Human Error Assessment Methods

For some time there has been an interest in exploring the underlying reasons, as well as probabilities, of human error. As a result there are currently several models, each developed by separate groups of analysts working in this field. Estimation methods are described in the UKAEA document SRDA-Rll, 1995. The better known are HEART (Human Error Assessment and Reduction Technique), THERP (Technique for Human Error Rate Prediction), and TESEO (Empirical Technique to Estimate Operator Errors). 

Kounavos, M. 2012. Human error and human reliability assessment methods. MSc thesis, Thessaloniki Aristotle University of Thessaloniki. 

The use of the AHP method enables the solutions for each possible human error identified, to be integrated within the analysis. This is unlike the methods reviewed in Section 9.2, where the solutions to reduce the risk levels (posed by human errors) are evaluated in the first instance, and then a re-iteration of the whole analysis is performed (assuming the implementation of the solution) to confirm the risk reduction. An approach using the AHP method for human error assessment and decision making applied to ship operations is presented in Section 9.5. 

This Chter describes a method using AHP to achieve this aim. The approach integrates the risk control option within the human error assessment framework to determine the best option for the identified hazards. The advantages of using the described approach for fishing vessels include ... 

Process Hazards Analysis. Analysis of processes for unrecogni2ed or inadequately controUed ha2ards (see Hazard analysis and risk assessment) is required by OSHA (36). The principal methods of analysis, in an approximate ascending order of intensity, are what-if checklist failure modes and effects ha2ard and operabiHty (HAZOP) and fault-tree analysis. Other complementary methods include human error prediction and cost/benefit analysis. The HAZOP method is the most popular as of 1995 because it can be used to identify ha2ards, pinpoint their causes and consequences, and disclose the need for protective systems. Fault-tree analysis is the method to be used if a quantitative evaluation of operational safety is needed to justify the implementation of process improvements. 

Core damage and containment performance was assessed for accident sequences, component failure, human error, and containment failure modes relative to the design and operational characteristics of the various reactor and containment types. The IPEs were compared to standards for quality probabilistic risk assessment. Methods, data, boundary conditions, and assumptions are considered to understand the differences and similarities observed. 

Williams, J. C., 1989, A Data-Based Method for Assessing and Reducing Human Error to Improve Operational Performance, Proceedings of the 1988 IEEE Fourth Conference on Human Factors and Power Plants, Monterey, CA, June 5-9, pp 436-450, IEEE. 

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. 

The use of a model of human error allows a systematic approach to be adopted to the prediction of human failures in CPI operations. Although there are difficulties associated with predicting the precise forms of mistakes, as opposed to slips, the cognitive approach provides a framework which can be used as part of a comprehensive qualitative assessment of failure modes. This can be used during design to eliminate potential error inducing conditions. It also has applications in the context of CPQRA methods, where a comprehensive qualitative analysis is an essential precursor of quantification. The links between these approaches and CPQRA will be discussed in Chapter 5. 

Task analysis is a fundamental methodology in the assessment and reduction of human error. A very wide variety of different task analysis methods exist, and it would be impracticable to describe all these techniques in this chapter. Instead, the intention is to describe representative methodologies applicable to different types of task. Techniques that have actually been applied in the CPI will be emphasized. An extended review of task analysis techniques is available in Kirwan and Ainsworth (1993). 

Improvements in the analysis of worker risk have resulted from an increased focus on worker activities and the adoption of more general methods for analyzing the effects of human error. For a number of reasons discussed in the NRC report Risk Assessment and Management at Deseret Chemical Depot and the Tooele Chemical Agent Disposal Facility (NRC, 1997), very little modeling of human performance was done in the 1996 QRA for TOCDF. For ex-... 

An important preliminary to separation of mixed domestic plastics is the cleaning and selection operation. A simple method to perform this operation consists of a selection platform where a number of trained sorters separate the different types of plastics by visual assessment. Because manual selection is hable to human error, selection platforms may be equipped with detectors such as electronic devices to check the quality of the selected material. 

One method for analyzing human reUability is a straightforward extension of probabilistic risk assessment (PRA)—in the same way that equipment can fail, so can a human make mistakes and slips. One technique for predicting human error rates is the THERP, which was developed in the 1950s. As with other PRA techniques, THERP models can use either point. 

Human errors continue to dominate as a contributing factor in aircraft accidents (see Annex A to this chapter). A Boeing study (2001) found that flight crew errors are listed as the primary cause in 66% of accidents and that despite the introduction of protective devices or systans, this percentage has remained relatively unchanged in recent years. An FAA study (2002) into Aeroplane Safety Assurance Processes concluded that the processes used to determine and vahdate human responses to failure and methods to include human responses in safety assessments need to be improved and that the industry challenge is to develop aeroplanes and procedures that are less likely to result in operator error and that are more tolerant to operator error when they do occur . 

Techniques which purport to assess reliability of systems in advance of their operations have been particularly closely associated with the development of the nuclear industry in order to gain public acceptance and an operating licence designers and builders of nuclear power plants have to demonstrate in advance that the designs and proposed methods of operation are safe. This requires a minutely detailed specification of the actual processes, a quantitative assessment of the likelihood of different kinds of failure, a quantitative assessment of the likelihood of different kinds of human error and, finally, modelling the combined effeas of all possible combinations of error and breakdown to give an overall assessment of safety. 

In current HRA practice, the most widely used dependence assessment method is the dependence model and method included in the Technique for Human Error Rate Prediction (THERP) HRA method (Swain Guttman 1983). The current practice has however a number of weaknesses. Often, the assessment is performed based on direct expert judgment so that the results lack traceability and repeatabftity. In some cases, simphfied expert elicitation approaches, hke decision trees (Gertman et al. 2004, Juluis et al. 2005) are used, which however are not based on a transparent expert ehcitation process (Podofillini et al., in prep.). 

Richei et al. (2001) introduced the Human Error Rate Assessment and Optimizing System (HEROS) to evaluate and optimize the man-machine interface in Probabihstic Safety Assessment (PSA). The authors firstly showed the major disadvantages of current HRA methods as ... 

Marseguerra M., Zio E. T ibrizzi M., 2006, Quantitative developments in the cognitive reliability and error analysis method (CREAM) for the assessment of human performance,/Innafa of Nuclear Energy 33(10) 894-910. 

Safety suffers from the variety of methods and models used to assess human performance. For example, operation is interested about human error while design is aligning the system to workload or situational awareness. This gap decouples safety assessment from design. As a result, design creates constraints at the sharp-end, which eventually leads to human errors. 

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