ATHEANA
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1) The ATHEANA framework provides a methodology for human reliability analysis (HRA) that examines the context and factors surrounding human errors and failures. 2) The key steps in ATHEANA include defining scenarios, identifying potential vulnerabilities and deviations, evaluating complicating factors, and assessing recovery potential. 3) ATHEANA aims to provide a richer understanding of human factors compared to other HRA methods by considering a wide range of performance shaping factors and scenario context.
ATHEANA
- 1. ATHEANA :An HRA Method & An Event Analysis Tool Presented by: Anand Kumar 11RE60R04 M.Tech(2nd YR) Reliability Engineering
- 2. CONTENTS: Introduction ATHEANA Framework Steps Involved Advantages & Disadvantages Observations References
- 3. INTRODUCTION: A TECHNIQUE FOR HUMAN EVENT ANALYSIS (ATHEANA) Sponsored By U.S. Nuclear Regulatory Commission Methodology development document (NUREG/CR-6350, 1996) Examination of Actual Human Error Event Determine "Error-forcing Context" for Significant Errors Implementation Guidelines (NUREG-1624, 2000) "Second Generation" HRA Methodology
- 4. INTRODUCTION: Human influences on system operation include Normal operation : control actions ⇒ Planned human actions Maintenance actions : service, •procedures •training inspection, test, etc. ⇒ Unplanned actions Control of small disturbances in •usually not credited in a PSA “abnormal” operation •develop a plan based on PSA insights Termination of the development of a disturbance : reach a safe state Mitigation of consequences of a disturbance
- 5. CONTD.. Human Error, Human Failure Event • “any member of a set of human actions that exceeds some limit of acceptability… out-of-tolerance action, where limits of tolerable performance are defined by system” * • “divergence between the action actually performed and the action that should have been performed” ** system-based and PSA-based perspective Note: an action required, e.g. by procedures, in the given situation can be a HE from the PSA perspective! The more neutral term Human Failure Event (HFE) is generally preferred today. * NUREG/CR-1278 A Technique for Human Error Rate Prediction ** NUREG/CR-6350 A Technique for Human Error Analysis (ATHEANA)
- 6. Difference from other HRA methods • able to identify and justify human failure events (HFEs) that not been included in PRA models. •identifying HFEs and associated unsafe actions and EFCs is similar to HAZOP study in that: a)a multidisciplinary team, lead by the HRA analyst, is required to apply the method, b) an imaginative yet systematic search process is used, and c) the ATHEANA search aids and the structure of its search process are designed to assist and stimulate thinking of new ways for accident conditions to arise
- 8. REASONS FOR ATHEANA: •Human events modeled in previous HRA/ PRA models were not considered to be consistent with the significant roles that operators have played in actual operational events; •The accident record and advances in behavioral sciences both supported a stronger focus on the contextual factors, especially plant conditions, in understanding human error; •Advances in psychology were integrated with the disciplines of engineering, human factors and PRA in modeling human failure events.
- 9. STEPS OF ATHEANA: •Define and interpret the issue •Define the scope of the analysis •Define the base case scenario •Define HFE and/or UAs •Identify potential vulnerabilities in operators, knowledge base •Search for deviations from the base case scenario •Identify and evaluate complication factors and links to performance shaping factors (PSFs) •Evaluate the potential for recovery •Quantify the HFE probability •Incorporate the HFE into PRA
- 10. BASIC STEPS OF ATHEANA Objectives and 1. DEFINE AND INTERPRET 2. DEFINE SCOPE Initiating events, technical concerns of PSA ISSUE OF ANALYSIS event sequences the analysis Relevant IEs, sequences, success criteria 3. DESCRIBE BASE CASE SCENARIOS Nominal parameter plots, expected plant and operator behavior FSAR, EOPs and other sources of 4. DEFINE HFEs AND UAs OF operator expectations CONCERN List of key actions that can cause undesired event PLANT PROCEDURES, EOPs and 5. IDENTIFY POTENTIAL MMI, TRAINING, ETC. operator “rules” VULNERABILITIES Operator expectations and tendencies, potential traps, etc. Plant procedures, indications (MMI), 6. SEARCH FOR DEVIATIONS training, etc. FROM BASE CASES Iterate Initial scenario context descriptions and possible UAs 7. IDENTIFY AND EVALUATE COMPLICATING FACTORS Scenario descriptions and specific UAs 8. EVALUATE RECOVERY POTENTIAL Qualitative assessment of EFCs for UAs / HFEs 9. RESOLVE ISSUE (INCLUDING 10. INCORPORATION INTO QUANTIFICATION) PSA
- 11. PERFORMANCE SHAPING FACTORS (PSFs): • Any factor that influences performance – depend on task and domain • Three classes of PSFs • external, i.e. those outside the individual environment, task characteristics, procedures. • internal, i.e. those that operate within the individual training, experience, stress. • stressors factors producing mental and physical stress, e.g. task speed and load, fatigue, vibration Performance Shaping Factors (PSFs). • PSFs allow adjustment of estimates for other situations • combinations of PSFs determine the reliability of performance • all quantification methods try to model PSF effects
- 12. ADVANTAGES: 1.provides a much richer and holistic understanding of the context concerning the Human factors. 2.leads to the enhancement of understanding as requires stakeholders and decision makers 3.increases the guarantee that the key risks associated with the Human Failure Events. 4.to estimate Human Error Probabilities considering a variety of differing factors and combinations. 5. ATHEANA allows for the consideration of a much wider range of performance shaping factors . 6.the method seeks to identify any interactions which affect the weighting of the factors of their influence on a situation
- 13. DISADVANTAGES: •From a Probability Risk assessment (PRA) stance, there is no HEP produced. So, fitting into Predictive Quantitative Risk Assessment is reduced. •Fails to establish details of the causal relationships between human factors . Thus, further work is required to establish the RCA of an incident. •The outcomes of the human errors under consideration are constrained by previously defined sequences of PSA accidents. •For the purposes of predictive analysis the theoretical foundations on which the ATHEANA methodology is based are considered to be ineffectual.
- 14. ATHEANA OBSERVATIONS •Severe errors are not caused by simple failures to follow procedural steps •Causes for severe errors: •Unexpected conditions not addressed by procedures or training •Misdiagnosis of conditions or required response •Refusal to believe contradictory indications or information •"Errors of commission" •Scenario context is the most important factor that determines likelihood of error •Plant conditions •Human performance-shaping factors
- 15. REFERENCES •S. E. Cooper, A. Ramey-Smith, J. Wreathal1,G. W. Parry, D. C Bley, W. J. Luckas, Jr., J. H. Taylor, and M. T. Baniere, “A Technique for HumanError Analysis (ATHEANA),” Brookhaven National Laboratory, Upton,NY NUREG/CR-6350, May 1996 •M. T. Baniere, J. Wreathall, S. E. Cooper, D. C. Bley, W. J. Luckas, and A.Ramey-Smith, “Multidisciplinary Framework for Analyzing Errors of Commission and Dependencies in Human Reliability Analysis,” Brookhaven National Laboratory, Upton, N NUREGKR-6265, August 1995.