[en] The problem of overprediction of neutron capture by ²³⁸U using commonly accepted resonance parameters from the ENDF/B-IV file is briefly considered

[en] The method of high-pressure liquid chromatography was used to separate metal cations and anions. Thereby the influence of different parameters on the separation of lanthanides by cation exchange and extraction chromatography was systematically investigated. The results were used to optimize that separation cycle, in which the elements from Z = 26 to Z = 101 were separated taking into account especially the group of actinides. These separations and the subsequent spectroscopy of gamma radiation, alpha particles and spontaneous fission fragments were used to determine formation cross sections in heavy ion reactions as a function of the atomic charge and the mass number. The most important point was the investigation of the collision of ²³⁸U ions at different bombarding energies. On the basis of the measured formation cross sections conclusions can be drawn on the reaction mechanism and the excitation function of the formation of transplutonium elements. According to the results it seems to be reasonable to use transfer reactions between ²³⁸U and ²³⁸U or ²⁴⁸Cm to synthesize superheavy nuclei around Z = 114. Until now that has been tried only with the help of fusion reactions and the results were negative. (orig.)

[en] The ²³⁸U + ²³⁸U collisions have been studied with effects of deformations and orientation included. The decay of such a super-superheavy nucleus might lead to the possibility of the formation of a superheavy nucleus or an exotic cluster as one of the product

[en] Lattice parameters, fast fission ratio, initial conversion ratio, thermal neutron fine structure, thermal neutron spectrum parameters and buckling, have been measured at CRNL for a wide range of natural uranium lattices. The lattices consisted of regular arrays of fuel clusters, containing natural U metal, UO₂, UC, U₃Si/Al cooled by D₂O, AIR, organic liquid and in a few cases H₂O, in D₂O moderator, for a wide range of lattice pitches. ²³⁸U resonance absorption rates in these lattices can be derived from the lattice parameters. These absorption rates have been related to effective ²³⁸U resonance integrals by means of the EPITHET computer code

[en] The total neutron cross section of ²³⁸U has been measured above 0.5 eV in precise transmission experiments and results are compared with ENDF/B-IV. Emphasis has been on measuring transmissions through thick samples in order to obtain accurate total cross sections in the potential-resonance interference regions between resonances. 4 figures, 1 table

[en] The paper reviews the large body of integral evidence on uranium-238 resonance capture accumulated since 1966, when attention was first drawn to a discrepancy between integral evidence and calculated results based upon differential data. The experiments cover many reactor types, laboratories and measurement techniques, and include studies of isotopic composition of discharge fuel. It is shown that the discrepancy still exists, although changes in other data (particularly uranium-235 resonance capture) have reduced the size of the deduced discrepancy to 4 to 8 percent. It is argued that the differences are within the uncertainties of measurement of parameters for the low lying resonances which dominate thermal reactor calculations. These were originally believed to be more accurate because it was thought acceptable to assume capture widths invariant and to average them over many resonances. Once this is not permitted the difference become explicable. 2 figures, 13 tables

[en] The primary objective of the independent verification was to determine if BJC performed the appropriate actions to meet the specified 'hot spot' cleanup criteria of 500 picocuries per gram (pCi/g) uranium-238 (U-238) in surface soil. Specific tasks performed by the independent verification team (IVT) to satisfy this objective included: (1) performing radiological walkover surveys, and (2) collecting soil samples for independent analyses. The independent verification (IV) efforts were designed to evaluate radioactive contaminants (specifically U-238) in the exposed surfaces below one foot of the original site grade, given that the top one foot layer of soil on the site was removed in its entirety.

[en] Using the quantum molecular dynamics model, we analyze the disappearance of flow in heavier colliding nuclei. A power law mass dependence (∝1/√A) is obtained in all the cases. Our results are in excellent agreement with experimental data which allows us to predict the balance energy for ²³⁸U+²³⁸U collision around 37-39 MeV/nucleon

No abstract available

No abstract available