Proceedings of the Eighth International Conference on Probabilistic Safety Assessment & Management (PSAM)
59 Semi-Quantitative Risk Assessment Supporting Decisions for Control Center Changeover (PSAM-0408)
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- Ris (Zotero)
- Reference Manager
In our days decision making in operation of technical facilities often enough is driven by economic aspects. Our thinking is dominated by economic effects which have to be achieved but not by capability and condition of technical facilities, technology or human factors. However those factors are also highly important for a positive outcome of changes brought by a decision. Will true life really show the often awaited cost reduction effects? What obstacles may come up during implementing our ideas to the real world? This is a classical task for risk analysis! So our statement is making decisions should go along with systematic risk management. A statement most people will agree with on the first sight. But what does it mean in detail?
Technical risks can be calculated and managed by the use of fault-tree-analysis or event-tree-analysis in a quantitative way or by using e.g. FMEA in a qualitative way. Also human errors can be evaluated by detailed methods. Here we already have difficulties supporting the decision making process in an efficient way. We should understand our role as risk managers as a service given to decision makers. If we as risk managers are generating too sophisticated models it is time consuming, too expensive and often enough not well understandable for the managers who at least have to make decisions.
Therefore we like to introduce our semi-quantitative approach for risk assessment. It is an approach, which is quickly understandable for those, who have to work with its results during decision making. They will also become adapted to systematic risk assessment for their every day's decision making work.
Let us show you an example taken from a real project. A power plant which was extended over the years to several blocks all with independent control rooms shall have a new common control center. The question is: How will the power plant availability influenced by such an extensive changeover?
This basic decision involves a lot of changes. Therefore all blocks with their different technique and operational organization and also demands of process engineering and maintenance had been a part of the evaluating model. The goal was to show the influence of the changeover to power generation availability. First the determining factors had to be found for the given concept. Those cover different aspects which are (A) directly connected to control room equipment, (B) connected to changes in process engineering and (C) work organization. Technique (A) factors are for instance age of control room technology, how many different subsystems are controlled by the center and automation level. Process engineering (B) factors are reliability respective the unavailability of subsystems, challenge rate for the equipment and its complexity. To make estimations about work organization (C) the following factors are important: familiarity with tasks to be performed, quality of information/signals, stress and distance to real facility. To all factors semi quantitative values are assigned as criteria of evaluation. Additionally those factors get an importance rating. Besides learning more where to put most attention during the decision making process, this analysis makes it clear by assessment results, how strong the decision for a control center changeover might change the risk situation (availability).