Identify Critical Risk Scenarios
Having performed the analysis of consequences and probabilities, the hazard scenarios, so-
called risk scenarios, which dominate the risk may be identified. Often the critical risk
scenarios are ranked in accordance with the risk contribution, but it is also useful to consider a
categorization in accordance with the components and subsystems they involve. This will
facilitate the subsequent planning of risk treatment.
Analysis of Sensitivities
The sensitivity analysis is useful for further analysis of the identified risk scenarios and
normally includes an identification of the most important factors for the risks associated with
the different critical risk scenarios. Also, the sensitivity analysis may include studies of “what
if” situations for the evaluation of the importance of various system simplifications performed
under the definition of the system. In this way the robustness of the analysis may be assessed,
but also possible ways of reducing the risks by modifying the system or the performance of its
components may be investigated.
Risk Assessment
The risk assessment process is merely a comparison of the estimated risks with the accepted
risks initially stated in the risk acceptance criteria. In the risk assessment the risk contributions
to the different criteria may be presented in terms of critical risk scenarios, components and
subsystems. Furthermore, the results of the sensitivity analysis may be included as a guideline
on possible measures to be taken for the reduction or control of risks, should they not be
acceptable.
Risk Treatment
Should the risks not be acceptable in accordance with the specified risk acceptance criteria, in
principle four different approaches can be made, namely:
Risk Mitigation: In essence, risk mitigation is implemented by reducing the probability of the
occurrence of the hazard scenario to zero; in practice by modification of the system. The risk
of corrosion damages in concrete structures may e.g. be mitigated by the use of non-corrosive
reinforcement.
Risk Reduction may be implemented by reduction (of the consequences and/or the
probability). In practice risk reduction is normally performed by a physical modification of
the considered system. Considering the risk of fatigue failures in welded joints, this might be
reduced by increasing the requirements for quality control of the performed welds.
Risk Transfer may be performed by e.g. insurance or other financial arrangements where a
third party takes over the risk. Therefore, risk transfer is normally associated with a cost.
Risks not related to cost consequences are normally non-transferable.
Risk Acceptance: As a last option if the risks do not comply with the risk acceptance criteria
and if other approaches for risk treatment are not effective, risk acceptance may be an option.
This may e.g. be the case when considering unacceptable economic risks and where the costs