[en] It has become obvious that collective inelastic excitation processes play a vital role in heavy-ion induced reactions and that such collective excitation must be treated using coupled-channel (CC) methods. This necessity was best demonstrated in analysis of the recent and very accurate measurements of both the elastic and inelastic scattering from highly deformed nuclei. In describing such scattering processes for heavy-ions, it is also essential to take into account nuclear excitations due not only to the usual nuclear interaction but also the Coulomb force, the latter of which is generally ignored in light-ion induced scattering. Doing CC calculations, including the effects of Coulomb excitation without introducing any further approximation is, however, very time consuming and thus practically impossible. This is primarily due to the long-range nature of the Coulomb potential. The aim is to make it feasible to carry out such calculations with the help of the WKB and Pade approximations. The WKB approximation was particularly used in solving the CC equations in the asymptotic region where the Coulomb force dominates. First the CC calculations are reformulated using these approximations, and then the development of a computer program, JPWKB, is discussed. An attempt is made to use the CC disorted waves, obtained from JPWKB, in calculating the cross sections for transfer reactions induced by heavy-ions (coupled-channel-Born-approximation (CCBA) calculations). A computer code, MARSWKB, has been prepared for such CCBA calculations. Using these newly developed codes, both CC and CCBA calculations, including Coulomb excitation effects, performed for a number of cases of heavy-ion scatteringand reactions, and results are compared with experimental data. These CC and CCBA calculations are found to explain data which defy explanation in terms of more simple theories such as the optical model and the distorted wave Born appromation (DWBA). approximation

[en] The utilization of modular sodium-to-supercritical CO₂ heat exchangers may yield significant improvements for an overall plant energy utilization. The consequences of a failure of the sodium CO₂ heat exchanger boundary, however, would involve the blowdown and intermixing of high-pressure CO₂ in a sodium pool, causing a pressurization which may threaten the structural integrity of the heat exchanger. Available data seems to indicate that the chemical reaction between sodium and CO₂ would likely produce sodium oxides, sodium carbonate, carbon and carbon monoxide. Information on the kinetics of the sodium-CO₂ reaction is virtually non-existent

[en] Vertical direction current-voltage (I-V) characteristics of Polypyrrole (PPy) nanotube (diameter of 120 nm) deposited on Au were measured at room temperature using a metal-coated tapping-mode atomic-force-microscope tip. Linear I-V characteristics are observed and resistance from the slope is decreased, as the contact force is increased. Using the Hertz model, the electrical resistivity, ρ, is estimated to be ρ ∼1 Ωcm consistent with that of bulk PPy film. In comparison, we report the I-V characteristics of PPy nanotube (diameter of 250 nm) in lateral electrodes configuration. To align the PPy nanotube, we applied the ac electric field across the lateral electrodes patterned on the SiO₂ substrate

[en] This report described the experimental apparatus and the operation for the Na-CO₂ reaction experiments, and the analysis results through the experiments on the temperature and pressure of the sodium and gas flow

[en] The pressure drop test was performed to verify the hydraulic performance of hybrid type spacer grid. And also, for the comparison of the hydraulic performance of the hybrid type spacer grid, the pressure drop tests were performed for the splitted vane type spacer grid (FOCUS) which had been developed in KWU and the reference spacer grid which has no vanes. The tests were conducted at the hydraulic test loop facility, Cold Test Loop-I. Three spacer grids are installed on the 5x5 fuel assembly for the tests. The differential pressure drops are measured for the spacer grids and the fuel rods. The loop flow rate, system pressure and temperatures are measured and controlled for the test conditions. The pressure loss coefficient of the plain spacer grid is lowest. The pressure loss coefficient of the hybrid spacer grid is 7∼10 % higher than the plain spacer grid due to the mixing vane resistance. The friction loss coefficients of the fuel rods are different from upper and lower part. There is need to correct the locations of the pressure taps to avoid the local unstable region due to the spacer grids

[en] This presentation deal with evolution of Technical Cooperation in nuclear science and technology and covers the following: Determining factors affecting global status of spent fuel management; Statistics: TC disbursements for selected activities; Progress to date: country examples; Future role of the IAEA. In achieving the established objectives steady progress was made, collaborative effort exists between participating Member States and IAEA to accomplish the objectives, IAEA is ready to expand TCP to strengthen management of Spent nuclear fuel (SNF) technology

[en] The abrupt current transition mechanism in p-type GaAs has been determined from numerical analysis with a model consisting of the current transport equations, the continuity equations, and the Poisson's equation, which are self-consistently coupled with the extended Brinkman-Rice picture and the Mott criterion. Results from the proposed model show clear evidence of a semiconductor-metal transition in p-type GaAs at doping density below the critical concentration and give an explanation of the abrupt current jump observed in the current density (J) versus voltage (V ) characteristics. The doping-density dependencies of the J - V characteristics are analyzed, and these results are compared to those from previously reported experimental observations.

[en] In the design of sodium_cooled fast reactor (SFR), the integrity of fuel is monitored as part of core monitoring. To perform this function, the fuel failure is real-time monitored and the continuous operation of reactor is determined by the severity of fuel failure. As any fuel failure is detected, then the failed fuel is located and the results are henceforth provided for the operation of failed fuel replacement. Any pin-hole or failure on the fuel clad makes cause of transferring a fission product into the core and then contaminates whole integrated reactor. When a fuel failure occurs, the system designed in this study monitors the integrity of fuel through detecting the fission gases and the delayed neutron radiated from failed fuel. To perform system functions, the system applies two types of detectors. One is a high purity germanium detector (HP-Ge) for monitoring the gamma-ray of fission gases existing in the reactor head and the other is a fission chamber for detecting the delayed neutron within the intermediate heat-exchanger (IHX). In addition a gas analyzer is used to detect and sort the tag gases leaked from each fuel so as to locate the failed fuel. This study describes three methods applied to the design of failed fuel monitoring system and the design concept of an integrated monitoring system based on them. Accordingly this report can be applied to the conceptual and basic design of SFR failed fuel monitoring system to be performed in the near future

[en] This document outlines the test results for the strength tests of the CANFLEX fuel bundle. Strength tests are performed to determine and verify the amount of the bundle shape distortion which is against the side-stops when the bundles are refuelling. There are two cases of strength test; one is the double side-stop test which simulates the normal bundle refuelling and the other is the single side-stop test which simulates the abnormal refuelling. the strength test specification requires that the fuel bundle against the side-stop(s) simulators for this test were fabricated and the flow rates were controlled to provide the required conservative hydraulic forces. The test rig conditions of 120 deg C, 11.2 MPa were retained for 15 minutes after the flow rate was controlled during the test in two cases, respectively. The bundle loading angles of number 13- number 15 among the 15 bundles were 67.5 deg CCW and others were loaded randomly. After the tests, the bundle shapes against the side-stops were measured and inspected carefully. The important test procedures and measurements were discussed as follows. (author). 5 refs., 22 tabs., 5 figs

[en] This project is aimed to support external users for the effective use of HANARO. The total number of projects selected as the beneficiary of the supporting program by MEST was 21 in this year. We supported 10 projects(1project is dropped) selected on the field of neutron beam utilization. In the field of materials and nuclear fuel irradiation test the 3 projects were selected and supported. In the fields of neutron activation analysis and radioisotope production, the number of selected and supported projects were 4 and 3 respectively. In order to broaden potential user base, maximize instrument utilization, and enhance cooperation with industries, universities and institutes, practice-oriented HANARO user training courses were held for neutron beam utilization and materials and nuclear fuel irradiation fields (total 3). This project is a kind of the user-based supporting program for the maximize of HANARO utilization. The development products and the ideas and suggestions of users obtained through this projects will be collected and applied to the development of next new facilities