The BEPU (Best Estimate Plus Uncertainty) Challenge in Current Licensing of Nuclear Reactors
NURETH-14 - 2011 September 25-30

Presented at:
2011 September 25-30
Toronto, Canada
Session Title:
O4-1 BEPU (Best Estimate code Plus Uncertainty) method, CSAU, Statistical Methods

Alessandro Petruzzi (GRNSPG, Università di Pisa)
Nikolaus Muellner (GRNSPG, Università di Pisa)
Francesco S. D'Auria (University of Pisa, GRNSPG, Italy)
Oscar Mazzantini (Nucleoeléctrica Argentina S.A.)


Within the licensing process of the Atucha II PHWR (Pressurized Heavy Water Reactor) the

BEPU (Best Estimate Plus Uncertainty) approach has been selected for issuing of the Chapter 15 on

FSAR (Final Safety Analysis Report). The key steps of the entire process are basically two: a) the

selection of PIE (Postulated Initiating Events) and, b) the analysis by best estimate models supported by

uncertainty evaluation. The key elements of the approach are: 1) availability of qualified computational

tools including suitable uncertainty method; 2) demonstration of quality; 3) acceptability and endorsement

by the licensing authority. The effort of issuing Chapter 15 is terminated at the time of issuing of the

present paper and the safety margins available for the operation of the concerned NPP (Nuclear Power

Plant) have been quantified.

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