• Nuclear Engineering and Technology
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• 제44권2호
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• pp.177-198
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• 2012

This paper reviews the fast reactor physics and computational methods. The basic reactor physics specific to fast spectrum reactors are briefly reviewed, focused on fissile material breeding and actinide burning. Design implications and reactivity feedback characteristics are compared between breeder and burner reactors. Some discussions are given to the distinct nuclear characteristics of fast reactors that make the assumptions employed in traditional LWR analysis methods not applicable. Reactor physics analysis codes used for the modeling of fast reactor designs in the U.S. are reviewed. This review covers cross-section generation capabilities, whole-core deterministic (diffusion and transport) and Monte Carlo calculation tools, depletion and fuel cycle analysis codes, perturbation theory codes for reactivity coefficient calculation and cross section sensitivity analysis, and uncertainty analysis codes.

• 한국의학물리학회지:의학물리
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• 제13권3호
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• pp.149-155
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• 2002

최근 들어 방사선 수송이론, 컴퓨터 하드웨어 성능, 및 병렬 연산 기법의 발전에 힘입어, 몬테카를로 기반의 선량계산 기법을 임상에 적용할 수 있게 되었다. 임상적용을 위해 개발된 몬테카를로 기반 선량계산 코드간의 계산 소요 시간과 정확도를 비교할 목적으로 제13차 ICCR (International Conference on the use of Computers in Radiation Therapy, Heidelberg, Germany, 2000) 학술대회에서 벤치마킹 절차서가 제안되었다. 최근, 본원에서도 임상적용을 목표로 28개의 인텔 펜티움 프로세서로 구성된 Linux cluster 시스템을 구축하고, 여기에 몬테카를로 선량계산을 위한 BEAMnrc 코드를 설치하였다. 본 연구의 목적은 위에서 제안된 벤치마킹 절차를 수행하여 본원에서 구축한 몬테카를로 선량계산 시스템의 정량적 성능 평가를 시도하고자 하는 것이었다. 벤치마킹 절차는 크게 다음의 세 과정으로 구성되어 있다. a) 30.5 cm $\times$ 39.5 cm $\times$ 30 cm 의 팬톰(5 ㎣ voxels) 에 대한 통계적 불확정도 2%이내 결과를 얻기 위한 광자선 선량계산 속도. b) 위 팬톰에 대한 전자선의 선량계산 속도. c) 비균질 평판 매질로 구성된 팬톰내 광자선 및 전자선의 선량계산 결과를 EGSr/PRESTA 계산 결과와 비교 제시. 18 MV 광자선에 대해 선량계산 속도 평가 결과 5.5분이 소용되었다. 전자선의 경우, 실제 계산 시간은 광자선에 비해 약 10배 정도 빨랐으나, 병렬 연산을 처리하기 위해 소용되는 추가 시간 때문에 전체 계산에 소요되는 시간은 광자선과 비슷하였다. 본 원에서 사용한 몬테카를로 코드는 EGSnrc로써 EGS4의 개선 버전으로 이들 간의 정확도 비교는 큰 의미가 없을 것으로 판단된다. 하지만 두 계산 결과가 기대했던 바와 같이 매우 잘 일치하였다. 결론적으로, 본원에서 구축한 몬테카를로 치료계획시스템은 임상적용에 무리가 없을 것으로 판단하였다. 추후 본 시스템을 본원에서 사용하는 상용 치료계획시스템과 인터페이스를 개발하여, 통합환경을 구축함으로써, 몬테카를로 기반의 치료계획시스템의 임상적용과 관련된 연구들을 수행해 나갈 계획이다.

• Structural Engineering and Mechanics
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• 제80권6호
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• pp.677-688
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• 2021

The building design codes and standards in many countries usually are either fully or partially adopted from the international codes. However, regional conditions like the quality of construction industry and different statistical parameters of load and resistance have essential roles in the code calibration of building design codes. This paper presents a probabilistic approach to assess the reliability level of adopted national building codes by simulating design situations and considering all load combinations. The impact of the uncertainty of wind and earthquake loads, which are entirely regional condition dependent and have a high degree of uncertainty, are quantified. In this study, the design situation is modeled by generating thousands of numbers for load effect ratios, and the reliability level of steel elements for all load combinations and different load ratios is established and compared to the target reliability. This approach is applied to the Iranian structural steel code as a case study. The results indicate that the Iranian structural steel code lacks safety in some load combinations, such as gravity and earthquake load combinations, and is conservative for other load combinations. The present procedure can be applied to the assessment of the reliability level of other national codes.

• 대한토목학회논문집
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• 제31권4A호
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• pp.323-329
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• 2011

대부분의 콘크리트구조설계기준은 구조물의 안전에 대한 여유를 확보하기 위해 하중계수 및 저항계수의 안전계수를 고려하고 있다. 이 안전계수는 하중과 저항의 통계적 불확실성을 적절하게 고려한 구조신뢰성 이론에 근거하여 결정되어야 하는데, 구조신뢰성 이론의 적용은 하중 및 저항에 대한 통계적 모델의 정립이 선행되어야 한다. 이 논문에서는 콘크리트 압축강도, 철근 항복강도 및 부재 단면치수의 통계적 변동성을 고려한 철근콘크리트 부재의 저항모델을 개발하였다. 통계모델 개발에 적용된 자료는 국내의 실험 및 시험 자료를 기초로 하였으며, 몬테칼로 시뮬레이션(Monte Carlo Simulation)기법을 적용하였다. 이 논문의 결과는 콘크리트 구조설계 기준의 검증 및 개정작업에 유용한 자료를 제공할 것으로 기대된다.

• 한국인터넷방송통신학회논문지
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• 제13권4호
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• pp.23-28
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• 2013

본 논문에서는 네트워크 코딩 및 파운 테인 코드를 사용한 간단한 양방향 전송 프로토콜을 제안한다. 특히, 제안된 기법의 경우, 두 소스는 중계기의 도움으로 서로에게 메시지를 전송하기위해 디지털 파운틴 코드를 사용한다. 또한, 중계기는 파운틴 코드와 네트워크 코딩을 사용하여 수신 받은 소스의 메시지를 서로의 소스에게 전송한다. 제안된 프로토콜의 성능을 평가하기위해 레일리 페이딩 채널에서 다양한 몬테-카를로 시뮬레이션을 통하여 전체 평균 처리량을 확인한다. 그 결과 제안된 프로토콜은 높은 SNR 영역에서 네트워크 코딩 기술을 사용하지 않는 두 방향 릴레이 전송 프로토콜보다 우수함을 확인하였다.

• Nuclear Engineering and Technology
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• 제52권9호
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• pp.1907-1916
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• 2020

In this work, the depletion capability implemented in Monte Carlo code MCS is investigated to predict the isotopic compositions of spent nuclear fuel (SNF). By comparison of MCS calculation results to post irradiation examination (PIE) data obtained from one pressurized water reactor (PWR), the validation of this capability is conducted. The depletion analysis is performed with the ENDF/B-VII.1 library and a fuel assembly model. The transmutation equation is solved by the Chebyshev Rational Approximation Method (CRAM) with a depletion chain of 3820 isotopes. 18 actinides and 19 fission products are analyzed in 14 SNF samples. The effect of statistical uncertainties on the calculated number densities is discussed. On average, most of the actinides and fission products analyzed are predicted within ±6% of the experiment. MCS depletion results are also compared to other depletion codes based on publicly reported information in literature. The code-to-code analysis shows comparable accuracy. Overall, it is demonstrated that the depletion capability in MCS can be reliably applied in the prediction of SNF isotopic inventory.

• Journal of Radiation Protection and Research
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• 제10권1호
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• pp.41-49
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• 1985

1,300 MWe 가압경수로 공동내에서 중성자의 흐름해석이 수행되었다. 중성자의 흐름을 해석하는데는 1차원 수송코드인 ANISN, 2차원 수송코드인 DOT3.5, 3차원 Monte Carlo 코드인 TRIPOLI-02와 이들을 접속시켜주는 DOTTRI 등의 전산코드가 이용되었고, 본 계산에 사용된 전산기는 IBM 3033형이었다. 계산된 선속 및 선량율은 900 MW 가압경수로의 공동내에서 측정한 측정치와 비교검토 되었고, 그 결과 중성자 군별로 약간의 오차는 있었으나 전체적으로 큰 오차는 없었다. 이 결과는 대용량의 원자로 차폐설계, 원자로보수시, 기타 원자로 공동내에 출입할 경우에 방사선방어상 필요한 방어수단을 제공하는데 기여하였다.

• 센서학회지
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• 제25권4호
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• pp.264-270
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• 2016

Self-powered neutron detector (SPND) is a sensor to monitor a neutron flux proportional to a reactor power of the nuclear power plants. Since an SPND is usually installed in the reactor core and does not require additional outside power, it generates electrons itself from interaction between neutrons and a neutron-sensitive material called an emitter, such as rhodium and vanadium. This paper presents the simulations of the depletion sensitivity evaluations based on MCNP models of rhodium and vanadium SPNDs and light water reactor fuel assembly. The evaluations include the detail geometries of the detectors and fuel assembly, and the modeling of rhodium and vanadium emitter depletion using MCNP and ORIGEN-S codes, and the realistic energy spectrum of beta rays using BETA-S code. The results of the simulations show that the lifetime of an SPND can be prolonged by using vanadium SPND than rhodium SPND. Also, the methods presented here can be used to analyze a life-time of those SPNDs using various emitter materials.

• Structural Engineering and Mechanics
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• 제54권1호
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• pp.149-168
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• 2015

In the bolted connections, bolt placements are generally described and are generally made in the direction of design effects and in the perpendicular direction to design effects. In these both directions, the reliability of the distance of bolts to the edges of connection plate and the distance of bolts to each other is investigated for high strength steel connections built up with high strength bolts in this study. For this purpose, simple SL (bearing type shear connection) and SLP (bearing type shear connection for body-fit bolts) type steel connections with St 52 grade steel plates with 8 different thicknesses and with 8.8D grade high strength bolts (HV) were constituted and analyzed under H (Dead Loads+Live Loads+Snow Loads+Roof Loads) and HZ (H Loads+Wind Loads+Earthquake Loads) loadings. Geometric properties, material properties and design actions were taken as random variables. Monte Carlo Simulation method was used to compute failure risk and the first order second moment method was used to determine the reliability indexes of those different distances describing the placement of bolts. Results obtained from computations have been presented in graphics and in a Table. Then, they were compared with some values proposed by some structural codes. Finally, new equations were constituted for minimum and maximum values of distances describing bolt placement by regression analyses performed on those results.

• Earthquakes and Structures
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• 제3권1호
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• pp.17-35
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• 2012

Simplified equations for fundamental period of vibration of skeletal structures provided by most seismic design provisions suffer from the absence of any associated confidence levels and of any reference to their empirical basis. Therefore, such equations may typically give a sector of designers the false impression of yielding a fairly accurate value of the period of vibration. This paper, although not addressing simplified codes equations, introduces a set of mathematical equations utilizing the theory of error propagation and First-Order Second-Moment (FOSM) techniques to determine bounds on the relative error in theoretically calculated fundamental period of vibration of skeletal structures. In a complementary step, and for verification purposes, Monte Carlo simulation technique has been also applied. The latter, despite involving larger computational effort, is expected to provide more precise estimates than FOSM methods. Studies of parametric uncertainties applied to reinforced concrete frame bents - potentially idealized as SDOF systems - are conducted demonstrating the effect of randomness and uncertainty of various relevant properties, shaping both mass and stiffness, on the variance (i.e. relative error) in the estimated period of vibration. Correlation between mass and stiffness parameters - regarded as random variables - is also thoroughly discussed. According to achieved results, a relative error in the period of vibration in the order of 19% for new designs/constructions and of about 25% for existing structures for assessment purposes - and even climbing up to about 36% in some special applications and/or circumstances - is acknowledged when adopting estimates gathered from the literature for relative errors in the relevant random input variables.