Risk-based approach ALARP

This places much emphasis on the engineering of sufficient safety integrity into the safety-related systems to ensure that risks affected by those systems are reduced to a level that is as low as reasonably practicable (ALARP). There are many methods and techniques for achieving this. The lEC standard 61508 Functional safety of electrical/electronic/programmable electronic safety-related systems, for example, advocates a risk-based approach to determining the required safety performance of safety-related systems, and does so in the context of an overall safety life cycle. The success in the implementation of such an approach demands a suitable level of competence in the engineers involved in the determination of the safety requirements and in the realisation of such systems. 

The risk-based approach to dam safety evaluation should balance the public risk and the limited societal resources available to manage the particular risk. As shown in Fig. 1, it is cmisid-ered generally acceptable that the maximum level of societal risk to fatality is less than 10 per annum for loss of one life and the risk is less than 10 per annum when more than 100 lives would be lost in the event of a dam failure. The principle that the risks should be as low as reasonably practicable (ALARP) is generally followed in practice, and it is thus reasonable to use an annual probability of 10 and 10 for 100 and more fatalities. 

The risk management measure promoted by regulators and governments of nanomaterials is the "As Low As Reasonably Practical" (ALARP) approach (Workcover NSW, 2008 SWA, 2009a). There is a fundamental problem with this approach. ALARP is based on balancing the risk of exposure against the cost to lower the risk further to, what is commonly referred to as, a "tolerable risk." Effectively, ALARP defines risk as an economic decision—do I spend the money or not Regrettably, experience shows us, too often, that the answer is not. 

This system has proven to provide adequate levels of safety in the Gulf of Mexico and other similar areas where it is possible to abandon the location during a catastrophic event. In the North Sea where harsh environmental conditions exist, a different approach to safety has evolved which is based on developing a Safety Case and calculating an Individual Risk Rate (IRR) to show that the risk to any individual working in the facility is As Low As Reasonably Practicable (ALARP). 

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