Human reliability analysis steps

Such a task description invites task analysis, which would lead naturally to human reliability analysis (HRA). Indeed, perhaps the earliest work in this field applied HRA techniques to construct fault trees for aircraft structural inspection (Lock and Strutt 1985). The HRA tradition lists task steps, such as expanded versions of the generic functions above, lists possible errors for each step, then compiles performance shaping factors for each error. Such an approach was tried early in the FAA s human factors initiative (Drury et al. 1990) but was ultimately seen as difficult to use because of the sheer number of possible errors and PSFs. It is occasionally revised, such as in the current FRANCIE project (Haney 1999), using a much expanded framework that incorporates inspection as one of a number of possible maintenance tasks. Other attempts have been made to apply some of the richer human error models (e.g.. Reason 1990 Hollnagel 1997 Rouse 1985) to inspection activities (La-toreUa and Drury 1992 Prabhu and Drury 1992 Latorella and Prabhu 2000) to inspection tasks. These have given a broader understanding of the possible errors but have not helped better define the PoD curve needed to ensure continuing airworthiness of the civil air fleet. 

This simplistic calculation really entails much more work. In developing HEPs, it is important to consider data probability distributions, data dependence, and uncertainty limits. Again, refer to the Handbook of Human Reliability Analysis (Swain and Guttman, 1983,2011) for a step-by-step approach. 

Human reliability analysis is conducted in several steps. After the problem is defined the task is analyzed. During the next step the possible human errors are analyzed (event analysis). Factors that negatively influence human performance and error causes are immediately reduced and then quantified... 

The increasing use of Probabilistic Safety Assessment (PSA) to support regulatory and operational decisions requires that methods be developed to the extent possible on an empirically sound basis. For Human Reliability Analysis (HRA), this means that methods should be based on data from operational experience, studies in simulator environments, as well as theoretical cognitive models. A significant step in this direction has been achieved with the International and US HRA Empirical Studies, which aimed at an empirically-based understanding of the strengths and weaknesses of a number of HRA methods (Forester et al. 2013). 

The three basic steps of the human reliability analysis being performed to characterize accident management are identification of those actions to be modeled deterministically (based on a finite number of accident progression analyses), the assignment of screening (or simplified) probabilities that the action is not performed, and the development of more detailed probability bases for a subset of these actions. 

When performing human reliability assessment in CPQRA, a qualitative analysis to specify the various ways in which human error can occur in the situation of interest is necessary as the first stage of the procedure. A comprehensive and systematic method is essential for this. If, for example, an error with critical consequences for the system is not identified, then the analysis may produce a spurious impression that the level of risk is acceptably low. Errors with less serious consequences, but with greater likelihood of occurrence, may also not be considered if the modeling approach is inadequate. In the usual approach to human reliability assessment, there is little assistance for the analyst with regard to searching for potential errors. Often, only omissions of actions in proceduralized task steps are considered. 

If the results of the qualitative analysis are to be used as a starting-point for quantification, they need to be represented in an appropriate form. The form of representation can be a fault tree, as shown in Figure 5.2, or an event tree (see Bellamy et al., 1986). The event tree has traditionally been used to model simple tasks at the level of individual task steps, for example in the THERP (Technique for Human Error Rate Prediction) method for human reliability... 

ANALYSIS DOCUMENTATION. PrHA report documentation should include the PrHA worksheets, checklists, logic diagrams, human reliability analyses, and any other analysis made to better understand the scenarios. The PSM Rule requires that human factors that impact scenarios as cause or protection be expanded to analyze the basic cause of errors or response failures. For example, a cause may identify that an operator can turn the wrong valve to initiate an accident. The PSM Rule requires that basic causes also be identified. For example, valve is not labeled the operator has not been trained on the operation or the operator forgot the step. There may be more than one basic cause. (See also Section 3.2, paragraph on Human Factors.)... 

Of course the glucose electrode is just one example of this multifaceted character. Biosensors are used extensively in process control in industry and permit automation. They eliminate sampling and analysis steps, thereby reducing the amount of human intervention and the number of personnel, and increasing the procedure reliability and the product quality. On the whole, the use of biosensors is attractive because they lead to a higher quality product at a more competitive price. 

Environmental media are analyzed to identify contaminated areas and to determine if contaminant levels constitute a concern for human health. The detection of plutonium in air, water, and soil is of concern due to the potential for human exposure. There are many steps involved in the analysis of plutonium in environmental media. Reliable and accurate methods are available to detect plutonium in air. However, no detection limit or degree of accuracy was reported for the methods used to determine plutonium in soil and water. Attempts to improve these methods should be focused on separation techniques, increasing yields, and increasing the measurement efficiency. 

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