(An) assessment and development of drift-flux correlation and its limitation in fast transient conditions of pressurized water reactors가압수형 원자로의 강한 과도상태에서의 유량 상관관계 평가 및 개발

Cited 0 time in webofscience Cited 0 time in scopus
  • Hit : 205
  • Download : 0
A drift flux model is an important two phase flow model used for safety analysis of an integral type water-cooled small modular reactor. In this thesis, an improvement is first suggested for the existing drift flux model and moreover the limitation of the model is also studied theoretically. A statistical assessment for multiple drift-flux correlations has been carried out using more than 1,600 experimental data compiled from open literature for various vertical and horizontal flow regimes and geometries. The test geometries include pipes, annulus, and fuel assemblies. The assessment results show that Hibiki & Ishii correlation is relatively the most accurate correlation with a mean absolute error of 16.2%, followed by Toshiba correlation and Antonio correlation with mean absolute errors of 17.45% and 17.69%, respectively. Furthermore, a new drift-flux correlation is developed based on the collected experimental data for each flow regime. The performance assessment of the new correlation demonstrates an improvement over earlier drift–flux correlations with a mean absolute error of 14.6%. The applicability of the drift-flux approach in the modeling of two-phase flow during fast transient scenarios is also verified, and the limiting conditions are theoretically defined based on the relaxation timescales between the flow phases. The limiting conditions reveal that the annular flow regime has the longest relaxation time scale due to the weak dynamic coupling between the liquid film and gas continuous phase. Therefore, whenever the drift-flux code is used to simulate fast transient scenarios of annular flow or mist flow regimes, the transient time of the system must be much less than the relaxation timescale. Finally, an integral effect test facility was used to evaluate the accuracy of a commercial thermal hydraulic code that is based on the drift flux approach by analyzing two accident scenarios, SBLOCA and CLOF. The results show an over prediction of the break flow in the case of SBLOCA, which may imply a limited capability of the drift-flux approach in modeling the transition between the vertical annular flow regime and the stratified flow regime.
Advisors
Lee, Jeong Ikresearcher이정익researcher
Description
한국과학기술원 :원자력및양자공학과,
Publisher
한국과학기술원
Issue Date
2021
Identifier
325007
Language
eng
Description

학위논문(석사) - 한국과학기술원 : 원자력및양자공학과, 2021.8,[iv, 54 p. :]

Keywords

Drift-flux model▼aSmall break loss of coolant accident (SBLOCA)▼aNuclear safety analysis▼aRelaxation time scale; 드리프트 플럭스 모델▼aSmall break loss of coolant accident (SBLOCA)▼a원자력 안전 분석▼a휴식 시간 척도

URI
http://hdl.handle.net/10203/295491
Link
http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=963489&flag=dissertation
Appears in Collection
NE-Theses_Master(석사논문)
Files in This Item
There are no files associated with this item.

qr_code

  • mendeley

    citeulike


rss_1.0 rss_2.0 atom_1.0