The ALARP is the most well known approach to set the acceptable level of risk. Many industries
such as, the Norwegian Petroleum Directorate, set this criteria as a cornerstone of the safety
legislation regime and focus on these criteria to control risk related to human, the environment,
and economic values (Avenet al., 2007). This term is based on this basic idea that, the risk
should be reduced to a level as low as reasonably practical without requiring “excessive”
investment (Investment in term of time, cost, and difficulty of implementation the prevention).
This means that the base case is that all identified improvements should be implemented, unless
it can be demonstrated that there is a gross disproportion between costs and benefits. Based on
this concept two boundaries are defined as “intolerable risk” and “negligible risk”, the interval
between these two boundaries is often called the ALARP region (see Figure 3.2) (Melchers,
2001; Aven et al., 2007; Sutton, 2010).