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Uncertainties in pressurized thermal shock analyses

Niffenegger, M.; Garrido, O. Costa; Mora, D.F.; Qian, G.; Mukin, R.; Sharabi, M.; Lafferty, N.; Niceno, B.


M. Niffenegger

O. Costa Garrido

D.F. Mora

G. Qian

R. Mukin

M. Sharabi

N. Lafferty

B. Niceno


Integrity assessment of reactor pressure vessels (RPVs) can be performed either by deterministic fracture mechanics (DFM) or/and by probabilistic fracture mechanics (PFM) analyses. In European countries and Switzerland, only DFM analyses are required. However, in order to establish the probabilistic approach in Switzerland, the advantages and shortcomings of the PFM are investigated in the frame of a national research project. Both, the results from DFM and PFM depend strongly on the previous calculated thermal-hydraulic boundary conditions. Therefore, complete integrity analyses involving several integrated numerical codes and methods were performed for a reference pressurized water reactor (PWR) RPV subjected to pressurized thermal shock (PTS) loads. System analyses were performed with the numerical codes RELAP5 and TRACE, whereas for structural and fracture mechanics calculations, the FAVOR and ABAQUS codes were applied. Additional computational fluid dynamics analyses were carried out with ANSYS/FLUENT, and the plume cooling effect was alternatively considered with GRS-MIX. The results from the different analyses tools are compared, to judge the expected overall uncertainty and reliability of PTS safety assessments. It is shown that the scatter band of the stress intensities for a fixed crack configuration is rather significant, meaning that corresponding safety margins should be foreseen. The conditional probabilities of crack initiation and RPV failure might also differ, depending on the considered random parameters and applied rules.


Niffenegger, M., Garrido, O. C., Mora, D., Qian, G., Mukin, R., Sharabi, M., …Niceno, B. (in press). Uncertainties in pressurized thermal shock analyses. In Proceedings of the ASME 2019 Pressure Vessels & Piping Conference PVP2019

Conference Name ASME 2019 Pressure Vessels & Piping Conference (PVP2019)
Start Date Jul 14, 2019
End Date Jul 19, 2019
Acceptance Date Apr 15, 2019
Deposit Date Apr 29, 2019
Journal Proceedings of the ASME 2019 Pressure Vessels & Piping Conference PVP2019
Publisher American Society of Mechanical Engineers
Book Title Proceedings of the ASME 2019 Pressure Vessels & Piping Conference PVP2019
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