of 2, 5, and 10 years. Hydraulic analysis was calculated to know the existing capacity of channel. The changing of land use were represented by average land use value ( Caverage ), which the value are 0,732; 0,725 and 0,747 for the year 2002; 2007 and 2017 respectively. Based on the results of flood discharge planning analysis, cumulative discharge in return periods of 10 years and hydraulic analysis, the flooding occurred at Darmo Indah channel (segment 5-2) by comparing capacity discharge 2,49 m3 / s and cumulative discharge 4,360 m3/s, Darmo Harapan channel (segment 4-5) by comparing capacity discharge 2,90 m3/s and cumulative discharge 4,496 m3/s. Darmo Satelit channel (segment 7-8) by comparing capacity drainage 4,08 m3/s and cumulative discharge 4,586 m3/s and Simo Gunung channel (segment 18-19) by comparing capacity drainage and cumulative discharge 1,31 m3/s and 2,648m3/s. The capacity of existing secondary channels is not able to accommodate cumulative water discharge over the next 10 years. Therefore, the solution to overcome the flooding is by substituting existing channel box culvert. On the other had, another way to prevent flooding are maintenance and cleaning of solid waste and sedimention regularly.