• Journal of Welding and Joining
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• v.2 no.2
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• pp.1-6
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• 1984

피복아아크 용접봉(이하 용접봉이라 함)의 피복제는 염기도에 따라 산성, 중성, 염기성으로 대별할 수 있다. 용접에서의 화학야금반응은 제강의 화학야금반응과 원리는 비슷하나 양자간 크게 다른 점은 용접시의 반응시간이 극히 짧다는 점이다. 이와같이 반응시간이 짧다는 점 이외에도 작업자가 직접 용융반응을 지켜 보면서 반응후에 나타나는 제반 문제점에 대비하여야 하는 어려운 점이 있다. 제강반응은 전문가만의 독특한 기술인 반면 용접은 용접봉 제조자 뿐만 아니라, 용접작업자 고유의 기술이므로 용접야금반응을 상식화 하고자 하는데 본 고는 의의를 두고 있다. 피복제 중에서의 염기도의 변화, 즉 염기도에 영향을 크게 미치는 탄산칼슘의 양을 임의로 변화시키므로서 다음과 같은 현상을 기대할 수 있다. (1)용접 작업성의 변화 (2)용착 금속의 화학성분 변화 (3)용착금속의 조직 변화 (4) 용착금속내의 수소 함유량 변화 (5)용착금속의 기계적 성질변화 등이다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.11a
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• pp.331-331
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• 2015

차세대 원자로 핵연료의 성능을 제한하는 금속연료-피복관 상호반응 현상(FCCI)을 방지하기 위한 방안으로 Cr 도금기술의 적용성을 연구하였다. 도금 성능을 평가하기 위한 예비 시험 결과 Cr 도금층은 핵연료와 피복관의 상호반응을 억제함이 확인되었다. 도금층 성질을 개선하기 위한 연구와 함께 Cr층을 피복관 내면에 도금하는 연구를 수행하였다.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.13 no.3
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• pp.211-218
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• 2015

The reaction rates of ZIRLO cladding hulls with cross-section openings were investigated using a thermo-gravimetric analysis system in order to identify whether selective recovery of Zr from oxidized cladding hulls is possible. The experimental results showed that an oxidized ZIRLO cladding hull was not reactive with chlorine gas at 400℃. However, providing fresh cross-sections on one or both ends of the ZIRLO hulls enabled a chlorination reaction. This reaction was completed after 8 hours; a 14% increase on the 7 hours seen with a bare ZIRLO cladding hull. The Sharp-Hancock plot analysis results revealed that the contracting volume model is the best for describing the reaction between the cross-section opened ZIRLO hulls and chlorine gas under the condition of this work. It was concluded that the chlorination process can be employed for oxidized ZIRLO cladding hulls by providing cross-section openings.

• Journal of Soil and Groundwater Environment
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• v.9 no.1
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• pp.63-69
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• 2004

Hematite-coated sand was examined for the application of the PRB (permeable reactive barrier) to the arsenic-contaminated subsurface in the metal mining areas. The removal efficiency of As in a batch and a flow system was investigated through the adsorption isotherm, removal kinetics and column experiments. Hematite-coated sand followed a linear adsorption isotherm with high adsorption capacity at low level concentrations of As (＜1.0 mg/L). In the column experiments, high content of hematite-coated sand enhanced the removal efficiency, but the amount of the As removal decreased due to the higher affinity of As (V) than As (III) and reduced adsorption kinetics in the flow system. Therefore. the amount of hematite-coated sand, the adsorption affinity of As species and removal kinetics determined the removal efficiency of As in a flow system.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05c
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• pp.311-316
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• 1996

제어봉이탈사고시의 핵연료봉 거동을 연구로에서의 반응도사고 모사실험 결과와 기존의 핵연료 손상기준을 비교하여 분석하였다. 반응도사고시 고연소도 핵연료의 손상은 주로 PCMI 기구로 발생하는데, 고연소도에서의 피복관의 부식 및 수소화 그리고 방사선조사에 의한 연성감소와 산화층 박리로 인한 수소화합물의 국부적인 집중화로 인한 피복관의 현저한 연성감소가 주요 원인이었다. 기존의 핵연료 손상 기준에서 DNB가 일어날때 핵연료 손상이 발생한다는 가정은 낮은 핵연료엔탈피에서 핵연료 손상이 일어나는 것과 동일함을 확인하였으며, 현재까지 발표된 실험자료와 핵연료손상기구의 분석을 통해 연소도에 따른 반응도사고시의 핵연료손상기준을 예비적으로 유도하였다. 핵연료손상은 낮은 연소도에는 DNB로 발생하고 고연소도에서는 PCMI로 발생할수 있기 때문에, 과도상태에서의 고연소도 핵연료의 건전성 유지를 위해서는 피복관 산화층의 박리로 인한 수소화합물의 집중화로 피복관의 연성이 감소되는 것을 방지할 필요가 있다.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.11 no.1
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• pp.55-61
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• 2013

The recovery of Zr from Zircaloy-4 (Zry-4) cladding hulls using a chlorination method was demonstrated for complete conversion of Zr into $ZrCl_4$. A chlorination reaction was performed by reacting Zry-4 hulls for 8 h under a 70 cc/min $Cl_2$ + 70 cc/min Ar flow at $380^{\circ}C$. The initial weight of the reactant (51.7 g) decreased to 0.49 g after 8 h of operation, which is only 0.95wt% of the initial weight. The weight of the total reaction products was 121.7 g with a high Zr purity of 99.80wt%. Fe and Sn were identified as major (0.18wt%) and minor (0.02wt%) impurities of the reaction products, respectively. It was also shown that Zr exhibited a high recovery ratio of 96.95wt% with a relatively small experimental loss of 2.34wt%. Observation of the reaction residues revealed that the chlorination reaction was dominant along the longitudinal direction, and surface oxide layers remained as reaction residues. The high purity and recovery ratio of Zr proposed the feasibility of the chlorination technique as an effective hull waste treatment method.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2010.05a
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• pp.309-310
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• 2010

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.11 no.1
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• pp.69-75
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• 2013

The recovery of Zr from Zircaloy-4 (Zry-4) cladding hulls was demonstrated to investigate the effect of the oxidation process on the reaction rate of the chlorination reaction. In chlorination reaction experiments performed for 6 h, where reaction products were collected every 2 h, it was observed that a significant decrease in the reaction rate was caused by the oxidation process ($500^{\circ}C$, 10 h under an air atmosphere) within the reaction period of 0 - 2 h. The amount of reaction residue increased from 0.95 to 1.65wt% of initial weights in the fresh and Zry-500-10 (Zry-4 hulls oxidized at $500^{\circ}C$ for 10 h under an air atmosphere) hulls, respectively. The purity of the recovered Zr was identical at 99.61wt% for the fresh Zry-4 and Zry-500-10 hulls. Quantitative analysis of the chlorination reaction rate was performed by varying the reaction time from 0.5 to 1.0, 2.0, and 4.0 h. The fitting results showed that the relationship between weight loss and reaction time can be interpreted by a linear line with a slope of 23.35wt%/h for the fresh Zry-4 case, while two linear lines were necessary to fit the results of Zry-500-10. In addition, the slope values were 17.12 and 27.16wt%/h for (0 - 20) and (20 - 100)wt% loss regions, respectively.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.8
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• pp.470-477
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• 2017

In this study, the applicability of calcite, sand, and zeolite for the remediation of sediments contaminated with organics and nutrients were investigated. Sediments and seawater for water tank experiments were sampled from Pyeongtaek harbor, and 1 cm or 3 cm of calcite, sand, and zeolite were capped on the sampled sediments. pH, electric conductivity (EC), dissolved oxygen (DO), chemical oxygen demand (COD), total nitrogen (TN), and total phosphorus (TP) were monitored for 63 days. The sampled sediments were highly contaminated with organic matter and total nitrogen. DO in uncapped condition was exhausted within 10 days but DO in capping condition except 3 cm of zeolite capping was prolonged above 2 mg/L. Capping efficiency for interrupting COD release from sediments was in the following order: zeolite 1 cm > calcite 1 cm > calcite 3 cm > sand 3 cm ${\cong}$ zeolite 3 cm ${\cong}$ sand 1 cm. Zeolite was found to be effective for interrupting nitrogen release. T-P was not observed in both uncapped and capped sediment, i.e., all experimental conditions. It can be concluded that zeolite can be effectively used for the remediation of sediments highly contaminated with organic matter and nitrogen.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2000.11a
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• pp.35-36
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• 2000

핵연료의 피복관은 핵분열로부터 발생하는 방사성 핵분열생성물이 외부로 유출되는 것을 차단하는 첫번째 방어막의 역할을 하며, 피복관의 건전성은 정상 상태는 물론 이고 사고시에도 위해한 핵분열생성물의 방출을 억제하는 역할을 충분히 수행할 수 있도록 유지되어야 한다. 단사정 산화막 영역에서만 수증기 압력에 의한 산화가속 효과가 존재하는데, 아직 이를 설명할 수 있는 산화속도 모형이 설정되어 있지 않은 상태이다. 본 연구에선 실험자료를 근거로 하여, 절실히 요구되는 $1000^{\circ}C$ 이하 영역에서 의 수증기 압력을 고려한 산화속도식을 개발하여, 보다 정확한 원전 사고해석이 가능 하도록 하는데 기여하려 한다.