• Nuclear Engineering and Technology
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• 제50권2호
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• pp.229-236
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• 2018

Accident-tolerant fuels (ATFs) are currently of high interest to researchers in the nuclear industry and in governmental and international organizations. One widely studied accident-tolerant fuel concept is multilayer cladding (also known as coated cladding). This concept is based on a traditional Zr-based alloy (Zircaloy-4, M5, E110, ZIRLO etc.) serving as a substrate. Different protective materials are applied to the substrate surface by various techniques, thus enhancing the accident tolerance of the fuel. This study focuses on the results of testing of Zircaloy-4 coated with pure chromium metal using the cold spray (CS) technique. In comparison with other deposition methods, e.g., Physical vapor deposition (PVD), laser coating, or Chemical vapor deposition techniques (CVD), the CS technique is more cost efficient due to lower energy consumption and high deposition rates, making it more suitable for industry-scale production. The Cr-coated samples were tested at different conditions ($500^{\circ}C$ steam, $1200^{\circ}C$ steam, and Pressurized water reactor (PWR) pressurization test) and were precharacterized and postcharacterized by various techniques, such as scanning electron microscopy, Energy-dispersive X-ray spectroscopy (EDX), or nanoindentation; results are discussed. Results of the steady-state fuel performance simulations using the Bison code predicted the concept's feasibility. It is concluded that CS Cr coating has high potential benefits but requires further optimization and out-of-pile and in-pile testing.

• 방사선산업학회지
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• 제5권4호
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• pp.325-330
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• 2011

To predict the details of flow in industrial process unit, single photon emission computed tomography (SPECT) is a promising technique. Recently, industrial SPECT based on medical system has developed by researchers of the Korea Atomic Energy Research Institute (KAERI) and Hanyang University. In the present study, to confirm the effect of the number of detectors on image quality, and determine the optimal number of detectors in industrial SPECT, industrial SPECT system with various geometries were evaluated by the Monte Carlo simulation. CsI(Tl) detectors ($12mm{\times}12mm{\times}20mm$) with collimators (the geometric resolution of collimator $R_g$ was 4 cm at the center of the 30 cm diameter cylindrical vessel object) were modeled in a hexagonal array, and the point sources of $^{99m}Tc$, $^{68}Ga$, and $^{137}Cs$ were simulated at the center of the cylindrical vessel object using the MCNPX code. Then, the reconstruction images of each geometry were reconstructed using the expectation maximization (EM) algorithm. In this study, the reciprocity theorem was used to improve computation time required for system matrix of the EM algorithm. The result shows that the resolution of the reconstructed image was significantly improved by increasing the number of detectors in industrial SPECT system and more than 60 detectors will be required for the resolution of the reconstructed image.

• 한국추진공학회지
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• 제18권5호
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• pp.54-61
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• 2014

본 연구에서는 비정렬격자계를 사용하는 2차원 축대칭 DSMC 법을 사용하여 로켓 노즐에서 사출되는 플룸을 해석하였다. 오리피스의 출구 전압에 대한 배압의 비율이 높은 경우와 낮은 경우의 플룸에 대하여 해석을 실시하여 저고도와 고고도를 대표하는 두 가지 조건에서 플룸 유동의 차이를 관찰하였다. 저고도 플룸은 Mach disc 등 복잡한 유동 구조를 보인 반면 고고도 플룸은 단순 팽창만을 보였으며, 유동이 상류 방향으로 심하게 꺾였다. 또한 고도 20 km의 대기 조건에서 소형 로켓 노즐에서 사출되는 플룸에 대한 해석을 수행하여 연속체 해석 결과와 비교하였으며 과소팽창되는 로켓 플룸의 유동구조가 잘 나타났다. 또한, 플룸 내부에 국지적인 천이 유동이 발생할 수 있음을 확인하였다.

• Steel and Composite Structures
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• 제13권6호
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• pp.571-586
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• 2012

The paper addresses some key issues related to the design of composite slabs with cold-formed profiled steel sheets. An experimental programme is first presented, involving six composite slab specimens tested with a view to evaluating Eurocode 4 (EC4) provisions on testing of composite slabs. In four specimens, the EC4-prescribed 5000 load cycles were applied using different load ranges resulting from alternative interpretations of the reference load $W_t$. Although the rationale of the application of cyclic loading is to induce loss of chemical bond between the concrete plate and the steel sheet, no such loss was noted in the tests for either interpretation of the range of load cycles. Using the recorded response of the specimens the values of factors m and k (related to interface shear transfer in the composite slab) were determined for the specific steel sheet used in the tests, on the basis of three alternative interpretations of the related EC4 provisions. The test results confirmed the need for a more unambiguous description of the m-k test and its interpretation in a future edition of the Code, as well as for an increase in the load amplitude range to be used in the cyclic loading tests, to make sure that the intended loss of bond between the concrete slab and the steel sheet is actually reached. The study also included the development of a special-purpose software that facilitates design of composite slabs; a parametric investigation of the importance of m-k values in slab design is presented in the last part of the paper.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1996년도 춘계학술발표회논문집(1)
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• pp.185-190
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• 1996

RFSP is a computer program to do fuel management calculations for CANDU reactors. Its main function is to calculate neutron flux and power distributions using two-energy-group, three dimensional neutron diffusion theory. However, up to now the treatment has not been true two-group but actually "one-and-half groups". In other words, the previous (1.5-group) version of RFSP lumps the fast fission term into the thermal fission term. This is based on the POWDERPUFS-V Westcott convention. Also, there is no up-scattering term or bundle power over cell flux (H1 factor) for the fast group. While POWDERPUFS-V provides only 1.5 group properties, true two-group cross sections for the design and analysis of CAUDU reactors can be obtained from WIMS-AECL. To treat the full two-group properties, the previous RFSP version was modified by adding the fast fission, up-scatter terms, and H1 factor. This two-group version of RFSP is a convenient tool to accept lattice properties from any advanced lattice code (e.g. WIMS-AECL DRAGON, HELIOS...) and to apply to advanced fuel cycles. In this study, the modification to implement the true two-group treatment was performed only in the subroutines of the ＊SIMULATE module of RFSP. This module is the appropriate one to modify first, since it is used for the tracking of reactor operating histories. The modified two-group RFSP was evaluated with true two-group cross sections from WIMS-AECL. Some tests were performed to verify the modified two-group RFSP and to evaluate the effects of fast fission and up-scatter for three core conditions and four cases corresponding to each condition. The comparisons show that the two-group results are quite reasonable and serve as a verification of the modifications made to RFSP. To assess the long-term impact of the full 2-group treatment, it is necessary to simulate a long period (several months) of reactor history. It will also be necessary to implement the full two-group treatment of reactivity devices and assess the reactivity-device worths.ce worths.

• Journal of Dental Anesthesia and Pain Medicine
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• 제21권5호
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• pp.461-469
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• 2021

Background: The global population is aging rapidly, and accordingly, the number of patients with dementia is increasing every year. Although the need for dental treatment increases for various reasons in patients with dementia, they cannot cooperate during dental treatment. Therefore, behavioral management, including sedation (SED) or general anesthesia (GA), is required for patients with dementia. Thus, this study aimed to investigate the trends and effects of SED or GA in patients with dementia undergoing dental treatment in South Korea based on the Korean National Health Insurance claims data. Methods: This study utilized customized health information data provided by the Health Insurance Review and Assessment Service. Among patients with records of using sedative drugs during dental treatment from January 2007 to September 2019, patients with the International Classification of Diseases-10 code for dementia (F00, F01, F02, F03, and G30) were selected. We then analyzed the full insurance claims data for dental care. Age, sex, sedative use, and dental treatment of patients were analyzed yearly. In addition, the number of cases of GA or SED per year was analyzed, and changes in behavioral management methods with increasing age were investigated. Results: Between January 2007 and September 2019, a total of 4,383 (male, 1,454; female, 2,929) patients with dementia received dental treatment under SED or GA. The total number of SED and GA cases were 1,515 (male, 528 ; female, 987 ) and 3,396 (male, 1,119 ; female, 2,277) cases, respectively. The total number of cases of dental treatment for 4,383 patients with dementia was 153,051 cases, of which 2.22% were under GA and 0.98% were under SED. Midazolam was the most commonly used drug for SED. Conclusion: Although gingivitis and pulpitis were the most common reasons for patients with dementia to visit the dentist, GA or SED for patients with dementia was frequently used in oral and maxillofacial or periodontal surgery.

• Nuclear Engineering and Technology
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• 제53권12호
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• pp.4137-4141
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• 2021

As NPPs continue to operate, liquid waste continues to be generated, and containers are needed to store and transport them at low cost and high capacity. To transport and store liquid phase very low-level radioactive waste (VLLW), a container is designed by considering related regulations. The design was constructed based on the existing container design, which easily transports and stores liquid waste. The radiation shielding calculation was performed according to the composition change of barium sulfate (BaSO₄) using the Monte Carlo N-Particle (MCNP) code. High-density polyethylene (HDPE) without mixing the additional BaSO₄, represented the maximum dose of 1.03 mSv/hr (<2 mSv/hr) and 0.048 mSv/hr (<0.1 mSv/hr) at the surface of the inner container and at 2 m away from the surface, respectively, for a 10 Bq/g of ⁶⁰Co source. It was confirmed that the dose from the inner container with the VLLW content satisfied the domestic dose standard both on the surface of the container and 2 m from the surface. Although it satisfies the dose standard without adding BaSO₄, a shielding material, the inner container was designed with BaSO₄ added to increase radiation safety.

• Nuclear Engineering and Technology
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• 제51권5호
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• pp.1444-1450
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• 2019

The fast-neutron shielding behaviour (FNSB) of two clay-materials (Ball clay and Kaolin)of Southwestern Nigeria ($7.49^{\circ}N$, $4.55^{\circ}E$) have been investigated using effective removal cross section, ${\Sigma}_R(cm^{-1})$, mass removal cross section, ${\Sigma}_{R/{\rho}}(cm^2g^{-1})$ and Mean free path, ${\lambda}$ (cm). These parameters decide neutron shielding behaviour of any material. A computer program - WinNC-Toolkit has been used for computation of these parameters. The toolkit evaluates these parameters by using elemental compositions and densities of samples. The proficiency of WinNC-Toolkit code was probe by using MCNPX and GEANT4 to model fast neutron transmission of the samples under narrow beam geometry, intending to represent the actual experimental setup. Direct calculation of effective removal cross section ($cm^{-1}$) of the samples was also carried out. The results from each of the methods for each types of the studied clay-materials (Ball clay and Kaolin) shows similar trend. The trend might be the fingerprint of water content retained in each of the samples being baked at different temperature. The compositions of each sample have been obtained by Particle-Induced X-ray Emission (PIXE) technique (Tandem Pelletron Accelerator: 1.7 MV, Model 5SDH). The FNSB of the selected clay-materials have been compared with standard concrete. The cognizance of various factors such as availability, thermo-chemical stability and water retaining ability by the clay-samples can be analyzed for efficacy of the material for their FNSB.

• Coupled systems mechanics
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• 제8권4호
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• pp.339-350
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• 2019

A numerical simulation of the incompressible multiphase hydraulic jump flow was performed to compare the interface prediction through the use of the three RANS turbulence models: $k-{\varepsilon}$, $RNGk-{\varepsilon}$ and SST $k-{\omega}$. A three dimensional no submerged hydraulic jump and a two dimensional submerged hydraulic jump were modeled. Both the geometry and the mesh were created using the open source Gmsh code. The project's geometry consists of a rectangular channel with length and height differences between the two dimensional and three dimensional simulations. Uniform hexahedral cells were used for the mesh. Three refining meshes were constructed to allow to verify simulation convergence. The Volume of Fluid (abbr. VOF) method was used for treatment of the air-water surface. The turbulence models were evaluated in three distinct set up configurations to provide a greater accuracy in the flow representation. In the two-dimensional analysis of a submerged hydraulic jump simulation, the turbulence model RNG RNG $k-{\varepsilon}$ provided a better interface adjust with the experimental results than the model $k-{\varepsilon}$ and SST $k-{\omega}$. In the three-dimensional simulation of a no-submerged hydraulic jump the k-# showed better results than the SST $k-{\omega}$ and RNG $k-{\varepsilon}$ capturing the height and length of the ledge with a better fit with the experimental results.

• 한국수산과학회지
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• 제52권1호
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• pp.19-26
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• 2019

The objective of this study was to analyze bacteriological and chemical hazards in minimally processed commercial fish products, including Hwangtae (freeze-dried pollock), dried anchovy, fermented anchovy sauce, and salted and dried yellow croaker. Escherichia coli counts from all samples were below the regulation limits of the Korean Ministry of Food and Drug Safety Standards on Quality of Seafood and Seafood Products (Food Code). However, the food poisoning bacterium Staphylococcus aureus was detected at levels above $1.0{\times}10^2$ colony forming units (CFU)/g in Hwangtae, dried anchovy, and salted and dried yellow croaker, which are commonly ingested without heating and pose bacteriological hazards. The detection of S. aureus, an organism indicative of poor personal hygiene, which can be introduced by employees and multiply during distribution, indicates the necessity of improving the sanitary control of minimally processed commercial fish products. Histamine was not detected from dried anchovy or salted and dried yellow croaker, but was detected at some of the highest levels in fermented anchovy sauces. This result suggests that efforts to reduce the amount of histamine in fermented anchovy sauces are required.