Session: OAC-01-01 Application in Risk Management and System Reliability

Paper Number: 106384

106384 - Deterministic Leak-Before-Break Treatment of Uncertainties – Example Application 

The Canadian CANDU^® Industry has developed and is implementing a composite analytical approach (CAA) to demonstrate, with high confidence, appropriate safety margins for deterministic nuclear safety analysis of large-break loss-of-coolant accident events in existing CANDU reactors.  A key element of the CAA is the deterministic leak‑before‑break (CAA/DLBB) assessment for postulated through-wall cracks in all butt welds in the large‑diameter CAA in‑scope piping and reactor headers. 

The companion paper proposed approach integrates the uncertainties of the key leak-rate parameters into a single metric (a quantitative indicator of the uncertainty in the CAA/DLBB assessment, also known as, performance indicator).  This approach ensures that individual key leak-rate parameters are not taken out of the context of all the key leak-rate parameters.

This paper illustrates the application of this systematic approach for quantifying the uncertainty in the CAA/DLBB assessment to a specific postulated break location.  The example application illustrates how the bounding value of the leak-rate factor is quantified and compares the results from the analytical and numerical approaches and discusses how the proposed approach provides an unbiased estimate of the leak-rate factor for the postulated break location that is assessed.

Keywords:   leak-before-break, large-break loss-of-coolant accident, integrated uncertainties, figure of merit, bias, margins

Presenting Author: Maher Al-Dojayli Kinectrics Inc.

Presenting Author Biography: A technical expert at the Fitness For Service & Component Analysis, Kinectrics with a Ph.D. in Mechanical Engineering from the University of Toronto. A professional engineer with more than 20 years of in-depth experience in structural integrity assessment against plastic failures, creep, fatigue and fracture; leak before break assessment, Fitness-for-Service (FFS), ASME BPVC VIII, ASME BPVC III, ASME BPVC XI and API 579-1/ASME FFS-1.
Extensive knowledge and hands-on experience in the development and use of advanced linear and non-linear finite element methods for thermomechanical, structural static and dynamic analyses, crack propagation, optimization, fluid-structure interaction, CHT and ALE.

Authors:

Michael Kozluk CANTECH Associates
Maher Al-Dojayli Kinectrics Inc.
Renita Pavia Bruce Power L.P.
Ernie Mileta Ontario Power Generation