Causes major accidents

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 use of dangerous substances in chemical plants such as oil refineries, pesticide plants etc., can cause major accidents (toxic releases, fires, explosions etc.). Such an accident might result in adverse effects on the health of the workers at the chemical plant as well as on the population in the area around of it. 

CRIOP Part II helps us in analysing new accidents that may happen in the future in detail rather than at the summary level of the traditional technical risk analyses. The possibilities of transgressing barriers and the operators contributions are analysed successively, compare Figure 7.3 for the case of risks of fires and explosions. It starts by looking into the operators interventions in the process to control disturbances that, if not properly handled, may cause major accidents. In cases where there is a reasonable probability that the situation may deteriorate, the analysis proceeds by looking into the operators handling of the emergency situation. 

Hazards with the potential to cause major accidents have been identified. 

The first perspective is the traditional safety engineering approach (Section 2.4). This stresses the individual factors that give rise to accidents and hence emphasizes selection, together with motivational and disciplinary approaches to accident and error reduction. The main emphasis here is on behavior modification, through persuasion (motivational campaigns) or pimishment. The main area of application of this approach has been to occupational safety, which focuses on hazards that affect the individual worker, rather than process safety, which emphasizes major systems failures that could cause major plant losses and impact to the environment as well as individual injury. 

The traditional safety engineering approach to accident causation focuses on the individual rather than the system causes of error. Errors are primarily seen as being due to causes such as lack of motivation to behave safely, lack of discipline or lack of knowledge of what constitutes safe behavior. These are assumed to give rise to "unsafe acts." These unsafe acts, in combination with "unsafe situations" (e.g., imguarded plant, toxic substances) are seen as the major causes of accidents. 

One of the origins of this view of error and accident causation is the theory of accident proneness, which tried to show that a small number of individuals were responsible for the majority of accidents. Despite a number of studies that have shown that there is little statistical evidence for this idea (see, e.g., Shaw and Sichel, 1971) the belief remains, particularly in traditional industries, that a relatively small number of individuals accoimt for the majority of accidents. Another element in the emphasis on individual responsibility has been the legal dimension in many major accident investigations, which has often been concerned with attributing blame to individuals from the point of view of determining compensation, rather than in identifying the possible system causes of error. 

Where errors occur that lead to process accidents, it is clearly not appropriate to hold the worker responsible for conditions that are outside his or her control and that induce errors. These considerations suggest that behavior-modification-based approaches will not in themselves eliminate many of the types of errors that can cause major process accidents. 

Many data collection systems place the primary emphasis on the technical causes of accidents. There is usually a very detailed description of the chemical process in which the accident occurred, together with an in-depth analysis of the technical failures that are seen as the major causes. The human or system failures that may have contributed to the accident are usually treated in a cursory manner. Technically oriented reporting systems are very common in the CPI, where engineers who may be unfamiliar with human factors princi-... 

The first area focuses on the cultural and organizational factors that will have a major influence on the effectiveness of a human error data collection system and how well the information derived from such a system is translated into successful error reduction strategies. Regardless of how effectively the technical issues are dealt with, the system will not be successful imless there is a culture in the organization which provides support for the data gathering process. No data collection system aimed at identifying human error causes of accidents will be workable without the active cooperation of the workforce. 

The development of MORT was initiated by the U.S. Atomic Energy Commission, and is described in Johnson (1980). MORT is a comprehensive analytical procedure that provides a disciplined method for detennining the causes and contributing factors of major accidents. It also serves as a tool to evaluate the quality of an existing safety program. 

Good housekeeping can play a major part in maintaining a safe and environmentally sound place of work. Tripping over material not tidied away causes many accidents. Another source of potential injury is in the lack of secure storage of cleaning equipment, tools, etc. 

Khan, F.I. and Abbasi, S.A., Major accidents in process industries and an analysis of causes and consequences, /. Loss Prevent. Process Ind., 12, 361,1999. 

All of these chemicals pose an inhalation hazard but a toxic dose could also be obtained through skin absorption or ingestion. Factors that were considered when selecting potential candidate chemicals include global production, physical state of the material (i.e., gas, liquid, or solid), chemicals likely to cause major morbidity or mortality, potential to cause public panic and social disruption, chemicals that require special action for public health preparedness, history of previous use by the military, and/or involvement in a significant industrial accident. 

Similar remarks can be made about accident reports, it was observed that the focus of the majority is on the direct safety related deviations in the accident causation path, and almost no attention is given to the indirect safety related deviations. Indirect safety related deviations were mentioned but no attention was given to the fact that these deviations were in the causal path, re-occurring, and often present for a long time prior to the accident. Korvers (Korvers et al., 2002) gave some good examples by showing ten cases in which identical indirect safety related deviations present prior to accidents repeatedly caused similar accidents. 

We have thus far considered only steady-state operation of the CSTR and the PFTR. Thi, s is the situation some time after the process was started when all transients have died out, and no parameters vary with time. However, all continuous reactors must be started, an d parameters such as feed composition, flow rate, and temperature may vary because feed composition and conditions change with time. We therefore need to consider transier it operation of the CSTR and the PFTR. Transients are a major cause of problems in reactoir operation because they can cause poor performance. Even more important, problems during startup and shutdown are a major cause of accidents and explosions. 

One important reason to consider the nonisothermal reactor is because it is the major cause of accidents in chemical plants. Thermal runaway and consequent pressure buildup and release of chemicals is an ever-present danger in any chemical reactor. Engineers must... 

Excessive daytime sleeepiness (EDS) leads to impaired performance, diminished intellectual capacity, and is a major cause of accidents and other catastrophes (1). Thus, quantification of EDS is an important procedure, as positive findings willl require a thorough search and treatment of the cause or causes. The method of measurement, however, must be reliable and reproducible so that its results are respected in experimental and clinical settings. 

There have been numerous discussions about this accident, which produced the most casualties in the history of industrial disasters. Some arguments revolve around the direct cause of the accident. As is generally known, many major accidents have been caused by combinations of small accidents. The accident in Bhopal also happened as the result of a combination of serious mistakes the mixing of water with MIC caused by neglecting to put the metal sheet in place to separate reactive components, and the failures in operation of the exhaust gas scrubber and the flare stack. Such cases are frequently found where a safety device is temporarily removed because the device is troublesome. It is necessary to educate people that the reliability of a safety device should be tested and that the failure of a safety device can lead to unexpectedly terrible results. 

The important accidents involving commercial plants were the Three Mile Island Reactor partial meltdown accident, which did not breach the outer containment but totally ruined the plant, and the Chernobyl meltdown accident, which caused major releases of radioactivity to the atmosphere and global fallout. 

In 1982, the European Union s Council Directive 82/501/EEC on the major-accident hazards of certain industrial activities, also known as the Seveso Directive, was adopted. The Directive was mostly designed to promote information flow and created the requirement that each Member State (i.e., each country belonging to the European Union) appoint a Competent Authority to oversee safety issues. The Seveso Directive was amended twice, following major accidents at the Union Carbide chemical factory in Bhopal, India in 1984 (a leak of methyl isocyanate caused thousands of deaths), and at the Sandoz chemical warehouse in Basel, Switzerland in 1986 (fire-fighting water contaminated with mercury, organophosphate pesticides and other chemicals caused massive pollution of the Rhine River and the death of hundreds of thousands of fish). Both amendments, broadened the scope of the Directive, in particular to include the storage of dangerous substances. 

Although toxic releases, in general, are not the principal cause of major accidents (relative to fire and explosion) associated with the chemical industry, they are a just cause of "considerable public apprehension" [1327a]. This concern has been compounded by an event which occurred in Bhopal, India in December 1984, in which over 2500 people were killed by a single toxic release of methyl isocyanate. 

Prevent unauthorized, inappropriate, or poorly done modifications as they are the major cause of accidents ... 

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