• Nuclear Engineering and Technology
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• v.56 no.2
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• pp.437-443
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• 2024

The development and testing of inspection equipment is necessary for the safe deployment of advanced nuclear reactors. One proposed advanced reactor design is Westinghouse's lead-cooled fast reactor (LFR). In this paper, the process of achieving adequate wetting for an ultrasonic under-lead viewing system is discussed and results presented. Such a device would be used for inspection in the molten lead core during reactor outages. Wider tests into the wetting of various materials in molten lead at microscale were performed using electron microscopy. The possible mechanisms and kinetics for materials wetting in lead, particularly stainless steel and nickel, are proposed and discussed.

• Nuclear Engineering and Technology
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• v.56 no.4
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• pp.1460-1471
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• 2024

2D and 3D ultrasonic imaging has so far not been demonstrated in pure molten lead in the open literature. In this study the development of such an ultrasonic device for imaging is outlined and results from testing at 380 ℃ in lead are presented. The main difficulties were found to be achieving then maintaining suitable wetting while ensuring suitable durability of the device, both due to the harsh nature of molten lead and the elevated temperatures. The successful detection and imaging (2D and 3D), of differently shaped targets, where the features were above the size of the transmitted ultrasound beam was demonstrated.

• Korean Journal of Materials Research
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• v.12 no.1
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• pp.68-74
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• 2002

The lead has to be removed for the recycling of copper alloy. The lead cannot be removed from the copper alloy by oxidation. It can be removed by the evaporation because of its high vapor pressure. However, rare information is found on removal of lead from copper alloy. The purpose of present work is to provide a fundamental knowledges on the removal of lead from the copper alloy by evaporation. Gas injection was made in molten copper alloy, and the evaporation rate of lead was measured. The influence of Ar gas flow rata(2~4 L/min), initial contents of lead(2~4wt%Pb), temperature(1200~140$0^{\circ}C$) was investigated based on the thermodynamic and the kinetics. The rate constant is increased with increasing flow rate of Ar and temperature. Though amount of lead removed is increased with higher initial lead concentration, the rate constant is not changed significantly. The activation energy is estimated from the temperature dependence of the rate constant. Also removal of lead from the copper by adding chloride was made for the comparison.

• Korean Journal of Metals and Materials
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• v.50 no.8
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• pp.563-568
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• 2012

The wetting property and reflectivity of Sn-3.5Ag solder which was dip coated on a LED lead frame were investigated. The wettability of molten solder on Cu substrate was evaluated by the wetting balance tester, and surface tension was calculated from maximum withdrawal force and withdrawal time. Temperature of the molten solder in a bath was varied in the range of $250-290^{\circ}C$. With increasing temperature, the surface tension decreased a little. The reflectivity of Sn-3.5Ag coated on a substrate became a little lower than the highest current LED lead frame reflectivity.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.268-271
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• 2008

If a reactor vessel is failed to retain a molten corium in a postulated severe accident, the molten corium is released outside the reactor vessel into a reactor cavity. The molten corium would attack the concrete wall and basemat of the reactor cavity, which may lead to inevitable concrete decompositions and possible radiological releases. In the OECD/MCCI project, a series of tests were performed to secure the data for cooling the molten corium spread out at the reactor cavity and for the long-term CCI (Core Concrete Interaction). Also, a MCCI (Molten Core Concrete Interaction) analysis code, CORQUENCH was upgraded at Argonne National Laboratory with embedding the new models developed for the tests. This paper deals with analyses of MCCI at plant scale under the conditions of top flooding using the upgraded CORQUENCH code. The modeling approach is briefly summarized first, followed by presentation of a validation calculation that illustrates the predicative capability of the modeling tool. With this background in place, the model is then used to carry out a parametric set of scoping calculations that define approximate coolability envelopes for the LCS (Limestone Common Sand) concrete that has been evaluated in the OECD/MCCI project.

• Journal of Conservation Science
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• v.26 no.2
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• pp.157-169
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• 2010

This study focused on the material characteristics and archaeometric relationship between the molten glass and bronze materials within the crucibles and gilt-bronze Bodhisattva statue excavated from the Ssangbukri site in Buyeo, Korea. Yellowish green to red brown vitreous material in the crucibles was identified as lead glass which contained scarce amount of BaO, and low $Al_2O_3$ and CaO. Metallic molten material was identified as bronze of copper-tin-lead alloy with low amount of impurities that indicated well-refined materials. Also, cassiterite was used for raw metal ore of tin. The Bodhisattva statue consisted of major copper with trace impurities in the core metal, and gold amalgam in the gilded layer. Though lead isotopic analysis showed contradictory results in each lead glass, bronze and Bodhisattva statue that required further examination, it could be stated that the statue was made in the Ssangbukri site based on the high-level technical skills of bronze production.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.33 no.1
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• pp.19-33
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• 2023

Objectives: The purpose of this study is to systematically identify situations where exposure levels are expected to be high by structuring domestic lead measurement data according to exposure processes and activities. Methods: Occupational exposure data on lead was collected from the results of the Evaluation of Reliability of Working Environment Measurement conducted by the government from 2019 to 2020. Lead exposure characteristics were analyzed by PROC (process category) and activity. The Risk Characterization Ratios (RCRs) of five PROCs according to ventilation type and lead content were evaluated using the MEASE (Metal's EASE) model. Results: The exposure data on lead (n=250) was classified into 12 PROCs and 12 activities, with an average concentration of 0.040 mg/m³ and about 14% exceeding the occupational exposure limit of 0.05 mg/m³. Processes with high exposure levels were PROC 7 (industrial spraying), 23 (open processing and transfer operations of molten metal), 24 (mechanical treatment), 25 (welding), and 26 (handling of powder containing lead). The results of evaluating RCR for the five PROCs were greater than 1 or close to 1 even if local exhaust ventilation was used. Conclusions: There is a possibility that the concentration of exposure is high in the casting and tapping of molten metal containing lead, mechanical treatment such as fracturing and abrasion, handling of powder, spraying, battery manufacturing, and waste battery recycling processes. It is necessary to implement chemical management policies for workplaces with such processes.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.721-723
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• 1992

The electrical resistivity and piezoelectric properties have been studied for Lead Zirconate-Titanate(PZT) with $Nb_2O_5$ dopant, fabricated from conventional mixed-oxide powders and molten salt synthesis. The resistivity and electromechanical coupling factor(Kp) were increased with increasing Nb contents. The reason for increasing of the electrical resistivity below the Curie Temperature(Tc), It is believed that the p-type electrical conduction in PZT is caused by the lead vacancies. The electromechanical coupling factor(Kr) and piezoelectric constant $d_{33}$ were improved by Nb additives. This behavior can be explained as a compensation effect and $Nb^{5+}$ can serve as a donar and contribute electrons to the conduction process. As a result, the optimized $Nb_2O_5$ dopants on the PZT specimens were 0.75 wt%.

• Journal of Welding and Joining
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• v.22 no.2
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• pp.46-50
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• 2004

In today's highly competitive marketplace, it is of great significance for the manufacturing industry to reduce lead-time and costs fur the product development. Since first emerged in 1986, Rapid Prototyping (RP) technology has helped successfully to reduce time and costs. Recently, RP using functional materials such as metal has been researched. However RP using the molten metal has been struggling to resolve several drawbacks, such as dimensional inaccuracy, poor surface finish, post finishing, etc., that originate primarily from the overall deposition of molten metal for each layer. So, the purpose of this study is to develop a new RP technique using sheet metal and projection welding for reducing several drawbacks in occurring RP using molten metal. Also tensile and bending specimens were made by the developed RP process using projection welding and were verified.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.5
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• pp.378-383
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• 1998

Microstructure and additive effect of Lead Zirconate-Titanate(PZT) ceramics prepared by molten salt synthesis method with additives $Nb_2O_5, Fe_2O_3$ and MnO were investigated.The grain PZT ceramics ws decreased with the increase $Nb^{5+} or Fe^{3+}$ while increased with the increase $Mn^{2+}$ addition. The relative resistivity of PZT ceramics was increased with the increase $Mn^{5+}$ addition, while decreased with the increase $Mn^{2+}$ addition. And the dielectric and the piezoelectric constant of PZT ceramics showed 2,100 and 342pC/N at $Mn^{5+}$ addition of 0.75 mol%, respectively.