Elastic-Plastic Shakedown Assessment of Piping Using a Non-Cyclic Method Available to Purchase

The analysis for shakedown in nuclear Class 1 piping following NB-3600 of the ASME Boiler and Pressure Vessel Code contains several simplifications and can be overly conservative in some cases and potentially non-conservative in some others. A detailed elastic-plastic analysis following NB-3228.4, on the other hand, is computationally expensive and time consuming because an elastic-plastic model needs to be cycled to stabilization. A non-cyclic method to assess elastic plastic shakedown (absence of ratcheting) has been proposed and is applied to the analysis of some simple straight piping scenarios. Interaction diagrams similar to the Bree diagram are derived for other loading situations, such as thermal bending in conjunction with primary bending. The effect of piping boundary conditions on the ratchet boundary is explored.