Study of new features and their implementations in the nuclear reactor analysis Monte Carlo code - McBOX몬테칼로법을 이용한 원자로해석 방법론 연구 및 몬테칼로 McBOX 코드 개발

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We studied new features for the high-fidelity whole-core Monte Carlo (MC) analysis. Using the McBOX code implementing these features, we tested and demonstrated the performances of the three main features; 1) the MC k-eigenvalue simulation with the partial current-based coarse-mesh finite difference (p-CMFD) feedback (MC/p-CMFD), 2) the domain decomposed MC simulation via fission and surface source (FSS) iteration method, and 3) the transient MC simulation based on the predictor-corrector quasi-static (PCQS) method. On the 3-D continuous-energy whole-core problem, the MC/p-CMFD not only accelerated the convergence of the fission source distributions (FSDs) during inactive iterations, but also reduced the real variances of the local MC tallies and the inter-iteration correlations of local MC tallies. Furthermore, the MC/p-CMFD mitigated the spatial clustering phenomenon in the FSDs. We also generalized a variant p-CMFD method by introducing arbitrary factor α and investigated the acceleration performances of the MC/p-CMFD during inactive iterations. A comparison study was also given between the p-CMFD method and the fission matrix method in various aspects. For the practical use of the domain decomposed MC simulation via the FSS iteration method, the following four issues were considered and their corresponding remedies were presented: 1) To reduce the total execution time by overlapping communication and computation, the non-blocking communication in the message-passing interface (MPI) was applied, 2) To accelerate the slow source convergence of the fission and surface source distributions, the p-CMFD feedback was applied, 3) To reduce the idle times due to the different computing loads for local problems, the source splitting scheme was applied, and 4) To estimate the real variance, the history-based batch (HB) method was applied. For the transient MC simulation based on the PCQS method, the fission source iteration was applied to solve the transient fixed-source problem (TFSP), where the p-CMFD feedback was applied to accelerate the convergence of the FSDs. Due to the fission source iteration for the transient fixed-source MC simulation, a neutron history is always guaranteed to be terminated even in a super-prompt critical system and the numerical stability is enhanced. The major findings and results of the thesis are as follows: 1) The real variance and inter-iteration correlation of MC tallies was reduced by the p-CMFD feedback, 2) The FSS iteration method with a load-balancing scheme was proposed for the domain decomposed MC simulation, and 3) The framework of the transient MC simulation based on the PCQS method was established.
Advisors
Kim, Yong Heeresearcher김용희researcherCho, Nam Zinresearcher조남진researcher
Description
한국과학기술원 :원자력및양자공학과,
Publisher
한국과학기술원
Issue Date
2017
Identifier
325007
Language
eng
Description

학위논문(박사) - 한국과학기술원 : 원자력및양자공학과, 2017.8,[x, 145 p. :]

Keywords

Monte Carlo Simulation▼aMcBOX▼aPartial current-based Coarse-Mesh Finite Difference (p-CMFD) Method▼aDomain Decomposition Method▼aTransient Analysis; 몬테칼로 시뮬레이션▼aMcBOX▼a부분 중성자류 소격격자 차분법▼a영역분할 방법▼a과도해석

URI
http://hdl.handle.net/10203/241963
Link
http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=718871&flag=dissertation
Appears in Collection
NE-Theses_Ph.D.(박사논문)
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