Westinghouse Electric (Germany)

The Karlsruhe Institute of Technology (KIT) is participating on (Code Applications and Maintenance Program) CAMP of the US Nuclear Regulatory Commission (NRC) to validate TRACE code for LWR transient analysis. The application of TRACE for the safety assessment of BWR requires a throughout verification and validation using experimental data from separate effect and integral tests but also using plant data. The validation process is normally focused on safety-relevant phenomena for example, pressure drop, void fraction, heat transfer, and critical power models. The purpose of this paper is to validate selected BWR-relevant TRACE-models using both data of bundle tests such as the (Boiling Water Reactor Full-Size Fine-Mesh Bundle Test) BFBT and plant data recorded during a turbine trip event (TUSA) occurred in a Type-72 German BWR plant. For the validation, TRACE models of the BFBT bundle and of the BWR plant were developed. The performed investigations have shown that the TRACE code is appropriate to describe main BWR-safety-relevant phenomena (pressure drop, void fraction, and critical power) with acceptable accuracy. The comparison of the predicted global BWR plant parameters for the TUSA event with the measured plant data indicates that the code predictions are following the main trends of the measured parameters such as dome pressure and reactor power.

This paper compares the design rules of the ASME Boiler and Pressure Vessel Code, Section III, Division 1, Rules for Construction of Nuclear Facility Components, with German nuclear design standards for Class 1, 2, 3 components and piping. The paper is focused on a comparison of the equations for Design by Analysis and on Piping equations. The ASME Section III Code has been used in combination with design specifications for design of German nuclear power plants. Together with manufacturers, inspectors and power plant owners, the German regulatory authority decided to develop their own nuclear design standards. The current versions being used are from 1992 and 1996. New versions of KTA design standards for pressure retaining components (KTA 3201.2 and KTA 3211.2) are currently under development. This comparison will cover the major differences between the design rules for ASME Section III, Div. 1 and KTA standards 3201.2 and 3211.2 as well as code or standard organization by sections, paragraphs, articles and code development.

The values and rewards that animate community practice are not clearly visible to those in traditional medical training programs. Flexnerian education explicitly chose to exclude practitioners in favor of full-time faculties. Academic health centers today are organized to take maximum advantage of a reimbursement system that has been described as perverse; perhaps one of the perversities is that the values embedded in the reimbursement system (reimbursement driven by discrete services rather than overall health or function) have been internalized by trainees and their institutions, and other things valuable to patients and communities (longitudinal care, coordinated care, and appropriateness of care) have become invisible.

Abstract Worldwide, crystal plasticity models are currently developed to predict texture development during processing of material. Such models require a precise knowledge of the active deformation mechanisms. The activation energy for certain deformation modes will change with temperature and also depend on the chemistry of the alloy as well as the microstructure. Deformation mechanisms were studied in ZIRLO™ during room and high-temperature uniaxial compression testing. Materials with a strong crystallographic basal texture and a more random texture due to β-quenching were investigated with the aim of establishing the effect of temperature, microstructure, and texture on the active deformation modes during the initial stages of deformation. First, specimens were strained at room temperature, 180°C and 300°C to 2 % and 5 % or 10 % total strain and subsequently analyzed by Electron Back Scatter Diffraction (EBSD) to determine the texture evolution. It was found that a dramatic texture change was observed for all testing temperatures in the strongly textured specimen after only 5 % total strain, which can only be understood in terms of tensile twinning of {10 1¯2} ⟨1¯011⟩ being active mainly at room temperature and compressive twinning of {11 2¯2} ⟨1¯1¯23⟩ being operational at room and elevated temperature. The β-quenched specimens did not show any evidence of texture change when strained to 10 %. In-situ intergranular strains were measured by time-of-flight neutron diffraction during continuous compressive loading. This information enabled the development of a crystal plasticity finite element model (CPFEM), which was subsequently used to predict the stress state in individual grains. It was found that in the strongly textured material the spread of intergranular strain in the {0002} grain family (normal pointing towards the ND direction) results in some grains being in compression even though the mean stresses are tensile, which could explain the activation of the observed compressive twinning. The crystal plasticity model also demonstrated that the observed texture changes in the strongly textured material, including those at high temperature, cannot be explained by slip alone even when ⟨c+a⟩ slip is considered. In addition, the model showed that the dramatic difference in yield strength of the two conditions studied here cannot be solely attributed to the difference in texture but that grain size plays an important role.

44 papers discuss the history, processing, use, and properties of Zirconium and its alloys. Nearly half are concerned with the corrosion and hydriding of different Zirconium alloys. The techniques used to characterize the oxides and their microstructures and properties have become very advanced. The industry, including producers and users, expects that the work will lead to important conclusions about alloy development, optimization of the processing parameters, and station operating procedures so that the current and new Zirconium materials will continue to operate reliably to very high neutron fluences. Seven major topics include: • Properties at High Neutron Fluences • Hydrogen and Temperature Effects • Deformation and Fracture Studies • Processing and Alloy Development • Effect of Composition and Microstructure on Corrosion • Corrosion Simulation and the Effect of the Environment • Effects of Oxides on Oxidation and H Pickup Rates Audience:Scientists and engineers involved in the production and properties of components for use in nuclear reactors, their behavior during service and the property changes that occur with increasing neutron fluences.

In predetermining line current harmonics of controlled AC/DC converters, the effects of commutation and DC ripple must be taken into account frequently, as for example in the case of medium-size DC drive applications. Based on a suitable normalization, the dominant parameters determining the current harmonics are the line and DC side reactances, respectively, and the DC voltage. This forms the basis for a systematic comparison of the accuracy of analytical formulas, describing the commutation or the DC ripple effect only. By the aid of these results, the validity ranges of different approximation formulas can be estimated and the most important question answered concerning the proof of the conventional assumption of a sufficiently smoothed DC current. In order to predetermine line current harmonics as easily as possible, the most effective formula can be obtained out of corresponding decision areas. Thereby, the allowable error is restricted to 2% of the fundamental, confirmed by comparing results of digital simulation studies. >

Shielded metal arc weldments were made using 2 1 / 4 Cr-1Mo alloy steel electrodes (AWS 5.5 Class E9018-B3) and 1 1 / 4 Cr-½Mo alloy steel plates (ASME SA387 Grade 11 Class 2). The properties of these 38-mm (1 1 / 2 -in.)-thick weldments are compared in two conditions: (1) peened (all beads except the first and last layers were peened for 0.5 min), and (2) postweld heat treated (PWHT) at 704°C (1300°F). Both all-welded and transverse weld properties are compared. The hardness, yield strength and tensile strength (at both room and elevated temperature), and stress rupture strength for the peened weldments are higher than for the PWHT weldments. The creep rates for the peened weldments are lower than for the PWHT weldments. In general, the ductility and stress corrosion properties for the PWHT weldments are better than for the peened weldments.

Because of the potential deleterious effects of impurities in water and steam, the current sampling and analytical practices are being critically evaluated, and methods and utilization of analytical data are being improved. To control the corrosion and efficiency loss, particularly in turbines, once-through boilers, reactors, and nuclear steam generators, low parts-per-billion levels of impurities are being sampled and analyzed. The critical areas reviewed in this presentation are sampling, grab sample, continuous, and in situ analysis; analysis of organics; and utilization of the data for system control and corrosion prediction. Certain improvements and refinements in all these areas are discussed.

The two-dimensional plane strain equation of large plastic flow, expressed in terms of the stream function gradients, is modified using complex variables. The resulting governing equation is solved analytically for a class of nonlinear materials whose stress-strain rate behavior can be expressed by σ¯ = ce¯˙m. A one-to-one correspondence between the plastic flow equation using the Levy-Mises constitutive relations and the Navier-Stokes equation of fluid flow with zero inertia term is established for constant λ˙. This correspondence allows the existing fluid dynamic solution to be used for the plasticity analysis. An analytical solution of plane strain extrusion of linear material through square-cornered die is presented to illustrate the procedure.