[en] The outstanding feature of a modern Boiling Water Reactor is the direct-cycle arrangement, i.e. the steam generated in the reactor core is directly admitted to the turbine through the main steam lines. This design was established by a step-by-step approach and has been successfully applied for several years. (orig./TK)

[en] As introduction a short review of the most important factors influencing occupational exposures and the measures for reducing personal doses will be given. To lower depositions of activity at the inner surfaces of pipework and components as the most important radiation source, appropriate chemistry and filtering of the primary circuit water is being applied. Also leaking fuel which may lead to higher activity concentrations at different points of the plant could be avoided for longer operation periods in the last years. Examples of different measures done in the plant for reducing occupational exposures will be listed up. As an example for a work in higher radiation fields in which doses could successfully be lowered by different means as operational provisions, personnel training, extended experience, remote manipulators etc. the inspection and repair of steam generator tubing is being dealt with in more detail

[en] Terahertz radiation reveals the dynamics of charge screening. Physicists have realized during the last two decades that the physical properties of many condensed-matter systems are often best described in terms of lumps of charge, known as quasiparticles, rather than by electrons and ions. In a crystal under equilibrium conditions, for example, the mutual repulsion of the electrons leads to a cloud of positive charge surrounding each individual electron. This 'dressing' of electrons leads to charge screening. In other words, a test charge placed far from an electron will feel the influence of a new entity with a smaller charge, rather than the charge on the 'bare' electron. In the February issue of Physics World, Torsten Meier and Stephan W Koch of Philipps University, Germany, describe a pioneering experiment by Alfred Leitenstorfer and co-workers at the Technical University in Munich. They generated an electron-hole plasma in a sample of gallium arsenide using very short laser pulses and followed its temporal evolution with a short electrical pulse. Simply speaking, the Munich team has directly measured how long it takes for dressing and screening to develop. (U.K.)

[en] The authors calculate the thermodynamics for a simple model of a spin glass interacting with superconducting electrons. Distinct behavior is predicted for the thermodynamic critical field and other thermodynamic indices that could be verified in experiments

No abstract available

[en] The authors have calculated the thermodynamic critical field and deviation function for a proximity system with paramagnetic impurities in the strong scattering limit. For the proximity effect, they use the model of McMillan and for the impurity scattering the model of Shiba and Rusinov. Important deviations from BCS behavior are predicted, as is also the case when the specific heat difference is computed. Special attention is given to the jump in the specific heat at T_c and a previous calculation is corrected

[en] The personnel dosimeters used in the nuclear power plant, the measuring methods for the different proceedings, and the operational experiences are reported. For the employment of persons, especially during refuelling, repair and service phases, it is important to determine the personnel doses received fast and definitely for determining the existing free doses. A computer record which can be set up up to twice a day gives information about doses caught and free doses. In case of employment of a larger number of persons in the controlled area, measures should be taken for a fast and uncomplicated dose controlling at the entrance of the controlled area. A dose passport used in the nuclear power plants of the FRG makes possible to easily determine the dosis of external personnel. (orig.)

No abstract available

[en] The moderately doped (≥10% holes) t-J model is shown to have a large electronic Fermi surface, compatible with Luttinger's theorem. The full single-particle Green's function is calculated by diagonalization techniques. We present strong evidence for quasiparticle-like behavior, with a dispersion consistent with the bandstructure of the noninteracting limit, and a width of the coherent band scaling proportional to J for J< t. (orig.)

[en] The superconducting specific heat jump for the s-f hybridization model of UBe₁₃ of Overhauser and Appel is calculated. The narrow peak in the density-of-states is found to enhance the size of the jump relative to the BCS value of 1.43, but in weak coupling the increase is insufficient to agree with the measured value for UBe₁₃. The Kondo lattice model of Razafimandimby, Fulde and Keller is considered as a possible modification, but in weak coupling a simple estimate shows that this cannot increase the specific heat jump significantly. It is speculated, however, that a consistent picture may still be possible with conventional strong coupling corrections. (author)