Accident prediction

Theodore Barry and Associates, Inc. (1972). Accident prediction investigation study. Los Angles, California Author, NTIS No. PB 221 000. 

Zheng Xiazhong Zheng Gen Paul 2004. Building construction safety accident prediction methods applied research [J], People Yangtze, 35(l) 52-55. 

In the UK the most severe accident predicted should be within the Station Management s capability to bring under control with the assistance of local and national emergency services. 

The successful use of both the HAZOP study and the what-if analysis is dependent on the expertise and experience of the individuals who make up the review teams. Essentially, both are really nothing more than exercises in communication. While each method can be conducted as a separate analysis, the what-if analysis is almost always a primary component of a complete HAZOP study. Information is presented, discussed, analyzed, and recorded. Specific safety aspects and requirements are identified so that appropriate design considerations can be determined. The objective is accident prediction, and the end result is accident prevention. 

Most boiling water reactors have automatic depressurisation systems. Severe accidents predicted to occur at boiling water reactors often involve failure of these automatic systems to ftmction. Improvements of the systems are being investigated. 

TRL junction design models ARCADY, PICADY and OSCADY provide accident predictions for specific junction layouts. 

Black swan accidents Predicting and preventing the unpredictable... 

Lum, H Reagan, J.A. 1995. Interactive Midway Safety Design Model Design accident Predictive Module. Public Roads Magazine. hUp //www.fhwa.dot.gov/ publications/pubIicroads/95winter/p95wil4.cfm PIARC, 2010. www.piarc.org. 

Part 2 deals with detailed statistical analysis of accident data, in order to identify or understand road safety critical issues and develop accident models. The issue of the evolution of the nnmber of road fatalities in Poland, in relation to economic factors, is presented, along with an analysis aiming to identify the risk of road traffic injuries for pedestrians, cyclists, car occnpants and PTW riders in Rhone, France, based on a road trauma registry and travel snrveys. Fnrthermore, interesting accident prediction models for main rural roads in Hnngaiy are developed, with imminent and obvious practical applications. 

In the first step, a screening process will be applied to separate the major potential hazards these will be addressed in more detail. QRA techniques are used to evaluate the extent of the risk arising from hazards with the potential to cause major accidents, based on the prediction of the likelihood and magnitude of the event. This assessment will be based on engineering judgement and statistics of previous performance. Where necessary, risk reduction measures will be applied until the level of risk is acceptable. This of course is an emotive subject, since it implies placing a value on human life. 

The next part of the procedure involves risk assessment. This includes a deterrnination of the accident probabiUty and the consequence of the accident and is done for each of the scenarios identified in the previous step. The probabiUty is deterrnined using a number of statistical models generally used to represent failures. The consequence is deterrnined using mostiy fundamentally based models, called source models, to describe how material is ejected from process equipment. These source models are coupled with a suitable dispersion model and/or an explosion model to estimate the area affected and predict the damage. The consequence is thus determined. 

Many sophisticated models and correlations have been developed for consequence analysis. Millions of dollars have been spent researching the effects of exposure to toxic materials on the health of animals the effects are extrapolated to predict effects on human health. A considerable empirical database exists on the effects of fires and explosions on structures and equipment. And large, sophisticated experiments are sometimes performed to validate computer algorithms for predicting the atmospheric dispersion of toxic materials. All of these resources can be used to help predict the consequences of accidents. But, you should only perform those consequence analysis steps needed to provide the information required for decision making. 

The accuracy of absolute risk results depends on (1) whether all the significant contributors to risk have been analyzed, (2) the realism of the mathematical models used to predict failure characteristics and accident phenomena, and (3) the statistical uncertainty associated with the various input data. The achievable accuracy of absolute risk results is very dependent on the type of hazard being analyzed. In studies where the dominant risk contributors can be calibrated with ample historical data (e.g., the risk of an engine failure causing an airplane crash), the uncertainty can be reduced to a few percent. However, many authors of published studies and other expert practitioners have recognized that uncertainties can be greater than 1 to 2 orders of magnitude in studies whose major contributors are rare, catastrophic events. 

Human error contributed to about 50% of the accident sequences m the RSS but none of the human error data came from the nuclear power industry. Furthermore, very high failure rates 0.5 to 0.1/action) were predicted but are not supported by the plant... 

Answer Use the plant s PSA to determine the risk of accidents that include containment failure from overpressurization. Then make a preliminary design of a vented containment that has sufficiently low impedance to the gas at the pressure predicted for the most severe accident sequences such that the containment is not damaged. This containment bypass will include iodine and HEPA filters as well as scrubbers and a discharge through a stack. Estimate the dose that the population would get using this bypass for comparison with the PSA result for ruptured containment sequences. 

Hazards analysis techniques fall in two broad categories. Some techniques focus on hazards control by assuring that the design is in compliance with a pre-existing standard practice. These techniques result from prior hazards analysis, industry standards and recommended practices, results of incident and accident evaluations or similar facilities. Other techniques are predictive in that they can be applied to new situations where such pre-existing standard practices do not exist. 

Baker and his colleagues (1983) compared the Strehlow et al. (1979) curves to experimental data, then applied them in research programs, accident investigations, and predictive studies. They developed the methods for use of Strehlow s curves. 

Chapter 4 focuses on techniques which are applied to a new or existing system to optimize human performance or qualitatively predict errors. Chapter 5 shows how these teclmiques are applied to risk assessment, and also describes other techniques for the quantification of human error probabilities. Chapters 6 and 7 provide an overview of techniques for analyzing the underlying causes of incidents and accidents that have already occurred. 

The successes of the traditional approach have largely been obtained in the area of occupational safety, where statistical evidence is readily available concerning the incidence of injuries to individuals in areas such as tripping and falling accidents. Such accidents are amenable to behavior modification approaches because the behaviors that give rise to the accident are under the direct control of the individual and are easily predictable. In addition, the nature of the hazard is also usually predictable and hence the behavior required to avoid accidents can be specified explicitly. For example, entry to enclosed spaces, breaking-open process lines, and lifting heavy objects are known to be potentially hazardous activities for which safe methods of work... 

The various analytical methods for predicting and reducing human error can be assigned to four groups or sections. In order to make a start on any form of analysis or prediction of human error, it is obviously necessary to gather information. The first section therefore describes a number of techniques that can be applied to acquire data about what the worker does, or what happened in an accident. 

The third category of methods addressed in this chapter are error analysis and reduction methodologies. Error analysis techniques can either be applied in a proactive or retrospective mode. In the proactive mode they are used to predict possible errors when tasks are being analyzed during chemical process quantitative risk assessment and design evaluations. When applied retrospectively, they are used to identify the underlying causes of errors giving rise to accidents. Very often the distinction between task analysis and error analysis is blurred, since the process of error analysis always has to proceed from a comprehensive description of a task, usually derived from a task analysis. 

Although accidents of these types occur infrequently, they may present a greater potential for loss titan fires, explosions, or spills. Since natural disasters are difficult to predict and prevent, one is obliged to rely more heavily on precautions designed to minimize tlie impact of an occurrence of a natural disaster, such as emergency plamting. 

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