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. 

Drogaris, G. 1993. Major Accident Reporting System Lessons Learned from Accidents Notified. Elesevier Science Publishers,B.V., Amsterdam. 

Limit stocks, some ingredients such as MbOCA and MEK have potential for major accidents. 

Off-site areas likely to be affected by major accidents and estimates of levels of harm which might result. 

SI 1999/981 Planning (Control of Major Accident Hazards) Regulations... 

EEC Directive on major accident hazards (Seveso Directive)... 

EC Directive on the control of major-accident hazards involving dangerous substances... 

Decision regarding a harmonized critena for dispensations from 96/82/EC on major accident hazards... 

SI 2000/179 European Communities - Town and Country Planning - The Planning (Control of Major - Accident Hazards)(Scotland) Regulations 2000... 

HS(Gj25 The Control of Industrial Major Accident Hazards Regulations 1984 (CIMAHj further guidance on... 

A guide to the Control of Major Accident Hazards Regulations 1999 - COM AH-guidance on Regulations Health and safety at quaiTies... 

Regulate the design and operation of defined major hazard installations. All necessary measures are required to prevent and limit the consequences of major accidents. Operators of upper-tier sites must produce a detailed Safety Report those of lower-tier sites must prepare a Major Accident Prevention Policy. 

The Rohm and Haas Major Accident Prevention Program (Ren-shaw, 1990 Berger and Lantzy, 1996 Hendershot, 1991a) is based on potential accident consequence analysis and uses checklists based on inherently safer design principles to identify ways to eliminate or reduce hazards. 

Renshaw, F. M. (1990). A Major Accident Prevention Program. Plant/Ofterations Progress 9, 3 (July), 194-97. 

In addition to these formal studies of human error in the CPI, almost all the major accident investigations in recent years, for example, Texas City, Piper Alpha, Phillips 66, Feyzin, Mexico City, have shown human error as a significant causal factors in design, operations, maintenance or the management of the process. Figures 4.4-1 and 4.4-2 show the effects of human error on nuclear plant operation. 

Cox, R.A., editor, 1989, Mathematics in Major Accident Risk Assessment, Clarendon Press Oxford. 

You can quickly identify these plant sections by reviewing process flow diagrams and valving arrangements. Isolation points are defined by control valves or powered block valves that can be remotely activated. Process hazard analysis techniques help you identify the maximum credible accident scenarios. (Note that manual valves should not be considered reliable isolation points unless they are located to be accessible following a major accident. However, remotely-activated valves can only be considered reliable isolation points if there are adequate reliability engineering and maintenance programs in place.)... 

The analysis of accidents and disasters in real systems makes it clear that it is not sufficient to consider error and its effects purely from the perspective of individual human failures. Major accidents are almost always the result of multiple errors or combinations of single errors with preexisting vulnerable conditions (Wagenaar et al., 1990). Another perspective from which to define errors is in terms of when in the system life cycle they occur. In the following discussion of the definitions of human error, the initial focus will be from the engineering and the accident analysis perspective. More detailed consideration of the definitions of error will be deferred to later sections in this chapter where the various error models will be described in detail (see Sections 5 and 6). 

In an offshore oil production platform, a major accident occurred partly because pump seals failed and therefore an antifoaming agent was not delivered to a crude oil separator. The fact that the pump seals were defective should have been picked up during routine inspections, but the inspections were neglected because of production pressures. The failure to carry out the inspections was a latent error. 

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. 

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. 

This chapter has adopted a broad perspective on data collection and incident analysis methods. Both qualitative and quantitative aspects of data collection have been addressed, and data collection approaches have been described for use with large numbers of relatively low-cost incidents or infrequently occurring major accidents. 

Improvements in safety and environmental performance will come only slowly. Major accidents are rare, even with poorly managed programs, and any reduction in these will be evident only after several years. Areas where early improvements might be expected are spill response and occupational injuries where improved processes should be effective soon after installation. Work place exposure and environmental emissions may improve over a period of several months. 

The preceding sections have given only a sampling of the major accidents that have occurred tlu-oughout history. However, there have been numerous other incidents, which were perhaps less renowned but certainly not less tragic to the families of the victims. E.xaniples of some less renowned accidents arc ... 

Some environmentalists anticipated a major accident like that of the Exxon Valdez. When plaiiiiing for the Trans-Alaska Pipeline took place during the energy crisis of the early 1970s, it was controversial because of the conflicts of balancing the needs of oil... 

Other inspection services available include the examination of steel structures (new and existing), electrical wiring installations, containers (to meet Statutory Instm-ment No. 1890), dangerous substances (carriage by road in road tankers or tank containers) to meet Statutory Instmment No. 1059, examination of second-hand plant prior to purchase, plant undergoing repair or modification, the Control of Industrial Major Accident Hazard Regulations (CIMAH) Statutory Instmment No. 1902 and Control of Substances Hazardous to Health (COSHH) and Pressure Systems Regulations. 

For new sites with 50 tons or more of LPG the Control of Major Accident Hazards Regulations 1984 apply. For sites which will have 300 tons or more (shortly to be reduced to 200 tons or more) these Regulations impose additional duties on site operators which include the prior submission of a safety report . This report has to set out the potential hazards of the plant and the means by which the risks are reduced to an acceptable level. The LPGITA has produced a Guide to the Writing of LPG Safety Reports which supplements the general guidance in the HSE booklet HS(R)21. 

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