[en] This paper presents core simulator consolidation work done at Global Nuclear Fuel (GNF). The unified simulator needs to supercede the capabilities of past simulator packages from the original GNF partners: GE, Hitachi, and Toshiba. At the same time, an effort is being made to produce a simulation package that will be a state-of-the-art analysis tool when released, in terms of the physics solution methodology and functionality. The core simulator will be capable and qualified for (a) high-energy cycles in the U.S. markets, (b) mixed-oxide (MOX) introduction in Japan, and (c) high-power density plants in Europe, etc. The unification of the lattice physics code is also in progress based on a transport model with collision probability methods. The AETNA core simulator is built upon the PANAC11 software base. The goal is to essentially replace the 1.5-energy-group model with a higher-order multigroup nonlinear nodal solution capable of the required modeling fidelity, while keeping highly automated library generation as well as functionality. All required interfaces to PANAC11 will be preserved, which minimizes the impact on users and process automation. Preliminary results show statistical accuracy improvement over the 1.5-group model

[en] This paper proposes a goods transportation system with a pinning-type superconducting magnetic levitation guide setting in a vacuum passage and describes the system outline. Load characteristics of the superconducting levitation guide used this system are analyzed by a newly developed electromagnetic field analysis program; then, it is evaluated for whether it has sufficient load characteristics as a non-contact guide for this system. Calculation results show that the superconducting levitation guide has sufficient levitation force in the large gap, which become an effective space for thermal insulation between the magnetic rail at room temperature and superconductors cooled to cryogenic temperatures. Comparison between calculated and measured values was done to examine program validity in a small model; it showed good agreement both quantitatively and qualitatively

[en] A new nodal diffusion method for BWR core analysis has been developed, based on the modified one (one-and-a half) group scheme. In this New Modified Cone Group (NMIG) method, neutron flux and material distributions within a node are explicitly represented to combine the heterogeneous effects for the fuel assembly into homogenized reactor calculations. The intranodal thermal flux distribution is expanded with the analytical solutions of the diffusion equation. The nodal power density and the interface net current are calculated, taking the intranodal thermal flux shape into consideration. Coupling coefficients of the fast flux are calculated by making use of transverse integration techniques. There is essentially no need for core dependent adjustable parameters in the present method, since boundary conditions are derived in a consistent manner. A pin power reconstruction method was developed on the same basis as that used for the nodal method. The local power distribution is readily obtained from the intranodal flux distribution. Calculation time for nodal equations is comparable to that for the conventional modified one group method. This makes it possible to apply the present method to on-line core evaluation. Verifications of the present methods were made by comparing the results to those obtained by heterogeneous fine-mesh multi-group diffusion calculations. The NMIG method accuracy is shown to be fairly good

[en] The uranium enrichment pilot plant at PNC Ningyo-Toge Works, Japan, started operation in August 1979. Since then, inspection activities by the government of Japan and the International Atomic Energy Agency (IAEA) have been carried out. A basic measure of safeguards is evaluation of material unaccounted for (MUF) by closing the material balance. As the plant now produces uranium of <5% enrichment, a material balance is closed only once a year. Until now, eight physical inventories have been taken. This paper describes the operator's procedures for material accountability and the values of MUF reported to the government of Japan and the IAEA

[en] A production method of a covariance matrix from a nuclear model calculation is described. An optical model is used to estimate the covariance matrix of the ⁵⁴Fe total cross section, and a Hauser-Feshbach and a precompound models are used for the covariance matrices of ^54,56Fe(n,p) reaction cross sections. These matrices are calculated from the uncertainties of level density parameters, a precompound parameter, and the optical potential parameters for neutron, proton, and α-particle. The neutron optical potential parameters and their uncertainties are evaluated from the experimental total and elastic scattering data, while the other parameters and their uncertainties are evaluated from the experimental ^54,56Fe(n,p), (n,α), (n,2n), (n,Xp) and (n,Xα) reaction cross sections. (author)

[en] Only limited number of studies have been done concerning the effect of resonance interference on the resonance integral I and its variation δI with fuel temperature T, inspite of its possible importance. Nuclides studied so far are Th-232 in ThO² rod, U-238/Cs-133 in BWR fuel rod, homogeneous mixtures of U-238/U-235/Pu-239, U-Pu chains/FP's (fission products) and Th-U chains/FP's. General conclusions seem to be that the effect of the major nuclide B (e.g., U-238, Pu-240) on the resonance integral IB of the minor nuclide B (e.g. U-235, Pu-239, FP's) is sometimes fairly large, while the presence of the nuclide B scarcely affect the resonsance integral IA of the nuclide A and its variation δIA with fuel temperature. The above conclusions, however, were made a little obscure because of, the confusion between the competitive effect and the overlap effect of resonance absorptions, and the complication of the phenomena involved. In the present paper, the problem is simplified, still preserving the essence of the resonance interference mechanism in a heterogeneous system. Definitions of IA and IB, which contain only the overlap effects, are given for a system consisting of resonance nuclides A and B, and other non-resonance nuclides. Using the above IA and IB, the quantitative evaluations of the overlap effects are given for a typical BWR lattice. Combinations of resonance levels considered are the main levels of Pu-240, U-238 (nuclide A) and overlapping levels of Rh-103, Cs-133, Sm-150, Gd-155 and Gd-157 (nuclide B). Gadolinium isotopes are included here because 2 to 4% Gd²O³ is used in BWR fuel rods as burnable absorber

[en] When a dispersion relation between real and imaginary potential is considered, the contribution of the volume type imaginary potential is embedded in the real potential while the surface peaked potential causes the surface peaked component in the real potential. We attempt to estimate this surface peaked real potential of ²⁰⁹Bi. In addition, we fit a Brown-Rho parametrization to the imaginary potential in a conventional optical model analysis, and we estimate the energy dependencies of the optical potential parameters due to the dispersion relation. (author)

[en] During the past five years, several nondestructive assay (NDA) radiation systems have been used by the International Atomic Energy Agency and Japan Nuclear Safety Bureau for both accountability and surveillance of mixed oxide fueled reactors in Japan. The facilities include the Joyo and Monju test and prototype fast breeder reactors as well as the Fugen Experimental Advanced Thermal Reactor. The NDA sensors include gamma-ray and neutron detectors to identify the presence of plutonium-bearing fuel assemblies. The NDA systems operate in the continuous unattended mode and data are used to obtain both quantitative information for the plutonium input to the reactors and to supplement the containment and surveillance systems. (author)

[en] The bulk magnetization of metallic Gd decreases with increasing pressure and disappears at 7 GPa. The Curie temperature reduces with pressure, and the ferromagnetic signals disappear above 7 GPa in the wider temperature region. These experimental results are discussed on the pressure induced frustration of the RKKY interactions among the ⁸S_7/2 state of localized 4f electrons

[en] A tri-n-octylphosphine oxide (TOPO) microcapsule has been developed for separating uranium from sulfuric acid solutions that have been used to decontaminate uranium waste. The distribution coefficient of the uranium was about 100 ml/g for a sulfuric acid concentration of 0.1-1.0 mol/L. The separation factor for uranium from iron, a representative metal dissolved in waste solution, was about 1000. A 1 g of TOPO microcapsule can remove uranium from about 50 mL of waste solution. The spent microcapsule easily decomposed when heated to about 300- 500 deg. C completely decomposed when heated to 300 deg. C. This TOPO microcapsule is thus well suited for volume reduction of uranium-bearing waste. (authors)