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[en] Low cycle fatigue (LCF) behavior of hot-bending 347 SS for each position in a simulated PWR environments was studied for the application of surge line pipe. To evaluate the effect of hot-bending on the LCF behavior of 347 SS, LCF tests were performed in room temperature (RT) air and simulated pressurized water reactor (PWR) water environments. The LCF life of 347 SS was much shorter in PWR water than in RT air. Meanwhile, LCF life of hot-bent 347 SS was somewhat longer than that of the as-received condition both in RT air and PWR water. Microstructure analysis showed the development of dislocation structure near niobi-um carbide particles and increase in dislocation density for the hot-bent 347 SS, which acted as a barrier to dislocation movement and suppressed the serrated flow in hysteresis loop during the LCF test. Therefore, the degree of hardening was greater for the hot-bent 347 SS. In addition, a clear correlation was found between the degree of hardening and LCF life. In conclusion, the development of dislocation structure near niobium carbide along with increase in dislocation density could have contributed to the longer LCF for the hot-bent 347 SS in both RT air and PWR water
[en] This book gives, descriptions of computer simulation, computational materials science, typical three ways of computational materials science, empirical methods ; molecular dynamics such as potential energy, Newton's equation of motion, data production and analysis of results, quantum mechanical methods like wave equation, approximation, Hartree method, and density functional theory, dealing of solid such as pseudopotential method, tight-binding methods embedded atom method, Car-Parrinello method and combination simulation.
[en] The present study concerns itself with the condensation oscillation phenomena by steam-jetting into subcooled water through a sparger in the In-containment Refueling Water Storage Tank (IRWST) of Advanced Power Reactor 1400 (APR 1400) to mitigate the beyond design basis event. The scaling methodology and the similarity correlation between the test facility and the real plant is implemented. The scaling parameters are derived by use of three governing equations: mass conservation equations, momentum conservation equations, and energy conservation equation. This scaling approach produces the global scaling parameters such as geometrical parameters, time constants and friction parameters. The steam cavity volume playing a major role in condensation oscillation phenomena is included in the scaling parameters. In the corroboration stage, various experimental tests are conducted. The scaling-related parameters experimentally considered are water temperatures, mass flux, discharge system volumes, tank sizes, source pressure, steam-jetting directions, and numbers of discharge holes. Each scaling parameter is ranked in terms of their relative importance for the condensation oscillation phenomena. At around the water temperature of 80 .deg. C, unstable condensation occurs and the oscillation amplitude becomes its maximum. With an increase of the steam mass flux, the steam cavity enlarges and the oscillation amplitude increases. In low steam mass flux, water inertia plays an important role in the motion of the steam cavity. In high steam mass flux, the steam cavity infinitesimally oscillates. When an additional volume is connected in with pipe run locations, the larger the additional volume, the oscillation amplitude decreases, accordingly. It is concluded that the additional volume acts like as another source of steam-jetting and provides a volume of dampening the perturbation wave translated upstream. The thickness of the boundary layer that encloses the steam cavity is found to be equal to the maximum length of the steam cavity formed. In order to preserve the scaling similarity, the thickness of the minimum boundary layer should be kept. Variations of the oscillation amplitude are small when steam-jetting directions are altered. The Reynolds number, the Jacob number, and the Weber number are used to correlate the steam cavity length. The experimental ranges of Re, Ja, and We, are 7.06 x 104 ∼ 1.23 x 106, 10.82 ∼ 43.27, 1.42 x 104 ∼ 1.23 x 105, respectively. Three key scaling parameters are identified and empirically correlated with the maximum amplitude of pressure oscillation: flow restriction coefficient, area ratio of discharge hole to steam cavity, and density ratio of water to steam. The concept of a reduction factor is introduced for estimating the oscillation amplitude of multi-hole spargers with test data from a single-hole sparger. Based on the assumption that the condensation flux at equilibrium is equal to the mass flux through the discharge hole at equilibrium, the second order linear differential equation for the oscillation frequency can be derived. The density-weighted Strouhal number derived from second- and third-order linear differential equations are compared with experimental data
[en] Understanding of the chemical behaviors of radionuclides in a deep geological system is a matter of cardinal importance for the safety assessment of nuclear waste repository since the mobility of radionuclides is closely dependent of various geochemical reactions in aquifer systems. Therefore, knowledge of reliable chemical thermodynamic data is a prerequisite for the prediction of radionuclide and/or pollutant migration. Hydrolysis behaviors of uranium(VI) have been studied in the temperature range from 15 .deg. C to 75 .deg. C by utilizing TRLFS (time-resolved laser fluorescence spectroscopy). Fluorescence properties (fluorescence spectrum shape, position and lifetime) of the uranium(VI) hydroxide species, namely, UO22+, (UO2)2(OH)22+, (UO2)3(OH)5+, and (UO2)3(OH)7- were investigated with the time-resolved fluorescence intensity and a numerical fit method. With increasing temperature, the spectrum peak width was broadened, and the fluorescence lifetime was rapidly decreased due to dynamic quenching. Spectroscopic properties resulted from the present work were in good agreement with other literature data. The formation constants for the uranium(VI) hydroxide species were calculated to be log K'2,2 = -4.3 ± 0.6 for (UO2)2(OH)22+, log K'3,5 = -15.4 ± 0.3 for (UO2)3(OH)5+, and log K'3,7 = -28.2 ± 0.7 for (UO2)3(OH)7- at I = 0.5 M H/ NaClO4 and at 25 .deg. C. As expected, strong hydrolysis reactions of uranium(VI) chemical species were observed at elevated temperature, and the temperature-dependent formation constants were compared with some computational methods like the DQAUNT equation and the constant enthalpy equation. Both results are in good agreement with each other. In addition, the activation energies based on the Arrhenius equation were obtained from the temperature-dependent fluorescence lifetimes. Finally, the formation of Ca-UO2-CO3 complexes as being one of the dominant uranium complexes in natural groundwater systems was also investigated as a function of the uranium and calcium concentrations at room temperature. Based on the fluorescence characteristics, four different binary/ternary uranium(VI) carbonate and hydroxide species, Ca(UO2)(CO3)32-, Ca2(UO2)(CO3)3(aq), UO2(CO3)22-, and UO2(OH)3- were identified in the pH range of 7 - 12. These fluorescence results were discussed and compared to the findings in natural groundwater sample
[en] The phenomenon which the heat transfer coefficient between a heated wall and fluid with change from the liquid phase to the vapor phase of fluid near the heated wall decreases suddenly is generally called a CHF phenomenon. In case of a heat flux control system, there is a sudden increase of wall temperature. A CHF is a flux at the situation, and this is an important factor in a heat transfer system. The enhancement of CHF means the increase of efficiency of the heat transfer system due to perform normal operation at higher heat flux, and it also means the increase of safety due to increase the safety margin. Therefore, many researchers have studied about methods and applications of the CHF enhancement for 30 years. In this study, the effect of tri-sodium phosphate (TSP) and boric acid on the CHF enhancement was studied. Both TSP and boric acid are used to control pH in nuclear power plants. TSP is a kind of surfactant, and several surfactants, include TSP, have been reported to have an effect on the enhancement of heat transfer. Nothing has been reported in case of boric acid, yet. The CHF experiment was performed with mass flux ranged 100-500 kg/m"2s and two inlet subcooling temperatures of 25, 50 .deg. C under atmospheric pressure. In case of TSP, one inlet subcooling temperature of 50 .deg. C was used. The test section was vertical circular SS316 tube having the inside diameter of 10.98 mm. The heated length is 224 mm, and it was heated by a heat flux control system using electricity. Fluids filled in the test loop were plain water, TSP solutions, and boric acid solutions. TSP solutions had three concentrations (0.2, 0.4, 0.6%), and boric acid solutions had four concentrations (0.2, 0.4, 0.6, 0.8%). In case of TSP, 21.4% enhancement of CHF was observed at inlet subcooling temperature of 50 .deg. C and extremely low mass flux (100 kg/m"2s). In case of boric acid, 14% enhancement of CHF was observed at inlet subcooling temperature of 50 .deg. C and extremely low mass flux (100 kg/m"2s), and 33.5% enhancement of CHF was observed at inlet subcooling temperature of 25 .deg. C and relatively high mass flux (500 kg/m"2s). The CHF was higher in high subcooling temperature of 50 .deg. C than low subcooling temperature of 25 .deg. C
[en] This book introduces outline of disaster, measures for disaster prevention, frequency and strength of disaster occurrence, and safety and safety management in companies. It also deals with responsible system for safety management, measures for machinery safety disaster such as placement of machinery, environmental safety in working places including disaster relationship according to temperature and humidity, measures for electricity safety disaster such as electric shock, safety management of facilities, examination of safe works including gas explosion, and safety management of construction places.
[en] In this report, the performance for PZR of SMART has been evaluated in which the passive cold PZR and PRHRS had been installed and the FW control system that reactor power is controlled by FW flow rate had been adopted. After the present analysis of the coolant volume of PZR end cavity, it was evaluated that the results could be satisfied if the coolant volume and pressure are controlled in order to be maintained within their set points. Also after the analysis of the gas volume, it was evaluated that the results is much satisfied. Especially, it was analyzed that the peak pressure of end cavity is raised only about 50%(0.6 MPa) as contrasted with the commercial plants. Also, the relieving capacity for pilot operated safety relief valve(POSRV) of SMART was analyzed. The related requirements of 10 CFR 50.55a (c) (1), ASME Code, Sec. III, NB-7000, NUREG-0800 were applied to the analysis. After the present analysis, it was evaluated that the RCS peaking pressure is about 18.2 MPa, 107% of system design pressure, and that it has 3% margin against the design requirement. Also, after the additional analysis, it was evaluated that the open dead/stroke time of POSRV has just a little effect on the peak pressure of PZR EC and MCP discharge
[en] In this report we reviewed the state of the art of the SOVs that have been used in nuclear power plants. It is divided into two parts, the general concerns and license-related concerns. In the general concerns, we reviewed the SOVs' installed locations and objectives, also the SOVs' 'fail as is' function, and also the SOVs' flow resistance coefficients. In the license-related concerns, we reviewed the Regulatory Guide 1.73, IEEE std 382-1972, 382-1985, Information Notices, Generic Letter 91-15, and NUREG-1275, Vol. 6. The reviewed results are follows. - In NSSS of nuclear power plants, SOVs are primarily used in the vent systems. The main reasons are that SOVs are superior to the other actuators in fail open/close functions. - It is possible for SOVs to be the 'fail as is' position. For this case only, a different separated power is required. - SOVs shape in globe type. If the inherent characteristics that SOVs have are required and also the lower flow resistance coefficients are necessarily required, it is difficult to be satisfied by SOVs. - Many common-mode SOV failures have resulted from subjecting SOVs to ambient temperatures in excess of their original design envelop. Such common-mode SOV failures have resulted from localized steam leaks, incorrect estimates of ambient temperatures. - Many common-mode SOV failures have occurred because the estimated service lives did not properly include the life-shortening effects of heatup resulting from continuous coil energization. Many licensees have been unaware of this situation
[en] The pilot operated safety relief valve(POSRV) is a overpressure protection device. But the POSRV is additionally designed to be functioned as a fast depressurization device differently from the pressurizer safety valve(PSV). So, the POSRV assembly takes on the complicated configuration differently from the PSV, and also its configuration and component parts are much different according to its manufacturers. The objective of the study is to investigate the state of the art for POSRV. We want that the findings of the study are put to practical use as a selection guide to the utilities or system designers which want to purchase the POSRV. In this study, we selected the SEBIM and CCI made goods as the subject of investigation, and have investigated the technical characteristics and operating principles of the goods. However, in this report, the comparative contents with other company which were issued by one company were not handled. Also the advantages or disadvantages between two companies were not handled. Only the technical characteristics and operating principles with each company were described. For reference, the main considerations to select the POSRV' type are follows. - the characteristics of the system that the POSRV is to be installed - the fitness of the POSRV for the system - the requirements related to the function and operation of the POSRV - the vender's opinion
[en] This book introduces solar cell production. It is made up eight chapters, which are summary of solar cell with structure and prospect of the business, special variable of solar cell on light of the sun and factor causing variable of solar cell, production of solar cell with surface texturing, diffusion, metal printing dry and firing and edge isolation, process of solar cell on silicone wafer for solar cell, forming of electrodes, introduction of thin film solar cell on operating of solar cell, process of production and high efficiency of thin film solar cell, sorting of solar cell and production with background of silicone solar cell and thin film solar cell, structure and production of thin film solar cell and compound solar cell, introduction of solar cell module and the Industrial condition and prospect of solar cell.