[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 including this project in this year. We supported 1,850 hr measurements for the 24 requests of the 16 projects selected on the field of neutron beam utilization. In the field of materials and nuclear fuel irradiation test the 2 projects were selected and supported for 108 samples. In the fields of neutron activation analysis and radioisotope production the number of selected and supported projects was 1 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. The online neutron beam time allocation system was developed and applied successfully for the HRPD in this year. We are planing to apply this system to other neutron beam instruments in the near future. 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. Also, by using the 'HANARO utilization and research information management system(HANARO4U)' we construct the research network among users at industries, universities and institutes. This network is expected to increase HANARO utilization and enhance productivity of the facilities

[en] In the steel making process, it's hard to control the amount and the distribution of nitrogen. Also nitrogen makes spots in the PTA analysis. So it's very important to evaluate the effect of nitrogen on the PTA for the analysis of boron distribution. The objects of this report are like these. - Evaluation of nitrogen effect for analysis of boron distribution by PTA - Evaluation of nitrogen distribution of the boron-free steel by PTA

[en] The particle tracking autoradiography(PTA) is a very useful method to investigate the boron distribution through the large sample area. The PTA method for boron uses the phenomenon that boron irradiated by neutron emits Li-ion and alpha particle; boron distribution can be obtained by observing the traces of the emitted particles. At HANARO in KAERI, a study for observing the boron distribution has been performed for several years. Recently, the experimental techniques were improved to provide reliable images for samples of various composition. In this report, the PTA method and experimental techniques were described in detail and the experimental results of the sample polishing, the amount of neutron irradiation and the etching time were reported. As a result, the optimum conditions for the analysis of boron distribution with respect to the amount of added boron were appeared

[en] Boron is very useful element in steels to improve the mechanical properties. In steel matrix, boron exist several types such as solute, segregation in grain boundary and many kinds of precipitate, which influence the properties of the steel. But, detecting of boron using X-ray or ion-beam is not easy because boron is very light atom than iron. However neutron gives the clear image of boron distribution from the particle tracking autoradiography (PTA) method. The PTA method of boron uses the phenomenon that boron irradiated by neutron emits Liion and alpha particle. Boron distribution can be obtained by observing the traces of the emitted Li-ion and alpha particle. At HANARO, the study for observing of boron distribution has been performed several years ago. Recently, the experimental techniques were improved for the reactor power of 30 MW. In this paper, improved experimental techniques were described and some results for boron added low-carbon steel plate were introduced

[en] Hot-rolled sheet steels are normally supplied to satisfy such customer-defined specifications as yield strength, tensile strength and total elongation. Typically, as yield strength (or yield-to-tensile ratio) increases, relative ductility decreases. Boron-added low carbon steel is recommended for the automotive parts because of its excellent ductility. While the effect of boron on tensile strength is known through its influence on the hardenability, its influence on the evolution of ferrite morphology and elongation is still controversial. In this study, the effect of nano-sized precipitates and addition of boron on the mechanical properties of low carbon steels was investigated to make clear the precipitation behavior with rolling temperature. In order to quantitatively investigate the behavior of the precipitates in boron-added (BA) and boron-free (BF) steels during rolling process, a small angle neutron scattering (SANS) and a neutron powder diffraction technique were used. In addition, we describe the influence of hot rolling temperature on the mechanical properties of the boron-added low carbon steels

[en] A precise measurement of the residual stress magnitude and distribution is an important factor to evaluate the lifetime or safety of the materials, because the residual stress affects the material properties, such as the strength, fatigue, etc. In the case of a fighter jet, the lifetime and safety of the parts of the landing gear are more important than that of a passenger airplane because of its frequent take offs and landings. In particular in the case of training a fighter jet, a precise evaluation of life time for the parts of the landing gear is strongly required for economic reason. In this study, the residual stress of a part of the landing gear of the training fighter jet which is used to fix the landing gear to the aircraft body was investigated. The part was used for 2000 hours of flight, which corresponds to 10 years. During this period, the fighter jet normally takes off and lands more than 2000 times. These frequent take off and landing can generate residual stress and cause a crack in the part. By measuring the neutron diffraction peaks, we evaluated the residual stress of the landing gear part

[en] The Particle Tracking Autoradiography(PTA) technique based on the 10B(n, α)7Li fission reaction with a solid detector(LR115 film) has become a powerful tool for studying the behavior of boron distribution in materials. In this study, it is investigated in changing the method that the film on the specimen attach, the etching time to film and the surface roughness of the specimens

[en] Principles of residual stress measurements by neutron diffraction and the residual stress instrument installed at 30MWt HANARO reactor in KAERI are considered. In-depth residual stress distribution was measured in aluminum VAMAS round robin sample and welded stainless steel plate, which showed high ability of the instrument for the stress measurements in components

[en] Neutron scattering is usually classified into classes according to the measuring information. One is the elastic neutron scattering which can give us structural information of a material and the other is the inelastic neutron scattering which concerns on the dynamics inside the material. 'Elastic' means that there is no energy change in the neutron during the interaction (scattering) with a matter. Therefore the elastic scattering is easier to understand and to carry out an experiment than the inelastic scattering. Since the commissioning of the Korean modern research reactor (HANARO) in 1995, elastic neutron scattering instruments have been constructed and open to the public users, sequentially

[en] The residual stress instrument installed at HANARO reactor in KAERI is described and the results of residual stress measurements in different samples are described to depict the present status of the residual stress measurements at HANARO reactor. The perspectives for the future development of the instrument are outlined.