Does the analysis take into account uncertainties in the estimation process?
The fact that most failure probabilities are not single values, but distributed about a mean should be accounted for in risk analysis. If there is no information on the probability distribution of the probability, it must be concluded that the upper figure is just as likely as the lower figure. An analogous situation that Assessors may encounter in safety reports that are not based on QRA is when the Operator justifies safe operation by reference to a standard. It is possible that different standards call for higher safety margins or are based on different assumptions. In such cases, in the absence of information to the contrary, the most demanding should be adopted or complied with.
