• Nuclear Engineering and Technology
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• 제50권2호
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• pp.268-279
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• 2018

The ALCYONE multidimensional fuel performance code codeveloped by the CEA, EDF, and AREVA NP within the PLEIADES software environment models the behavior of fuel rods during irradiation in commercial pressurized water reactors (PWRs), power ramps in experimental reactors, or accidental conditions such as loss of coolant accidents or reactivity-initiated accidents (RIAs). As regards the latter case of transient in particular, ALCYONE is intended to predictively simulate the response of a fuel rod by taking account of mechanisms in a way that models the physics as closely as possible, encompassing all possible stages of the transient as well as various fuel/cladding material types and irradiation conditions of interest. On the way to complying with these objectives, ALCYONE development and validation shall include tests on $PWR-UO_2$ fuel rods with advanced claddings such as M5(R) under "low pressure-low temperature" or "high pressure-high temperature" water coolant conditions. This article first presents ALCYONE V1.4 RIA-related features and modeling. It especially focuses on recent developments dedicated on the one hand to nonsteady water heat and mass transport and on the other hand to the modeling of grain boundary cracking-induced fission gas release and swelling. This article then compares some simulations of RIA transients performed on $UO_2$-M5(R) fuel rods in flowing sodium or stagnant water coolant conditions to the relevant experimental results gained from tests performed in either the French CABRI or the Japanese NSRR nuclear transient reactor facilities. It shows in particular to what extent ALCYONE-starting from base irradiation conditions it itself computes-is currently able to handle both the first stage of the transient, namely the pellet-cladding mechanical interaction phase, and the second stage of the transient, should a boiling crisis occur. Areas of improvement are finally discussed with a view to simulating and analyzing further tests to be performed under prototypical PWR conditions within the CABRI International Program. M5(R) is a trademark or a registered trademark of AREVA NP in the USA or other countries.

• Applied Microscopy
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• 제22권2호
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• pp.1-14
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• 1992

This experiment was performed to study the morphological responses of the parafollicular cells of rat following X-ray irradiation. Male rats were divided into normal and experimental groups. The head and neck region of the rat, under sodium thiopental anesthesia, was exposed to 3,000 rads or 6,000 rads of radiation in a single dose, respectively. The source was a Mitsubishi Linear Accelerator ML-4MV. The target to skin distance was 80 cm, and the dose rate was 200 rads/min. The rate of experimental groups were sacrificed on the 6th hour, 2nd and 6th day after X-ray irradiation. Pieces of the tissue taken from the thyroid gland were fixed in 2.5% glutaraldehyde-1.5% paraformaldehyde (0.1M Millonig's phosphate buffer, pH 7.3), and in 1% osmium tetroxide (0.1M Millonig's phosphate buffer, pH 7.3), and embedded in araldite mixture. The ultrathin sections stained with uranyl acetate and lead citrate were observed with JEM 100 CX-II electron microscope. The results were as follow; 1. Two types of the parafollicular cells, according to their electron densities, were found, i. e., light cells and dark cells. 2. Three types of the parafollicular cells, according to their sizes of secretory granules were found, i.e., small granule cells ($85nm{\pm}20.1;64{\sim}102nm$), medium granule cells ($120nm{\pm}26.5;77{\sim}179nm$), and large granule cells ($165nm{\pm}25.7;128{\sim}189nm$). 3. The differential ultrastructural changes of the cells according to their cell types, i.e., dark and light cell, or small, medium and large granule cells, were hardly observed in the time and dose range covered by this study. 4. The morphological changes of the parafollicular cells were not pronounced after exposure to 3,000 rads of X-ray. 5. Swollen cisternae of the granular endoplasmic reticulum and partial cytolysis were observed after exposure to 6,000 rads of X-ray. 6. Above results suggest that the parafollicular cells showed the alterations of mitochondrial and granular endoplasmic reticular swelling, and partial cytolysis, but only in doses of 6,000 rads.

• Nuclear Engineering and Technology
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• 제8권4호
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• pp.231-242
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• 1976

중 준위 방사성 폐액의 증발 농축물을 불용성 물질로 고형화하기 위해 blown asp-halt와 straight asphalt를 혼합사용하여 제조된 bitumen-waste 고화체로부터 방사성핵종의 용출에 대한 고화체의 호학적 특성 및 용출 조건의 영향에 대해서 조사하였다. 고압 및 저온하에서 120일동안 $^{90}$ Sr 및 $^{137}$Cs의 용출율은 상압 및 상온때 보다 낮은 용출율을 보였으며, 40wt%염을 함유한 고화체에 대한 인공 해수 및 증류수에 대한 용출율의 영향은 별로 차이점이 관찰되지 않았다. 순수 asphalt 및 고화체의 연화점은 $^{60}$Co 조사에 의해 총선량 증가와 함께 증가 됐으나, 5.8$\times$$10^{8}$ rad, 까지 조사된 asphalt는 부피 증가나 팽윤 현상이 나타나지 않았다. 또한 Infrared spectra에 의해 blown asphalt의 functional group을 확인하였고, 계속 방사선에 의한 영향등을 조사중이다.

• 시스템엔지니어링학술지
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• 제13권1호
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• pp.33-39
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• 2017

This paper describes the system engineering approach for the heat transfer analysis of plus7 fuel rod for APR1400 using, a commercial software, ANSYS. The fuel rod is composed of fuel pellets, fill gas, end caps, plenum spring and cladding. The heat is transferred from the pellet outward by conduction through the pellet, fill gas and cladding and further by convection from the cladding surface to the coolant in the flow channel. The goal of this paper is to demonstrate the temperature and heat flux change from the fuel centerline to the cladding surface when having maximum fuel centerline temperature at 100% power. This phenomenon is modelled using the ANSYS FEM code and analyzed for steady state temperature distribution across the fuel pellet and clad and the results were compared to the standard values given in APR1400 SSAR. Specifically the applicability of commercial software in the evaluation of nuclear fuel temperature distribution has been accounted. It is note that special codes have been used for fuel rod mechanical analysis which calculates interrelated effects of temperature, pressure, cladding elastic and plastic behavior, fission gas release, and fuel densification and swelling under the time-varying irradiation conditions. To satisfactorily meet this objective we apply system engineering methodologies to formulate the process and allow for verification and validation of the results acquired. The close proximity of the results obtained validated the accuracy of the FEM analysis of the 2D axisymmetric model and 3D model. This result demonstrated the validity of commercial software instead of proprietary in-house code that is more costly to develop and maintain.

• 한국환경보건학회지
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• 제31권1호
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• pp.7-14
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• 2005

Exposure of skin to UVB radiation can cause the induction of inflammation and impairment of contact hypersensitivity(CHS) response. Several studies have shown that polyphenolic compounds isolated from EGb 761 afford protection against UVB. In this study, we demonstrated that topical application of EGb 761, before 1MED(1.4 KJ/$m^2$), 1.5MED (2.1 KJ/$m^2$), 2MED (2.8 KJ/$m^2$) of UVB exposure to ICR mice prevented UVB-induced inflammation and inhibition of the contact hypersensitivity response. The skin-fold swelling from 1MED, 1.5MED, 2MED of UVB exposure highly significantly increased after twice irradiation. Topical application of EGb 761(0.1%, 1%, 4%), 5 days prior to UVB exposure reduced skin thickness compared to non-treated mice. Exposure of shaved abdominal skin of mice to 1MED, 1.5MED and 2MED of UVB radiation resulted in suppression of contact sensitization through the skin to 56.23%, 65.12%, 74.02%, compared to normal unirradiated skin. Topical application of EGb 761(0.1%, 1%, 4%), 5 days prior to or 5 days after exposure to 1MED and 2MED of UVB resulted in protection against suppression of contact hypersensitivity in mouse dorsal skin. These protective effects were dependent on the dose of EGb 761 employed. The present study show that EGb 761 protect UVB-induced inflammation and immune suppression. Also, we suggest that EGb 761 can provide protection from photoimmunosuppression.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제28권1호
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• pp.68-72
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• 2006

Mucoepidermoid carcinoma is one of the most common malignant salivary gland neoplasm. It occurs over a wide age range, and is most common in the parotid gland and usually appears as an asymptomatic swelling. Pain or facial nerve palsy may develop. Minor salivary gland tumors also typically appear as asymptomatic swellings, which are sometimes fluctuant and have blue or red color that can be mistaken clinically for a mucocele. Histopathologically the mucoepidermoid carcinoma is composed of a mixture of mucous-producing cells and squamous (epidermoid) cells. Low-grade tumors show prominent cyst formation, minimal cellular atypia, and relatively high proportion of mucous cells. Mucoepidermoid carcinoma of the minor salivary glands are treated usually by assured surgical excision. For low-grade neoplasm, only a modest margin of surrounding normal tissue may need to be removed, but high-grade or large tumors warrant wider resection. Postoperative radiation therapy also may be used for more aggressive tumors. Mucoepidermoid carcinoma of the oral minor salivary glands generally have a good prognosis, because they are mostly low-to intermediate grade tumors. We present a case of mucoepidermoid carcinoma managed with surgical enucleation and postoperative irradiation and a good clinical result with review of literatures.

• KSBB Journal
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• 제11권4호
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• pp.481-488
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• 1996

Chitin 유도체의 다양한 응용성에도 불구하고 chi­tin의 강한 내약품성과 적당한 용매부재로 산업적인 용도개발은 매우 부진한 실정 이다. 이와 같은 chitin 의 강한 내약품성을 완화시키는 방법의 하나는 chi­tin을 가수분해하여 MCC를 제조동}는 것이다. 기존의 MCC 제조공정은 주로 강산을 사용하는 공정이어서 사용한 산을 제거하거나 회수하기 위해 많은 후처리가 필요하다. 그래서 이를 대체할 수 있는 공정으로 초음파와 과산화수소를 붉은 엽산과 함께 사용하는 공정을 개발하였다. 이 공정의 주요변수로는 산농도, 팽윤시간 및 온도 그리고 초음파 조사시간 및 주파수이고 이들 변수가 분자량에 미치는 영향을 조사하였다. MCC의 분자량은 chitin 분자량 크기의 약 1/8인 30,000 정도였고, 어떤 일정한 크기에 접 근해 가는 것을 발견하였다. 이와 같은 현상은 cellu lose의 분자배열모델을 도입하여 해석하였다. Chitin 과 MCC 모두 섬유형태로 되어 었으며, MCC의 fi bril 크기는 chitin의 fibril 크기보다 훨씬 작음을 알 수 있었다.

• Nuclear Engineering and Technology
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• 제9권4호
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• pp.223-236
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• 1977

가압수형 인자로에 사용되는 이산화우라 핵연료통의 역학적 열적설계 및 성능 분석을 위한 종합적 전산 코드가 개발되었다. PROD 1.0으로 명명된 이 코드에는 연료소자에서 반경 방향으로의 출력 침체, 연료소자의 균열, 고밀화 및 팽창, 핵분열기체의 방출, 피복관의 크립, 냉각수에 의한 열전달 및 부식층의 형성 둥의 제반 현상이 고려되었다. 이 FROD 1.0 코드로써 이차원적 온도 분포, 변형도, 응력 및 피복관 내압 등이 연소시간의 함수로서 적절한 전산 시간이내에 산출된다. 이 코드는 또한 종류가 다른 열중성자로에 쓰이는 산화 연료에도 응용필 수 있다. FROD 1.0의 응용으로서 원자로의 정상가동 상태와 미국 원자력학회 분류의 제 2상태에 해당하는 두 가지의 출력 경로에 더하여, 고리 원자력 발전소 1호기의 초기 노심에 장전된 핵연료봉의 연소특성을 예측하였다. 예측결과는 최종 안전 심사 보고서에 기술된 핵연료봉 설계기준과 비교되었으며 둘 사치의 차이점이 논의되었다.

• Nuclear Engineering and Technology
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• 제46권2호
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• pp.147-158
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• 2014

In order to investigate how the microstructure of fuel/matrix-interaction (FMI) layers change during irradiation, different U-7Mo dispersion fuel plates have been irradiated to high fission density and then characterized using scanning electron microscopy (SEM). Specifially, samples from irradiated U-7Mo dispersion fuel elements with pure Al, Al-2Si and AA4043 (~4.5 wt.%Si) matrices were SEM characterized using polished samples and samples that were prepared with a focused ion beam (FIB). Features not observable for the polished samples could be captured in SEM images taken of the FIB samples. For the Al matrix sample, a relatively large FMI layer develops, with enrichment of Xe at the FMI layer/Al matrix interface and evidence of debonding. Overall, a significant penetration of Si from the FMI layer into the U-7Mo fuel was observed for samples with Si in the Al matrix, which resulted in a change of the size (larger) and shape (round) of the fission gas bubbles. Additionally, solid fission product phases were observed to nucleate and grow within these bubbles. These changes in the localized regions of the microstructure of the U-7Mo may contribute to changes observed in the macroscopic swelling of fuel plates with Al-Si matrices.

• 대한치과기공학회지
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• 제42권3호
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• pp.202-207
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• 2020

Purpose: This study is a comparative analysis of the strain according to deposition in a constant temperature water bath after manufacturing ultraviolet (UV)-cured artificial teeth. Methods: As a control group, 10 ready-made artificial teeth were selected as the first molar on the right side of the maxilla (RT group). Silicone was used as a duplicate of the artificial denture teeth. Experimental teeth were prepared in two groups using the prepared silicone mold. In the first experimental group, the UV-cured resin was injected into the negative silicone, followed by irradiation with a UV-curing machine for 5 minutes (5M group). In the second experimental group, the UV-cured resin was injected into the negative silicone, and then irradiated for 30 minutes using a UV-curing machine (30M group). The one-way ANOVA was performed, and post-test was analyzed by Tukey. Results: When immersed in a water bath for 15 days, it was found to be -0.3% in the RT group, -0.6% in the 5M group, and -0.7% in the 30M group. The results revealed -0.2% in the RT group, 0.2% in the 5M group, and -0.2% in the 30M group when they were in the bath for 30 days. Conclusion: In the water bath, the swelling was greater when deposited for 1 to 15 days, but was less when deposited for 15 to 30 days.