Nuclear-thermal analysis of a unit fuel element in HTGRs based on two-temperature homogenized model = 두 온도 균질화법에 의한 고온가스로 핵연료요소체의 핵열해석

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In either pebble-bed or block type design of high temperature gas-cooled reactors (HTGRs), heterogeneous composition and structure leads to difficulty in thermal analysis of the fuel elements (fuel pebbles and fuel compacts, respectively). Thus, a homogenization model becomes essential. Currently, a simple volumetric-average thermal conductivity approach is used. However, this approach lacks basis and is non-conservative in that it underestimates the fuel temperature. In this thesis, we propose a homogenization model that is not only easy to implement but also gives a more realistic temperature distribution in a fuel pebble or a fuel compact, providing the fuel-kernel and graphite-mixture temperatures separately. For a given problem, homogenized parameters are obtained at steady-state through matching the analytic solution for the homogenized fuel element to the reference solution of the heterogeneous fuel element. The reference solutions are provided by the Monte Carlo method. Transient thermal analyses are performed using the homogenization model, in which finite difference method (FDM) in space discretization and explicit scheme in time scale is applied. By providing the power history, temporal changes in temperatures can be computed. A reactor point kinetics model is then coupled with the two-temperature thermal transient model for more accurate neutronics evaluation with Doppler temperature feedback. Several test scenarios are studied, including external reactivity insertion and coolant cooldown events.
Advisors
Cho, Nam-Zinresearcher조남진researcher
Description
한국과학기술원 : 원자력및양자공학과,
Publisher
한국과학기술원
Issue Date
2010
Identifier
418852/325007  / 020054534
Language
eng
Description

학위논문(박사) - 한국과학기술원 : 원자력및양자공학과, 2010.2, [ vii, 55 p. ]

Keywords

Thermal Analysis; Monte Carlo; Two-Temperature Homogenized Model; HTGR; Reactor Point Kinetics Model; 원자로 점동특성 모델; 열해석; 몬테칼로; 두 온도 균질화법; 고온가스로

URI
http://hdl.handle.net/10203/49025
Link
http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=418852&flag=dissertation
Appears in Collection
NE-Theses_Ph.D.(박사논문)
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