The cost–benefit analysis indicates that for the holding time considered; 20 years, the expected benefit/cost ratio is over 3 (with discount 5%), thus supporting a decision to invest. The uncertainties stemming from the incompleteness of the event tree and possible biases in the expert judgements on the branching probabilities, however, suggests that sensitivity analyses must be conducted in order to check the robustness of the results. In its simplest form, sensitivity analysis may be carried out by perturbating the branch- ing probabilities p(Ei) by e.g., 10%. The necessity of performing sensitivity analysis was also confirmed by the experts’ feedback