Validation of Constraint-Based Assessment Methodology in Structural Integrity (VOCALIST), Final report
Project ID: FIKS-CT-2000-00090Funded under: FP5-EAECTP C
This paper provides a detailed summary of the main results and conclusions from VOCALIST and points out their contribution to advances in constraint-based methodology for structural integrity assessment. In particular, the output from VOCALIST has improved confidence in the use of K(J)-T(stress) and K(J)-Q approaches to assessments of cleavage fracture where the effects of in-plane constraint are dominant. Cleavage fracture models based on the Weibull stress, sigma(W), have been shown to be reliable, although current best practice advice suggests that sigma(W) should be computed in terms of hydrostatic stress (as distinct from maximum principal stress) for problems involving out-of-plane loading. Correspondingly, the results suggest that the hydrostatic parameter, Q(H), is the appropriate one with which to characterise crack-tip constraint in analysing such problems. The materials characterisation test results generated as part of VOCALIST have provided added confidence in the use of sub-size specimens to determine the Master Curve reference temperature, T(0), for as-received and degraded ferritic RPV materials. The usefulness of correlating the Master Curve reference temperature, T(0), with the constraint parameter, Q, has been demonstrated; however, the trend curves derived require further development and validation before they can be used in fracture analyses. The output from VOCALIST has contributed in providing the validation of methodology necessary to underpin the diffusion of constraint-based fracture mechanics arguments in RPV safety cases, with potential applications including WWER as well as Western-style LWR reactor types.
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Record Number: 8174 / Last updated on: 2006-11-09