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71.
72.
Philip Tipping 《International Journal of Pressure Vessels and Piping》1996,66(1-3):17-25
The susceptibility and tendency for nuclear power plant (NPP) components to undergo changes in their mechanical and physical properties in the course of the NPP lifetime is generally termed as “ageing”. The light water reactor (LWR) nuclear environment is not a begnign one; it is characterized not only by fast neutrons, which can degrade metallic structures, but also relatively high temperatures of coolant water (around 300°C) which may contain impurities (e.g. sulphate, chloride, peroxides) which can cause corrosion. The hydrodynamical conditions of the coolant in steam generators, for example, can cause thermal fatigue, erosion and corrosion; suspended particulate matter can accelerate erosion processes which can lead to wall thinning and lowering of safety margins. Ageing is, therefore, a very complex mixture of factors concerned with materials, temperatures, times of exposure to environments which vary with time and with respect to chemical composition and flow charactertistics.
The paper describes a few ageing phenomena which can be considered important due to their impact on nuclear safety issues; their influence on economic aspects (availability) of NPP is outlined. Mitigation measures for NPP component ageing problems are given together with recommendations for addressing such issues in NPP now and in the future. 相似文献
73.
对新研制的两种电解防污开关恒流源所采用的不同逆变器、开关功率管、直流工作电源及取样方式的工作状态、工作特性进行了分析比较。在研制过程中,重点解决了恒流电源工作的安全可靠性、稳定性、抗干扰能力及输出范围宽等问题。 相似文献
74.
隆德县在大水沟农村饮水工程建设管理中,科学规划,优化设计方案,完善政策措施,创新管理体制和运行机制,尤其是用水户全过程参与工程建设管理、实行“两部制”水价、实施工程定期检查养护制度、建立工程管理单位目标责任考核制度、执行水费统一管理和提留统筹费等一系列做法.确保了国家投资效益的充分发挥和工程的可持续利用. 相似文献
75.
Manabu Ishitobi Takeshi Myoi Koji Soshin Eiji Hiraki Mutsuo Nakaoka 《Electrical Engineering in Japan》2005,153(3):79-87
This paper presents a single lossless inductive snubber‐assisted ZCS‐PFM series resonant DC‐DC power converter with a high‐frequency high‐voltage transformer link for industrial‐use high‐power magnetron drive. The current flowing through the active power switches rises gradually at a turned‐on transient state with the aid of a single lossless snubber inductor, and ZCS turn‐on commutation based on overlapping current can be achieved via the wide range pulse frequency modulation control scheme. The high‐frequency high‐voltage transformer primary side resonant current always becomes continuous operation mode, by electromagnetic loose coupling design of the high‐frequency high‐voltage transformer and the magnetizing inductance of the high‐frequency high‐voltage transformer. As a result, this high‐voltage power converter circuit for the magnetron can achieve a complete zero current soft switching under the condition of broad width gate voltage signals. Furthermore, this high‐voltage DC‐DC power converter circuit can regulate the output power from zero to full over audible frequency range via the two resonant frequency circuit design. Its operating performances are evaluated and discussed on the basis of the power loss analysis simulation and the experimental results from a practical point of view. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 153(3): 79–87, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20126 相似文献
76.
针对小城镇建设过程中的通风节能问题进行了研究,提出了通风供热水一体化的系统方案.该方案利用廉价、清洁的太阳能解决小城镇通风与供热水的问题,系统具有经济性、环保性、实用性,也为国家节能利用方面提供了新思路,为建设节约型社会做出新贡献,为解决城镇建设的能源消耗提供新的解决方案. 相似文献
77.
根据7号高炉中控室供电状况,进行了供电平衡分析。调整两段负荷,使供电平衡安全。 相似文献
78.
In new institutional economics, the variance in institutions explains differences in cross-country output per capita. Institutions may also explain how the supply of oil is affected within oil-producing countries. For example in the early 1970s, as nominal oil prices increased from $3 per barrel to $11 per barrel, a number of OPEC oil producers changed the institutional environment by nationalizing their oil production and putting under government control all petroleum-related capital and infrastructure. This affected oil supplies. Similar institutional changes may be happening again now that oil prices are rising. In particular, the newly democratic Russia may be following the same path. The Russian government has already effectively taken over control of much of the oil production capacity in the country and is still heavily involved in natural gas production. In this paper, we will look at the Russian upstream oil industry as it changed from central planning to a market-oriented sector and is now swaying toward re-nationalization. Some of the laws and institutional transitions will be detailed in order to elucidate what has taken place. 相似文献
79.
介绍了城市轨道交通直流牵引供电系统的构成,详细叙述了直流牵引供电系统的主要电气设备及其连接方法,以及系统的运行方式.另外,还简单介绍了系统配置的直流保护以及保护原理和保护作用. 相似文献
80.