[en] In chapter 3 the experiments are described which have been carried out to study the reaction of tellurium with the fuel cladding. The reaction between these materials leads to the formation of stable zirconium telluride compounds on the surface of the cladding. Through this reaction tellurium is retained in the fuel pin. Only after complete oxidation of the cladding tellurium is released and can be transported further; then its chemical form, either elemental tellurium or tin telluride, depends on the relative amounts of steam and hydrogen present. Interaction of tellurium with cesium does occur as well. Therefore, the cesium-tellurium system has been investigated. Chapter 4 describes the study of the compounds which exist in this system, as well as the determination of the phase diagram and the measurements of the thermodynamic properties of the compound Cs₅Te₃. The following chapters describe the study of the zirconium-tellurium phase diagram, the determination of the crystal structures of two zirconium telluride compounds which have a notable mutual resemblance, and the measurement of the thermodynamic properties of Zr_1+xTe₂ and Zr₅Te₄. The tellurium vapour pressure measurement of Zr_1+xTe₂ is treated in chapter 8. The Knudsen effusion method has been applied to measure the tellurium pressures in a limited composition range of Zr_1+xTe₂ at high temperatures. The last chapter deals with the processes that influence the chemical form and the release of tellurium during a reactor accident. The thermodynamic properties which have been measured, are applied in a calculation of the chemical form of tellurium under accident conditions

[en] The cesium-tellurium system in the region between 33 and 55 at.% Te has been investigated with X-ray diffraction and DSC. The existence of the compounds Cs₅Te₃ and CsTe is demonstrated. The latter compound exhibits a structural transition at elevated temperature, as does the compound Cs₂Te. The earlier reported compounds Cs₃Te₂ and Cs₅Te₄ do not exist. (orig.)

[en] Interaction of tellurium vapour with Zircaloy during the initial stage of an accident will lead to retention of tellurium in the core. For reliable estimation of the release behaviour of tellurium, it is necessary to know which zirconium tellurides are formed during this interaction. In this work the reaction of tellurium with Zircaloy-4 has been studied, using various reaction temperatures and tellurium vapour pressures. The compound ZrTe_2-x is formed on the surface of the Zircaloy in a broad range of reaction temperatures and vapour pressures. It is found that the formation of the more zirconium-rich compound Zr₅Te₄ is favoured at high reaction temperatures is combination with low tellurium vapour pressures. (orig.)

[en] Structural, thermodynamic and phase properties in the Na₂S-H₂O system for application in a chemical heat pump have been investigated using XRD, TG/DTA and melting point and vapour pressure determinations. Apart from the known crystalline phases Na₂S·9H₂O, Na₂S·5H₂O and Na₂S a new phase Na₂S·2H₂O has been proven to exist. Na₂S·((1)/(2))H₂O is not a phase but a 3:1 mixture of Na₂S and Na₂S·2H₂O, presumably stabilised by very slow dehydration kinetics. The vapour pressure-temperature equilibria of the sodium sulphide hydrates have been determined and a consistent set of thermodynamic functions for these compounds has been derived. XRD measurements indicate the topotactic character of the transitions between the hydration states

[en] Effects of liming and shading on growth and yield of soybean examined. Treatments consisted of two factor, i.e. Liming at three levels (0.5, 1.0 and 1.5 equivalent Al-dd) and shading at four levels (unshaded, shaded with one, two and three layers of Filtering clothes). The experiment was conducted at Research Station, Bogor Research Institute for Food Crops. The treatment was arranged in split plot design. The faction on radiation reduced by one, two and three layers of filtering clothes were 35 percent, 50 percent and 60 percent respectively. Response of the crop liming is independent of shading (no interaction effect). In general, the effect increasing liming was not significant but higher liming reduced growth and yield of the crop. Furthermore, response of the crop to shading was quadratic. It was found that optimum radiation for growth and yield of soybean was between 275 and 340 Iy/day. There was an indication that optimum radiation intensity of more than 340 ly/day narrower planting space was suggested in order to obtain a leaf area index of more 4.0, while in areas with radiation intensity of less than 275 ly/day, wider planting space was preferable in order to obtain a maximum leaf area index of between 3.0 and 3.5

[en] The space-time kinetics code IQSBOX/IQSBWR (PWR/BWR) was developed to analyze tast transients and off-nominal conditions in the core of light-water reactors. The capabilities of the code system and its further development are described. The development includes the implementation of an efficient data management system and coupling to the open channel model TORC. For the verification of IQSBOX a single rod drop and a reactor trip have been calculated. For the qualification of IQSBWR pressure-transients have been examined. The results of the calculations are in good agreement with the experiments. (orig.)

[en] The biological activity of the (+)-S- and (-)-R-enantiomers of niguldipine, of the (-)-S- and (+)-R-enantiomers of felodipine and nitrendipine, and of rac-nisoldipine and rac-nimodipine was investigated in vitro and in vivo. Inhibition of coronary vasoconstriction due to the thromboxane A2 (TxA2)-mimetic U-46619 in guinea pig Langendorff hearts, displacement of (+)-[³H]isradipine from calcium channel binding sites of guinea pig skeletal muscle T-tubule membranes, and blood pressure reduction in spontaneously hypertensive rats were determined. The enantiomers were obtained by stereoselective synthesis. Cross-contamination was less than 0.5% for both S- and R-enantiomers of niguldipine and nitrendipine and less than 1% for those of felodipine. From the doses necessary for a 50% inhibition of coronary vasoconstriction, stereoselectivity ratios for (+)-(S)-/(-)-(R)-niguldipine, (-)-(S)-/(+)-(R)-felodipine, and (-)-(S)-/(+)-(R)-nitrendipine of 28, 13, and 7, respectively, were calculated. The potency ratio rac-nisoldipine/rac-nimodipine was 3.5. Ratios obtained from binding experiments and antihypertensive activity were (+)-(S)-/(-)-(R)-niguldipine = 45 and 35, (-)-(S)-/(+)-(R)-felodipine = 12 and 13, (-)-(S)-/(+)-(R)-nitrendipine = 8 and 8, and rac-nisoldipine/rac-nimodipine = 8 and 7, respectively. Highly significant correlations were found between the in vitro potency of the substances to prevent U-46619-induced coronary vasoconstriction and their affinity for calcium channel binding sites as well as their antihypertensive activity

[en] Interaction of tellurium vapour with Zircaloy during the initial stage of an accident will lead to retention of tellurium in the core. For reliable estimation of the release behaviour of tellurium, it is necessary to know which zirconium tellurides are formed during this interaction. In this work the reaction of tellurium with Zircaloy-4 has been studied, using various reaction temperatures and tellurium vapour pressures. The compound Zr_1+xTe₂ is formed on the surface of the Zircaloy in a broad range of reaction temperatures and vapour pressures. It is found that the formation of the more zirconium-rich compound Zr₅Te₄ is favoured at high reaction temperatures in combination with low tellurium vapour pressures. ((orig.))

[en] The chemical form of the fission product tellurium during a reactor accident has been studied experimentally. Release experiments of tellurium were conducted under simulated LWR accident conditions. It is found that tellurium is retained by the Zircaloy cladding until oxidation of the cladding is almost complete. During this oxidation, tin in the cladding is segregated and reacts with tellurium. The release of tellurium is found to be dependent on the oxygen potential. High oxygen potentials lead to a release as elemental tellurium, low oxygen potentials lead to a release as tin telluride. (orig.)

[en] In the zirconium-rich part of the Zr-Te system the stoichiometric compounds Zr₅Te₄ and Zr₃Te exist. The crystal structures of both compounds have been investigated. The crystal structure of Zr₅Te₄ has been resolved by Rietveld refinement of neutron powder diffraction data. It has a tetragonal body-centered unit cell with lattice parameters a = 1.07649(6) nm, c = 0.38403(3) nm, spacegroup I4/m, and is isostructural with Ti₅Te₄. The profile agreement factors are R_p = 4.38%, R_wp = 5.91% and S = 2.22. The crystal structure of Zr₃Te has been resolved by Rietveld refinement of the X-ray powder diffraction data. It has a tetragonal body-centered unit cell with lattice parameters a = 1.13382(6) nm and c = 0.56265(5) nm, space-group I anti 4, isostructural with Ni₃P, with profile agreement factors R_p = 12.5, R_wp = 13.6% and S = 1.06. The structural similarities between both compounds are discussed