[en] Detection of creep damages in centrifugally cast HK-40 reformer furnace catalyst tube is a common problem for the safety and scheduled operation of chemical plants. This study was focused on the development of an automatic ultrasonic scanning device with which the creep damage of welded zone of HK-40 reformer tubes is detected and evaluated

[en] The correlation of isotope composition of neodymium with the burnup in the spent U₃Si/Al fuel from Hanaro reactor has been investigated experimentally. The total burnup as determined by Nd-148 method. The contents of the U, Pu and Nd elements and their isotope compositions, after their separation from the spent fuel samples were determined by isotope dilution mass spectrometric method using ²³³U, ²⁴²Pu and ¹⁵⁰Nd as spikes. The burnup values, U and Pu isotope compositions, and Pu/U ratios determined were expressed by the correlation with neodymium isotopes. The correlations between neodymium isotopes and burnup parameters in the spent U₃Si/Al fuel were compared with those in PWR uranium dioxide fuel

[en] Electrodeposition system consisting of deposition cell, Pt electrode, planchet and cell holder was installed in connection with constant power supplier. Optimum condition for the electrodeposition of Am-241 and Cm-244 was found to be 1200 mA and one hour in 0.1MNaHSO₄-0.53MNa₂SO₄ buffer solution. Diethylenetriaminepentaacetic acid(DTPA) gave a decreasing effect of electrodeposition of Am-241. Martrix effect of electrodepositions due to sample media with or without organic compounds(DTPA-lactic acid) was not found in a single nuclide or both of Am-241 and Cm-244. The average deposition yields are 91.7±1.7% in Am-241 and 99.2±0.97 in Cm-244, respectively. This method was applied to the determination of Am-241 and Cm-244 in spent unclear fuels with alpha-spectrometry

[en] Microstructure and mechanical properties of most steels change by heat treatment. Such variation of structure and properties of steel cause an impedance change on electromagnetic induction coil. The objective of this study is, by searching the relationship between the mechanical property or microstructural changes and impedance value of induction coil, to examine the applicability of a monitoring the heat treated condition of products nondestructively

[en] Accurate measurement of green density of compacted part in the powder metallurgy industry is rather fundamental but extremely important process that decide the quality of the sintered part. In case of green sheet P/M product, the green density as well as the distribution of the density must be examined for the same reasons. Currently in most cases, density measuring process is being performed applying conventional Archimedes principles. However this method is not only time-consuming but also often inaccurate because of the inherent nature of the process, such as part sectioning, closing of surface porosity with wax and weighing in air and in water. Therefore, it is necessary to develop a faster and more accurate method to measure the density of green sheet P/M product. In this work, a nondestructive density measurement device using gamma-ray absorption principles was constructed and the optimum condition for measuring green density of P/M sheet and its distribution was sought. The results showed that this method was very effective in terms of measuring time and accuracy

[en] Ultrasonic backscattering waves were measured to determine fiber orientation and lay-up order of fiber-reinforced composites. The experiments have been carried out by using focused transducer and water immersion method. As the polar angle, azimuthal angle and frequency changed. Variation of the amplitude of backscattered wave were observed. Especially, the maximum backscattering peaks was observed when fiber orientation was normal to the propagation vector of incident ultrasonic pulse. The results showed that the bend width of backscattering peak which scattered from upper layer was wider than that from lower layer. Therefore, from bend widths of bacscattering peak, lay-up order of CFRP can be determined.

No abstract available

[en] In this research, nondestructive test using a radioisotope, ²⁴¹Am gamma-ray, was accomplished in order to evaluate the fiber volume fraction of the accumulated composite layers such as glass fiber/epoxy and carbon fiber/epoxy. Attenuation coefficients of the fiber and resin were measured respectively by NaI(T1) detector. The fibers volume fraction was measured for various thickness of composite layers between 2 and 20mm. Fiber volume fraction of the composite layers were also measured for various amount of fibers. The experimental errors from nondestructive test using gamma-ray were in the range of ±1∼2.5% in comparison with those from observation by optical microscopy. By selecting the optimum energy and activity of radioisotope, this method can provide a new means for the evaluation of the fiber volume fraction

[en] The ultrasonic method, which is well known as non-destructive test method, is widely used to evaluate the material damage caused by degradation practically. However, this method is just used for measuring the crack size and the thickness loss of tube. The purpose of this study is to investigate the applicability of the ultrasonic technique for the evaluation of carburized material and to suggest the correlations between the ultrasonic characteristics and carburized degradation. The miniaturized specimens(40x20x6.3mm) are adopted from the HK-40 (25Cr-20Ni-0.4C) centrifugal cast tube after carburization treatment. Carburization was carried at 1200 .deg. C by the pack method. The results of ultrasonic test present that the longitudinal wave velocity increased with the increase of carburized depth. The correlation between the longitudinal wave velocity and carburization was changed with the density and Young's modulus. Therefore, the average velocity in the materials carburized for 336 hours and the unused one were 5,840 m/s and 5,755 m/s at 5 MHz, respectively. With the obtained results from this study, it can be recognized that the technique using the ultrasonic velocity property is very useful method to evaluate the degree of carburized material non-destructively

[en] The reagent vial wastes disposed of in hospital every year are usually polluted by the beta-emitted nuclide having short half-life. Their activities are very low to the extent of background. In case of the beta-emitted nuclide separation, it is so ineffective and complex that more simple method is needed. In this study, new beta-ray measure method to solve these problems is proposed. By using new method, the real activity could be determined by predicting the measurement efficiency of the nuclide from the simulation of detection method and by measuring with ultra low level radioactivity detection system. Result from EGS4(Electron-Gamma Shower) simulation and SBD(Surface Barrier Detector) measurement were compared by using the point source of Ba-133 to verify the adequacy of simulation. About ± 17% error between the theoretical simulation and the measurement was observed. The quantity of radiation without measuring the standard source could be determined by using the theoretical detection efficiency and the SBD measurement result