More on Non-Linear Design Verification of Nuclear Power Piping According to ASME III NB/NC

A nuclear piping system which is found to be disqualified, i.e. overstressed, in design evaluation in accordance with ASME III, can still be qualified if further non-linear design requirements can be satisfied in refined non-linear analyses in which material plasticity and other non-linear conditions are taken into account. Our work presented earlier in ICONE16 categorized the design rules in ASME III into linear design and non-linear design rules and examined the corresponding design requirements. In this paper, a more in-depth review of these rules for service limit level D is conducted. In particular, several rules which are currently intensively applied but often found to be inconsistent and confusing in Sweden are studied and discussed in detail. Suggestions for improvements and guides for a reasonable application of these rules, which have been practiced in several ongoing projects, are given.