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DESIGN OF LSDS FOR ISOTOPIC FISSILE ASSAY IN SPENT FUEL
Lee, Yongdeok,Park, Chang Je,Kim, Ho-Dong,Song, Kee Chan Korean Nuclear Society 2013 Nuclear Engineering and Technology Vol.45 No.7
A future nuclear energy system is being developed at Korea Atomic Energy Research Institute (KAERI), the system involves a Sodium Fast Reactor (SFR) linked with the pyro-process. The pyro-process produces a source material to fabricate a SFR fuel rod. Therefore, an isotopic fissile content assay is very important for fuel rod safety and SFR economics. A new technology for an analysis of isotopic fissile content has been proposed using a lead slowing down spectrometer (LSDS). The new technology has several features for a fissile analysis from spent fuel: direct isotopic fissile assay, no background interference, and no requirement from burnup history information. Several calculations were done on the designed spectrometer geometry: detection sensitivity, neutron energy spectrum analysis, neutron fission characteristics, self shielding analysis, and neutron production mechanism. The spectrum was well organized even at low neutron energy and the threshold fission chamber was a proper choice to get prompt fast fission neutrons. The characteristic fission signature was obtained in slowing down neutron energy from each fissile isotope. Another application of LSDS is for an optimum design of the spent fuel storage, maximization of the burnup credit and provision of the burnup code correction factor. Additionally, an isotopic fissile content assay will contribute to an increase in transparency and credibility for the utilization of spent fuel nuclear material, as internationally demanded.
Afreeca 인터넷 방송 서비스에서의 사용자 행동 분석
박용덕(Yongdeok Park),박건우(Kunwoo Park),권태경(Taekyoung Kwon),최양희(Yanhee Choi) 한국정보과학회 2008 한국정보과학회 학술발표논문집 Vol.35 No.1
광대역 통신망의 발달과 더불어 정보통신 및 디지털 영상 기기의 대중화로 인해 텍스트 및 사진 위주의 정보 전달과 달리 소리와 영상을 기반으로 한 멀티미디어 정보 전달이 우리 생활 속의 일부로 자리 잡고 있다. 이러한 멀티미디어 정보 전달에 있어 트래픽 분산을 위한 P2P(Peer to Peer) 방식의 실시간 스트리밍 서비스에 대해 많은 연구가 있었다. 본 논문에서는 "사용자"를 중심에 두고 사용자의 서비스 이용에 대한 패턴을 파악하기 위해 사용한 "Afreeca" 인터넷 방송서비스와 사용자 패턴 수집 방법에 대해 설명한 다음, 수집된 결과를 이용하여 컨텐츠 특성별 사용자 패턴의 차이와 특징을 분석해 보았다.
DEVELOPMENT OF LEAD SLOWING DOWN SPECTROMETER FOR ISOTOPIC FISSILE ASSAY
Lee, YongDeok,Park, Chang Je,Ahn, Sang Joon,Kim, Ho-Dong Korean Nuclear Society 2014 Nuclear Engineering and Technology Vol.46 No.6
A lead slowing down spectrometer (LSDS) is under development for analysis of isotopic fissile material contents in pyro-processed material, or spent fuel. Many current commercial fissile assay technologies have a limitation in accurate and direct assay of fissile content. However, LSDS is very sensitive in distinguishing fissile fission signals from each isotope. A neutron spectrum analysis was conducted in the spectrometer and the energy resolution was investigated from 0.1eV to 100keV. The spectrum was well shaped in the slowing down energy. The resolution was enough to obtain each fissile from 0.2eV to 1keV. The detector existence in the lead will disturb the source neutron spectrum. It causes a change in resolution and peak amplitude. The intense source neutron production was designed for ~E12 n's/sec to overcome spent fuel background. The detection sensitivity of U238 and Th232 fission chamber was investigated. The first and second layer detectors increase detection efficiency. Thorium also has a threshold property to detect the fast fission neutrons from fissile fission. However, the detection of Th232 is about 76% of that of U238. A linear detection model was set up over the slowing down neutron energy to obtain each fissile material content. The isotopic fissile assay using LSDS is applicable for the optimum design of spent fuel storage to maximize burnup credit and quality assurance of the recycled nuclear material for safety and economics. LSDS technology will contribute to the transparency and credibility of pyro-process using spent fuel, as internationally demanded.