Investigation of aerodynamic barrier-based approach for consequence mitigation of a radioactivity release accident at a nuclear power plant원자력발전소 방사성 물질 환경유출사고의 사고완화를 위한 공기역학적 장벽 기반 접근법에 대한 조사

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Existing safety paradigm does not offer engineered means to mitigate the consequences of a radioactivity release accidents at a nuclear power plant. The recent Fukushima accident has demonstrated the very possibility of beyond design base conditions that could jeopardize the functionalities of safety systems to the extent that Defense in Depth (DiD) layers of protection are breached and fission product release to the environment occurs. Out-containment mitigation of radiological consequences by suppressing the spread of radioactive material has been identified as a means of protection. This dissertation examines a new accident management approach based on aerodynamic barriers to limit the dispersion of radioactive material in the event of containment failure. The approach is based on using airflow movement generated by aerodynamic barriers around reactor containment to confine and capture the released fission products. The fundamental theory and elements of aerodynamic barriers are advanced in relation to their utilization in limiting the spread of radioactive material in the event of containment failure in combination with an integrated suction system. Based on this development, a conceptual design is devised to confine, capture and treat fission products following containment failure using aerodynamic barriers. Computational fluid dynamic (CFD) modeling based on Euler-Lagrange method is used to simulate the behavior of released fission products under the implementation of aerodynamic barriers and the relevant performance parameters are derived to assess the effectiveness. This study demonstrates the feasibility of aerodynamic barrier approach using six aerodynamic towers under a set of standard containment failure states and a reference wind speed of 5m/sec. Aerodynamic barrier placement distance is identified as a key parameter for confining radionuclide at elevated containment leak rates, and a correlation is proposed to select proper distance based on the bounding containment leak rate. This study also evaluates the effect of wind conditions, and finds that aerodynamic barrier parameters for the selected wind speed (with an average momentum ratio of 2.3) are sufficiently robust to handle wind loads in the range of 2-8m/sec (or momentum ratio between 15-1) without requiring an adjustment. For wind speeds less than 2m/sec, adjusting discharge angle inwards by $10^o$ is sufficient to ensure effectiveness of aerodynamic barriers. For all other wind speeds (4-10m/sec), maintaining average momentum ratio of 2.3 (by adjustment of aerodynamic barrier discharge speed) can provide necessary protection against wind infiltration with radionuclide confinement. The verification and validation of the computational model is also performed. The validation is performed by assessing model predictions against available experimental data of constituent benchmark problems as well as the experiments performed using an in-house scaled-down experimental setup using particle image velocimetry (piv) measurements. Future studies are recommended to assess long-term performance of the proposed approach in the field or a wind tunnel. Also, it will be interesting to explore further applications of using aerodynamic barriers in angular arrangement.
Advisors
Yim, Man Sungresearcher임만성researcher
Description
한국과학기술원 :원자력및양자공학과,
Publisher
한국과학기술원
Issue Date
2020
Identifier
325007
Language
eng
Description

학위논문(박사) - 한국과학기술원 : 원자력및양자공학과, 2020.2,[xi, 129 p. :]

Keywords

Nuclear Power Plant▼aNuclear Safety▼aSevere Accident▼aRadiological Consequence Mitigation▼aCFD▼aOpenFOAM; 원자력 발전소▼a핵 안전▼a심각한 사고▼a방사선 결과 완화▼aCFD▼aOpenFOAM

URI
http://hdl.handle.net/10203/283515
Link
http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=902013&flag=dissertation
Appears in Collection
NE-Theses_Ph.D.(박사논문)
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