How to make a fuel rod modelling code meet the requirements of design applications

The tasks of the fuel rod designer and the resulting requirements on fuel rod modelling codes are described in the first part. These requirements have increased during recent years in connection with the goal to increase the burnup. Cutting of overconservatism can contribute to this goal, but this needs good and accurately calibrated models. The second part of the paper discusses the special rules which control the use of a fuel rod modelling code in design applications. It is demonstrated how an uncontrolled piling-up of scatter bands and parameter bounds will very rapidly end in hypothetic results. Only a reasonable coordination of unfavourable input parameters leads to “realistic” conservatism from an engineer's point of view. A sound data base is the prerequisite for the respective methods. Further efforts will be necessary to qualify codes and procedures for future probabilistic methodologies.     

X-masking during logic BIST and its impact on defect coverage

We present a technique for making a circuit ready for logic built-in self test by masking unknown values at its outputs. In order to keep the silicon area cost low, some known bits in output responses are also allowed to be masked. These bits are selected based on a stuck-at n-detection based metric, such that the impact of masking on the defect coverage is minimal. An analysis based on a probabilistic model for resistive short defects indicates that the coverage loss for unmodeled defects is negligible for relatively low values of n.     

Mechanical properties and microstructure of boron-alloyed steel 19 MnB 4

Microalloying elements are useful to achieve maximum improvements of the mechanical properties in boron alloyed steels supposedly because they form precipitates with nitrogen and carbon to protect boron from precipitation. On the other hand, they are most useful for austenitic grain refinement and for the generation of the required minimum austenitic grain size (MAGS). A second heat treatment (700°C 9h/air) before quenching the Jominy samples is only efficient in a certain range of austenitic grain size. No increase of hardenability is observed above a certain plateau austenitic grain size (PAGS) for each steel group. A minimum austenitic grain size (MAGS) is required to achieve maximum strength. Boron can only improve the hardenability and tensile properties, if the austenitic grain size before martensitic transformation is optimal. Titanium appears to be the most effective element to prevent boron precipitation. The hardenability, yield and impact strength of the steel group B–AI–Ti is good, especially for sample 44.     

Modelling deformation texture formation by orientation flow fields

Model calculations of the development of straight and cross-rolling textures were carried out. The texture is represented in terms of a series of expansions. The changes of the texture coefficients by a small deformation step can be expressed in terms of the coefficients themselves multiplied by a texture change matrix [α]. Integration over the deformation degree η from any starting texture thus gives the deformation texture formation. In the present calculations, the fully constrained Taylor model was used (but other models can equally well be chosen). This model has no unique solutions for most orientations, i.e. it allows several different orientation changes for the same starting orientation. It was shown that this effect is essential in order to obtain model textures which do not only agree in type but also in magnitude with experimental textures.     

Pseudo-Satellitefilm Using Fractal Clouds to Enhance Animated Weather Forecasting

We have developed a system enabling the National German Meteorological Office to generate pseudo-satellite images and video sequences based on their weather forecasting simulation data. With our system meteorologists can visualize the past and the current weather situation, evaluate their simulation results, and produce animated weather forecast videos broadcasted by several television stations. Realistic images are generated by interpolating the extremely coarse weather simulation data grid and enhancing the result using fractal clouds. It also enables the meteorologists to interactively change the forecast data in order to compensate the lack of accuracy or the known errors in their simulation models. Our system TRITON enables the visualization of complex weather simulations in a more natural way by presenting an intuitively understandable forecast.