PSI - Issue 68

Vitalii Antonchenko et al. / Procedia Structural Integrity 68 (2025) 1305–1311 Vitalii Antonchenko et al. / Structural Integrity Procedia 00 (2025) 000–000

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From the presented results, we can see that the values of the SIF calculated using the current approach and VERLIFE coefficients are in good agreement with the calculated SIF in the FEM. The total error for the all tested problems with all load factors does not exceed 1%. Due to the fact that the first-order polynomial solution cannot reflect the actual stresses field, the SIF solution included in SOU[3] has a significant error in case of weld residual stress analysis, but even for a pressure loading the error of more than 5% is observed. Also, we can see that it has a poor tolerance for the linear loading with a significant error. 3.2. Results of one PTS scenario The ultimate purpose of the developed methods is application to the real PTS events, thus it is quite natural to test them using one of the scenarios. From the previous results it is obvious that SOU can not be used for the calculations of SIF from WRS, thus its application to the real PTS is quite limited, still it is interesting to estimate its errors, compared to the modern approaches. The figures below show the results of the SIF calculation for the full accident scenario using the own factors, VERLIFE and SOU. These calculations were verified by calculating the FE model with an embedded defect. The full FE model of the RPV and sub-modeling technology were used to calculate the full accident scenario. The calculation was performed for the defect in the weld zone № 4.

Fig. 4 SIF for a axial crack for the deepest point A and a point on the interface B

SIF for a circumferential crack for the deepest point A and a point on the interface B

Fig. shows the change in SIF for the axial orientation of the defect. Error! Reference source not found. shows the variation of the SIF for the circumferential orientation of the defect. As we can see, the SIF values for point A calculated from the own and VERLIFE coefficients are in good agreement with the ANSYS results for both defect orientations. Also, we can clearly see that SOU methodology has significant error and should not be used for fracture mechanics evaluation of PTS event. Conclusions In the current study we have investigated the applicability of different approaches to PTS analysis for WWER type of reactors 1. JRC VERLIFE procedure based on the proposed Chapuliot solution is well-suited for the PTS analysis in WWERs despite the fact that it was developed for the cladded plate 2. SOU NAEK solution can not be used, since it has very limited formulation only membrane and bending components for BM and membrane for cladding are considered. Thus it can’t consider WRS, moreover linear component produce significant errors. 3. Instead of the old SOU solutions in the current study the polynomial coefficients are calculated (for WWER specifically), which can be easily included in the standard.