[en] The authors show that an adequate modeling of the water gap in BWR fuel element models using the code TRITON requires an explicit consideration of the Dancoff factors. The analysis of three modeling options reveals that considering the moderating effects of the water gap coolant for the peripheral fuel elements the resulting deviations of the U-235 and Pu-239 concentrations are significantly reduced. The increased temporal calculation efforts are justified with respect to the burnup credits for criticality safety analyses.

[en] CASTOR casks are designed for the transport and dry storage of spent light water reactor fuel or nuclear waste, like for instance vitrified waste. The subcriticality of CASTOR V casks is mainly assured by: the limitation of the fissile content of the fuel, the geometrical positioning of the fuel assemblies within a basket, and the neutron absorbing structures. Using the example of CASTOR V type casks, an outline of the methodology of criticality analyses for CASTOR casks is presented. The development of models for normal and accidental conditions of transport is presented. The criticality safety analyses are performed with the KENO codes and with the SCALE 238-group ENDF/B-V cross section library. This methodology has been developed over the last 15 years and has been successfully applied to various licensing procedures

[en] Low-lying collective vibrational excitations in ⁹⁴Mo have previously been investigated with electron scattering experiments at the 130 MeV superconducting electron accelerator S-DALINAC. The evaluation of the measured form factors as a function of momentum transfer had supported the one-phonon interpretation of symmetric and mixed-symmetric states (MSSs) which have been defined in the framework of IBM-2. In the neighbouring even-even isotone ⁹²Zr formed by N=52 neutrons with two valence neutrons and Z=40 with no protons occupying the π(g_9/2) sub-shell a stronger configurational isospin polarization of the one-phonon states than in ⁹⁴Mo is expected. In order to verify this expectation, a new electron scattering experiment at the S-DALINAC has been performed. Our data and a comparison to the momentum-transfer dependence of the form factor of the 2⁺ states are presented. The E2 transition strength of the one-quadrupole phonon states and the E3 transition strength of the one-octupole phonon state have been extracted and are compared to previously derived spectroscopic data on MSSs of ⁹²Zr.

[en] To measure the form factor of isospin polarized one-quadrupole phonon states of ⁹²Zr at the Z = 40 proton subshell closure and to compare it to the momentum-transfer dependence of the form factors for the one-quadrupole phonon states predicted by the Quasiparticle Phonon Model, the 2⁺ states of ⁹²Zr have been investigated with an electron scattering experiment at the S--DALINAC. The relative E2 excitation strength to off-yrast 2₂⁺ state was also extracted in a model-independent systematic procedure. A comparison with the data on ⁹⁴Mo and previous spectroscopic information on MSSs of ⁹²Zr will be given.

[en] For direct final disposal of spent fuel elements the POLLUX concept and the BSK3 concept were developed in the 90ies. A further alternative is the final disposal in large transport casks. The reference container is the CASTOR ^registered cask. The authors describe studies on important parameters of this cask that are useful for relevant scenarios of extended safety analyses. If the criticality safety can be demonstrated for conservative upper bound long-term scenarios the safety can be expected for more realistic configurations. Criticality calculations were performed with the internationally approved and validated code system SCALE using the Monte-Carlo program KENO Va and KENO VI. The worst case scenarios include brine ingress and corrosion of the support structures. The authors show that the backfilling of the boreholes with magnetite or U3O8 is enhancing the subcriticality.

[en] Magnetic quadrupole modes in the selfconjugate nuclei ²⁴Mg, ²⁸Si and ³²S have been studied in 180 electron scattering at the S-DALINAC. The experimental form factors and B(M2) strength distributions are compared to particle-core shell-model calculations which provide a satisfactory description of the experimentally observed fragmentation. The role of orbital contributions (the so-called ''twist mode'') and of a quenching of the spin response are investigated. (orig.)

[en] An approach of the epitaxial jointing of the GdBa₂Cu₃O_{7 – δ}-based tapes using the YBa₂Cu₃O_{7 – δ} layer is proposed. The structural and electrical characteristics of the formed joint have been investigated. Using the scanning transmission electron microscopy, the cross section of the joined region has been studied, partial melting of the YBa₂Cu₃O_{7 – δ} layer has been observed, and the solid-phase diffusion with the formation of the (Gd, Y)Ba₂Cu₃O_{7 – δ}, Y₂BaCuO₅, BaCuO₂, and CuO phases has been established. It is shown that the current-carrying capability of the superconducting joint is over 30% of the initial tape current.

No abstract available

[en] In this work, the development of a superconducting joint between GdBa₂Cu₃O_7−x-based second-generation high temperature superconducting tapes using a thin YBa₂Cu₃O_7−x intermediate layer is presented. The critical current of the superconducting joint was 18 A, which is about 30% of the current in the original tape. The persistent field decay of the one-turn loop showed a joint resistance of less than 6 · 10⁻¹³ Ω at 77 K. (paper)

[en] Studies of the ²H(e,e') reaction of Θ = 180 were performed at the S-DALINAC at an incident electron energy E₀ = 27.8 MeV and 74 MeV. At such low momentum transfers (q = 0.28 fm^-1 and 0.72 fm^-1, respectively) magnetic dipole transitions are expected to give the dominant contributions to the breakup cross sections. An energy resolution of ΔE = 45 keV (FWHM) was achieved at the lower incident energy. Thus, the measured deuteron-electrodisintegration cross section at threshold can be used to obtain the cross section for the np → dγ reaction applying the principle of detailed balance. Accurate information about this process is of great interest in nuclear astrophysics, specifically with regard to Big-Bang nucleosynthesis. The experimental data are in excellent agreement with theoretical calculations based on a nucleon-nucleon potential model, after the inclusion of meson-exchange and isobar effects. (orig.)