The R5 volume 2/3 procedures [1] were developed by British Energy (now EDF Energy) to assess the high temperature response of uncracked metallic structures under steady state or cyclic loading. They contain the basic principles of:
• Application of reference stress methods
• Consideration of elastic follow up
• A ductility exhaustion approach to calculate creep damage accumulation.
These considerations represent a fundamental distinction from ASME BPVC Section III, Subsection NH [2].
This paper draws on literature review and experience to explain the principal differences in the limits of application, cycle construction and damage calculation between these codes/procedures focusing on creep-fatigue damage determination. The implications of the differences between the codes and standards are explored.
The output of this work is aimed at two groups of structural integrity engineers; those using these codes and standards to assess existing conventional and nuclear plant, and also those looking to ASME and R5 to design Generation IV PWRs with design temperatures much elevated from those of Generation III and III+.
The conclusions from this paper offer some practical guidance to structural integrity engineers which may assist in selecting the more appropriate procedure to assess creep-fatigue damage for a particular situation.
