• Journal of the Computational Structural Engineering Institute of Korea
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• v.15 no.3
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• pp.471-480
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• 2002

In this paper, the thermal stress analysis of spent nuclear fuel disposal canister in a deep repository at 500 m underground is carried out for the basic design of the canister. Since the nuclear fuel disposal usually emits much heat, a long term safe repository at a deep bedrock is used. Under this situation, the canister experiences the thermal load due to the heat generation of spent nuclear fuels in the basket. Hence, in this paper the thermal stress analysis is executed using the finite element method. The finite clement code Eot the analysis Is not written directly, but a commercial code, NISA, is used because of the complexity of the structure and the large number of elements required for the analysis. The analysis result shows that even though the thermal stress is added to the stress generated by the hydrostatic underground water pressure and the swelling pressure of the bentonite buffer, the total stress is still smaller than the yield stress of the cast iron. Hence, the canister is still structurally safe when the thermal loads we included in the external loads applied on the canister.

• Proceedings of the KOR-BRONCHOESO Conference
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• 1987.05a
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• pp.13.1-13
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• 1987

저자들은 1984년 12월 17일부터 1987년 2월 26일까지 경희대학교 의과대학 부속병원 이비인후과 및 흉부외과에서 경험한 9례의 기관협착증환자를 대상으로 임상적 고찰을 하여 다음과 같은 결과를 얻었다. 1) 연령 및 성별분포는 여자 3례, 남자 6례이었고, 10세이하 3례, 10대 2례, 20대 2례, 40대 이상이 2례 이었다. 2) 원인은 지속적 기관내삽입관에 의한 경우가 4례이었고 1례는 선천성 혈관기형인 double aortic arch에 의해 기관이 눌리어 기도협착증상이 있었던 경우이었다. 상기관절개술에 의한 경우가 2례, 경부외상 1례, 기관내 종양 2례이었다. 3) 협착부위의 길이는 1.5cm에서 2cm까지가 4례로 가장 많았고 3cm이내가 2례, 4cm이내 1례, 6cm이내 1례이었다. 4) 치료는 보존적인 방법으로 내시경하에서 육아조직 및 반흔조직을 laser를 이용하여 제거한 후 silastic stent 혹은 Montgomery T-tube 삽입후 4주에서 6주후 제거하여 치료한 경우가 2례이었고 협착부위절제 및 단단문합술을 시행한 경우가 6례이었다. 1례에서는 aortic arch division을 시행하였다. 5) 예후는 9례중 단단문합술을 시행한 6례 그리고 보존적 방법으로 laser를 이용한 육아조직의 제거 및 지지물삽입을 시행한 3례에서 모두 현재까지 재발은 보이지 않고 있다. 6) 기관협착의 길이가 1.5cm에서 4cm까지의 경우에는 supralaryngeal release procedure없이 단단문합술을 시행하였고 협착길이가 6cm인 1례에서는 supralaryngeal release를 하여 tension없이 문합술을 시행할 수 있었다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.17 no.4
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• pp.413-421
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• 2004

In this paper, a structural analysis for the pressurized water reactor(PWR) spent nuclear fuel disposal canister which is deposited under the 500m deep underground is carried out to predict the creep deformation of the canister while the underground water and swelling bentonite pressure are applied on the canister. Usually the creep deformation may be caused due to the Pressure and the high heat applied to the canister even though additional external loads are not applied to the canister. These creep deformations depend on the time. In this paper, oかy the underground water and bentonite swelling Pressure are considered for the creep deformation analysis of the canister, because the heat distribution inside canister due the spent fuel is not simple and depends on time. A proper creep function is adopted for the creep analysis. The creep analysis is carried out during $10^8$ seconds. The creep analysis results show that the creep strains are very small and these strains occur usually in the lid and bottom of the canister not in the cast iron insert. A much smaller strain is found in the cast iron insert. Hence, the creep deformation doesn't affect the structural safety of the canister, and also the creep stress which shows the stress relaxation phenomenon doesn't affect the structural safety of the canister.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.2
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• pp.211-222
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• 2011

In this paper a structural analysis of the PWR(pressurized water reactor) canister with 102cm diameter is carried out to evaluate the structural safety of the canister for the impact force occurring at the moment of collision with the ground in the falling plumb down accident from the carriage vehicle which may happen during the canister handling at the spent nuclear fuel disposal repository. For this, a rigid body dynamic analysis of the canister is executed to compute the impact force using the commercial CAE system, RecurDyn, and a nonlinear structural analysis is performed to compute stresses and deformations occurring inside the canister for this computed impact force using the commercial FEM code, NISA. From these analysis results, the structural safety of the canister is evaluated for the falling plumb down accident from the carriage vehicle due to the inattention during the canister handling at the repository. The rigid body dynamic analysis performed assuming the canister as a rigid body shows that the canister falls plumb down to the ground in two types. And also it shows that early collision impact force is the biggest one and following impact forces decrease gradually. The height of the carriage vehicle in the repository is assumed as 5m in order to obtain the stable structural safety evaluation result. The nonlinear structural analysis of the canister is executed for the biggest early impact force. The structural analysis result of the canister shows that the structural safety of the PWR canister is not secured for the falling plumb down accident from the moving carriage vehicle because the maximum stresses occurring in the cast iron insert of canister are bigger than the yield stress of the cast iron.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.5 no.3
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• pp.229-238
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• 2007

In this paper, structural design requirements and safety evaluation criteria of the spent nuclear fuel disposal canister are studied for deep geological deposition. Since the spent nuclear fuel disposal canister emits high temperature heats and much radiation, its careful treatment is required. For that, a long term(usually 10,000 years) safe repository for the spent nuclear fuel disposal canister should be secured. Usually this repository is expected to locate at a depth of 500m underground. The canister which is designed for the spent nuclear fuel disposal in a deep repository in the crystalline bedrock is a solid structure with cast iron insert, corrosion resistant overpack and lid and bottom, and entails an evenly distributed load of hydrostatic pressure from underground water and high pressure from swelling of bentonite buffer. Hence, the canister must be designed to withstand these high pressure loads. If the canister is not designed for all possible external loads combinations, structural defects such as plastic deformations, cracks, and buckling etc. may occur in the canister during depositing it in the deep repository. Therefore, various structural analyses must be performed to predict these structural problems like plastic deformations, cracks, and buckling. Structural safety evaluation criteria of the canister are studied and defined for the validity of the canister design prior to the structural analysis of the canister. And structural design requirements(variables) which affect the structural safety evaluation criteria should be discussed and defined clearly. Hence this paper presents the structural design requirements(variables) and safety evaluation criteria of the spent nuclear fuel disposal canister.