• Nuclear Engineering and Technology
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• v.54 no.11
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• pp.4146-4158
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• 2022

Ultra-high performance concrete (UHPC) has been widely utilized in military and civil protective structures to resist intensive loadings attributed to its excellent properties, e.g., high tensile/compressive strength, high dynamic toughness and impact resistance. At present, aiming to improve the defects of the traditional vertical concrete cask (VCC), i.e., the external storage facility of spent fuel, with normal strength concrete (NSC) shield, e.g., heavy weight and difficult to fabricate/transform, the feasibility of UHPC applied in the shield of VCC is numerically examined considering its high radiation and corrosion resistance. Firstly, the finite element (FE) analyses approach and material model parameters of NSC and UHPC are verified based on the 1/3 scaled VCC tip-over test and drop hammer test on UHPC members, respectively. Then, the refined FE model of prototypical VCC is established and utilized to examine its dynamic behaviors and damage distribution in accidental tip-over and end-drop events, in which the various influential factors, e.g., UHPC shield thickness, concrete ground thickness, and sealing methods of steel container are considered. In conclusion, by quantitatively evaluating the safety of VCC in terms of the shield damage and vibrations, it is found that adopting the 300 mm-thick UHPC shield instead of the conventional 650 mm-thick NSC shield can reduce about 1/3 of the total weight of VCC, i.e., about 50 t, and 37% floor space, as well as guarantee the structural integrity of VCC during the accidental drop simultaneously. Besides, based on the parametric analyses, the thickness of concrete ground in the VCC storage site is recommended as less than 500 mm, and the welded connection is recommended for the sealing method of steel containers.

• Nuclear Engineering and Technology
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• v.51 no.2
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• pp.588-599
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• 2019

This research presents a structural design of high-level waste (HLW) container using ultra-high performance fiber reinforced concrete (UHP-FRC) material. The proposed design aims to overcome the drawbacks of the existing concrete containers which are heavy, difficult to fabricate, and expensive. In this study, the dry storage container (DSC) that commonly used at Canadian Nuclear facilities is selected to present the proposed design. The design has been performed such that the new UHP-FRC alternative has a structural stiffness equivalent to the existing steel-concrete-steel container under various loading scenarios. Size optimization technique is used with the aim of maximizing stiffness, and minimizing the cost while satisfying both the design stresses and construction requirements. Then, the integrity of the new design has been evaluated against accidental drop-impact events based on realistic drop scenarios. The optimization results showed: the stiffness of the UHP-FRC container (300 mm wall thick) is being in the range of 1.35-1.75 times the stiffness of existing DSC (550 mm wall thick). The use of UHP-FRC leads to decrease the container weight by more than 60%. The UHP-FRC container showed a significant enhancement in performance in comparison to the existing DSC design under considered accidental drop impact scenarios.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.26 no.5
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• pp.359-371
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• 2013

This paper is the first paper among two papers which constitute the paper about the rigid body dynamic analysis on the spent nuclear disposal canister under accidental drop and impact on to the ground. This paper performed the general theoretical study on the rigid body dynamic analysis. Through this study the impulsive force which is occurring in the spent nuclear fuel disposal canister under accidental drop and impact to the ground and required for the structural safety design of the canister is intended to be theoretically formulated. The main content of the theoretical study is about the equation of motion in the multibody dynamics. On the basis of this study the impulsive force which is occurring in the multibody in the case of collision between multibody is theoretically formulated. The application of this theoretically formulated impulsive force to computing the impulsive force occurring in the spent nuclear fuel disposal canister under accidental drop and impact to the ground is investigated.

• Journal of The Korean Society of Clinical Toxicology
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• v.20 no.1
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• pp.35-38
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• 2022

Many commonly used household chemicals and medical eye drops look alike, resulting in a worldwide increase in incidences of accidents caused by confusion between similar-looking agents. In this case report, we present two patients who visited the emergency department following inadvertent instillation of tinea pedis treatment solution instead of eye drops. Both patients developed corneal chemical burns following the accidental application. Notably, the visual acuity and symptoms eventually recovered for both patients after hospitalization. However, complete recovery occurred only after several weeks. Both patients were relatively old and had been prescribed eye drops after previous ophthalmic surgery. Since the eye is a sensory organ that receives visual information, ocular injuries significantly affect the quality of life and social functioning of the patient. Incidences of accidental misidentification of eye drops are steadily increasing in South Korea; unfortunately, regulatory policies are unavailable to avoid such hazards. Therefore, physicians should be mindful of the potential risks associated with misidentification of everyday household products and must spend time educating patients when prescribing eye drops. Policy regulations are warranted for products with containers that resemble eye drop bottles. Such items need to be clearly labeled with additional warnings to prevent misidentification and accidental ocular instillation.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.4 no.2
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• pp.139-152
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• 2006

A spent fuel storage cask is required to prove the safety of a canister under a hypothetical accidental drop condition. A hypothetical accidental drop condition means that a canister is assumed to be a lee drop on to a pad of the storage cask during loading it into a storage cask. A pad of the storage cask absorbs shock to maintain the structural integrities of a canister under a hypothetical accidental drop condition. In this paper a finite element analysis for various pad structures was carried out to improve the structural integrity of a canister under a hypothetical accidental drop condition. A pad of a storage cask was designed a steel structure with concrete. The 1/4 height of a pad was modified with a structure composed of a steel and a polyurethane foam as a impact limiter. The effect of a shape of a steel structure was studied. The effects of the thickness of a steel structure and the density of a polyurethane foam was also studied.

• Journal of the Korean Society of Safety
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• v.27 no.5
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• pp.135-140
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• 2012

In this study, the behavior of pollutant was calculated at Paldang reservior according to several scenarios of the accidental water pollution by means of the numerical models for forecasting water quality. Also managemental plans for situation of the accidental water pollution happening at Paldang watershed were simulated. According to the simulating results, a plan of increase of discharge at Cheongpyeong dam reduced the peak concentration of pollutants, whereas extended the time for stopping water intake. Another plan, drop of water elevation at Paldang dam, decreased seriously the time for stopping water intake although there were a little effect to decrease the peak concentration. Thus it was concluded that appropriate combinations of the plans for the increase discharge and the dropping water elevation should be used to deal with the accidental water pollution at Paldang watershed.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.30 no.5
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• pp.415-425
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• 2017

Stresses occur in the spent nuclear fuel disposal canister due to the impulsive forces incurred in the accidental drop and impact event from the transportation vehicle onto the ground during deposition in the repository. In this paper, the comparative study of finite element analysis for stresses occurring in various models of the spent nuclear fuel disposal canister due to these impulsive forces is presented as one of design processes for the structural integrity of the canister. The main content of the study is about the design of the structurally safe canister through this comparative study. The impulsive forces applied to the canister subjected to the accidental drop and impact event from the transportation vehicle onto the ground in the repository are obtained using the commercial rigid body dynamic analysis computer code, RecurDyn. Stresses and deformations occurring due to these impulsive forces are obtained using the commercial finite element analysis computer code, NISA. The study for the structurally safe canister is carried out thru comparing and reviewing these values. The study results show that stresses become larger as the wall encompassing the spent nuclear fuel bundles inside the canister becomes thicker or as the diameter of the canister becomes larger. However, the impulsive force applied to the canister also becomes larger as the canister diameter becomes larger. Nonetheless, the deformation value per unit impulsive force decreases as the canister diameter increases. Therefore, conclusively the canister is structurally safe as the diameter increases.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.5
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• pp.451-457
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• 2015

This paper presents the analytical closed form solution for the impact load of a collision between rigid bodies and its application to a spent nuclear fuel disposal canister accidentally dropped and impacted on the ground. This paper performed a study on the numerical rigid body dynamic analysis to compute the impact load between two rigid bodies, especially, the impulsive force which is applied to the spent nuclear fuel disposal canister in the accidental drop and impact event on the ground. Through this study the impulsive force which is occurring in the spent nuclear fuel disposal canister under accidental drop and impact event on the ground and required in the process of structural safety design of the canister is computed numerically. The main content of this numerical study is about the technical method how to compute the impulsive force applied to the canister under the accidental drop and impact event on the ground by using the commercial computer code for the rigid body dynamic analysis. On the basis of this study a problem to compute the impulsive force which is occurring in the canister in the case of collision with the ground is numerically treated. This numerically computed impulsive force is compared with the theoretical value, which shows a good agreement.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.26 no.5
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• pp.373-384
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• 2013

This paper is the second paper among two papers which constitute the paper about the rigid body dynamic analysis on the spent nuclear fuel disposal canister under accidental drop and impact to the ground. This paper performed the numerical study on the rigid body dynamic analysis. Through this study the impulsive force which is occurring in the spent nuclear fuel disposal canister under accidental drop and impact to the ground and required for the structural safety design of the canister is computed numerically. The main content of this numerical study is about the technical method how to compute the impulsive forces occurring in the canister under accidental drop and impact to the ground by using the commercial rigid body dynamic analysis computer codes. On the basis of this study the impulsive force which is occurring in the canister in the case of collision with the ground is numerically computed. This numerically computed impulsive force is increasing as the canister weight is increasing, and the canister falls plumb down and collides with the ground in three types according to the analysis results.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.11
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• pp.2805-2816
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• 1994

This paper describes dynamic finite element analyses performed to study the dynamic behaviors of a shipping container under the impact onto rigid target due to the accidental fall from the hight of 9 m. Using two and three dimensional techniques, the shipping container which gave the maximum damage, ten different drop orientations are considered ; at intervals of $5^{\circ}$ from $45^{\circ}$ to $90^{\circ}$ According to the present results, the orientation of the shipping container which gave the maximum damage is $85^{\circ}$ from horizontal for oblique drop in the primary impact. In the optimal design of the shipping container, the impact limiter material must be considered importantly because it's proper selection affects the weight and the manufacturing cost of the shipping container. The analysis of the shipping container in this paper demonstrated that the shipping container is structurally sound relative to the regulatory drop test requirements.