Risks reduction

By taking the risk score, equating it with the percentage of risk reduction, and comparing the cost of risk reduction to the benefits, a thorough evaluation can be made of whether or not the risk reduction justifies the effort. 

For example, it may cost a lot of money to improve the instrumentation on a control circuit. The cost of reducing this risk would not be justified, as the possibility of an undesired event occurring because of the instrumentation is extremely slight, and the consequence of the risk would be a minimal interruption only. 

Where hazardous chemicals are to be used or disposed of, a priority consideration must be to reduce tire risks from them to a minimum. To enable this to be achieved it is necessary to know the hazards presented by the substances and tire possible envirorrmental effects if they escape. When the use of a hazardous substance is proposed the following questions need to be addressed  

Where hazardous chemical(s) are used they should be assessed to determine the impact on the environment. Such an assessment should also consider the effect of intermediates and breakdown products that may be produced. The assessment should include consideration of the effect of the materials on the atmosphere, the sewage treatment system, controlled waters, land and groxmdwater, and waste disposal routes. The risk assessment should include an estimation of the risk from the hazardous materials, the magnitude of the effects, and the probability of an occurrence. Included should be an evaluation of the significance of the hazards and the consequences should the environment be affected. It is a structured approach to setting priorities for controlling the hazards. The risk assessment will provide iiiformation of where control measures will need to be applied to prevent an impact on the environment. 

Regardless of how risk levels are determined, the UK Health and Safety Executive suggests that the hierarchy for risk reduction shown below should be followed  

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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. 

G. M. Shaul, U.S. EPH Risk Reduction Engineering Eaboratoy (RRELJ Treatability Database, rev. 5.0, REEL, Environmental Protection Agency, Cincinnati, Ohio, Aug. 3, 1994. 

The fact that ceU culture-derived products are often injected into humans as therapeutic agents makes it imperative that there be no component in the final product that can pose a potential health risk to the patient. Health risks can be introduced into a product from many sources including the ceUs themselves raw materials, such as semm, media components, etc materials used in purification, eg, antibodies and external contamination. Eor a therapeutic product such risk factors are identified at the outset and ways of reducing them to acceptable levels are designed into the process. Before a product is released by the EDA the manufacturer has to demonstrate this risk reduction by rigorous validation of the process. 

Most of these methods are commonly employed in the downstream processing of the desired ceU culture technology product. Hence, most of the time it is only necessary to demonstrate that the designed process is reducing the putative risk factors to acceptable levels. Validation methods employed for risk reduction are discussed in the Hterature (25). 

Additionally, the EPA pubhshes a newsletter entitled Pollution Prevention News that contains information including EPA news, technologies, program updates, and case studies. The EPA s Risk Reduction Engineering Laboratoiy and the Center for Environmental Research Information has pubhshed several guidance documents, developed in cooperation with the California Department of Health Services. The manuals supplement generic waste reduction information presented in the EPA s Waste Minimization Opportunity Assessment Manual (Ref. 9). 

The objective of a risk analysis is to reduce the level of risk wherever practical. Much of the benefit of a risk analysis comes from the discipline which it imposes and the detailed understanding of the major contributors of the risk that follows. There is general agreement that if risks can be identified and analyzed, then measures for risk reduction can be effectively selected. 

The analysis of a risk—that is, its estimation—leads to the assessment of that risk and the decision-making processes of selecting the appropriate level of risk reduction. In most studies this is an iterative process of risk analysis and risk assessment until the risk is reduced to some specified level. The subjec t of acceptable or tolerable levels of risk that coiild be applied to decision making on risks is a complex subject which will not oe addressed in this section. 

For all risk measures it is possible to estimate the risk level of the current process as well as the risk levels from incorporation of various risk reduction alternatives. Management can then use this information as an important input in the final risk decision-making process. 

Provide External Risk Reduction Facility (ERRF)... 

The book does not focus on occupational safety and health issues, although improved process safety can benefit each area. Detailed engineering designs are outside the scope of the book. This book intends to identify issues and concerns in batch reaction systems and provides potential solutions to address these concerns. This should be of value to process design engineers, operators, maintenance personnel, as well as members of process hazards analysis teams. While the book offers potential solutions to specific issues/concerns, ultimately the user needs to make the case for the solutions that best satisfy their company s requirements for a balance between risk reduction and cost. In many instances the book provides one or more sources of additional information on the subject which could be of value to the reader. 

QRA results can guide decision makers in their quest for continuous improvement in risk reduction, but zero risk is an unattainable goal. Any activity involves some risk. Even if it were hypothetically possible to eliminate the risk of every accident scenario in a QRA, some risk would still remain because no QRA examines every possible accident scenario. At best a QRA identifies the dominant contributors to risk from the system as it existed at the time of the analysis. Once those are eliminated, other minor risk contributors (including many that were left out of the original QRA because they were negligible contributors, as well as new risks introduced by changes to eliminate the original risks) remain as the new dominant risk contributors. 

If A occurs, C is the most likely cause. Therefore, further risk-reduction efforts should be first directed toward C. 

The process by which the results of a risk analysis (i.e., risk estimates) are used to make decisions, either through relative ranking of risk-reduction strategies or through comparison with risk targets... 

Davis, G. A., L. Kincaid, D. Menke, B. Griffith, S. Jones, K. Brown, and M. Goergen (1994). The Product Side of Pollution Prevention Evaluating the Potential for Safe Substitutes. Cincinnati, Ohio Risk Reduction Engineering Laboratory, Office of Research and Development, U. S. Environmental Protection Agency. 

Hendershot, D. C. (1988). Risk Reduction Alternatives for Hazardous Material Storage. Proc. 1988 Hazardous Materials Spills Conference, May 16-19, 1988, Chicago, III., 611-618. New York American Institute of Chemical Engineers. 

RiskAchievement Worth Increment Risk Reduction Worth Ratio... 

The relationships between the importance measures is based on the assumption that the systems are not reconfigured in response to a component outage. If this is done, the basic definition of the importance measure is still valid but there is not such a simple relationship. Disregarding this complication, some interpretations of the importances may be made. The Bimbaum Importance is the risk that results when the i-th system has failed (i.e., it is the A, term in Equation 2.8-9). Inspection Importance and RRWI are the risk due to accident sequences containing the i-th system. Fussell- Vesely Importance is similar except it is divided by the risk so may be interpreted as the fraction of the total risk that is in the sequences contains the Q-th system. The Risk Achievement Worth Ratio (RAWR) is the ratio of the risk with system 1 failed to the total risk and is necessarily greater than one. The Risk Achievement Worth Increment (RAWI) is the incremental risk increase if system 1 fails and the Risk Reduction Worth Ratio (RRWR) is the fraction by which the risk is reduced if system 1 were infallible. 

Using the information and result of Problem 4, Calculate the Bimbaum, Inspection, Fussell-Vescly, Risk Reduction Worth Ratio, Risk Reduction Worth Increment, Risk Achievement Worth Ratio, and Risk Achievement Worth Increment for each of the components A through G. Do your results agree with the equivalences in Table 2.8-1 ... 

Obviously, the risk of hazardous chemicals is reduced by a minimized inventory using just-in-time procurement. If further inventory reduction is not feasible, additional risk reduction may be achieved by dispersing the inventory to multiple site locations so a release in one location does not allcci other locations of inventory. 

Hazards and Operability (HAZOP) analysis is an accident detection and prevention technique used primarily by the chemical process industry (CPI) (Lees, 1980). Even though the CPI operates in a different regulatory environment from the commercial nuclear power industry, the goals of risk reduction while maintaining productivity are similar. 

Importance - calculates and displays three importance measures, Fussell-Ve.scly, Risk Reduction Ratio, Risk Increase Ratio, for each event in the system, sequence, or end state. 

VIEW is the quantification module. All minimal cutsets are stored in the speciiic libraries for the fault trees, supercomponents and sequences. VIEW recalculates the point estimates. It computes and displays the Fussel-Vesely importance, risk increase and risk reduction measures. 

Prioritize Safety Improvements. This uses the detailed analysis (2) to identify items having high risk importance. Engineering analysis identifies and costs candidate improvements which are selected on the bn. o of risk reduction for a given cost. ... 

Even, limited PSAs use and contain much information. This information may come as memos and process reports and flow sheets, equipment layout, system descriptions, toxic inventory, hazardous chemical reactions, test, maintenance and operating descriptions. From this, data and analyses are prepared regarding release quantities, doses, equipment reliability, probability of exposure, and the risk to workers, public, and environment. An executive summary analysis is detailed, and recommendations made for risk reduction. Thus the information will be text, calculations of envelope fracture stresses, temperatures, fire propagation, air dispersion, doses, and failure probabilities - primarily in tabular form. 

Risk Reduction Factors Coutrol/ rator responses. Alarms, Control system response. Manual anti automatic ESD, Fire/gas detection system Sa/ety System Responses Relief valves. Depressurization system. Isolation systems, High reliability trips. Back-up systems... 

Evaluate whether it is acceptability with risk reduction measures, or move the facility to a recently refurbished LPG storage facility. 

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