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Workshop on the Extended Best Estimate Plus Uncertainty (EBEPU) Analysis

Under the IAEA TC Regional Project RER9129, the IAEA in collaboration with the Polytechnic University
of Madrid and the Spanish Nuclear Safety Council (CSN) will conduct the Regional Workshop on Extended Best Estimate Plus Uncertainty (EBEPU) Analysis in Madrid, Spain from 16 to 20 June 2014. The five-day workshop will provide a forum for 35 participants from 20 Central and East European countries participating in the TC Project RER9129 and 20 local participants to exchange information pertaining to: Postulated Initiating Events (PIE); Options for Design Basis analysis from SSG-2; Best Estimate Plus Uncertainty (BEPU) methodologies; Risk Analysis: PSA and integrated methods; EBEPU; EBEPU and Defence in Depth; EBEPU and Design Extension; EBEPU and LOCA reclassification; and Loss Of Feed Water (LOFW) analysis under EBEPU. The workshop will conclude with a general discussion of the future prospects of EBEPU.


In 2009, the IAEA published in their Safety Standards the IAEA Specific Safety Guide SSG-2 on Deterministic Safety Analyses for Nuclear Power Plants. This Guide addresses four options for the application of Design Basis analysis. The first option uses conservative codes/models and conservative Initial and Boundary (I&B) conditions. Option 2 uses realistic codes/models but with conservative I&B conditions. Option 3 uses realistic codes/models and realistic I&B conditions and therefore needs also to consider the associated uncertainties. Today, it is known as the Best Estimate Plus Uncertainty (BEPU) option.

Option 4, or EBEPU as it is currently known, is not developed in the SSG-2 document. The Safety Guide only indicates that Option 4 is an attempt to combine insights from probabilistic safety analyses with a deterministic approach, which results in a risk informed safety analysis. In Options 1 – 3, the availability of safety systems is based on conservative assumptions whereas, in Option 4, the availability of safety systems is derived by probabilistic means.

The June workshop will address these issues and many more.

For more information on the workshop, please see the workshop introduction, take a look at the workshop draft agenda, or send an email to the GSAN Contact Point.