TG54 suggestion to qualify all the nozzle loads as Sustained-type is excessively conservative.

In fact, regardless the local stress calculation method (e.g. WRC/analytical or FEA), the stress Qualification/Check shall be performed as per ASME VIII-2 part 5 requirements.

ASME VIII-2 post-2007 Editions require the external piping loadings induced on nozzles "by the restrained free end displacements of the attached pipe" (e.g. the external loadings developed by the restrained pipe expansion/contraction) to be considered for Pm (general membrane) and PL (local membrane) Code stress qualification ONLY within the Nozzle Reinforcement Area limits, as defined by ASME VIII-2 para. 4.5.

Outside the Nozzle Reinforcement Area limits, Pm (general membrane) and PL (local membrane) Code stresses should be qualified without external piping thermal expansion/contraction loads consideration.

Resultant Secondary Pm+Pl+Q Code stress shall include external piping thermal expansion/contraction loads' effect + gross-structural discontinuity concentration effects throughout the whole shell-nozzle junction.

When local stress analysis is performed by FEA approach using PRG Software (Nozzle Pro, FE Pipe, FE 107 modules), the software algorithms perform the required assessments and computations in accordance with Code requirements.

When local stress analysis is performed using Caesar II WRC107 module, then:

1) One typical run as per Case (1) as described above shall be performed, with ASME VIII-2 Stress Indexes ACTIVATED, and WITHOUT Pressure Thrust Load included (e.g. ASME VIII-2 Stress Indexes are already taking account of longitudinal pressure stress concentrations);

2) One additional run with Operating Loads (Weight+Pressure+Thermal = W+P1+T1) defined as Sustained-type, WITH Pressure Thrust Force Considered and ASME VIII-2 Stress Indexes excluded, in order to check Pm and Pm+Pl membrane stresses only. Any Pm+Pl+Q overstress should be ignored in this case. In addition, if Reinforcing Pad outside edge is located beyond the ASME VIII-2 Reinforcement Area, any potential Pm and Pm+Pl overstress at the Pad peripheral edge (e.g. Pad-Shell outside joint) shall be ignored.

Similar approach should be employed for local stress analysis as per WRC297 Bulletin.