[en] Proceeding from a summary of measuring methods for determining the concentration of fissionable material in nuclear materials two essential methods for the determination of uranium 235/uranium 238 are described in detail

[en] An increase in heat supply on the basis of nuclear power, mainly by power-heat coupling in nuclear power plants, requires heat transfer over distances longer than those used up to now. The choice of optimal construction and operation parameters of the district heating transit systems increases the transportability of hot water. Optimal structural parameters are presented in relation to territorial boundary conditions. Economical problems are discussed comparing heat supply from heating stations situated near the consumer site with heat supply by means of pipelines connecting nuclear power stations with long-distant consumer sites

[en] Dynamical processes in the main-steam system of power plant units can be studied by means of simulation models. The mathematical model chosen for the pipeline plays an essential role. Based on the one-dimensional viscous flow equations for instationary processes in steam pipings are presented. The expected changes of pressure and mass transfer in the main steam system including reducting and safety valves are investigated after load dump of the turbo-generator of a nuclear power plant unit

[en] A nonlinear model is presented for secondary coolant circuits of nuclear power plants with PWR type reactors. The model is used for simulating the behaviour of the whole fresh steam line system under operational and accidental conditions. The behaviour of the facilities during the malfunction of components or during the occurrence of leaks in the fresh steam line system, as well as their effects on operation and safety of the nuclear power plant unit are discussed

[en] The release of fission products from nuclear fuels is a main problem of safety-related investigations as the radioactive inventory has to be considered the main potential risk for the environment. Due to the complex character of the problem computer codes are to be applied. The GABUDA code simulates the bubble transport inside the fuel, whereas the SPAGAF code is suited for the calculation of normal operation parameters of fuel elements in PWR type reactors. Investigations considering the release of fission gas into the primary coolant circuit are executed by the AFBETA code

[en] Problems and possibilities of applying semiconductor detector spectrometers in radiometric analyses are described. A summary of the state of the art and tendencies of device engineering and spectra evaluation is given. Liquid-nitrogen cooled Li-drifted Si-detectors and high-purity Ge-detectors are compared. Semiconductor detectors working at room temperature are under development. In this connection CdTe and HgI₂ semiconductor detectors are compared. The use of small efficient computers in the spectrometer systems stimulates the development of algorithms for spectra analyses and for determining the concentration. Fields of application of energy dispersive X-ray spectrometers are X-ray diffraction and X-ray macroanalysis in investigating the structure of extensive surface regions

[en] A brief review of operational experiences and accidents concerning sodium-cooled fast breeder reactors is given. Up to now there were no emergencies or accidents in which human lives or environment have been seriously exposed to danger by the radioactive inventory of a sodium breeder reactor

[en] The stimulated desorption of atomic or molecular species of solid surfaces by electron, photon or ion beams is investigated for its applicability in surface analysis. Two models for the energy transfer to the adsorbate - substrate - complex are discussed. The particle stimulated desorption gives information about the bond structure of absorbed atoms and molecules, the geometrical structure of the surface molecules, and the energy state at the solid surface

[en] The high-pressure test loop HOVAL 1 used for simulating loss-of-coolant accidents is described. It is laid out according to the coolant parameters of WWER type reactors (T = 260 ⁰C, p = 10 MPa, v = 2.8 m/s)

[en] On the basis of an one-group model spectral density functions are analyzed for the power noise of an infinite homogeneous reactor. The fluctuation of the coolant inlet temperature acts as noise source. Space-dependent effects are proved by numerical calculations and suited to localize the noise source by means of analyzing noise signals measured with appropriate detector position