Risk assessment frequency scale

Societal risk concerns the risk assessment by society on a national level related to the number of casualties due to a certain hazardous event (Vrijling et ah, 1998). The societal risk can be modelled by the frequency of exceedance curve of the number of fatalities, a FN-curve. The FN curve can be described on a double logarithmic scale in the following form (Jonkman, 2007). 

For analytical balances and microbalances the contribution of the components to measurement uncertainty are very different. For the lower weighing range, repeatability is by far the most important. For precision balances and industrial scales, this is less prominent. But testing frequencies (see Sect. 29.1.6) are, via risk assessment, for these balances are largely determined by checking repeatability and sensitivity. 

Risk assessment is not a precise science. The assessment of risk fundamentally considers a number of factors, namely the likelihood or probability that an accident or incident could be caused, the severity of the outcome, in terms of injury, damage or loss and the number of people affected, and the frequency of exposure to risk. A simple method of assessing it is through the use of risk ratings taking into account the factors of probability, severity and frequency on a scale from 1 to 10 in each case. (Some systems use only probability and severity factors.)... 

The US Nuclear Regulatory Commission (NRC) Safety Evaluation Report (U.S. NRC, 2014) gives the criteria for risk assessment based on core damage frequency and the time scales for the use of safety and nonsafety systems, as derived from a full-scope Probabilistic Risk Assessment (PRA) analysis (Bhatt and Wachowiak, 2006). This NRC approach states the safety guidelines as follows ... 

ABSTRACT On the strength of experience with risk analysis methodology in IT-operating enterprises, an approach has to be able to deal with limited resources. This prompts an analyst to perform a heuristic and biased approach, which is typically a questiomiaire structured by a IT security standard. The difficulty is to draw up a limited set of concise IT security related questions, which result in meaningful outcomes for IT risk analysis purposes. In the proposed approach, the Code of Practice ISO/IEC 27002 is used to structure the analysis and to restrict the number of questions. The Code s recommendations are rephrased and a Guttman scale is introduced for an IT security FMEA-like risk analysis approach. For frequency assessments it is assumed that an implemented high-level security measurement resiilts in low frequencies of imdesired events. The paper pictures the adapted IT-FMEA approach and presents the results of a feasibihty study at Switzerland s leading telecom provider. 

---