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[en] The performance of refrigerator compressor has a significant influence on the coefficient of performance of the refrigerator. In order to find out the main cause for the variation of the performance, this paper presents a three-dimensional fluid structure interaction (FSI) model of the refrigerator compressor and an experimental investigation to verify the model. To record the p-V indicator diagram, a refrigerator compressor was modified and the pressure sensor was installed. Based on the FSI model, the variation of pressure in the cylinder that influenced the performance of compressor was identified by varying working condition, rotating speed and refrigerant. The FSI model and result could provide useful information for both performance testing and optimization of compressor performance. (paper)
[en] Absolute measurements of neutron fluence are an essential prerequisite of neutron-induced cross section measurements, dosimetric investigations and neutron beam lines characterisation. Independent and precise neutron flux measurements can be performed with respect to the H(n,p) elastic cross section. However, the use of silicon proton recoil detectors is not straightforward below incident neutron energy of 1 MeV, due to a high background in the detected proton spectrum. A new gaseous proton-recoil detector based on a double ionisation chamber, has been designed to answer the challenge. The detector is constituted by a H-rich deposit (polypropylene, mylar foil or tristearin deposit), and a segmented ΔE-E ionization chamber (4*4*12 cm3), read by a 64 pads Micromegas-based detection plane. The chamber is filled with gas (CF4 or N2-CO2) at an adjustable pressure, from few tens of mbar to few tens of 100 mbar, to reduce as much as possible the detector sensitivity to Compton electrons. Tests have confirmed the low electron sensitivity of the detector, making it well suited for neutron energies down to 200 keV in a gammas and electrons dense environment. The ΔE-E coincidences, coupled to a 3D proton track analysis, enables the disentanglement between direct and scattered neutrons
[en] There are different types of off gases generated during various operations of reprocessing of spent nuclear fuels. These off gases also carries significant amount of particulate activity which are treated at various steps in clean-up systems before being discharged to environment through tall stack. At final stage of every off gas clean-up system there is a dedicated deep bed and HEPA filters which remove the particulate activity. Therefore filtration efficiency of deep bed and HEPA filters play important role in controlling the discharges of particulate activity into environment. There are various method for efficiency test of off gas filters such as DOP (Di-octyl Phthalate) test, Methylene blue test, Sodium flame test, Uraniane test, radioactivity measurement etc. For efficiency test of newly installed off gas filters, DOP test is considered as standard method at nuclear industry. However during active operation DOP test is not used because of interference of radioactive contamination. To overcome these difficulties a compact efficiency test module designed and developed inhouse at reprocessing plant Tarapur. The efficiency of off gas filters (Deep bed and HEPA) can be determined by this module with error less than 1 % provided the inlet beta count rate is more than 100 cps, hence it is a replacement of DOP efficiency test method
[en] In this study, we designed, constructed, and operated an experimental facility to realize the inlet conditions to evaluate a turbine exhaust heat exchanger of a space launch vehicle. The entire facility consists of a steam generator for high-temperature fluid simulation and a flow stabilizer to ensure uniform flow. The inlet conditions at the target heat exchanger are a pressure of 0.22 MPa and a temperature of 773 K. For a 10-s combustion test at a pressure of 0.22 MPa, the resulting temperature was 850 K. The pressure was measured with 7 % error, and the temperature was uniformly realized at about 10 % higher than the target temperature. Based on this, it is expected that performance tests of the pressurized heat exchanger will be conducted in the future.
[en] A Double Crystal Monochromator (DCM) has been prepared for neutron energy selection at Ex-core Neutron irradiation Facility (ENF) in HANARO research reactor, and has widely used for neutron bragg edge imaging. Neutron bragg edge imaging is very powerful technique because the visualization of phase change and distribution in steel sample is possible . The design and mechanical operation of this DCM already introduced in 2015. In this paper, the results of performance test are presented and discussed. We have prepared DCM for neutron bragg edge imaging and confirmed that it is working well using neutron beam at ENF. We have plans to carry out neutron bragg edge imaging experiment with some steel sample during next operation period of HANARO.
[en] As a result, the enhancements were derived, and performance was compared with the slant type to select the optimal method. Also, the optimal angle of the cutter angle that can process multiple types of nuclear fuel rods was obtained, and the enhancements after the test were reflected for the enhanced design of the horizontal device. Simulated nuclear fuel rods were used to carry out the slitter performance evaluation. In the slitting test of the rod-cuts (zircaloy tube+aluminum pellets), the optimal slitting slope value of the cutter roller was 133, the slitting force obtained from load cell and RS232 was 210 kgf, and the slitting speed was 12.5 mm/s, which could split 1 rod within 5 minutes. Also, Solid works was used for modeling of multi types of the rods, and as a result of matching and verifying the cutter roller and various rods, the optimal angle of the cutter roller for multi types of PWR assembly rods splitting was derived as 32.7 .deg. C, and as a result of using zircaloy rods for the horizontal decladding device performance test, the horizontal slitter enhancements for hydraulic system, rods step input part, and cutter roller output part, etc. were derived and the design data were obtained.
[en] Content delivery network (CDN) allows internet providers to locate their services, to map their coverage into networks without necessarily to own them. CDN is part of the current internet infrastructures, supporting multi server applications especially social media. Various works have been proposed to improve CDN performances. Since accesses on social media servers tend to be short but frequent, providing redundant to the transmitted packets to ensure lost packets not degrade the information integrity may improve service performances. This paper examines the implementation of rateless code in the CDN infrastructure. The NS-2 evaluations show that rateless code is able to reduce packet loss up to 50%. (paper)
[en] The advantage of the SCO2 power generation system is the moderate operating temperature which can be used in various heat sources. In addition, the system has the compact size, because the SCO2 cycle is operated above the critical point (31.1 .deg. C, 73.8 bar). Korea Atomic Energy Research Institute (KAERI) has started to develop the SCO2 power generation system. Various experimental and theoretical conditions with different main components have been analyzed for optimizing cycle operation techniques. Recently, KAERI has started a project which develops the SCO2 power generation system for waste heat recovery. The target of turbine inlet temperature is around 450 .deg. C. Figure 1 shows the P&ID of the SCO2 power generation system. The system consist of a simple-recuperated cycle. After the SCO2 compressor performance test, the power generation system will be installed. The present study shows the experimental setup for the SCO2 performance test facility. Performance test of the SCO2 compressor is important because it is related to the cycle performance and efficiency. The target of the pressure ratio is 1.75 with having 68% compressor efficiency. The SCO2 compressor performance test facility is under construction and the performance test will be started on October, 2018.