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김종운,홍서기,이영욱 한국원자력학회 2014 Nuclear Engineering and Technology Vol.46 No.2
Scattering source calculations using conventional spherical harmonic expansion may require lots of computation time totreat full-coupled three-dimensional photon-electron transport in a highly anisotropic scattering medium where their scatteringcross sections should be expanded with very high order (e.g., P7 or higher) Legendre expansions. In this paper, we introduce a modified scattering kernel approach to avoid the unnecessarily repeated calculations involvedwith the scattering source calculation, and used it with parallel computing to effectively reduce the computation time. Itscomputational efficiency was tested for three-dimensional full-coupled photon-electron transport problems using our computerprogram which solves the multi-group discrete ordinates transport equation by using the discontinuous finite element methodwith unstructured tetrahedral meshes for complicated geometrical problems. The numerical tests show that we can improvespeed up to 17~42 times for the elapsed time per iteration using the modified scattering kernel, not only in the single CPUcalculation but also in the parallel computing with several CPUs.
우명현,홍서기 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.11
In this paper, a new multi-group neutron-gamma transport calculation code system STRAUM-MATXST for complicated geometrical problems is introduced and its development status including numerical tests is presented. In this code system, the MATXST (MATXS-based Cross Section Processor for SN Transport) code generates multi-group neutron and gamma cross sections by processing MATXS format libraries generated using NJOY and the STRAUM (SN Transport for Radiation Analysis with Unstructured Meshes) code performs multi-group neutron-gamma coupled transport calculation using tetrahedral meshes. In particular, this work presents the recent implementation and its test results of the Krylov subspace methods (i.e., Bi-CGSTAB and GMRES(m)) with preconditioners using DSA (Diffusion Synthetic Acceleration) and TSA (Transport Synthetic Acceleration). In addition, the Krylov subspace methods for accelerating the energy-group coupling iteration through thermal up-scatterings are implemented with new multi-group block DSA and TSA preconditioners in STRAUM.
iBEST: A PROGRAM FOR BURNUP HISTORY ESTIMATION OF SPENT FUELS BASED ON ORIGEN-S
김도연,홍서기,안길훈 한국원자력학회 2015 Nuclear Engineering and Technology Vol.47 No.5
In this paper, we describe a computer program, iBEST (inverse Burnup ESTimator), that wedeveloped to accurately estimate the burnup histories of spent nuclear fuels based onsample measurement data. The burnup history parameters include initial uraniumenrichment, burnup, cooling time after discharge from reactor, and reactor type. Theprogram uses algebraic equations derived using the simplified burnup chains of majoractinides for initial estimations of burnup and uranium enrichment, and it uses theORIGEN-S code to correct its initial estimations for improved accuracy. In addition, wenewly developed a stable bisection method coupled with ORIGEN-S to correct burnup andenrichment values and implemented it in iBEST in order to fully take advantage of the newcapabilities of ORIGEN-S for improving accuracy. The iBEST program was tested usingseveral problems for verification and well-known realistic problems with measurementdata from spent fuel samples from the Mihama-3 reactor for validation. The test resultsshow that iBEST accurately estimates the burnup history parameters for the test problemsand gives an acceptable level of accuracy for the realistic Mihama-3 problems.
하나로를 이용한 비파괴검사용 169Yb 저에너지 밀봉선원 개발
손광재,홍순복,장경덕,한현수,박울재,이준식,서기석,한인수,조운갑,이성식 한국비파괴검사학회 2008 한국비파괴검사학회지 Vol.28 No.1
169Yb industrial NDT sealed sources were developed by using Yb2O3 pellets as the target and demonstrated for their performance. To produce the pellets, optimal compacting and sintering conditions were determined experimentally. Source holders for 169Yb were designed and fabricated. After assembling an active source produced from HANARO with the developed source holder, a demonstration experiment was performed to compare the quality of the radiographs from 192Ir and soft X-rays. This demonstration study showed that the developed 169Yb produced better radiographs than 192Ir for a carbon steel with less than a 4mm thickness. 본 연구에서는 하나로 및 동위원소생산시설을 활용하여 비파괴 검사에 사용되는 169Yb 선원의 생산기술을 개발하였다. 천연 존재비 0.14%의 168Yb을 20% 까지 농축한 Yb2O3 분말을 표적물질로 사용하였고 이 물질의 방사화를 위하여 펠릿 성형기술 및 장치를 개발하였다. 중성자 조사를 위한 표적캡슐 및 기존 192Ir 선원 조사기에 사용이 가능한 선원 어셈블리를 설계·제작하였다. 또한, 하나로를 이용하여 약 5 Ci의 방사능 강도를 갖는 시험용 선원을 제작하여 192Ir 선원과 비파괴검사 성능을 비교 평가하여 선원의 우수함을 확인하였고 선원캡슐의 안전성시험을 실시하여 캡슐의 안전성을 검증하였다.
황대희,홍서기,김재천,김기동,김용균 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.67 No.8
RAON is a Korean heavy-ion accelerator complex that is planned to be built by 2021. Deuterons (53 MeV) and protons (88 MeV) accelerated by using a low-energy driver linac (SCL1) are delivered to the neutron production target in the Neutron Science Facility (NSF) to produce high-energy neutrons in the interval from 1 to 88 MeV with high fluxes of the order of 1012 n/cm2-sec. The repetition rate of the neutron beam ranges from 1 kHz to 1 MHz, and the maximum beam current is 12 μA at 1 MHz. The beam width is 1 2 ns. The high-energy and high-rate fast neutrons are used to estimate accurate neutron-induced cross sections for various nuclides at the NSF. A MICROMEGAS (MICRO Mesh Gaseous Structure), which is a gaseous detector initially developed for tracking in high-rate, high-energy physics experiments, is tentatively being considered as a neutron beam monitor. It can be used to measure both the energy distribution and the flux of the neutron beam. In this study, a MICROMEGAS detector for installation at the NSF was designed and investigated. 6Li, 10B, 235U and 238U targets are being considered as neutron/charged particle converters. For the low-energy region, 6Li(n,)t and 10B(n,)7Li are used in the energy range from thermal to 1 MeV. 235U(n,f) and 238U(n,f) reactions are used for high-energy region up to 90 MeV. All calculations are performed by using the GEANT4 toolkit.