of risk mitigation and/or risk reduction or transfer are higher than the desired risk reduction.
Risk acceptance may normally not be pursued when risks to personnel are considered, and if
so usually only for limited periods of time.
Monitoring and Review
Risk analyses may be performed as already stated for a number of decision support purposes.
For many engineering applications such as monitoring of the safety of offshore oil production
platforms, cost control during large construction projects and inspection and maintenance
planning for bridge structures, risk analysis is a living process involving a constant feedback
of information from the considered system to the risk analysis. Whenever new information is
obtained, the risk analysis may be updated and in this manner used as a vehicle for optimizing
the system performance in regard to the specified acceptance criteria.
1.5 Detailing of Risk Analysis
Risk analysis, as shall be seen, might be performed at various levels of detail. Therefore, for
the purpose of communicating the results of a risk analysis it is important that the degree of
detailing used for the analysis is indicated together with the analysis results. Otherwise, the
decision–maker, who bases his decision-making on the result of the risk analysis, has no
means for assessing the quality of the decision basis.
No general agreement has been established in this regard so far, but in the nuclear industry the
following categorization has been agreed for so-called probabilistic risk analysis (PRA) or
probabilistic safety analysis (PSA).
Level 1: Analysis of the probability of occurrence of certain critical events in a nuclear
power plant.
Level 2: Analysis of the probability of occurrence and the consequences of certain
critical events in a nuclear power plant.
Level 3: As for level 2, but in addition including the effect of humans and the loss of
human lives when this might occur.
Whether this classification is also useful in other application areas can be discussed, but the
idea of classifying the levels of risk analysis is under any circumstances a useful one.
1.6 Sources of Risk in Engineering
Risks in engineering may be caused by a number of different sources, including natural
hazards, technical failures, operational errors and malevolence.
Generally speaking, any activity such as the realization of a power plant has a certain hazard
potential, i.e. the sum of all things that can go wrong. Of course not all of the things that
potentially might go wrong will in fact go wrong, it clearly depends on the probability that the