Sensitivity studies and uncertainty analysis

Use of the best estimate codes as recommended for both deterministic and probabilistic safety analysis should be complemented by sensitivity studies and/or by uncertainty analysis. 

INSAG-3 Rev. 1 [4], rather than probabihstic safety criteria, states the following objective for future nuclear power plants Another objective for these future plants is the practical elimination of accident sequences that could lead to large early radioactive release, whereas severe accidents that could imply late containment failure would be considered in the design process with realistic assumptions and best estimate analysis so that their consequences would necessitate only protective measures limited in area and in time.  

Uncertainty studies in the framework of deterministic safety analysis are meant as statistical combinations of the influence of the plant conditions, code models and associated phenomena on the results. These studies should be used to confirm that the actual plant parameters will be bounded by the results of calculation plus uncertainty with a specified high confidence. A combination of sensitivity studies, code to code comparisons, code to data comparisons and expert judgements are typically used to estimate uncertainties. 

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