Abstract
The task of regulatory body staff reviewing and assessing a realistic large break
loss-of-coolant accident evaluation model is discussed, facing the actual regulatory licensing environment
related to the acceptance of the analysis of emergency core cooling system performance. Especially, focus is
directed to the question of how to fulfill the requirement of quantifying the uncertainty in the calculated results
when they are compared to the acceptance criteria for this system. As it is recognized that the regulation
governing the loss-of-coolant accident analyses was originally developed by the United States Nuclear
Regulatory Commission, a description of its evolution is presented. When using a realistic evaluation model
to analyze the loss-of-coolant accident, different approaches have been used in the licensing arena. The
Brazilian regulatory body has concluded that, in the current environment, the independent regulatory
calculation is recognized as a relevant support for the staff decision within the licensing framework of
a realistic analysis.