Experience distribution, accidents

Workers compensation insurance is not in its simplest form a preventive measure it is merely a way of distributing the costs of injury across all employers. It can be made to serve a preventive function if the insurance premiums paid by employers are stmctured to reflect the accident experience of the particular employer. If companies with high accident rates have to pay correspondingly high premiums this should, in theory, give employers a vested interest in the health and safety of their workers, assuming a carefully designed scheme. 

From the statistical perspective, accidents - including traffic accidents - by their nature are rare events. As such in a given period most people do not experience them. When aggregated over a short period of time (such as a year) they are distributed in such a manner - known as a Poisson distribution - in which very few people may have three accidents or more, a few have two accidents, and more people have one accident. However, the overwhelming majority of people have no accidents at all. We can all verify this for ourselves if we simply consider the accident experience over the past year of all the people we know personally. Despite the apparent concentration of accidents within a small sub-sample, this is still a random distribution of rare events. Thus, and this has been empirically demonstrated, if we were to... 

Human actions can initiate accident sequences or cause failures, or conversely rectify or mitigate an accident sequence once initiated. The current methodology lacks nuclear-plant-based data, an experience base for human factors probability density functions, and a knowledge of how this distribution changes under stress. 

A plant accident is more likely to luippen during tlie startup of a new plant or a retro fit process because new equipment usually experiences a high failure rate during the early or break-in period. The overall process is best described by the Weibull distribution. The Weibull Distribution or tlie batlitub curve is a tliree-... 

Separation of Plutonium from Air-monitoring Samples. Plutonium-238 2 6 yPu and 21+0Pu have been introduced into environment because of the experiments of nuclear explosion in air and of some accidents of the artificial satellites. Analysis of the plutonium is needed to elucidate the distribution of the plutonium in air and the rate of descent to the surface. For this purpose analytical procedures have been developed and utilized for routine measurements of the air-borne plutonium (18). 

Not all accidents and exposure variables are available in ASEAN countries, especially for what is considered necessary for meaningful comparisons like (fatalities, km. veh, fatalities by type of road user, by age distribution, by time, driving experience, types of vehicles, types of travel, etc.). 

The experiments in the CSTF vessel showed that for most accident scenarios the assumption of a homogeneous distribution of the aerosols in the free volume is justified, in particular during periods when steam and/or other hot gases rise from the lower levels of the containment. Such a situation induces natural convection forces which are strong enough to keep the aerosol concentration reasonably uniform. In addition, the experiments demonstrated that the steam condensation... 

Figure 13.8 Distribution of accidents by age and experience. (Derived from Hale and...

The effectiveness of a SHE information system has traditionally been determined by its ability to provide the necessary basis for decisions on remedial actions. In order to close the loop, i.e. to go from experience to action, the efficiency of each subsystem or function is critical. A weak link such as an inadequate distribution of information will break up this loop. This is irrespective of the quality of other functions. The end result, the prevention of accidents, is ultimately determined by the decision-makers ability to ask for and use the available information. 

Experience from accident-concentration analyses in different industries suggests that 50 per cent or more of the accidents belong to typical accident concentrations of the specific branch of industry. The rest of the accidents are more evenly distributed. When we introduce measures directed at the accidents of the concentrations, we will initially experience a positive development through relatively moderate efforts. The remaining accidents will, however, be more evenly distributed and hence more difficult to grasp and remedy through focused measures. 

Extreme-value projection has some similarities to severity distribution analysis but utilises the most severe case for each period only (Briscoe, 1982). This can be a month, quarter or year. The value of this method lies in the possibility of anticipating how long a time we may expect it to take until the company experiences a really severe accident, e.g. a fatality or an accident involving major monetary loss. This is done through extrapolation based on data from less severe accidents. The method also gives input to an evaluation of whether a company has adequate control of its accident risks or not. Extreme-value projection utilises advanced statistics but is relatively simple to use in practice by applying special plotting paper. 

It should, however, be considered that accident considerations as presented here allow only a definition of the measures to be taken into account around the nuclear facility. Emergency planning feasibility allows the analysis of aspects of the population distribution. Considerable experience and judgment is necessary to establish the acceptability as a whole of the population distribution around any nuclear facility. 

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