Non-Linear Analysis Design Rules
Part 2b: Assessment of Non-Linear Benchmark Results

Cooperation in Reactor Design Evaluation and Licensing – Mechanical Codes and Standards Task Force

September 2020

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In the area of non-linear analysis design rules, the topics identified by the MCSTF for investigation with a view to harmonized approaches are: review and comparison of the current code requirements in non-linear analysis for different failure modes (plastic collapse, plastic instability, local failure and buckling) and some degradation mechanisms (fatigue, plastic shakedown) (Part 1); definition of international benchmark problems to compare the existing non-linear analysis practices (Part 2a) and assessment of the benchmark results (Part 2b); and development of harmonized “recommended industrial practices" (Part 3).

This report is Part 2b of the series of reports on the non-linear analysis design rules.

In this report, the results of the two benchmarks for non-linear analysis of nozzles under pressure, thermal and piping loads are presented, compared, and assessed to highlight any differences which may emerge due to assumptions and interpretations made by international participants, even when the same design is being analyzed using similar software. Discussion is presented identifying the difficulties in these non-linear analyses and to give an insight into any differences observed in the submitted results.

The final goal of this activity is to offer recommendations for internationally harmonized practices in non-linear analysis which will be reported in Part 3.