A summary of the recently completed Phase I of the variety of structural and fracture mechanics techniques. A Project for Fracture Analysis of Large-Scale International 3-d workshop was held in Boston, Massachusetts (U.S.A.), Reference Experiments (Project FALSIRE) is presented, during May 1990, at which 37 participants representing 19 Project FALSIRE was created by the Fracture Assessment organizations presented a total of 39 analyses of the Group (FAG) of Principal Working Group No. 3 of the experiments. The analysis techniques employed by the Organization for Economic Cooperation and participants included engineering and finite-element Development/Nuclear Energy Agency's Committee on the methods, which were combined with JR fracture Safety of Nuclear Installations (CSNI). The CSNI/FAG methodology and the French local approach. For each was formed to evaluate fracture prediction capabilities experiment, analysis results provided estimates of variables currently used in safety assessments of nuclear vessel such as crack growth, crack-mouth-opening displacement, components. Members are from laboratories and research temperature, stress, strain, and applied J and K values. A organizations in Western Europe, Japan, and the United comparative assessment and discussion of the analysis States of America (U.S.A.). To meet its obligations, the results are presented; also, the current status of the entire CSNI/FAG planned Project FALSIRE to assess various results data base is summarized. Generally, these results fracture methodologies through interpretive analyses of highlight the importance of adequately modeling structural selected large-scale fracture experiments. The six behavior of specimens before performing fracture experiments used in Project FALSIRE (performed in the mechanics evaluations. Applications of the various fracture Federal Republic of Germany, Japan, the United Kingdom, methodologies were found to be partially successful in and the U.S.A.) were designed to examine various aspects some cases but not in others. Based on these assessments, of crack growth in reactor pressure vessel (RPV) steels some conclusions concerning predictive capabilities of under pressurized-thermal-shock (PTS) loading conditions, selected ductile fracture methodologies, as applied to RPVs The CSNI/FAG established a common format for subjected to PTS loading, are given, and recommendations comprehensive statements of these experiments, including for future development of fracture methodologies are supporting information and available analysis results, made. Finally, proposals for future work in the context of a These statements formed the basis for evaluations that were Phase II of Project FALSIRE are included. performed by an international group of analysts using a iii NUREG/CR-5997
A series of six wide-plate crack-arrest tests was recently completed by the Heavy-Section Steel Technology program at the National Bureau of Standards, Gaithersburg, MD, using tensile-loaded specimens of A533 Grade B Class 1 steel. Crack-arrest data were obtained at temperatures in the transition range and above the onset of the Charpy upper shelf, thereby providing a basis for the development and evaluation of improved fracture-analysis methods. The 1 by 1 by 0.102-m single-edge-notched (SEN) specimens were welded to long straight pull tabs and subjected to a transverse linear temperature gradient before loading. The crack tips were sharpened by hydrogen-charging an electron-beam weld. The tests were designed to obtain crack arrest near the middle of the specimen where the temperature would produce a high-toughness level in the upper transition region of the material. The specimens were instrumented with strain gages and thermocouples. Initial static design calculations were made using textbook formulas. Additional calculations, using an assumed set of KID versus ˙a and T relations and an effective stress wave concept, confirmed the reasonableness of tentative design parameters. Pretest and posttest dynamic finite-element calculations were performed for each test. Computed results are compared with transient data for crack-line strains, crack speed, crack-opening displacement, arrest location, and postarrest tearing. Results from both application-mode and generation-mode dynamic analyses are presented. The arrest toughness values calculated from the test data are summarized for temperatures ranging from the transition into the Charpy upper-shelf range.
Fifteen wide-plate crack.-arrest tests have been completed to date, ten utilizing specimens fabricated from A533B class 1 material (WP-1 and WP-CE series), and five fabricated from a low upper-shelf base material (WP-2 series). Each test utilized a single-edge notched specimen that was subjected to a linear thermal gradient along the plane of crack propagation. Test results exhibit an increase in crack-arrest toughness with temperature, with the rate of increase becoming greater as the temperature increases. When the wide-plate test results are combined with other large-specimen results the data show a consistent trend in which the K Ia data extends above the limit provided in ASME Section XI. i. INTRODUCTION Current light-water reactor (LWR) pressure-vessel safety assessment methods are based in large measure on Sects. Ill and XI of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (B&FVC). In pressurized-thermal-shock. (PTS) scenarios, flaws on the inner surface of a reactor pressure vessel (RPV) have the greatest propensity to propagate because they are in the region of highest thermal stress, lowest temperature, and greatest irradiation damage. If such a flaw begins to propagate radially j through the vessel wall, it will extend into a region of higher fracture toughness due to the higher temperatures and less irradiation damage. Although the thermal stresses may decrease with propagation depth, the stress-! intensity factor caused by the elevated-pressure loading will be increasing. ' The fracture toughness correlations contained in the ASME B&PVC embody the position _that one cannot assume a crack-arrest toughness value (K,) above 220 MPa*/m for LWR pressure-vessel steels. The imposition of this limit is
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