Action error analysis

Action error analysis Fault tree analysis Event tree analysis Comparlsan analysis CRIOP... 

Action error analysis analyses interactions between machine and humans. It is used to study the consequences of potential human errors in task execution related to directing automated functions. 

Figure 4.17 shows a useful format for documenting the results of error analysis. This is based on the HTA in Figure 4.2. For every critical error (e.g., action omitted) the implications or consequences for the system and the possibilities...

Based on the collected information, a decision/action (DA) chart was developed to provide an overview of the main decisions involved in the blowdown operation and the main influential factors such as time stress, conflicting responsibilities, risk of gas ignition etc. Task Analysis and Error Analysis of the blowdown operation were subsequently carried out to obtain a description of the sequence of tasks steps and the likely human error modes which could occur. 

One of the most noticeable ergonomic deficiencies in both control rooms was the number of panels that had to be scanned and monitored during the scenarios, and the number of rapid actions required at opposite ends of the control room. The need for virtually simultaneous actions and movements would have been discovered and resolved in the design stage had a task analysis and human error analysis been carried out on an emergency operation. 

The company has in place numerous checks and balances to prevent human error quality assurance (QA)-driven processes require validation (secondary checks/rechecks) of operator actions, sampling/analysis, etc. 

If nonconformances or deviations to the project plan or IQ protocol are encountered during the software IQ testing, these must be documented, analyzed, resolved, reviewed, and approved. The resolution process must indicate what additional actions must be taken to provide a conforming product (e.g., return the program to development for error analysis and correction, and re-execute the test script after correction the nonconformance was due to an inaccuracy in the test script, review and update the test script, etc.). After the successful resolution of the nonconformance has been obtained, the original test, the nonconformance information, and the retest must all be retained, approved, and reviewed by the appropriate personal. 

An evaluation method to determine the probability that a system-required human action, task, or job will be successfully completed within the required time period and that no extraneous human actions detrimental to system performance will be performed. It provides quantitative estimates of human error potential due to work environment, human-machine interfaces, and required operational tasks. Such an evaluation can identify weaknesses in operator interfaces with a system, quantitatively demonstrate improvements in human interfaces, improve system evaluations by including human elements, and demonstrate quantitative prediction of human behavior. See also ATHEANA (A Technique for Human Error Analysis) Human Error Analysis. 

The hardware associated with a BPCS operator action is not covered by the standard. However, its performance should be monitored to ensure that it is sufficient. Formal PFD calculation is typically not required. Human factors should be considered in the design of any critical operator activity. For example, the design of the BPCS operator interface should incorporate human factors engineering (HFE) principals to ensure that the operator responds adequately to an alarm or process indication. However, a detailed human-error analysis is not required for operator actions implemented in the BPCS. Refer to Table B-1 for additional allocation and risk-reduction guidance. 

Alarm Saturation. Errors in analysis can result when an operator is asked to cope with too many alarms. Operators often must scan a series of alarms as they occur, deduce what is happening within the process, draw conclusions, and take the appropriate action. Errors of analysis occur when, after properly observing a valid set of data, an operator draws a wrong conclusion or responds inappropriately. These errors can be avoided by assigning priorities to alarms in order to guide the operator. 

A Technique for Human Event ANAlysis (ATHEANA) was developed by the nuclear industry due to a perceived need for a human error analysis tool that more closely modeled actual operational events and which put a stronger focus on contextual factors. The quantification is based around three calculations. Eirst, calculating the probability of an Error Eorcing Condition (EEC i.e. the probability that the plant will be in a state which may induce an error). This is determined by a combination of plant conditions and PSEs. Second, the probability of an Unsafe Action (UA). And third, the probability of not recovering from the initial UA. This third area incorporates the possibility of alarms and/or feedback to the operator allowing them to correct the UA. 

This focus in this chapter is on analytical methods for measuring action spectra, with emphasis on those derived from fluence-response data. For a set of examples, the reader can consult studies of Phycomyces, not only studies of its phototropism but also of the light-growth response, carotene synthesis, and differentiation," as well as studies of other blue-light systems.The later studies on Phycomyces employed formal data analysis methods — including error analysis (and error propagation )... 

Beyond the key recommendation of basing action spectra on fluence-response curves, readers are encouraged to apply formal data analysis techniques, including error analysis, for analyzing experimental results in action spectroscopy research. Details on such methods are available elsewhere. ... 

It is important to note that vahdation typicahy only brings a measurement under suspicion. It does not verify that the measurement is incorrect. Safety is paramount. Some vahdation analysis could result in concluding that the measurement is invalid when, in fact, the comparison information is invahd. It is not difficult to extrapolate that actions could result from this erroneous conclusion which would place maintenance and operating personnel in jeopardy. Validation merely raises suspicion it does not confirm errors or measurement. 

Errors of omission and com mission are identified for every human action appearing in the task-analysis table. A human action (or lack thereof) constitutes an error only if it has at least the potential for reducing the probability of some desired event or condition. The existence of this potential should be identified with the system analysts. 

For every human action appearing in the task-analysis table, errors of omission and commission should be pinpointed. 

Human reliability [lata NJUREG/CR-1278 was supplemented by judgment of system analysts and plant personnel. Human error probabilities were developed from NUREG/CR-12 8, human action time windows from system analysis and some recovery limes from analysis of plant specific experience. Data sources were WASH-1400 HEPs,Fullwood and Gilbert assessment ot I S power reactor Bxp., NUREG/ CR -127K. and selected acro ptice li.it.j... 

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. 

Error Prediction for Safety Analysis and Proactive Error Reduction This procedure is performed when error modes are being identified (e.g., critical action omitted, alternative imsafe action carried out) as part of a predictive safety analysis (e.g., CPQRA) or as part of a proactive error reduction process (see Chapter 4). 

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