冷水机组节能驱动与控制系统的选择与计算（二）

本文提出一种在工程设计中能快速列表计算、具有几种不同节能驱动与控制系统的冷水机组的综合部分负荷性能系数LPLV的方法。这些部基于LPLV的标准公式和它们的特性曲线族图表。比较它们的IPLV的计算结果的大小,即能选择高效驱动节能控制系统。     

System-level hazard analysis using the sequence-tree method

A system-level PHA using the sequence-tree method is presented to perform safety-related digital I&C system SSA. The conventional PHA involves brainstorming among experts on various portions of the system to identify hazards through discussions. However, since the conventional PHA is not a systematic technique, the analysis results depend strongly on the experts’ subjective opinions. The quality of analysis cannot be appropriately controlled. Therefore, this study presents a system-level sequence tree based PHA, which can clarify the relationship among the major digital I&C systems. This sequence-tree-based technique has two major phases. The first phase adopts a table to analyze each event in SAR Chapter 15 for a specific safety-related I&C system, such as RPS. The second phase adopts a sequence tree to recognize the I&C systems involved in the event, the working of the safety-related systems and how the backup systems can be activated to mitigate the consequence if the primary safety systems fail. The defense-in-depth echelons, namely the Control echelon, Reactor trip echelon, ESFAS echelon and Monitoring and indicator echelon, are arranged to build the sequence-tree structure. All the related I&C systems, including the digital systems and the analog back-up systems, are allocated in their specific echelons. This system-centric sequence-tree analysis not only systematically identifies preliminary hazards, but also vulnerabilities in a nuclear power plant. Hence, an effective simplified D3 evaluation can also be conducted.