Risk assessment quantification process

RISK ASSESSMENT Quantification to the risk relating to one or several hazards (including the process of determining these) (CEN/TR 15419). 

Performance-influencing factors analysis is an important part of the human reliability aspects of risk assessment. It can be applied in two areas. The first of these is the qualitative prediction of possible errors that could have a major impact on plant or personnel safety. The second is the evaluation of the operational conditions under which tasks are performed. These conditions will have a major impact in determining the probability that a particular error will be committed, and hence need to be systematically assessed as part of the quantification process. This application of PIFs will be described in Chapters 4 and 5. 

In addition, the chapter will provide an overview of htunan reliability quantification techniques, and the relationship between these techniques and qualitative modeling. The chapter will also describe how human reliability is integrated into chemical process quantitative risk assessment (CPQRA). Both qualitative and quantitative techniques will be integrated within a framework called SPEAR (System for Predictive Error Analysis and Reduction). 

This chapter has provided an overview of a recommended framework for the assessment of human error in chemical process risk assessments. The main emphasis has been on the importance of a systematic approach to the qualitative modeling of human error. This leads to the identification and possible reduction of the human sources of risk. This process is of considerable value in its own right, and does not necessarily have to be accompanied by the quantification of error probabilities. 

Risk management decisions follow the identification and quantification of risk, and they are determined by risk assessments. During the regulatory process, risk managers may request that additional risk assessments be conducted to justify the risk management decisions—the risk assessment and risk management processes are therefore intimately related. 

The risk assessment requires information about potential risks, effects, and impacts on current processes and environments. Process risk assessment is mainly determined by the probability of process interruption, system down times, and restart of a system. Typical chemical risk assessments comprise identification of hazards for personnel, customers, and environment, qualitative assessment of potential adverse consequences of the contaminant, and evidence of their significance. The previously described systems for toxicology estimation are useful software modules in this process. Environmental risks require additional dose-response assessments as well as quantification of exposure to determine the dose that individuals will receive. Einally, a qualitative assessment of the probability for recurrence of the exception is performed, or — in the case of systematic occurrence — the exception is linked to similar cases. 

Consideration should also be given to the quantification of potential adverse effects from extending the reaction time beyond the optimum condition. Product decomposition and by-product formation are often observed under these circumstances. This information can be beneficial in scale-up operations when reaction times are extended beyond the specified period because of unforeseen circumstances. This information is also important in evaluation of this variable as a potential critical process parameter for the process risk assessment. 

Quantification of risk due to an environmental exposure to a particular pollutant is always a complex process, since the multiplicity of other pollutants and factors have an impact on the individual at the same time, and the particular exposure investigated is only one of the factors. Risk assessment of airborne particulate matter is even more complex in addition to the aforementioned challenges is the... 

The process of risk assessment can be defined as t/ie evaluation and quantification of the likelihood of undesired events and the likelihood of injury and damage that could be caused by the risks. It also involves an estimation of the results resulting from undesired events. 

Of course, the problem is the danger of quantifying information that is not easily quantifiable. When data are too ambiguous or nebulous to be of utility, you can use a pseudo-quantification approach such as the hazard risk index. Risk assessment is based on the numerical comparison between risk events. Part of the risk assessment process is to compare, contrast, and evaluate risks. This risk evaluation becomes a ranking and comparison process and uses probability differences (matched with other factors such as severity of consequences) to do it. 

The Change Safety Analysis (CSA) aims to integrate a formal approach to system safety hazard management, quantification of system safety requirements, and system safety assurance. The Change Safety Analysis and Risk Assessment Process encapsulate the following ... 

Any machine is characterized by the possibility that it may be a threat to operators or third parties. It is necessary to analyze any interface between a machine and man by some of the methods of risk assessment. Scientific research only confirmed that the relevance of analyses results cau be expected especially when the identification, quantification, risk assessment, and the choice of methods for risk minimization are not left to the human factor, but are instead carried out using modern procedures from IT. The human factor— man—is not able to process in a short time the extensive amount of information within complex engineering systems or complicated constructions of modern machines. 

The theory and application of systematic risk assessment is a part of effective risk control processes. Methods for risk assessment or estimation allow the quantification of the risks and, thus, provide top managers with relevant information for risk reduction within the Man-Machine-Environment system. The following theses form the basis for the risk assessment methods selection (see also Chapter 1) ... 

Risk assessment by means of immeasurable quantification is used if there is no clear interface between the individual elements of the Man-Machine-Environment system, and in the process of the assessment it is difficult to precisely determine the values of probability (frequency) and consequence of a negative event. This includes MIL STD 882C elaborated by the US Department of Defense and is quite frequently utilized mainly by small and medium-sized enterprises. 

The modeling of earthquake-induced damage can be either probabilistic or deterministic or, since seismic risk assessment is a multistep process, a combination of both. The benefit of probabilistic analysis is that they can account for the many xmcertainties associated with seismic risk assessments of infrastructure. These include xmcertainties in the quantification of seismic hazard, the relationship between seismic hazard and component damage, and the relationship between component damage and component functionality. 

The Chemical Process Industry (CPI) uses various quantitative and qualitative techniques to assess the reliability and risk of process equipment, process systems, and chemical manufacturing operations. These techniques identify the interactions of equipment, systems, and persons that have potentially undesirable consequences. In the case of reliability analyses, the undesirable consequences (e.g., plant shutdown, excessive downtime, or production of off-specification product) are those incidents which reduce system profitability through loss of production and increased maintenance costs. In the case of risk analyses, the primary concerns are human injuries, environmental impacts, and system damage caused by occurrence of fires, explosions, toxic material releases, and related hazards. Quantification of risk in terms of the severity of the consequences and the likelihood of occurrence provides the manager of the system with an important decisionmaking tool. By using the results of a quantitative risk analysis, we are better able to answer such questions as, Which of several candidate systems poses the least risk Are risk reduction modifications necessary and What modifications would be most effective in reducing risk ... 

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