A parametric study on pressure–temperature limit curve using 3-D finite element analyses

Abstract In order to operate a reactor pressure vessel (RPV) safely, it is necessary to keep the pressure–temperature ( P – T ) limit during the heatup and cooldown process. While the ASME Code provides the P – T limit curve for safe operation, this limit curve has been prepared under conservative assumptions. In this paper, the effects of conservative assumptions involved in the P – T limit curve specified in the ASME Code Sec. XI were investigated. Three different parameters, the crack depth, the cladding thickness and the cooling rate, were reviewed based on 3-D finite element analyses. Also, the constraint effect on P – T limit curve generation was investigated based on J – T approach. It was shown that the crack depth and constraint effect change the safety region in P – T limit curve dramatically, and thus it is recommended to prepare a more precise P – T limit curve based on finite element analysis to obtain P – T limit for safe operation of a RPV.