[en] The objective of this paper is to tackle methodological issues associated with the inclusion of cognitive and dynamic considerations into Human Reliability methods. A methodology called Human Error Risk Management for Engineering Systems is presented that offers a 'roadmap' for selecting and consistently applying Human Factors approaches in different areas of application and contains also a 'body' of possible methods and techniques of its own. Two types of possible application are discussed to demonstrate practical applications of the methodology. Specific attention is dedicated to the issue of data collection and definition from specific field assessment

[en] This report summarizes results, obtained by the participants in the Reliability Benchmark Exercise on Common Cause Failures (CCF-RBE). The reference power plant of the CCF-RBE was the NPP at Grohnde (KWG): it is a 1300 MW PWR plant of KWU design and operated by the utility Preussen Elektra. The systems studied were the Start-up and Shut-down system (RR/RL) and the Emergency Feedwater System (RS) both systems that can feed water into the steam generators in the emergency power mode. The CCF-RBE was organized in two phases: 1. The first phase: during which all participants have performed an analysis on the complete system as defined by the assumed boundaries, i.e. the Start-up and Shut-down system (RR/RL) and the Emergency Feedwater System (RS). 2. The second phase: in which the scope was limited to the RS system. This limitation in scope was agreed upon in the discussion on the results of the first phase, which showed that, within the boundaries of the exercise, RR/RL and RS systems could be considered independent of each other. This report gives an overview of the works carried out, the results obtained and the conclusions and lessons that could be drawn from the CCF-RBE

[en] This paper gives an overview of the current state of the art in man machine systems interaction studies, focusing on the problems derived from highly automated working environments and the role of humans in the control loop. In particular, it is argued that there is a need for sound approaches to design and analysis of Man-Machine Interaction (MMI), which stem from the contribution of three expertises in interfacing domains, namely engineering, computer science and psychology: engineering for understanding and modelling plants and their material and energy conservation principles; psychology for understanding and modelling humans and their cognitive behaviours; computer science for converting models in sound simulations running in appropriate computer architectures. (author)

[en] This paper gives an overview of the current state of the art in man-machine system interaction studies, focusing on the problems derived from highly automated working environments and the role of humans in the control loop. In particular, it is argued that there is a need for sound approaches to the design and analysis of man-machine interaction (MMI), which stem from the contribution of three expertises in interfacing domains, namely engineering, computer science and psychology: engineering for understanding and modelling plants and their material and energy conservation principles; psychology for understanding and modelling humans an their cognitive behaviours; computer science for converting models in sound simulations running in appropriate computer architectures. (orig.)

[en] The Fast Breeder Reactor fuel performance during normal operating conditions is analyzed in this paper by means of a semianalytical model making use of some physical simplifying assumptions. In particular the fuel densification process and the pin temperature distribution are treated by coupling a three constant density zones model with the analytical solution of the monodimentional heat conduction equation. Fuel and clad swelling, fuel thermal conductivity and fission gas release are obtained from given HEDL empirical correlations while a very simplified treatment of the fuel-clad gap conduction and no stress analysis calculations are performed. The fast running computer code developed from this model (RESTRUC) is adopted as 'module' of steady state pin performance in the European Accident Code (EAC), a large computer system developed for the analysis of Hypothetical Core Disruptive Accidents (HCDA) in Fast Breeder Reactors (FBR). Various test cases and in particular the calculation by means of the EAC adopting RESTRUC of the steady state of a BOEC core for a large FBR have shown satisfactory results in comparison with other codes performing the same type of calculations

[en] This paper has the aim of reviewing and discussing some of the key issues in the domain of Man-Machine Interaction (MMI), with particular reference to the techniques currently adopted for the analysis and evaluation of human factors in the safety of Nuclear Power Plants (NPP). Therefore, the most known methodologies used in mechanistic PRA analysis for modelling human errors are firstly described. Then, the need of a more complete and deterministic representation of the operator's reasoning and motor behaviour is debated, showing how this represents a fundamental complement to the merely probabilistic quantification of performances for approaching correctly the overall problem of MMI. Finally, a cognitive model, based on a hierarchical goal-oriented approach and driven by fuzzy logic methodology, currently being developed within the JRC Ispra, is briefly presented and discussed as the counterpart to the 'classical' methodologies for studying human errors, indentifying limits and boundaries of applications of both types of approaches. (orig.)

[en] This paper describes the basic features of a new concept of incident simulator, Response System Analyzed (RSA) which is being developed within the CEC JRC Research Program on Reactor Safety. Focusing on somewhat different aims than actual simulators, RSA development extends the field of application of simulators to the area of risk and reliability analysis and in particular to the identification of relevant sequences, to the modeling of human behavior and to the validation of operating procedures. The fundamental components of the project, i.e. the deterministic transient model of the plant, the automatic probabilistic driver and the human possible intervention modeling, are discussed in connection with the problem of their dynamic interaction. The analyses so far performed by separately testing RSA on significant study cases have shown encouraging results and have proven the feasibility of the overall program

[en] In this paper, the ongoing research at Joint Research Centre-Ispra on the simulation of man-machine interaction is reviewed with reference to the past experience of system modelling and to the advances of the technological world. These require the coalescence of mixed disciplines covering the fields of engineering, psychology and sociology. In particular, the complexity of man-machine systems with respect to safety analysis is depicted. The developments and issues in modelling humans and machines are discussed: the possibility of combining them through the System Response Analyser methodology is presented as a balanced to be applied when the objective is the study of safety of systems during abnormal sequences. The three analytical tools which constitute the body of system response analysis namely a quasi-classical simulation of the actual plant, a cognitive model of the operator activities and a driver model, are described. (author)

[en] A simulation study of a PWR station black-out ATWS has been performed by applying Response Surface Methodology (RSM) on the data obtained by inspecting the ALMOD code. The case under study has shown that the a priori information which alone could be inadequate, is optimally utilized if coupled with a preliminary sensitivity analysis through RSM techniques. In particular the engineering selection of the model variables and the rank order of the remaining ones had to be modified after an RSM preliminary sensitivity analysis. An other qualifying feature of the exercise is the use of randomization of the variables not included in the model in order to coherently exploit the methodology in its full efficiency. This procedure is able to give a figure of merit of the global importance of the neglected variables through the analysis of residuals. Results show that the proposed technique is an effective tool for selecting the most important accident variables and that the body of information gained is significant with respect to the number of observations performed

[en] In this paper the issues identified in modelling humans and machines are discussed in the perspective of the consideration of human errors managing complex plants during incidental as well as normal conditions. The dichotomy between the use of a cognitive versus a behaviouristic model approach is discussed and the complementarity aspects rather than the differences of the two methods are identified. A cognitive model based on a hierarchical goal-oriented approach and driven by fuzzy logic methodology is presented as the counterpart to the 'classical' THERP methodology for studying human errors. Such a cognitive model is discussed at length and its fundamental components, i.e. the High Level Decision Making and the Low Level Decision Making models, are reviewed. Finally, the inadequacy of the 'classical' THERP methodology to deal with cognitive errors is discussed on the basis of a simple test case. For the same case the cognitive model is then applied showing the flexibility and adequacy of the model to dynamic configuration with time-dependent failures of components and with consequent need for changing of strategy during the transient itself. (author)