This paper gives an overview of the new 'Fuel Rod Analysis Toolbox', which is a program for the pre-processing of input data for fuel rod performance codes with a graphical user interface. It consists of three different modules that can handle several tasks such as data condensation, merging and synchronization. The 'Fuel Rod Analysis Toolbox' helps:to reduce the amount of input data,to simplify the setup of input files for complex data sets with input from experimental data as well as input resulting from neutronics or thermo-hydraulics codes, andto reduce computation time.These advantages are already evident for complex fuel rod analyses employing a conventional one-and-a-half-dimensional code but they become even more important for two- or three-dimensional approaches. (C) 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

During irradiation in the Halden Reactor data such as linear rating, coolant temperature, or reactor state are routinely stored every 15 minutes, in the case of special events even at shorter time intervals. Because of the long irradiation times of up to several years, a huge amount of data is produced which is considered to be too much for direct input into fuel performance codes. In order to reduce the amount of data, various data-condensation procedures have been developed, which are briefly discussed. An innovative data-condensation method based on multidimensional minimisation is presented. The condensation factor obtained so far for Halden irradiations is 25–40, which is sufficient for a modern fuel rod performance code like TRANSURANUS. This new condensation method avoids all loss of experimental data and doubtful averaging of temperatures associated with other more drastic condensation methods. Up to now, the so-called reactor state variable, which defines the reactor operation (e. g. constant, decreasing or increasing power), has not been used. The introduction of this variable should further improve this new condensation method.

During irradiation in the Halden Reactor data such as linear rating, coolant temperature, or reactor state are routinely stored every 15 minutes, in the case of special events even at shorter time intervals. Because of the long irradiation times of up to several years, a huge amount of data is produced which is considered to be too much for direct input into fuel performance codes. In order to reduce the amount of data, various data-condensation procedures have been developed, which are briefly discussed. An innovative data-condensation method based on multidimensional minimisation is presented. The condensation factor obtained so far for Halden irradiations is 25-40, which is sufficient for a modern fuel rod performance code like TRANSURANUS. This new condensation method avoids all loss of experimental data and doubtful averaging of temperatures associated with other more drastic condensation methods. Up to now, the so-called reactor state variable, which defines the reactor operation (e. g. constant, decreasing or increasing power), has not been used. The introduction of this variable should further improve this new condensation method.

At temperatures below about 30 mK in Si:B the phase relaxation time T-2 of the two-level systems associated with the acceptor ground state can be determined from the decay of the two-pulse echo. It has been shown to depend on the concentration of interacting resonant states if the latter is high enough. This concentration is not only given by the boron concentration but depends also on internal and external stress, and the magnetic field. Under conditions of low concentration T-2 becomes long and we observe a modulation of the echo decay. From its dependence on magnetic field strength we can associate this modulation with the interaction of the acceptor hole with the Si-29 nuclei (I = 1/2) present within the extended acceptor wave function. The interaction with the central boron nucleus does not seem to contribute to the observed modulation. (C) 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

At present a comprehensive verification of the fuel rod performance code TRANSURANUS is being performed using irradiation data from the International Fuel Performance Experiments (IFPE) Database and the OECD Halden Reactor Project. For this verification standard models and options are applied. Recent developments have concentrated on high-burn-up phenomena, such as the local thermal conductivity and the local porosity in the High Burn-up Structure (HBS). In this paper, fuel centre temperatures are calculated by the TRANSURANUS code with standard options and compared with measured temperatures, under steady-state conditions. More than 40 000 data points have been analyzed in total. They cover UO 2 fuel (both for Western-type LWR and for Russian-type VVER) and MOX fuel for LWR. It is shown that the vast majority of fuel centre temperatures predicted by the TRANSURANUS code deviates from the measured values by less than 10 %. For all standard fuel configurations the actual deviations are considerably smaller. The spread is of the same order of magnitude as the uncertainties in the measurements (due to power calibration and thermocouple calibration). The present analysis does not reveal any general bias. It can be concluded that under the studied conditions the TRANSURANUS code predictions of the fuel centre temperatures are very satisfactory.

Phonon echoes, sound amplification, and acoustic solitons are observed in Si:B at temperatures below about 25mK depending on the density of states of two-level systems associated with the acceptor ground state. We report on the influence of acceptor concentration, external stress and magnetic field and we compare our results with those associated with the two-level systems in glasses.

Complicated physical processes govern diffusional fission gas release in nuclear fuels. In addition to the physical problem there exists a numerical problem, as some solutions of the underlying diffusion equation contain numerical errors that by far exceed the physical details. In this paper the two algorithms incorporated in the TRANSURANUS code, the URGAS and the new FORMAS algorithm are compared. The previously reported deficiency of the most elegant and mathematically sound FORMAS algorithm at low release could be overcome. Both algorithms are simple, fast, without numerical problems, insensitive to time step lengths and well balanced over the entire range of fission gas release. They can be made available on request as FORTRAN subroutines.

Caesium is one of the most important fission products and must be considered in all aspects of the fuel cycle. Numerous radial profiles of caesium and xenon have been measured by electron probe microanalysis (EPMA). These profiles are very similar and it has been concluded that the effective diffusion coefficient of caesium is very close to that of xenon. In this paper the effective diffusion coefficient of caesium is quantified. This information is used for the interpretation of radial xenon distributions at ultra-high burn-up measured by EPMA.

It is shown by energy- and time-resolved phonon spectroscopy with superconducting tunnelling junctions that acoustic phonon scattering depends on the size of oxygen precipitates in the annealed Czochralski silicon crystals. After thermal treatments around 1050°C we find a series of rather narrow scattering resonances that shift under stress. They are possibly due to electronic excitations of acceptor-like states related to oxygen aggregation.

It is known since long that OH− and OD− defects form tunneling states with 〈100〉 symmetry in certain alkali halide crystals. Surprisingly, recent measurements of the dielectric susceptibility and of the infra-red absorption indicated that the tunnel splitting of the heavier isotope OD− is larger by a factor of 1.4 compared to that of OH−, although one would expect the opposite behavior from the difference in mass of hydrogen and deuterium. These surprising findings are yet only shown for those levels accessible in dielectric experiments. We have investigated NaCl:OD− by means of phonon spectroscopy with superconducting tunnel junctions in order to obtain additional information on the level scheme of OD− tunneling states in NaCl. Since the selection rules pertinent to dielectric measurements are different from those in elastic experiments, it becomes possible to study different transitions within the level scheme. Indeed, we find a resonance, which clearly can be attributed to OD− defects. A comparison with earlier measurements by Kinder and Windheim on OH− in NaCl leads to the conclusion that the anomalous isotope dependence is also found for the levels which are involved in phonon transitions, which confirms that the isotope effect is indeed connected with the tunnel splitting.

Complicated physical processes govern fission gas release in nuclear fuels. Besides the physical problem, there is a numerical problem since some solutions of the underlying diffusion equation have numerical errors that by far exceed the physical details. In this paper, the efficiency and the accuracy of some numerical solutions are analysed. Random operation histories were generated and the errors inherent in each algorithm evaluated over a wide range of up- and down-ramps by comparing the results with the quasi-exact ANS-5.4 algorithm. The URGAS algorithm can be considered as well balanced over the entire range of fission gas release. The new FORMAS algorithm is superior at fission gas release above f≈0.05 and may in a physical sense be considered as an exact solution in this range. Unfortunately, the deficiency of this most elegant and mathematically sound algorithm at low fission gas release could not be fully overcome. However, in view of the many inherent uncertainties, both algorithms are considered as sufficient to be used in a fuel rod performance code. All algorithms analysed in detail can be made available on request as FORTRAN subroutines.

Electric-dipole spin resonance of the deep acceptor Zn(-)(S) in Si reveals close gamma(8) and gamma(7) ground states with zero-field separation of only 0.31 meV as compared to the 43 meV of the two valence bands. With Lande's formula for the g factors of a 2T2 state split by spin-orbit interaction into gamma(8) and gamma(7) this nearness can be interpreted as strong quenching of the orbital moment. The observed dependence on the Zn isotopic mass indicates a dynamic contribution of the acceptor atom to the electronic state as is expected for a Jahn-Teller effect.

The rotational states of Oi in natural Ge as determined by phonon spectroscopy are found to be shifted in isotopically enriched Ge : Oi crystals. These shifts are larger than compatible with the line width in natural Ge if only the motion of the quasi-free Ge–O–Ge molecule is considered. Because of the reduced isotope scattering of the phonons in the enriched Ge the position of higher excited states could be determined. This allows to estimate the height of the axial potential barrier by extending to Ge : O the Yamada–Kaneta model for Si : O.

Using acoustic phonon spectroscopy with superconducting tunnelling junctions we have investigated the phonon scattering due to oxygen precipitation in heat-treated silicon samples with different oxgen and carbon contents. The results are compared to the infrared absorption of these samples.

Phonon scattering resonances in the energy range between 0.4 and 4 meV are observed in GaAs : O by phonon spectroscopy with superconducting tunnel junctions. At least two narrow lines with small stress-coupling can be associated with interstitial oxygen by comparison with IR-spectra. Two broad lines with large stress coupling probably belong to B-O-complexes formed during the growth process. By annealing in the 1000 degrees C range the depth of the oxygen-related lines is varied and a pair of resonances appears also in high-purity material caused by an unknown defect in(tro)duced by the annealing. The phonon resonances can be consistently fitted using a improved calculation of emission and transfer characteristics. (C) 1999 Elsevier Science B.V. All rights reserved.

By phonon spectroscopy with superconducting tunnelling junctions we have investigated α-quartz before and after electron irradiation with doses of 0.8–3.0×1019e−/cm2. In the various samples we obtain two types of irradiation-induced spectra each containing a series of sharp acoustic scattering resonances with energies in the meV region. One of the spectra containing a series of doublets can be fitted by assuming transitions within anharmonic or soft potential type deep double well potentials.

Various types of precipitates are known to form in oxygen-rich silicon depending on annealing history and codoping with carbon. We have used superconducting tunnelling junctions for phonon spectroscopy in the range of wavelengths corresponding to the size of such agglomerates. Frequency- and time-resolved measurements in transmission and backscattering geometry show increased elastic scattering in the whole energy range after annealing. Additionally, a broad-band inelastic scattering component is associated with carbon-lean material and narrow-band scattering around 410 GHz is observed for carbon-rich samples after annealing above 1200 degrees C. These variations are compared with those observed around the 9 mu m oxygen line in low-temperature infrared spectroscopy.

The extension of the light water reactor burnup equations of the TRANSURANUS code to heavy water reactor conditions is described. Existing models for the fission of 235U and the buildup of plutonium in a heavy water reactor are evaluated. In order to overcome the limitations of the frequently used RADAR model at high burnup, a new model is presented. After verification against data for the radial distributions of Xe, Cs, Nd and Pu from electron probe microanalysis, the model is used to analyse the formation of the high burnup structure in a heavy water reactor. The new model allows the analysis of light water reactor fuel rod designs at high burnup in the OECD Halden Heavy Water Reactor.

Electric-dipole spin resonance (EDSR) spectra at 24, 34, and 60 GHz of Si:Be show six absorption lines with characteristics similar to those previously observed for the Gamma(8)(+) ground state(1)) of group-III single accepters. From the dependence on Fermi level position we attribute these absorptions to the singly ionized substitutional double acceptor Be-s(-). The observed strong nonlinearity of the Zeeman splitting can be approximately described by a Hamiltonian containing terms up to second order in the magnetic field. A much better description is achieved by including the interaction with the Gamma(7)(+) state derived from the split-off valence band, if one assumes that it lies only about 0.6 meV above the ground state.

We investigated the phonon scattering in heat-treated Ct-silicon with different carbon concentrations by means of energy-resolved phonon spectroscopy with superconducting tunnelling junctions. The investigated samples were subjected to a typical "intrinsic gettering" thermal cycle (1100 degrees C + 750 degrees C + 1050 degrees C). After the 1050 degrees C step samples with measurable carbon content show a series of at least three relatively sharp absorptions above 3 meV, which we attribute to geometrical resonances caused by the excitation of geometric eigenvibrations of oxygen aggregates with sizes corresponding to the phonon wavelength. Comparison to infrared absorption is made.