Increasing the production of the Mo-99 isotope by modernizing the design of targets irradiated in the experimental channels of the VVR-c reactor

There are various ways to obtain Mo-99. Some of them are widely used in industrial production, others are in the research stage with the aim of increasing the product yield. The main industrial method for obtaining Mo-99 using a nuclear reactor is the fragmentation method. This method provides for the presence of a uranium target and a nuclear reactor. The target is placed in the channel of the reactor core and irradiated with neutrons for the required time. After that, the target is removed from the channel to the “hot” chamber for the chemical separation of Mo-99. This is how Mo-99 is obtained practically all over the world. The paper considers the fragmentation method for producing Mo-99, which is implemented on the basis of the engineering and technological complex of the VVR-c research nuclear reactor. In order to increase the yield of Mo-99, a modernized model of the “tube-in-tube” target is proposed. The assessment of the production of Mo-99 and the cooling efficiency of the modernized target was carried out. The calculations were performed using the VisualBurnOut and Ansys CFX software packages. Computational studies have shown an increase in the energy release and the amount of the produced Mo-99 isotope in the target of the modernized design. In the most stressed zones, the target wall temperature exceeds the water saturation temperature. Surface boiling occurs in these zones. As a result, turbulization and mixing of the near-wall boundary water layer increases. This improves heat dissipation.

Numerical Prediction of the Second Peak in the Nusselt Number Distribution from an Impinging Round Jet

The results of numerical simulations of a single impinging round jet, using different numerical parameters are presented. To simulate the heat transfer in industrial drying with arrays of different jets the heat transfer for a single round jet (Re=23000 based on jet’s diameter and bulk velocity and the dimensionless jet’s outlet to target wall distance= 2) is used as a test case to validate the numerical model. The distribution of the Nusselt-number serves as a benchmark and the computational cost with regard to CPU-time and memory requirements should be minimal. To accurately predict the intensity and position of the secondary peak from an impinging flow, different approaches for turbulence modeling are considered and their results are compared with data from the literature. The influence of the grid size and the grid shape is analyzed and the grid-independent solution is determined. The results using different implementations of the SST k-omega model, as the best compromise between the computational cost and accuracy are compared. Low Re damping modification in the implementation of SST K-ω has an important role in the prediction of the secondary peak. Good results can be achieved with a coarse grid, as long as the boundary region is appropriately resolved. Polyhedral grids produce good quality results with lower memory requirements and cell numbers as well as shorter run times.

Aircraft Impact Effects on an Aged NPP

The impact of an aircraft is widely known to be one of the worst events that can occur during the operation of a plant (classified for this reason as beyond design). This can become much more catastrophic and lead to the loss of strength of/collapse of the structures when it occurs in the presence of ageing (degradation and alteration) materials. Therefore, since the performance of all plant components may be affected by ageing, there is a need to evaluate the effect that aged components have on system performance and plant safety. This study addresses the numerical simulation of an aged Nuclear Power Plant (NPP) subjected to a military aircraft impact. The effects of impact velocity, direction, and location were investigated together with the more unfavorable conditions to be expected for the plant. The modelling method was also validated based on the results obtained from the experiments of Sugano et al., 1993. Non-linear analyses by means of finite element (FE) MARC code allowed us to simulate the performance of the reinforced concrete containment building and its impact on plant availability and reliability. The results showed that ageing increases a plant’s propensity to suffer damage. The damage at the impact area was confirmed to be dependent on the type of aircraft involved and the target wall thickness. The greater the degradation of the materials, the lower the residual resistance capacity, and the greater the risk of wall perforation.

Ce- and B-Doped Silica Fibers for Monitoring Low-Energy Proton Beams on a Medical Cyclotron

Many medical isotopes can be produced on a small cyclotron. The alignment and profiles of low-energy proton beams from cyclotrons used for medical radioisotope production, such as the TR13 cyclotron at TRIUMF, Canada, cannot be directly quantified during dose delivery with simultaneous constant feedback and sharp spatial resolutions. Doped silica fibers are a potential solution that has been tested at TRIUMF. To measure the effects of irradiation inside an isotope production target, we attached fibers to the outside of an 18O gas target and measured the light output during irradiation. Different dopants, fiber diameters, and target materials were investigated. It was found that 200 µm diameter Ce- and B-doped fibers produce signals linearly proportional to the beam current. This only deviated when the target was moved such that the beam was steered into the target wall, increasing the production of prompt radiation and causing the beam current to decrease but the fiber signal to increase. With the technique described here, the beam can be monitored on the target, including its steering and its overall alignment with the target.

PENGARUH LATIHAN KECEPATAN DAN KELINCAHAN TERHADAP LEMPAR TANGKAP BOLA KASTI UNTUK SISWA- SISWI KELAS IV SEKOLAH DASAR NEGERI 19 KOTA BENGKULU

This study aims to determine whether speed and agility exercises have a significant effect on improving catching abilities in roundball games. The method used in this study is the experimental method, with the independent variables being speed and agility, and the dependent variable is the round ball catching technique. The sample used in this study was 40 students - 19 public elementary school students and as a comparison for students at the base of the city of Bengkulu. The data collection instrument or tool used in this study is a 30-meter sprint, running back and forth with a distance of 10 meters with 4 times back and forth and throwing a catch into the target wall of 2 meters in 30 seconds. Based on the management and analysis of the data obtained, the results of this study are the initial test average of 42.65. agility 19.66 and catching 59.60 the average test finally speeds 56.14. Agility 5.06 and throw catch 7.20 - the average difference of 1.9. The conclusion of this study, judging from the data, is that speed and agility training have a significant effect on round ball catching. Keywords: exercise speed and agility

Balancing WAAM Production Costs and Wall Surface Quality through Parameter Selection: A Case Study of an Al-Mg5 Alloy Multilayer-Non-Oscillated Single Pass Wall

The purpose of the study was to propose a strategy to assess the potential reduction of the production cost during wire+arc additive manufacturing (WAAM) based on the combination of wire feed speed (related to deposition rate) and travel speed (related to deposition time). A series of experiments, using a multilayer-non-oscillated single pass wall made of an Al-Mg alloy, was conducted. The quality of the wall was assessed through the lateral surface waviness and top layer undulation. The concepts of Surface Waviness and Buy-to-Apply indices were introduced. Initially, the range of travel speed (TS) that provided layers with acceptable quality was determined for a given wire feed speed (WFS), corresponding to a constant current. Then, the effect of the increase of production capacity of the process (though current raising, yet maintaining the ratio WFS/TS constant) on the wall quality for a given condition within the TS range was assessed. The results showed that the useful range of TS prevents too rough a waving surface below the lower limit and top surface undulation over the higher limit. However, inside the range, there is little quality variation for the case under study. Finally, simulations of deposition time were developed to demonstrate the weight of the TS on the final deposition time and wall quality as a function of a target wall width. This respective weight showed the existence of a complex and unpredictable, yet determined, power of a combination of TS, target wall geometry, and dead time between subsequent layers. It was verified to be possible to find optimized TS as a function of different target geometries.

Effects of the Forcing Frequency on Pulsating Impinging Jet Behavior and the Boundary Layer on the Target Curved Wall

In the present work, time-dependent responses of Nusselt number, friction coefficient and pressure profiles to the passage of groups of coherent structures along a curved impingement wall, is considered. It is meant to replicate a more realistic picture of the flow. The jet considered belongs to heating applications where the jet flow temperature is higher than that of the impingement wall. The flow was simulated using Large Eddy Simulation with the Dynamic Smagorinsky sub-grid-scale model. The plane jet was forced at frequencies increasing gradually to a maximum of 2200 Hz with an amplitude equal to 30% of the mean jet velocity. The computational domain was divided into 16.5 million hexahedral computational cells whose resolution was assessed based on the turbulence scales. It was found that for low forcing frequencies (e.g., 200Hz), coherent forced primary vortices induced by the pulsations are separated by less organized vortices naturally induced similar to those of the unforced jet. It could be seen that the natural vortices have moderate effects on the boundary layer development on the impingement surface starting at relatively short distances from the stagnation point compared to the forced vortices. Increasing the forcing frequency to 1000Hz reduces the distance separating successive forced vortices causing the pairing phenomenon to occur at a certain distance along the target wall. Increasing the forcing frequency further to 2200Hz makes the pairing phenomenon followed by vortex breakdown to occur at shorter distances along the target wall. The smaller forcing frequencies yield large and strong distant vortices which affect the dynamical field noticeably in conjunction with an important deterioration of heat transfer due to their strong mixing effect and entrainment of cold air from the surroundings. On the other hand, high frequencies generate smaller vortices which are relatively close to each other. Thus, they have a weaker effect allowing the growth of the boundary layer on the target wall up to a distance equal to four times the jet-exit width where the minimum heat transfer is observed. In fact, the small successive vortices form a sort of shield preventing the cold air from the surroundings to reach the target wall until their breakdown.

Investigations on the Heat Transfer and Flow Characteristics in a Trapezoid Duct for Turbine Blade Leading Edge

To evaluate the application of the impingement cooling in a trapezoidal duct, particularly the influence on internal cooling of the cross flow and swirl flow. Experimental and numerical studies have been performed. The experiment focuses on the heat transfer characteristics in the duct, when the numerical simulation focuses on the flow characteristics. Four Reynolds numbers (10000, 20000, 30000 and 40000), six cross flow mass flow ratios (0, 0.1, 0.2, 0.3, 0.4 and 0.5) and two impingement angle (35° and 45°) are considered in both the experiment and the numerical simulation. The temperature on the target wall and the exit side wall is measured by the thermocouples, when the realizable k-ε turbulence model and enhanced wall treatment are performed using a commercial code Fluent. The results show that only part of the jets contribute in the heat transfer enhancement on the target wall, the other jets improve a large anticlockwise vortex occupied the upper part of the duct and drive strong swirl flow. The heat transfer on the exit side wall is enhanced by the swirl flow. The cross flow is induced in the duct by the outflow of the end exit hole. It deflects the jets and abates the impingement cooling on the target wall in the downstream region but has no evidently effect on the heat transfer on the exit side wall. Higher impingement angle helps to augment the impingement cooling on the target wall and improves the resistance ability of the jets against the effect of the cross flow. The heat transfer enhancement ability on the target wall and exit side wall in the present duct is compared to that of a smooth duct. The Nusselt number of the former is about 3 times higher than that of the latter. It indicates that the impingement and swirl play equally important roles in the heat transfer enhancement in the present duct. Empirical dimensionless correlations based on the present experiment data are presented in the paper.

Pengembangan tes keterampilan dasar olahraga bola tangan bagi mahasiswa

Artikel ini bertujuan untuk: (1) menyusun butir-butir tes keterampilan dasar olahraga bola tangan, dan (2) mengetahui validitas dan mengestimasi reliabilitas tes keterampilan dasar olahraga bola tangan. Metode penelitian yang digunakan adalah research and development. Subjek penelitian 30 mahasiswa. Instrumen pengumpulan data berupa lembar observasi dan kuesioner. Jumlah judge yang terlibat 3 orang. Validitas diketahui dengan validitas isi dan reliabilitas instrumen menggunakan korelasi Inter Rater. Hasil penghitungan koefisien korelasi, diketahui bahwa skor rater 1 = 0,999, skor rater 2 = 0,996, dan skor rater 3 = 0,991. Hasil penghitungan reliabilitas diestimasi dengan Koefisien Alpha sebesar rxx = 0,994. Hasil pengembangan tes keterampilan dasar olahraga bola tangan bagi mahasiswa menghasilkan 3 (tiga) jenis tes yaitu: (1) Tes keterampilan passing dengan sasaran ke tembok ( waktu: 30 detik), (2) Tes keterampilan dribbling (waktu: 30 detik), (3) Tes keterampilan flying shoot melakukan 3 kali tembakan dari tiga posisi: kiri, tengah, dan kanan.Kata kunci: pengembangan tes, keterampilan dasar, bola tangan DEVELOPMENT OF HANDBALL BASIC SKILLS TEST FOR STUDENTSAbstractThis article aims to: (1) develop a grain handball basic skills test, and (2) determine the validity and reliability of estimating handball basic skills test. The method used is research and development. Subject of the study 30 students. Data collection such as observation sheets and questionnaires. Number judge involved three people. Validity determined by content validity and reliability of the instrument using the correlation Inter Rater. The results of the correlation coefficient calculation, it is known that the rater score 1 = 0.999, the rater score 2 = 0.996, and the score rater 3 = 0.991. The results estimated by the reliability calculation of Alpha Coefficient rxx =0,994. The result of the development of the form of handball basic skills test for students produce three (3) types of test are: (1) The test of passing skills the target wall (time: 30 seconds), (2) the tests of dribbling skills (time: 30 seconds) (3) The tests of flying shoot skills from three positions: left, center, and right.Keywords: test, development, handball basic skill

Effect of Target Wall Curvature on Heat Transfer and Pressure Loss From Jet Array Impingement

Experiments to investigate the effect of target wall curvature on heat transfer and pressure loss from jet array impingement are performed. A jet plate configuration is studied with constant hole diameters and spacings. The geometry of the jet plate has streamwise jet spacings of 5.79 jet diameters, spanwise jet spacings of 4.49 jet diameters, and a jet-to-target plate distance of 3 jet diameters. For the curved case, the radius of the target plate is r/D = 31.57. A flat target wall setup with identical geometric spacing is also tested for direct comparison. Jet spacings were chosen such that validation and comparison can be made with open literature. For all configurations, spent air is drawn out in a single direction, which is tangential to the target plate curvature. Average jet Reynolds numbers ranging from 55,000 to 125,000 are tested. A steady-state measurement technique utilizing temperature-sensitive paint (TSP) is used on the target surface to obtain Nusselt number distributions. Pressure taps placed on the sidewall of the channel are used to evaluate the flow distribution in the impingement channel. Alongside the experimental work, CFD was performed utilizing the v2 − f turbulence model to better understand the relationship between the flow field and the heat transfer on the target surface. The main target of the current study is to quantify the impact of target wall radius and the decay of heat transfer after the impingement section, and to check the open literature correlations. It was found that the target wall curvature did not cause any significant changes in either the flow distribution or the heat transfer level. Comparisons with established correlations show similar level but different trends in heat transfer, potentially caused by differences in L/D. CFD results were able to show agreement in streamwise pitch-averaged Nusselt number levels with experimental results for the curved target plate at higher Re numbers.