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The revised U.S. Nuclear Regulatory Commission(NRC), Regulatory Guide(RG) 1.20, rev.3 requires the evaluation of the potential adverse effects from pressure fluctuations and vibrations on piping and components for the reactor coolant, steam, feedwater, and condensate systems. Detailed vibration analyses for the systems attached to the steam generator are very difficult, because these piping systems are very complicated. This paper suggests a screening method for the flow-induced vibration of acoustic resonances and pump-induced vibration of the piping systems attached to the steam generator in order to conduct the APR1400 comprehensive vibration assessment program. This paper seeks to address the areas such as potential vibration sources, and methods to prevent the occurrence of acoustic resonances and pump-induced vibration of piping systems attached to the steam generator, for conducting the APR1400 comprehensive vibration assessment program. The screening method in this paper will be used to estimate the flow-induced vibration of the piping systems attached to the steam generator for the APR1400.

We conducted and verified the structural safety analyses for a type B transport package for a radioactive waste drum. The type B package is used to transport one high-level radioactive waste drum from a waste facility to a temporary site in a nuclear power plant. It is important that the structural integrity of a type B transport package should be maintained under normal transport conditions such as the free drop test, the stacking test and the penetration test, and accident conditions of transport such as the 9 m height free drop test and the puncture test. Based on the ASME Boiler and Pressure Vessel Code, Section III, Division 3 we evaluated the structural safety integrity of the type B package for a radioactive waste drum using finite element analysis. For the stacking test condition the maximum stress is a very low value when compared with the stress limits. The impact of the penetration bar on the overpack does not affect the containment part. For the free drop test condition and the puncture test condition the local stresses appear at the impact part and the containment part connected with the inner structure. The maximum stresses for all of the conditions are lower than the stress limits, so the structural integrity of the type B package for a radioactive waste drum was maintained. Also, the structural safety analyses were verified by using the data acquired from the 9 m drop and the puncture tests of the real model. The analytic accelerations of the 9 m drop test are similar to the test results. For the puncture test condition the analytic result is conservative when compared to the test. The analysis for the structural safety of the type B package reveals conservative results and it is proved that its structural integrity is maintained under normal and accident conditions of transport.

A spent fuel storage cask is required to prove the safety of its canister under a hypothetical accidental drop condition which means that the canister is assumed to be free dropped on to a pad of the storage cask during the loading of the canister into a storage cask. In this paper, finite element analyses and verifying tests for a shock-absorbing effect of a pad in a spent fuel dry storage cask were carried out to improve the structural integrity of the canister under a hypothetical accidental drop condition. The pad of the storage cask was originally designed as cylindrical steel structure filled with concrete. The pad was modified by using the structure composed of steel and polyurethane-foam instead of the quarter of the upper concrete as an impact limiter. The effects of the shape and the thickness of the steel structure and the density of the polyurethane-foam which was used in between steel structures were studied. As the optimized pad of a spent fuel dry storage cask, the quarter of the upper concrete was replaced with 12 mm thick circular steel structure and polyurethane-foam whose density was 85 kg/m 3 . The drop tests of a 1/3 scale model for the canister on to the original pad and the optimized pad were conducted. The effect of the pad structure was evaluated from the drop tests. The optimized pad has a greater shock-absorbing effect than the original pad. In order to verify the analysis results, strains and accelerations in the time domain by the analytical methods were compared with those by a test. The numerical method of simulating the free drop test for a dry storage cask was verified and the numerical results were found to be reliable.

In this study the effect of a free drop impact on the bolted joint of the transport package of radioactive material was studied under various directions. A drop test of a type A or a type IP transport package of radioactive material should be conducted under normal transport conditions. After a drop test the radioactive content of the transport package should not be loss or dispersal. A bolt tension during a drop impact under various directions was measured using a force sensor. And the torque to loosen a bolt was measured after the tests. A bolt tension measured by the tests was compared with the result of a finite element analysis. The effect of the drop direction was examined. The vertical drop directions shows larger bolt tension than horizontal drop. For the torque to loosen a bolt, a horizontal drop condition shows larger value than a vertical drop direction.

A numerical study was conducted to evaluate some creep deformation parameter forms. These forms, which have been developed in Part 1, include both the C∗ parameter and ETM δ5 based parameter. They use a separated format that is being verified both experimentally and numerically. The experimental part of the study, Part 2, was conducted with a Mg alloy, AZ31, using notched fracture mechanics specimens. The same material and geometry is being used for this numerical study. The numerical results show that the separated form of the equation appears to be validated. The results were further used to look at the relationships between the various creep deformation parameters. These results show that the C∗ parameter and δ5 rate are related in ways that make it easy to evaluate one from the other.

Kim et al. suggested an experimental method to determine the Q parameter in situ from the out-of-plane displacement and the in-plane strains on the surface of side necking near the crack tip. In this paper, the procedure to evaluate the stress triaxiality near a crack tip such as the Q parameter is to be polished in the details for simplicity and accuracy. That is, Q and hydrostatic stress are determined only from the out-of-plane displacement, but not using in-plane strain, which is hard to measure. And also, the plastic modulus is determined by an alternative way. Through three-dimensional finite element analyses for a standard CT specimen with 20% side-grooves, the validities of the new procedures are examined in comparison to the old ones. The effect of location where the displacements are measured to determine the stress triaxiality is explored.

A way to measure the second parameter of CT specimens is described. The displacement which is measured continuously from visual images of the lateral surface during crack growth is used to calculate the A, as a function of crack growth. The crack length is measured by DCPD(Direct Current Potential Drop) method and the J-resistance curve is determined according to ASTM standard E1737-96. To prove the validity of this method, three dimensional finite element analyses were performed, and variations of the displacements and along the thickness were explored. As the result, it has been shown that the measured from the visual images of the lateral surface and the corresponding can be regarded as the average through the thickness for 1T and 1/2T specimens of SA106Gr.C steel.steel.

Results of fracture experiments of brass/solder/brass sandwich CTS (Compact Tension-Shear) specimens are presented together with observations of the crack propagation behavior and the fractographs. The fracture behaviors of the interface crack are analyzed by the finite element method with a modified boundary layer formulation. Several fracture mechanisms and the corresponding criteria are examined. And the crack growth behavior and fracture toughness are predicted. As the results various crack growth procedures such as the crack jump to another interface on the opposite side, the nucleation of a new crack far from the initial crack front, and the asymmetric relation of fracture toughness versus mode mix J∞c−φ can be successfully explained. The fractographs, the crack growth behaviors, and stress-strain distribution along the interface are inter-related.

In the two parameter approaches, one of the second parameters, T-stress, Q and A2 is used together with J-integral to describe the constraint loss near the crack tip under large scale yielding states. Among the second parameters, Q seems to be most promising from a practical point of view because it applies for three-dimensional geometries. In order to determine the Q for a given geometry and load, however, three-dimensional elastic-plastic finite element analysis, which is time consuming and costly, has had to be performed so far. In this work an experimental method to measure Q-parameter insitu is described. The basic idea comes from the fact that side necking near a crack tip indicates the loss of stress triaxiality, which can be scaled by Q. From the out-of-plane displacement and the in-plane strain measured on the surface of side necking near the crack tip, stress field averaged through thickness is calculated and then Q is determined from the difference between the stress filed and the HRR field corresponding to the identical J-integral. To prove the validity, three-dimensional finite element simulation has been performed for a CT configuration with side-grooves. Q-value which was calculated directly from the near-tip stress field is compared with that determined by simulating the experimental procedure according to the proposed method, that is, the Q-value determined from the lateral displacement and the in-plane strain. Also, the effect of location where the displacement and strain are measured is explored. Moreover, an easy way for measuring the displacement and strain simultaneously is described. That is based on Stereoscopic Digital Photography and high resolution Digital Image Correlation (DIC) software, and can be performed along with conventional fracture tests. A case study for a CT specimen of ferritic steel is presented.Copyright © 2003 by ASME