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Risk Assessment. Marvin Rausand
Читать онлайн.Название Risk Assessment
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isbn 9781119377221
Автор произведения Marvin Rausand
Жанр Математика
Издательство John Wiley & Sons Limited
5.4 Risk Acceptance Criteria for Other Assets than Humans
The discussion above is primarily concerned with risk to humans. For other types of assets, other considerations may apply. Brief comments are given on the two most important, environment and economic risk.
Environmental RACs are based on the principles discussed earlier in this chapter. The ALARP principle is commonly applied and the precautionary principle was originally developed specifically for environmental applications. The underlying principles of the ALARP principle can be applied to environmental consequences, although the term “environment” covers an extremely wide range of vulnerable assets, from natural beauty, to individual species (being it animals, insects, fish, plants, etc.), to complete ecosystems. Comparing these and assessing the risk on a consistent level is clearly challenging.
Economic considerations are usually simple, and risk acceptance can in most cases be based solely on cost–benefit analysis. The option with the highest benefit is normally the preferred option. In some cases, consideration of worst‐case consequences may be necessary. This is because the consequences in some cases may be catastrophic, in the sense that a company goes bankrupt if certain events occur. In such circumstances, this may override a criterion based purely on costs and benefits.
5.5 Closure
There has been an ongoing discussion in the scientific community regarding the adequacy of RAC for making decisions about risk. Among the critics is Terje Aven (e.g. see Aven 2007 ; Aven and Vinnem 2005), who questions the use of RAC from a decision theoretical and ethical perspective. Risk acceptability evaluations must be based on ALARP‐considerations, he claims, and not static criteria that fail to address the relationships among risk, benefits, and improvement. In view of the fact that the benefits we gain from accepting a risk weigh so heavily, it may be reasonable to argue that we do not need a specific upper limit, but rely solely on weighing risk against benefits.
Johansen (2010) takes a more pragmatic perspective by suggesting that RAC should be evaluated according to their feasibility to the decision‐maker and the extent to which they promote sound decisions. The first issue is primarily a matter of how we measure risk, and the ability of different measures to rank alternatives and provide precise recommendations with little uncertainty. The second is a matter of how the criteria are derived (e.g. MEM versus ALARP) and the extent to which they encourage improvement or preservation of status quo and allow for balancing risk with other considerations. Although useful for evaluating risk, it is recommended that practitioners interpret RAC as guiding benchmarks rather than rigid limits of acceptability.
5.6 Problems
1 5.1 Acceptable risk is dependent on context and values. Find examples where there are differences in what risk we accept. Why do you think there are differences?
2 5.2 In discussions about oil exploration offshore, there is often disagreement between environmentalists and oil companies about what the risk and what can be tolerated. Identify reasons why they may have such different opinions.
3 5.3 What are the main differences between the GAMAB and the MEM principle?
4 5.4 Can you think of examples of hazardous activities that we still choose to do because they are useful to us? What is the risk and what are the benefits?
5 5.5 Three “pure” principles of risk acceptance are described in the chapter, equity, utility, and technology. List advantages and disadvantages of each of these principles if we apply just one of them for establishing RAC.
6 5.6 A risk analysis has been performed, and the risk has been calculated at 0.05 fatalities/yr. A risk reduction measure has been proposed and if this is implemented, the risk will be reduced to 0.04 fatalities/yr (20% reduction). The cost of this risk reduction measure is 1 million in investment and 0.2 million in operating costs. The risk reduction measure will have an effect for 20 years. For cost–benefit purposes, VSL is set to 25 million. Perform a cost–benefit analysis and decide if the risk reduction measure has a positive cost–benefit or not.
7 5.7 The results from a risk analysis will always be uncertain to a greater or smaller degree. For the case in the previous problem, the risk analyst has informed us that the initial risk estimate of 0.05 fatalities/yr is uncertain, and that it is likely that the risk is somewhere in the range 0.01–0.08 fatalities/yr. How will this uncertainty affect the results of the cost–benefit analysis (assume that the reduction in risk always is 20%)? What does this tell us about decision‐making based on results from risk analysis?
8 5.8 The precautionary principle is one possible approach to managing risk, particularly aimed at technology and developments that are new and where we do not necessarily know what the risk is. An example of a new technology is autonomous cars and other transport systems. What may the effect be on this type of new technology if we apply the precautionary principle in a strict sense?
9 5.9 Is GAMAB a useful principle for expressing what is acceptable risk if we introduce a completely new technology, e.g. autonomous transport systems? Are we willing to accept the same risk for a new system as an existing one? Find examples where this is not the case.
10 5.10 Consider a system development process and assume that you have identified a particular risk factor. Further, assume that you, based on an evaluation, decide to leave the risk factor as it is without implementing any risk reduction measure. Have you then, in fact, accepted the risk factor?
11 5.11 A new pesticide is proposed, based on a new and unproven mix of chemicals. Discuss the risk related to the introduction of this new pesticide in light of the precautionary principle. Formulate a set of questions to be answered before the pesticide is accepted for use.
12 5.12 List the main strengths and weaknesses of the GAMAB principle.
13 5.13 A company applies the following acceptance criterion for acute pollution events: If no traces or effects of the pollution can be observed five years after the pollution event, it is acceptable. Discuss this principle for acute pollution to the sea (e.g. oil spill).
14 5.14 A hazardous fluid needs to be transported through a densely populated area on a regular basis. Identify factors that need to be considered to decide whether the risk related to this transport is acceptable.
References
1 Ale, B.J.M. (2005). Tolerable or acceptable: a comparison of risk regulation in the United Kingdom and in the Netherlands. Risk Analysis 25: 231–241.
2 Ashenfelter, O. (2005). Measuring value of a statistical life: Problems and prospects, Working paper 505. Princeton, NJ: Princeton University.
3 Aven, T. (2007). On the ethical justification for the use of risk acceptance criteria. Risk Analysis 27: 303–312.
4 Aven, T. and Vinnem, J.E. (2005). On the use of risk acceptance criteria in the offshore oil and gas industry. Reliability Engineering & System Safety 90: 15–24.
5 Bottelberghs,