Abstract:

Nuclear safety has been extensively investigated by all, viz., licensees, authorities and researchers. The subject of assessment involves consideration of abnormal operating conditions including severe accidents beyond the design of the addressed nuclear power plant (NPP). Besides deterministic analysis of selected scenarios of abnormal operation, probabilistic safety analysis (PSA) is applied for a structured assessment of the frequencies of the variety of accident sequences that may develop for a set of initiating events. Both types of analysis address human factors and human reliability analysis (HRA) in the context of PSA. The assessment of human performance, in both deterministic and probabilistic analyses, is known as a critical issue and therefore subject to research in various disciplines.
Historically, the importance of human performance has been emphatically highlighted by the accidents in the NPPs of Three Mile Island (1979) and Chernobyl (1986) and include issues such as emergency operating procedures, operator training, accident management (AM), safety culture, human and organizational factors and undesired human interventions that aggravate the progression of a scenario (briefly denoted as errors of commission, EOC, in the context of PSA). Such issues also played a role in the Fukushima disaster (2011).
The investigations to overcome possible disaster comprise the identification of scenarios with difficult performance conditions (e.g., with deteriorated access to the location of action), the assessment of human reliability under a given condition and the derivations of proposals for improvements.
The papers included in this issue have gone through a rigorous two-stage blind-review process by the guest-editors and reviewers selected from amongst the best experts in safety and performability engineering. Our goal is to bring to the readership of IJPE some key papers that will kick-start a vibrant and fruitful stream of research and industry papers in the area of safety, human and organizational factors, and human reliability.
In the first paper, Accident Management under Extreme Events, by George Vayssier describes an overview of procedures, strategies, guidelines, equipment and organisational issues that are needed to protect a site against extreme events. It is based on lessons learned from large destructive events in the past, such as the 9/11 attacks in the US in 2001 and the Fukushima-Daiichi tsunami in 2011. The author emphasises that the total set of procedures and guidelines including the needed equipment and organisational provisions should be regularly inspected and tested.
In the second paper, A Systemic Approach to Oversee Human and Organizational Factors in Nuclear Facilities, by Claudia Humbel Haag and Bernd Linsenmaier, a view is supported that human and organizational factors (HOF) should be overseen both in their own right as well as in terms of their interactions and interferences. This implies that a nuclear facility ought to be seen as a socio-technical system, consisting of individuals, technology, and organization, all of which are interrelated or interacting and are embedded in an environment. The paper provides an interesting basis for integrating a systemic view and approach to these issues.
The third paper, Nuclear Plant Control Room Operator Modeling Within the ADS-IDAC, Version 2, Dynamic PRA Environment: Part 1 - General Description and Cognitive Foundations, by Kevin Coyne and Ali Mosleh, addresses the Accident Dynamics Simulator paired with the Information, Decision, and Action cognitive model in a Crew context (ADS-IDAC). By linking a realistic nuclear plant thermal-hydraulic model with a crew behavior model, ADS-IDAC creates a rich simulation environment.
The fourth paper is a continuation of previous one, viz., Nuclear Plant Control Room Operator Modeling within the ADS-IDAC, Version 2, Dynamic PRA Environment and presents: Part 2 - Modeling Capabilities and Application Examples, again by Kevin Coyne and Ali Mosleh and in this paper, the authors emphasize that the recent implementation of dynamic performance influencing factors (PIFs) reinforces the man-machine feedback loop and strengthens the transient modeling capabilities of ADS-IDAC. The recent implementation of a plant functional decomposition and diagnostic engine strengthens the ability to model knowledge based actions and procedure step skipping in ADS-IDAC.
The fifth paper, Case Study on Addressing the Error Forcing Context in Human Reliability Analysis, by Bernhard Reer and Oliver Str?ter, addresses the error-forcing context (EFC) quantitatively for a misdiagnosis in a decision-making process guided by an emergency operating procedure (EOP). Two approaches are proposed for the EFC-specific assessment of the human error probability (HEP). Some parameters of the probabilistic models are iteratively determined under the boundary condition to provide the best fit of the results from the ECF-specific HEP assessment.
In the sixth paper, A Guideline to HRA Data Collection from Simulations, by Jinkyun Park et al., provides a detailed data collection guideline that allows distinguishing the collectable HRA data items with the associated fact-based measurements (i.e., direct observables and objective surrogates). A couple of worksheets that are helpful for collecting HRA data from simulations in a systematic way are proposed, based on simulation records gathered from the requalification training sessions of domestic NPPs. It is justified to expect that fact-based HRA data can be secured from simulations, which will be useful for HRA practitioners to reduce the uncertainty of HRA results.
The seventh paper, Human Factors in Designing the Instrumentation and Control Systems Important to Safety, by Kazimierz Kosmowski, addresses some aspects of human factors in designing of the instrumentation and control (I&C) systems important to safety of hazardous plants and nuclear power plants, where the concept of "defence in depth” (D-in-D) is employed. It was emphasised that the functional safety analysis framework offers additional possibilities for more comprehensive dealing with the human factors and contextual human reliability analysis (HRA), in particular in cases of dangerous failures of the programmable control and protection systems.
The eighth paper, Benefits and Limitations of the New Consolidated PWROG Severe Accident Management Guidance (SAMG) – A Review of Some Critical Issues, by George Vayssier addresses a new approach that has been presented during the PSA 2013 conference in Columbia, South Carolina, USA, in September 2013. The article is an interesting reaction on a publication by the Pressurised Water Reactor Owners Group (PWROG) about its new SAMG.
Overall the special issue shows the importance of improving the Assessment of Human Reliability of Accident Management actions with less explicit procedural guidance and showed ways to better modeling of instrumentation performance, to lower limits for human error probabilities (in particular for human reactions to stress) and the inclusion of this issue into the development and improvement of Severe Accident Management Guidance (SAMG) or the organizational ability to cope with such events.
The Guest Editors would like to thank all the authors for their contributions and the reviewers for their dedication and the timely feedback provided to contributing authors of this special issue. The Guest Editors would also like to thank Prof. Krishna B. Misra, the Editor-In-Chief of IJPE, who was very helpful in the editing process as well as being a great and continuing supporter of performability knowledge dissemination.

Disclaimer: The views expressed in this special issue are solely those of the authors and do not necessarily represent the views of the editors.

Bernhard Reer(Ph.D.) started 1986 his professional career in field of HRA and PSA at the Jülich Research Center, Germany. He joined the Swiss Paul Scherrer Institute (PSI) in 1997 and since 2007, he is with the Swiss Federal Nuclear Safety Inspectorate (ENSI). At PSI he led the development of the CESA HRA method for the HRA of errors of commission. At ENSI, he works as a senior expert in various safety assessment areas including HRA and accident management (AM). In the post-Fukushima EU Stress Test of NPPs (2012), he was a leading author of country-specific AM review reports. Email: Email:bernhard.reer@ensi.ch

Oliver Str?ter (Prof. Dr. habil.) holds the Chair for Human Engineering and Organizational Psychology at the University of Kassel. His research is focused on safety and ergonomics with an additional focus on the aspects for achieving resilience in the organizational and inter-organizational contexts. His activities cover all sorts of high reliability organizations like nuclear, aviation, maritime or rail. From 2001, he worked for EUROCONTROL, the European Organization for the Safety of Air Navigation in Brussels, where he was amongst others responsible for the long term safety strategy of Air Traffic Management and headed the Safety Regulation work-package in the definition phase of the Single European Sky, SESAR. From 1992 until 2002 he worked for GRS (Gesellschaft für Anlagen- und Reaktorsicherheit), part of the German Nuclear Regulatory Body and developed methods for incident investigation and reliability assessment regarding the human impact on the safety of nuclear installations. Email: straeter@uni-kassel.de

Kazimierz T. Kosmowski Ph.D., Sc.D.) is an Associate Professor of the Department of Electrical and Control Engineering at the Gdansk University of Technology in Gdansk, Poland. He has taught at this university since July 1981. He holds a Ph.D. in Control Engineering and a Sc.D. in Electrical Engineering from Gdansk University of Technology.

His research interests include mathematical modeling of reliability and risk assessment of technical systems, functional safety of the programmable control and protection systems, and human reliability analysis. He has published in journals such as the International Journal of Occupational Safety and Ergonomics, Risk Decision and Policy, Journal of Loss Prevention in the Process Industries, the International Journal of Performability Engineering, and Springer-Verlag Book/Volume of Advances in Intelligent Systems and Computing.

His current research has been focused on functional safety and reliability of hazardous plants, layer of protection analysis, optimising reliability and safety, safety and security management, human factors engineering, cognitive human reliability, industrial automation safety and security, and human machine/system interfaces. He organises courses within a certification programme for specialists responsible for functional safety in industry. He is a member of the Polish Safety and Reliability Association. Email: k.kosmowski@ely.pg.gda.pl