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[en] Most of world power plant traditionally use the cooling with water, and the types of cooling system are different from each other. The 85% of cooling system are once-through cooling system and closed cycle wet cooling system. There are two dry cooling system which are direct and indirect cooling system. In direct type, turbine exhaust is directly cooled by air-cooled condenser. In indirect system, turbine steam is cooled by recirculating intermediate cooling water loop, then the loop is cooled by air-cooled heat exchanger in cooling tower. In this paper, the purpose is to remove MMR waste heat, 24 MWth by using newly designed tower. The possibility of enhancing cooling performance by solar energy is analyzed. The simple cooling tower and solar cooling tower are presented and two design should meet the purpose of removing MMR waste heat, 24 MW. In simple cooling tower, as the number of finned tube increase, the required chimney height decreased. In solar cooling tower, as the collector radius increased, the required chimney height is decreased. To optimized the solar cooling tower, the cost analysis was conducted to find low cost tower. To analyze solar cooling tower further, consideration of solar energy performance at night should be analyzed.
[en] This paper presents an overview of the advanced passive safety systems implemented in the NuScale nuclear energy facility. During normal operation, each NuScale containment is fully immersed in a water-filled stainless steel lined concrete pool that resides underground. The pool, housed in a Seismic Category I building, is large enough to provide more than 30 days of core and containment cooling without adding water. After 30 days, the decay heat generation is sufficiently small that natural convection heat transfer to air on the outside surface of the containment coupled with thermal radiation heat transfer is completely adequate to remove core decay heat for an indefinite period of time. These passive safety systems can perform their function without requiring an external supply of water, power, or generators. (author)
[en] This round table session on strategic energy planning comprises separate presentations by the two authors, with some general discussion. It is agreed that nuclear energy will be needed in the next century, and may double. Much of the expansion will occur in developing countries. Fossil fuels will come from increasingly 'dirty' sources such as lignite and tar sands, adding pollution problems to the concern posed by carbon dioxide. Renewable energy sources should be taken seriously. Any assessment of fusion energy must take account of the fact that problems of containment and radioactive waste will be more difficult for fusion than for fission. 7 figs
[en] This keynote address is based on the findings of the World Energy Council's Commission 'Energy for tomorrow's World'. Forecasts up to and beyond the year 2020 are provided for several different economic and ecological assumptions. It is predicted that fossil fuels will continue to dominate, that real pressures on petroleum and gas supplies will develop, that nuclear energy will grow, that beyond 2020 the 'new' renewable sources, particularly solar, will grow steadily, and that targets for limiting emissions of greenhouse gases are unattainable. 6 figs
[en] The dry cooling systems commonly use extended surface, called fin, to increase surface area and heat transfer performance. The finned surfaces ideally have zero thermal resistance and show uniform temperature distribution. Direct contact heat transfer is getting interests as innovative solution in the dry cooling system. Hot fluid flows into the air and heat transfer occurs without physical barrier between the fluid and air, thus the heat transfer performance is high. For getting large surface area in the direct contact heat transfer system, the hot fluid is emitted as small droplet shape or thin falling film. UCLA published the Direct Contact Liquid-on-String Heat Exchanger (DILSHE) that the hot fluid flows along strings, and is cooled by air. Drexel published Spray Freezing of Recirculating PCM system that the hot fluid is sprayed as droplet shape into air and the cooled fluid returns to the pool. In KAIST, dry cooled waste heat removal system that applies the direct contact heat transfer technology has been being designed. This study conducted analysis for direct contact heat transfer on the film along vertical straight string. Physical modeling on the film, heat transfer analysis and pressure loss, and cooling tower analysis were conducted. When the string radius is larger than 1 mm, the film along the string doesn't break and stable film forms. As the string radius increases, the required cooling tower height is increased but the increase is very small.
[en] The Supercritical Water Cooled Reactor(SCWR) is being developed with it's operational conditions of a pressure over 25MPa and temperature of 290∼550 .deg. C. Many experiments have observed that the heat transfer coefficient of a fluid in the pseudo-critical region shows a different behavior from that of the conventional forced convection. One very specific characteristic of the heat transfer is called the 'heat transfer enhancement', or 'normal heat transfer' which shows a larger heat transfer coefficient than the Dittus-Boelter correlation in a relatively low and moderate ratio of the wall heat flux to the mass velocity(q/G). At a high heat flux, the wall temperature increases sharply and the heat transfer coefficient becomes low. This phenomenon is called 'heat transfer deterioration'. This paper is focused on the prediction capability of the heat transfer deterioration. In order to examine the reliability of the embedded turbulence models of FLUENT at a supercritical pressure, a series of simulations for the vertical upward flow of water in a heated tube were performed
[en] Condensation phenomena occur during the PCCS operation cooling the containment through phase change heat transfer. Accordingly it is important to enhance the condensation heat transfer performance. Condensation mode is commonly classified as filmwise condensation (FWC) and dropwise condensation (DWC). DWC heat transfer performance has an order of magnitude higher than FWC heat transfer performance. In DWC process, condensed liquid droplets attach to the surface and prevent transfer of heat to the cooled surface. Generally the condensate is removed by gravity. When removal rate of condensate is high, DWC heat transfer performance will be enhanced. In terms of removal rate, superhydrophobic surface, which is recently in the spotlight, is expected to have capability to enhance the DWC heat transfer efficiency by reducing droplet size. In this study, we investigated condensation heat transfer performance on micro and nano structured superhydrophobic surface. Condensation experiments on the micro and nano structured superhydrophobic surface were carried out and compared with those on the smooth hydrophobic surface in terms of heat transfer performance and condensed droplet morphologies. Through the experiments, we found that superhydrophobicity disappeared under the condensation circumstance. As a result, heat transfer performance on the superhydro-phobic structured surface decreased compared with that on the smooth hydrophobic surface. In order to enhance the condensation heat transfer performance with superhydrophobic property, condensation mechanism on superhydrophobic surface and the conditions for sustaining superhydrophobicity should be studied more
[en] In this presentation author deals with electric power systems of Europe as well as with electric power system of the Slovak Republic. Anticipated shut downs of Slovak NPPs and start up of new NPPs are reviewed.
[en] In this study, the Finite Element (FE) stress analyses of the interference-fit flywheel assembly for reactor coolant pumps are performed, and design analogies with those of nuclear pressure vessels investigated. Using the FE model, stress solutions for the flywheel at the standstill, normal operation speed, design overspeed, and the joint release speed are obtained. Releases of the interference stresses caused by the centrifugal loads and associated deformation developed during the flywheel rotation are investigated. It is noted that using the FE stress model more insights into stresses in the flywheel assembly are attained including the deformation-controlled ones, and a feasibility to apply the pressure vessel design analogy in design evaluations for the flywheel assembly is evidenced by a limited evaluation