Hartree-Fock Compton profiles for the elements

Orbital and total-atom Compton profiles are given for the elements. Hartree-Fock wavefunctions were used in the numerical calculations for atomic numbers 1 ≤ Z ≤ 36 and relativistic Dirac-Hartree-Fock wavefunctions for atomic numbers 36 ≤ Z ≤ 102.     

Hartree-Fock values of coupling constants,polarizabilities, susceptibilities,and radII for the neutral atoms,helium to nobelium

Presented here are the values, obtained with Hartree-Fock functions, for the spin-orbit, magnetic-dipole, and electric-quadrupole coupling constants, electric-dipole polarizabilities, magnetic susceptibilities, and atomic radii for the ground and some excited states of the neutral atoms from He to No.     

Discrete elements model for evaluating impact and impulsive response of reinforced concrete plates and shells subjected to impulsive loading

The application of a discrete element representation of solids to the analysis of reinforced concrete plates and shells is discussed. Yielding of steel as well as fracture of concrete are duly accounted for by means of constitutive criteria that quantifies coupling between both effects. Comparison with experimental results show excellent correlation.     

New results and open problems in the theory of the Vlasov equation

The theory of existence and uniqueness of solutions of the Vlasov equation is not yet complete. We state two theorems about the local existence of strong solutions and about the global existence of weak solutions. Some questions, however, have yet to be answered. In particular this concerns global existence of strong solutions, uniqueness of and conservation of energy for weak solutions.     

Method for detecting unsealed fuel elements in VVER and RBMK fuel assemblies and test results

A method is described for detecting unsealed fuel elements in VVER and RBMK fuel assemblies in a cooling pond. The method is based on detecting water which has seeped under the cladding of an unsealed fuel element. The results of testing the method on unsealed VVER-440, -1000, and RBMK-1000 fuel assemblies are presented. Translated from Atomnaya énergiya, Vol. 106, No. 2, pp. 84–88, February, 2009.     

A differential model for equivalent parameters Application to two residual heat removal systems parameterization and interpretation of results

The work presented in this paper has been carried out in the frame work of the innovation and future reactors R&D activities in the CEA-France. It consists of the comparison of two residual heat removal systems (RHRS's) with regard to their respective reliability and maintainability. High parameterization capability was required in order to enable the identification of the relative weight of different sub-systems and principal components in each RHRS. An exhaustive parameteric analysis was carried out using the Differential Model for Equivalent Parameters (DMEP). Parameters like components reparability, human failures and common mode effects could be analysed for both RHRS candidates. Some intuitive designer choices have also been assessed.     

Strain-based finite elements for the analysis of cylinders with holes and normally intersecting cylinders

A finite element solution to the problems of stress distribution for cylindrical shells with circular and elliptical holes and also for normally intersecting thin elastic cylindrical shells is given in the present paper. Quadrilateral and triangular curved finite elements are used in the analysis. The elements are of a new class, based on simple independent generalised strain functions insofar as this is allowed by the compatibility equations. The elements also satisfy exactly the requirements of strain-free-rigid body displacements and uses only the external “geometrical” nodal degrees of freedom to avoid the difficulties associated with unnecessary internal degrees of freedom.A rectangular curved element was first developed and applied to the analysis of the familiar pinched cylinder and barrel vault problems (Ashwell and Sabir [1]). The results converge rapidly for displacements as well as for stresses. Further tests were carried out to investigate the ability of this element in predicting the high stresses in the neighbourhood of applied concentrated loads, (Sabir and Ashwell [2]). The loads considered were either radial or axial forces as well as moments about tangents to the circular cross section. The results obtained were not only in agreement with those of Forsberg and Flügge [3] but when plotted for the complex parameters defining proportions of the shell and flexibility as suggested by Calladine [4], their general forms corresponded closely with theoretical predictions.In the present paper we first develop strain based quadrilateral and triangular elements and apply them to the solution of the problem of stress concentrations in the neighbourhood of small and large circular and elliptical holes when the cylinders are subjected to a uniform axial tension. These results are compared with analytical solutions based on shallow shell approximations and show that the use of these strain based elements obviates the need for using an inordinately large number of elements.Normally intersecting cylinders are common configurations in structural components for nuclear reactor systems and design information for such configurations are generally lacking. The opportunity is taken in the present paper to provide a finite element solution to this problem. A method of substructing will be introduced to enable a solution to the large number of non banded set of simultaneous equations encountered. The solutions show good agreement when compared with experimental results of Corum, Bolt, Greenstreet and Gwaltney [5].     

Upper bound methods for use in the design and assessment of axisymmetric thin shells subjected to cyclic thermal loading

Upper bound methods are used to calculate interaction diagrams showing the structural behaviour of axisymmetric thin shell components under cyclic thermal loading conditions and constant mechanical load. After a review of these upper bound methods and their implementation, a number of typical examples of thermal loading situations are examined in detail, including stationary thermal cycling, Bree type thermal loading and the effects of moving temperature fronts, as well as the effects of changes in shell thickness. It is demonstrated how interaction diagrams calculated by this method may be used in the design and assessment of components under these loading conditions.     

A new approach to finding magic numbers for heavy and superheavy elements

For at least 60 years, scientists have known that certain numbers of protons or neutrons in nuclei formed closed shells of some kind, producing additional stability to nuclei that possess these properties. The most stable nuclei, or nuclei exhibiting enhanced stability, are called doubly magic. Only recently, Lucas has explained that the magic numbers are really composites of several sub shells filling, rather than being single shells. In addition, his theory leads to a conclusion that protons and neutrons fill sub shells in a different way. This is because the protons are charged particles, and by Coulomb repulsion they try to get as far away from each other as possible, hence tending to occupy the outer regions of nuclei. Neutrons, being uncharged but possibly polarizable, tend to occupy both outer and inner shells and to possibly increase the number in an outer shell when the nuclei are heavy in a similar way to electrons filling in inner shells in the Lanthanide and Actinide series.Using these ideas, and following a simple modification of Lucas’ geometrical packing scheme, individual candidates for new magic proton numbers and new magic neutron numbers have been identified. Amazingly, these new magic numbers correspond to the experimentally identified superheavy element distribution to a very large extent, and even correspond to magic numbers suggested using very sophisticated theoretical physics methods and computations. As an added bonus, the newly suggested magic numbers correspond to the long lived Thorium and Uranium isotopes, and to the Fermium isotopes, which may help explain the shape of the Peninsula of Heavy isotopes. They also suggest going back to reassess somewhat lighter isotopes to see if some magic effects have been missed.     

Techniques for the preparation and identification of transplutonium elements

A short review of the discovery of transuranium elements is given and methods of preparing and identifying them are described. The results of a thorough experimental check of the work of a group of scientists from the USA, Britain, and Sweden on the preparation of element 102 are given.A radical new method used for preparing isotopes of element 102 is described in detail. Data on the properties of two isotopes of this element are given. The half-life of an isotope of element 102 with a mass number of 254 is 3 sec and the -particle energy is 8. 3 Mev. In 30% of the cases of decomposition, this isotope undergoes spontaneous fission. According to preliminary data, the isotope of element 102 with a mass number of 253 has an -particle energy of 8. 8 Mev.The agreement of the results of this work with the data obtained by G. N. Flerov et al. is noted. In conclusion, possible ways of preparing and identifying elements with an atomic number Z above 102 are examined briefly.Report read at the Eighth Mendeleev Congress in Moscow (March, 1959).     

Comparison of the results of calculations and post-reactor investigations of VVÉR-1000 fuel elements with burnup 49 MW·days/kg

The results of calculations performed with the PINw99, TRANSURANUS (V1M1V03), and TOPRA-2 computer programs are compared with data obtained from post-reactor investigations of fuel elements which operated for four years in the No. 1 unit of the Zaparozh’e nuclear power plant with a VVéR-1000 reactor to burnup ≈ 49 MW·days/kg. The initial data are analyzed, and a comparison is made of the computed and experimental elongation of the fuel elements (49 fuel elements), the yield of gaseous fission products and the subcladding pressure (35 fuel elements), and the decrease of cladding diameter and fuel-cladding gap width. It is shown that these computer programs can be used to calculate VVéR fuel elements. __________ Translated from Atomnaya énergiya, Vol. 101, No. 6, pp. 413–420, December, 2006.     

Experimental and computed results for fluid-structure interactions with impacts in the HDR blowdown experiment

The HDR experimental facility has been used for several blowdown experiments in order to study fluid-structure interactions and loadings on the pressure vessel internal structures of a pressurized water reactor. We have developed the code FLUX to analyse the motions in the initial blowdown period.This paper describes a new type of HDR experiments (V34) and compares the experimental results with the FLUX-code results. As novel feature, the core barrel is not rigidly clamped to the vessel as in earlier experiments but supported with gaps such that the core barrel can move freely upwards for about 2 mm and horizontally for 0.3 mm at the upper flange. At the lower core-barrel edge, snubbers restrict the horizontal motion to about + 1.4 mm and −2.8 mm.The experimental results show that the core barrel is deflected sidewards until it hits the snubber at the lower edge and then swings back to hit the opposite snubber. By this some kinetic energy is lost due to plastic snubber deformations. At the same time, the measurements show that the core barrel lifts rather uniformly from its support upwards until it hits the upper constraint. Several bounces up and down are observed until the core barrel becomes fixed probably due to friction from the side.This situation has been pre- and post-computed with the new FLUX-version which contains a very effective algorithm to treat supports with gaps and resultant impacts. For treatment of plastic supports, a simple model is added. Pre-computations were not meaningful because of large deviations in the pre-estimated initials gaps. However the computed pressure-field is not influenced very much by these parameters and predicted very well. This was favoured by the isothermal fluid initial conditions. Post-computations show sufficient agreement with respect to computed core barrel motion. The axial motion is described very well. Some problems remain which are due to the model for the upper flange support.Impacts do not results in greatly enlarged loadings, strains or accelerations for this situation.     

Facility for the irradiation of fuel elements in the SM-2 and MIR reactors with variable operating regimes

Conclusions The procedures and irradiation facilities developed for testing fuel elements at a variable power have received experimental verification in the SM-2 and MIR reactors, and have shown satisfactory operating efficiency of all units. During the experiments, no appreciable effect of the facilities was noted on the operation of the reactors into which they were loaded, and on the testing conditions in other channels. These procedures at the present time are being used in investigations conducted in the SM-2 and MIR reactors, for verification of the operating efficiency of the fuel elements of power reactors in different variable operating cycles.Translated from Atomnaya Énergiya, Vol. 58, No. 2, pp. 97–100, February, 1985.     

Determination of the 238U capture to total fission ratio in alternate depleted uranium/polyethylene shells with D-T neutrons

Aiming at checking the conceptual design of the subcritical blanket in the fusion–fission hybrid reactor, an integral experiment was carried out on an alternate depleted uranium/polyethylene-shell setup with D-T neutrons using activation technique. 18 depleted uranium foils were placed at 90° direction to the incident D beam, and the distribution of the ²³⁸U capture to total fission ratio was determined by measuring the 277.6 keV γ ray generated by neutron capture of ²³⁸U and the 293.3 keV γ ray generated by fission of ²³⁵U and ²³⁸U. The ratios were generally between 1 and 2 in the depleted uranium shells, with relative uncertainties between 3.0% and 5.5%. The ratios were calculated by the MCNP4B code employing ENDF/B-VI nuclear data library, the discrepancies between calculations and experiments were all within 6%, and the average calculation to experiment(C/E) ratio was 0.998.     

Dirac-Fock-Slater calculations for the elements Z = 100, fermium,to Z = 173

Listed here for the elements Z = 100, fermium, to Z = 173 are energy eigenvalues and total energies found from relativistic Dirac-Fock-Slater calculations. The effect of high ionization on the energy eigenvalues is presented for two examples. The use of these tables in connection with the energy levels of superheavy elements and molecular orbital (MO) x-ray transitions in superheavy quasiatoms, is discussed. In addition, a brief comparison between the results of the Dirac-Fock-Slater and Dirac-Fock calculations is given.