[en] In Germany Probabilistic Safety Analysis (PSA) are part of the evaluation of a nuclear power plants safety. The German PSA guide stipulates that the used software must enable a PSA according to the state of the art. This software must be qualified to assure that its features, mathematic methods and its performance enable a PSA like this. In this research work specifications and requirements are developed, which allow the testing of software. A procedure was developed to qualify PSA software according to the PSA guide and the experiences of users of PSA. Setting up a procedure, a tool for a systematic and uniform examination was crated. Additionally the options, mathematic fundamentals and performance of PSA-programs were analyzed. According to this all programs that were analyzed are capable to sovle their original task, that is the calculation of the safety of high available system based on high available components. Against that the requirements of modern PSA, e.g. to handle less available functions, HRA and fire analyses, based on the use of modern software and the implementation of new developments in the field of PSA are not supported adequately by all programs. (orig.)

[en] Safety systems and components, especially in nuclear power plants, are very complex and require a high reliability. The most common tool to define the reliability is the fault tree analysis. A systematic review is necessary to verify the correctness of these complex analyses. The aim of this work is to formulate requirements for a review from the standpoint of an independent expert. (author)

[en] The self-powered neutron detector (SPND) is a widely used flux monitor in thermal nuclear reactors. Although this is a mature technology, the current state of the art is tuned for a thermal neutron spectrum, so many of the devices currently in use lack sensitivity to fast neutrons. Because current in SPNDs is produced through nuclear reactions with the neutron flux inside a reactor, sensitivity in SPNDs is determined by the neutron cross section of the neutron-sensitive portion of the detector, termed the emitter. This neutron cross section drops by orders of magnitude between thermal and fast neutron energies for many emitters in currently used SPNDs, with a corresponding drop in current from the detector. This paper discusses efforts to develop a fast-spectrum self-powered neutron detector (FS-SPND) that is sensitive to neutrons with energies ranging from 0.025 eV up to 1 MeV. An in-depth analysis of Evaluated Nuclear Data File (ENDF)/B-VII.1 neutron-capture cross sections was performed, and four new materials were identified that are suitable emitter candidates for use in measuring fast neutrons. All four materials are stable mid-shell nuclei in the region between doubly magic ¹³²Sn and ²⁰⁸Pb. Each candidate was simulated with the Geant4 Monte Carlo simulation toolkit to optimize overall detector efficiency. Key words: fast-spectrum nuclear reactor / instrumentation and controls / nuclear reactor / self-powered neutron detector / sodium-cooled fast reactor / Versatile Test Reactor

[en] Laser generated plasmas have good prospects as X-ray sources for time-resolved diffraction experiments in solid state research because of the large number of X-ray photons which will be emitted per unit solid angle and wavelength interval. A modified two-crystal diffractometer will be described, which uses the particular advantages of laser plasmas as X-ray flash sources. Requirements for the source will be determined and discussed. (author)

[en] Only multiple X ray diagnostics could be identified as a common risk factor in a leukaemia cluster that appeared between 1985-1989 in the municipality of Sittensen in northern Germany. In order to judge if the effect could be explained by irradiation dose, estimates were done in two of the leukaemia cases and seven former patients of a practice where some of the leukaemia cases had been treated for orthopaedic reasons. The methods used for the reconstruction of doses were physical simulation and biological dosimetry by dicentric chromosomes in peripheral lymphocytes. Compared to the Bremen laboratory control the mean frequency of dicentric chromosomes in the lymphocytes of the seven volunteers was significantly elevated. An overexposure of about 12-fold could be derived compared to state of the art X raying. At least two cases of the leukaemia cluster in Sittensen can therefore be correlated to an overexposure by diagnostic X rays. (author)

[en] According to the supervising procedure of nuclear power plants in Germany a continuous control and evaluation of all safety relevant activities is necessary. Probabilistic Safety Analyses (PSA) enable an overall plant evaluation and a deeper knowledge of functional dependencies and connections. The results of a PSA are used to derive and evaluate activities to optimise the safety standard. (author). 4 refs., 5 figs

[en] Results are reported on the study of the structure of optically thick laser plasmas from the intensity of X-ray spectral lines. The analysis of plasma images provides information about the average velocity of the plasma expansion, the hydrodynamic efficiency and the rate of the target evaporation. (orig.)

[en] Short communication

[en] An X-ray Schlieren technique is suggested to be used for control of shell targets designed for experiments on laser fusion which utilizes a two-crystal diffractometer. One-dimensional magnified photographs of shell targets produced by this method demonstrate that shell thicknesses of (>=) 3 μm may be determined with an accuracy of +-0.15 μm

[en] The broadening of the resonance line of the helium-like ion of phosphorus emitted by a laser plasma is discussed. The broadening is interpreted as a Doppler frequency shift of the emission of high-energy P⁺₁₃ ions. The energy spectrum of these fast ions is determined. The temperature of the electrons responsible for the ion acceleration is estimated