Verification Study of Probabilistic Fracture Mechanics Analysis Code for Reactor Pressure Vessel During Pressurized Thermal Shock
Issue:
Volume 10, Issue 2, April 2022
Pages:
17-24
Received:
14 March 2022
Accepted:
1 April 2022
Published:
14 April 2022
Abstract: This investigation is to present a verification study of probabilistic fracture mechanics (PFM) analysis code for a reactor pressure vessel (RPV) during pressurized thermal shock (PTS). The probabilistic fracture mechanics code FAVOR, developed by Oak Ridge National Laboratory, is used to calculate the conditional probabilities of crack initiation and penetration for welds that are located in the RPV beltline region. The procedure includes deterministic analyses of the temperature and stress distributions through the vessel wall at the PTS, and probabilistic analyses on the vessel failure probability as a result of PTS transients. The RPV geometries, material properties, and properties related to embrittlement are those in taken from previous studies. Two previously suggested hypothetical transients, which may seriously affect RPV integrity, are also taken into account. To verify the results of PFM round robin analysis of RPV during PTS events, several models and Monte Carlo methods for determining PFM performance are used and they agree on the accuracy of the failure assessment is obtained. The present work can be regarded as various important factors about performing PFM that affect in evaluating the structural safety and operational stability of RPVs. The comparisons of the paper also support the finding that the FAVOR code is very practically useful in assessing failure probability.
Abstract: This investigation is to present a verification study of probabilistic fracture mechanics (PFM) analysis code for a reactor pressure vessel (RPV) during pressurized thermal shock (PTS). The probabilistic fracture mechanics code FAVOR, developed by Oak Ridge National Laboratory, is used to calculate the conditional probabilities of crack initiation ...
Show More
Energy Based Approach to Evaluate Self-Excited Vibrations of Wheelsets Caused by Adhesion Characteristics
Issue:
Volume 10, Issue 2, April 2022
Pages:
25-34
Received:
4 March 2022
Accepted:
22 April 2022
Published:
28 April 2022
Abstract: Throughout the homologation process, especially in Germany, the torsional load acting on the wheelset due to drive train oscillations must be evaluated. The maximum values of these dynamic torsional moments are strongly influenced by the adhesion conditions in the wheel/rail contact and the slip velocity range between wheel and rail due to drive control dynamics. The adhesion conditions are hard to measure and to reproduce. Hence, it is time-consuming to prove that the measured dynamic moments cover the possible maximal values. The proposed energy method allows a proper prediction of maximum dynamic moments, assuming critical adhesion conditions and an appropriate drive train model. The criticality of the adhesion conditions is shown by measurements. The method is applied to different types of drive train. The predicted maximum values of the dynamic moments are compared with measurement results. During the drive control design phase, the energy method helps to determine a setting range of the slip velocity compatible with the wheelset axle strength. In the homologation process the method could replace measurements.
Abstract: Throughout the homologation process, especially in Germany, the torsional load acting on the wheelset due to drive train oscillations must be evaluated. The maximum values of these dynamic torsional moments are strongly influenced by the adhesion conditions in the wheel/rail contact and the slip velocity range between wheel and rail due to drive co...
Show More
