Quantitative risk analysis construction

As a result of the AIC s efforts, we now have a process for investigating accidents in which we construct an event tree for each incident. The tree is quite similar to a fault tree from the quantitative risk analysis discipline, except that in the investigations we often sacrifice some structural rigor to get the most results in a reasonable time. Basically, the process uses a team to reconstruct the chronology of the incident and to construct the event tree. We try to include those who are most familiar with what actually happened, including the injured person(s) if any. We use the same basic method to investigate process failures, spills, injuries, or any other system failures. Emphasizing the system aspects of the failure removes much of... 

WJe now have a process for investigating accidents in which we construct an Event Tree for each incident. The Tree is quite similar to a Fault Tree from the Quantitative Risk Analysis discipline, except that in the investigations we often sacrifice some structural rigor to get the most results in a reasonable time. 

Let us now turn our attention to the main steps of any procedure constructed to anticipate or respond to the risk analysis requirements set forth by the statutes reviewed above or voluntarily established as product standards by industries. It is important to note that this type of procedure is a technical means to arrive at a quantitative estimate. The decisions regarding the acceptability of the result is sociopolitical and is, therefore, beyond the scope of this discussion. 

Fault tree analysis is based on a graphical, logical description of the failure mechanisms of a system. Before construction of a fault tree can begin, a specific definition of the top event is required for example the release of propylene from a refrigeration system. A detailed understanding of the operation of the system, its component parts, and the role of operators and possible human errors is required. Refer to Guidelines for Hazard Evaluation (CCPS, 1992) and Guidelines for Chemical Process Quantitative Risk Assessment (CCPS, 2000). 

As diseussed above, expected utility can be reconciled with the two-stage stochastic framework. For example, if one uses the nonlinear coordinate transformation of real value into utility value given by the utility function (Figure 12.3), one can modify the view of the risk curve, as shown in Figure 12.12. If such utility function can be constructed based more on quantitative relations to shareholder value, then one does not need to perform any risk management at all. One could speculate that it suffices to maximize utility value, but only if one has identified the ultimate objective function associated with the company s optimum financial path. It is worth noting that anything less, like the net present value, which can be considered a utility function too, will require the analysis of different curves before a final choice is made. 

The purpose of this research is to construct probabilistic safety models for a typical loop-type FBR plant so that an overall safety assessment can be performed. It is expected that (1) a systematic evaluation on the plant safety is conducted based on the quantitative analysis, (2) the insights on measures to enhance system reliability and safety are provided, (3) the operation and maintenance procedures are established based on a risk-based consideration, and (4) useful information is given to the development of basic policy on safety design and evaluation of a large LMFBR. 

---