[en] It is shown that the Pauli hamiltonian for a spin-1/2 charged particle interacting with a magnetic point vortex has a dynamical super spl^*(2, 1) symmetry, which is the Wick-rotated super spl(2, 1) symmetry, on the plane except at the origin where the magnetic vortex is placed. Using this symmetry, the spectrum and the wave functions are constructed. (orig.)

[en] The determination of molybdenum and tungsten at low levels in geological materials by isotope dilution inductively coupled plasma mass spectrometry with sample introduction by electrothermal vaporisation is reported. This technique eliminates the need for the laborious, time-consuming separation steps associated with sample introduction by conventional nebulisation which not only impede productivity but also introduce analyte contamination. Analysis by isotope dilution is shown to be necessary in order to achieve precision values of less than 5% RSD (relative standard deviation) in the measurement step. Memory effects are evident in the determination of W due to carbide formation during ashing, in spite of the presence of Freon gas during vaporisation. Determination limits of 0.03 μg g^-1 for Mo and 0.06 μg g^-1 for W are obtained. Results for standard reference materials analysed by this procedure compare well with literature values. (author)

[en] The determination of tungsten and molybdenum in geological materials by isotope dilution and internal standardisation inductively coupled plasma mass spectrometry (ICP-MS) is reported. The sample is first decomposed by an alkaline fusion, the elements are then leached from the melt as their soluble oxy-anions, and taken through a separation procedure based on selective formation of their oxinate complexes with subsequent adsorption on activated charcoal. Rhenium is used as the internal standard for tungsten and ruthenium as the internal standard for molybdenum. This technique is shown to compensate well for any possible interferences, such as that arising from the presence of sodium. Relative standard deviations of 7 and 5%, and determination limits of 0.07 and 0.08μg g^-1 are obtained for tungsten and molybdenum, respectively, by isotope dilution ICP-MS. Results by both calibration methods are shown to be accurate and comparable to literature values of international reference materials. (author)

[en] A helium microwave-induced plasma (MIP) at atmospheric pressure has been generated in a modified TM₀₁₀ Beenakker cavity. The MIP was coupled with a laboratory-built mass spectrometer used to measure the isotope ratios of Fe, Br and Se, which are not easily measured by an Argon inductively coupled plasma (ICP) source, due to spectral interference. In helium MIP, the analyte signal intensities are maximum when a torch edge is sampled; unidentified molecular ions appear across the entire mass range when the torch center is sampled. The measured isotope ratios agree quite well with the accepted values, and the detection limits are in the low-ppb range. (author)

[en] The LSDS system is under development for analyzing isotopic fissile content applicable in a hot cell for the pyro process. The fuel assay area and nuclear material composition were selected for simulation. The source mechanism for efficient neutron generation was also determined. A neutron is produced at the Ta target by hitting it from accelerated electron. The parameters for an electron accelerator are being researched for cost effectiveness, easy maintenance, and compact size. The basic principle of LSDS is that isotopic fissile has its own fission structure below the unresolved resonance region. The source neutron interacts with a lead medium and produces continuous neutron energy, which generates dominant fission at each fissile. Therefore, a spectrum analysis is very important at a lead medium and fuel area for system working. The energy spectrum with respect to slowing down energy and the energy resolution were investigated in lead. A spectrum analysis was done by the existence of surrounding detectors. In particular, high resonance energy was considered. The spectrum was well organized at each slowing down energy and the energy resolution was acceptable to distinguish isotopic fissile fissions. Additionally, LSDS is applicable for the optimum design of spent fuel storage and management.The isotopic fissile content assay will increase the transparency and credibility for spent fuel storage and its re-utilization, as demanded internationally. (author)

[en] The authors solve the neutron diffusion equation by a wavelet Galerkin scheme in this paper. Wavelet functions are generated by dilation and translation operation on a scaling function. The wavelet functions are localized in space and have a recursive property, so these properties may be utilized to solve a differential equation that has severe stiffness. The wavelet Galerkin method (WGM) represents the solution as a summation of Daubechies' scaling functions, which are also used as the weighting function. The Daubechies' scaling functions have the properties of orthogonality and high smoothness. Unlike the finite element method, the weighting function is the Daubechies' scaling function, and the unknowns determined are not the fluxes of the nodes but the coefficients of the scaling functions. The scaling functions are overlapping in the nodes and require special treatment at interfaces between nodes and at the boundaries. They tested the WGM with several diffusion theory problems in reactor physics. The solutions are very accurate with increasing Daubechies' order and dilation order. The boundary conditions are also satisfied very well. In particular, the WGM provides very accurate solutions for heterogeneous problems in which the flux distribution exhibits very steep gradients. They conclude that it is worthwhile investigating further the WGM for reactor physics problems and that numerical integration and acceleration of the matrix equation must be improved so as to reduce computing time

[en] Recently, the price of resources rapidly increased and the stable supply of resources is a big issue internationally. Specially, countries which have highly dependency on the oil face more severe situation in the energy supply. Moreover, from the current environmental change, air pollution by carbon dioxide, drain of oil resource, increasing demand of electricity, and energy independence, nuclear energy is reconsidered and is the most feasible option in meeting the expanding world energy demand, as a sustainable manner. However, nuclear power plant has an inevitable situation in the production of radioactive wastes. Therefore, the management for spent fuel is an urgent problem and issue to be resolved for a safe next generation. The nuclear reactors related to nuclear fuel cycle are developed as a generation IV type. Nuclear fuel cycle facility will increase through GNEP and advanced nuclear fuel cycle program to expand the use of nuclear energy. pyro-processing is developed to reduce the volume and the radiotoxicity of spent fuels for a permanent storage, and to reuse fissionable elements in a spent fuel. The pyro-processing produces uranium and uranium-TRU (neptunium, plutonium, and americium) mixture. The uranium-TRU is fabricated for the fuel of sodium fast reactor (SFR), enhanced proliferation resistance. The development for a practical application of the assay of nuclear fissile materials was initiated in KAERI for pyro-process related SFR fuel cycle, compact and integrated spent fuel storage design and safety enhanced fuel recycle. The isotopic fissile assay is very important for reuse of fissile material. Specially, the accuracy of fissile assay in a recycled fuel including TRU enhances safety and economy in a nuclear power plant operation. Lead slowing down time spectrometer (LSDTS) is the most proper tool and being developed in KAERI. It has good feature to analyze the isotopic fissile contents in a near real time without an interference of neutron and gamma rays background from spent fuels[1]. Another advantage of the slowing down time spectrometer is the direct assay of fissile materials. Advanced and accurate assay of fissile material contents plays an important role for the increase of transparence and credibility of generation IV nuclear energy system. References: [1] YongDeok Lee, et al., 'Design of a Spent Fuel Assay Device Using a Lead Spectrometer' Nucl. Sci. and Eng., 131, 45, 1999. (authors)

[en] We have considered most general constructions of Calabi-Yau manifolds from complete intersections in products of weighted complex projective spaces. Some of them are closely related to the N=2 Landau-Ginzburg superconformal descriptions of string compactifications. (orig.)

[en] The material properties of DUPIC fuel, such as thermal conductivity, thermal expansion, creep rate, Young's modulus and hot hardness were measured using simulated DUPIC fuel to evaluate their effects on the irradiation behaviour such as the pellet-cladding mechanical interaction (PCMI). Experimentally characterised properties of the DUPIC fuel were employed in the performance evaluation code and the finite element analysis to estimate the ridge height, plastic strain of the cladding, and the hoop stress of the pellet and the cladding. Some fuel fabrication parameters were suggested for optimisation for a decrease in the PCMI of the DUPIC fuel as a result of a statistical sensitivity analysis. (authors)

[en] We consider the algebraic representations of Calabi-Yau manifolds corresponding to N=2 Landau-Ginzburg superconformal theories. For the 168 tensor products of minimal models giving central charge 9, which have diagonal configuration matrices, we obtain all algebraic representations and their Euler characteristics. It is found that the previous nongeometric results of the massless spectrum of Gepner's minimal models are in good agreement with these geometric results for the Calabi-Yau hypersurfaces of WCP⁴. We also consider nonminimal cases, which correspond to Calabi-Yau manifolds from complete intersections in products of WCP^N