[en] The detective quantum efficiency (DQE) of solid state detectors using cadmium tungstate scintillation crystal for x-ray computed tomography (CT) and various factors, which affect the DQE, were estimated by calculations using analytic model and Monte Carlo method. The scattered photon intensity and the cross talk ratio were simulated using MCNP code, and their reduction by collimators and spacers was calculated for their various sizes. The effects of collimators and spacers on the geometric efficiency were also taken into consideration. The absorption efficiency of cadmium tungstate crystal and the light col ection efficiency onto photodiodes surface for various surface conditions of crystal and reflectors were also calculated using DETECT code. As the results, there was no significant effect of cross talk and variations of the collection efficiency were very large and strongly affected the detector sensitivity. The absorption efficiency increased and the light collection efficiency decreased as the crystal height increased. Therefore, the critical height existed, that made the product of both efficiencies maximum. These estimation methods and results can be used to design or to evaluate performances of detection system for computed tomography

[en] Dual energy x-ray radiography can be used to separate soft and dense-material images for medical and industrial applications. It can be performed successfully with a line-scanning system because of its scatter-free nature. With area detectors, however, scattered radiation also contributes to the signal. This undesired behavior of scattered x-ray photons in radiography causes serious degradation of contrast in observed images, and poor separation of soft- and dense-material images. The percentage of scattered photons is typically 60 % to 70 % in the lungs and 80 % to 95 % in the mediastinum for a standard PA chest radiograph. Even though anti-scatter grids can reduce the scatter fractions to 20 % to 30 % in the lungs and 40 % to 60 % in the mediastinum, dual-energy radiography requires additional scatter correction. Several methods for scatter correction have been suggested to improve results. Such methods, however, require additional lead blocks or detectors, and additional exposures to estimate the scatter fraction for every correction. Others have used only one or two convolution kernels, even though the scatter point spread functions have different shapes as a function of object thickness. A new scatter correction method in dual-energy radiography called the TB scatter correction method is suggested by this study, based on iterative thickness estimation using unique scatter point spread functions. The TB correction method uses information from a dual-energy algorithm to correct the images. In order to verify the effectiveness of this method, a set of MCNP simulation and experiment was performed. The scatter information for each combination of thickness of two materials, aluminum-water phantom in simulation and aluminum-acryl phantom in experiment, was represented in the form of a scatter point spread function. Scatter point spread functions can be either simulated, or measured and induced by Fourier transform. The way to measure the scatter point spread function is also proposed, and it may give the great possibility for various other applications to the TB correction method. In TB correction, based on the uncorrected signals, the thickness of each material is calculated by a conventional dual-energy algorithm. The scatter information of corresponding thickness from the database of the scatter spread function is then used to correct the original signals. For the aluminum-water simulation, the iteration of TB scatter correction reduced the relative-thickness error from 32 % to 3.4 % in aluminum, and from 41 % to 2.8 % in water. As the experimental verification using aluminum and acryl, the TB correction method reduced the relative errors by 50 % to 5 %. The suggested TB scatter correction method has several merits over conventional methods. It does not use any additional hardware or exposure, and has better performance than others because of nearly exact correction in spatial distribution of scatter signals using material and thickness-dependent unique scatter point spread functions. One drawback of the proposed approach arises from a characteristic of the scatter point spread function. Scatter point spread functions with several different orders of object materials or with a different thickness of air gap may have different shapes and magnitudes. In contrast with CT, dual-energy radiography does not specify the arrangement of the material (i.e., which material is located on the top and which is on the bottom) These effects were not taken into account in this study, since preliminary simulation results indicated that these differences were insignificant in the range of interest for this study. And moreover, an idea for the modified TB correction method is suggested in this study for the application to chest radiography. Overall, the TB correction method considerably improved the dual-energy imaging. The TB scatter correction method can be applied to two-material dual-energy radiography such as mammography, contrast imaging, and industrial inspections. As additional application examples of dual-energy radiography, two works are also presented in this study. Preliminary experiments have been performed for detection of organic materials focusing on organic material detection by different high-energy detectors, which are use CsI and CWO as a scintillator. Organic and inorganic materials were successfully separated in a thin objects range. Generally, plastic explosives contain a high concentration of organic material, especially nitrogen and oxygen, and have a higher density than other organic materials. Using these characteristics, the organic material detection capability of a dual-energy method can be applied to an inspection system with simple modification of conventional systems. Volume estimation of solitary pulmonary nodules in chest radiography using dual-energy algorithm is suggested as the second application. Successful elimination of rib shadows with tissue-selective imaging and volume estimation of nodule with background rejection were performed. This method gave an accurate estimation of isolated solitary pulmonary nodules from the lung boundary, but with some errors for overlapping with the lung boundary. This estimation method, based on dual-energy subtraction, could be applied to detection and measurement of lung nodules in chest radiographic CAD. Even though those works do not use scatter correction method, further research may show other applications for the dual-energy scatter correction method

[en] KSC-4 transport cask and handling equipment should be safely stored and managed in the radiation controlled area. Therefore, it is necessary to approve the change of the PIEF’s warehouse to a radioactive waste storage facility. The purpose of this study is to obtain approval for change of license to the radioactive waste storage facility and to derive a plan for decontamination and decommissioning of KSC-4 cask. Basic data for decontamination and decommissioning of the transport cask were obtained by analyzing the decontamination and decommissioning technology for the spent fuel transport cask and nuclear facilities. The storage, decommissioning status and recyclability of unused cask were analyzed, and future treatment plan and recyclability of transport cask was suggested. The amount of radioactivity of the transport cask was predicted based on the results of measuring the internal radiation dose rate and contamination level of the KSC-4 cask. An analysis of the gas sampling method of the transport cask was performed and the concept of a gas sampling equipment was derived. An application for change of license has been submitted to the authority to convert PIEF’s warehouse into a radioactive waste storage facility. In addition, Q&A was conducted for two times of licensing review. After obtaining the change of license for the existing RG laboratory, the moving and installation of the equipment was completed, and applications for change of license the RI/NM laboratory were prepared. The results obtained from this study will be available as basic data for change of license to a radioactive idle equipment storage facility and decontamination & decommissioning of the KSC-4 cask

[en] In the context of this report, the basic concept of UNARMS was described and the development status and the process of KAERI's C/S and LANL's UNARM was described. UNARM system was divided into hardware and software at this report. At UNARM's hardware, MiniGRAND that measures neutron and gamma, MiniADC that measures energy spectrums of Uranium and Cesium, ISR/AMSR that measures neutron and camera system were described about features and use methods. And ILON that can be connected to instruments was described. MIC program that is designed for unattended collection and saving of data from multiple, distributed data acquisition instruments was explained at UNARM's software. Review programs that can be analysis data from saved data file were verified. Finally, the analysis of LANL laboratory's UNARM in operation was performed and upgraded as system that application is possible. And new review program was developed according to the upgrade system

[en] Highlights: • The possible ways to link between unit steps of pyroprocessing were discussed. • These linkage options affect the safeguards and proliferation resistance aspects. • Chance for representative sample and less losses is essential for the head-end process. • Salt transfer with less hold-up and inventory measurability is key main process. • This study is aimed at a further investigation with process technical aspects. - Abstract: Pyroprocessing technology has been actively developed at KAERI as one of the options to address the national spent fuel management issue. As much as the unit process development itself, the linkage method between each unit process is also of importance. There may be different linkage options between a set of two process units, or different options caused by different technologies for one of two unit processes connected to each other. The linkage method may affect the loss of nuclear materials and distribution of fission products, which are essential from the safeguards and proliferation resistance points of view. In this study, different technology options for some of the major process steps and possible linkage options were identified, and aspects of their proliferation resistance including the impact on the safeguards are discussed. Several options for decladding and feeding to electro-reduction, dross and the residual salt treatment of reduced materials as well as feeding to electro-refining, and salt transfer from electro-refining to electro-winning were identified and their technical and proliferation resistance aspects were analyzed. This study does not conclude any ranking of each option or suggest which option is the best. It is important to note that the objectives to review the process and linkage options are to give the basic characteristics and technical information related to safeguards measures and proliferation resistance and to suggest a conceptual idea for certain options to investigate further and enhance those aspects

[en] In dual-energy radiography using an area detector, it is needed to remove or correct scatter effects for proper separation of soft- and dense-component images. We suggest a new scatter correction method in dual-energy radiography. In the method, two-material object is separated as thickness images by dual-energy algorithm. Using this thickness information and a look-up table of scatter spread functions, scatter components are estimated and corrected in high- and low-energy radiographic images. We have simulated aluminum and water phantom images using MCNP code, and compared uncorrected and corrected resultant separated images. Average thickness-relative errors decrease from 32 % to 3.4 % for aluminum and 41 % to 2.8 % for water

[en] The Generation IV International Forum (GIF) emphasizes proliferation resistance and physical protection (PR&PP) as one of the main aspects to be considered regarding future nuclear energy systems (NESs). It was refined over the years through several case studies. This paper presents the current status of PRPPEM, researches that KAERI has done, and future WG's activities to update them. The experience in the process of developing and testing the PRPPEM formed the basis for a close interaction with the GIF SSCs/pSSCs in 2011 and gave light to a joint document which is emphasizing the PR and PP characteristics of the six GIF reactor technologies. This activity will not only shed light on PR and PP advancements of the current system designs, but also inform the PRPPWG future activities. The experience in the process of developing and testing the PRPPEM formed the basis for a close interaction with the GIF SSCs/pSSCs in 2011 and gave light to a joint document which is emphasizing the PR&PP characteristics of the six GIF reactor technologies. This activity will not only shed light on PR&PP advancements of the current system designs, but also inform the PRPPWG future activities.

[en] Nuclear power accounts for more than 30 percent of power production in Korea. Its significance has annually been increased. Disposal spent fuel containing uranium, transuranic elements, and fission products is unavoidable byproduct of nuclear power production. it is recognized that finding appropriate sites for interim storage of disposal spent fuel is not easy because isolated sites should be required. Pyro-processing technology, Pyro-processing should be operated under high radiation environment in hot-cell structures. Because of this reason, all workers should be unauthorized to access inside the hot-cell areas under any circumstances except for acceptable dose verification and a normal operation should be remotely manipulated. For the reliable normal operation of pyroprocessing, it is noted that an evaluation of the space dose distribution in the hot-cell environments is necessary in advance in order to determine which technologies or instruments can be utilized on or near the process as the Integrated Operation Verification System (IOVS) is measured. Not like the electroreduction and electro-refining hot-cells, the head-end hot-cell equips Camera Radiation Detector (CRD) in which plutonium is securely measured and monitored for the safeguard of the pyro-processing. Results have been obtained using F2 surface tally in order to observe the magnitude of the gamma-ray and neutron flux which pass through the surface of the process cell. Furthermore, T-mesh tally has also been used to obtain the space dose distribution in the headend hot-cell. The hot-cell was divided into 7,668 cells in which each dimension was 1 x 1 x 1m for the T-mesh tally. To determine the position of the CRD and the surveillance camera, divergent approaches were required. Because the purpose of the CRD which contains a gamma-ray detector and a neutron detector is to identify the material composition as the process proceeds, the position in which detectable flux is exposed is required, whereas excess flux can deteriorate the performance of the CRD and shorten its usage of period

[en] The PRIDE (PyRoprocessing Integrated inactive DEmonstration) is an engineering-scale pyroprocessing test-bed facility that utilizes depleted uranium (DU) instead of spent fuel as a process material. As part of the ongoing effort to enhance pyroprocessing safeguardability, UNDA (Unified Non-Destructive Assay), a system integrating three different non-destructive assay techniques, namely, neutron, gamma-ray, and mass measurement, for nuclear material accountancy (NMA) was developed. In the present study, UNDA's NMA capability was evaluated by measurement of the weight, "2"3"8U mass, and U enrichment of oxide-reduction-process feed material (i.e., porous pellets). In the "2"3"8U mass determination, the total neutron counts for porous pellets of six different weights were measured. The U enrichment of the porous pellets, meanwhile, was determined according to the gamma spectrums acquired using UNDA's NaI-based enrichment measurement system. The results demonstrated that the UNDA system, after appropriate corrections, could be used in PRIDE NMA applications with reasonable uncertainty. It is expected that in the near future, the UNDA system will be tested with next-step materials such as the products of the oxide-reduction and electro-refining processes. - Highlights: • PRIDE UNDA has been developed and characterized for nuclear material accountancy. • The performance was evaluated with pyroprocessing feed material: UO_2 porous pellets made of depleted uranium. • Total neutron counting, U enrichment, and mass measurements were performed for porous pellet samples of various weights. • "2"3"8U mass determination by neutron measurement showed the relative difference of 0.79–13.28% compared with actual mass. • The enrichment measured by gamma-ray spectroscopy was significantly underestimated by 42.07%.

[en] The Korea Atomic Energy Research Institute (KAERI) has developed a safeguards technology for pyroprocessing based on the Safeguards-By-Design (SBD) concept. KAERI took part in a Member-State Support Program (MSSP) to establish a pyroprocessing safeguards approach. A Reference Engineering-scale Pyroprocessing Facility (REPF) concept was designed on which KAERI developed its safeguards system. Recently the REPF is being upgraded to the REPF+, a scaled-up facility. For assessment of the nuclear-material accountancy (NMA) system, KAERI has developed a simulation program named Pyroprocessing Material Flow and MUF Uncertainty Simulation (PYMUS). The PYMUS is currently being upgraded to include a Near-Real-Time Accountancy (NRTA) statistical analysis function. The Advanced Spent Fuel Conditioning Process Safeguards Neutron Counter (ASNC) has been updated as Non-Destructive Assay (NDA) equipment for input-material accountancy, and a Hybrid Induced-fission-based Pu-Accounting Instrument (HIPAI) has been developed for the NMA of uranium/transuranic (U/TRU) ingots. Currently, performance testing of Compton-suppressed Gamma-ray measurement, Laser-Induced Breakdown Spectroscopy (LIBS), and homogenization sampling are underway. These efforts will provide an essential basis for the realization of an advanced nuclear-fuel cycle in the ROK