Sung-Deok Hong

Measurement of Weld Mechanical Properties of SUS316L Plate Using an Instrumented Indentation Technique

Different microstructures in the weld zone of a metal structure such as a fusion zone or heat affected zone are formed as compared to the parent material. Thus, the mechanical properties in the weld zone are different from those in the parent material. As the basic data for reliably understanding the structural characteristics of welded PCHE prototype made of SUS316L, the mechanical properties in the weld zone and parent material for a SUS316L plate are measured using an the instrumented indentation technique in this study.

Measurement of Weld Material Properties of Alloy 617 Using an Instrumented Indentation Technique

Abstract Different microstructures in the weld zone of a metal structure such as a fusion zone or heat affected zone are formed as compared to the parent material. Thus, the mechanical properties in the weld zone are different from those in the parent material. As the basic data for reliably understanding the structural characteristics of a welded PCHE specimen to be made of Alloy 617, the mechanical properties in the weld zone and parent material for a Alloy 617 plate are measured using an instrumented indentation technique in this study.Key Words : Instrumented indentation technique, Mechanical property, PCHE(Printed Circuited Heat Exchanger), Very high temperature reactor 1. 서 론 용접은 단품으로 이루어진 부품들을 원하는 형상의 구조물로 용이하게 형상화할 수 있는 편리한 접합 방법이다. 그런데 용접된 구조물의 용접 부위는 용접시에 투입된 열로 인하여 용융부 및 열영향부(Heat Affected Zone; HAZ)가 형성된다. 용융부 및 HAZ에서는 모재와는 다른 미세조직이 형성되고 용접에 의한 잔류응력 등으로 인하여 이 부위의 기계적 물성치도 모재와는 다를 수 있다 1) . 모재, HAZ, 용융부 등의 기계적 물성치가 다를 수 있기 때문에 용접된 구조물이 하중을 받을 경우, 거시적으로 보면 구조물의 구조특성 및 기계적 거동이 단일 물성치로 이루어진 구조물의 구조특성 및 기계적 거동과는 사뭇 다를 수 있다

Macroscopic High-Temperature Structural Analysis of PHE Prototypes Considering Weld Material Properties

®-X is being conducted on in a small-scale nitrogen gas loop at the Korea Atomic Energy Research Institute. Previous research on the macroscopic high-temperature structural analysis of PHE prototypes had been performed using base material properties owing to a lack of weld material properties. In this study, macroscopic high-temperature structural analyses considering the weld material properties were performed and the results were compared with those of a previous study.

High-Temperature Structural Analysis of a Medium-Scale Process Heat Exchanger Prototype

A process heat exchanger (PHE) in a nuclear hydrogen system is a key component for transferring the considerable heat generated in a very high temperature reactor (VHTR) to a chemical reaction that yields a large quantity of hydrogen. A performance test on a medium-scale PHE prototype made of -X is scheduled in a small-scale gas loop at the Korea Atomic Energy Research Institute. In this study, as a preliminary study before carrying out the performance test in the gas loop, high-temperature structural analysis modeling and macroscopic thermal and structural analysis of the medium-scale PHE prototype by imposing the established displacement boundary constraints were carried out under the gas loop test condition. The results obtained in this study will be compared with the performance test results of the medium-scale PHE prototype in the gas loop.

Effect of mechanical properties in the weld zone on the structural analysis results of a plate-type heat exchanger prototype and pressurized water reactor spacer grid

The mechanical properties in a weld zone are different from those in the base material owing to their different microstructures. A process heat exchanger in a nuclear hydrogen system is a key component to transfer high heat generated in a very high-temperature reactor to a chemical reaction that yields a large quantity of hydrogen. A spacer grid in pressurized water reactor (PWR) fuel is a structural component with an interconnected and welded array of slotted grid straps. Previous research on the strength analyses of these components was performed using base material properties owing to a lack of mechanical properties in the weld zone. In this study, based on the mechanical properties in the weld zone of components recently obtained using an instrumented indentation technique, strength analyses considering the mechanical properties in the weld zone were performed, and the analysis results are compared with previous research.

Structural Integrity Evaluation of a Lab-Scale PCHE Prototype under the Test Conditions of HELP

The intermediate heat exchanger (IHX) of a very high temperature reactor (VHTR) transfers 950°C heat generated from the VHTR to a hydrogen production plant. The korea atomic energy research institute (KAERI) has manufactured a lab-scale printed circuit heat exchanger (PCHE) prototype made of SUS316L, under consideration, as a candidate. In this study, as a part of a high temperature structural integrity evaluation of the lab-scale PCHE prototype, a macroscopic structural behavior analysis including structural analysis modeling and a thermal/elastic structural analysis was carried out under the test conditions of a helium experimental loop (HELP) as a precedent study for a performance test. The results obtained in this study will be compared with the test results of the lab-scale PCHE prototype.

High-Temperature Structural Analysis of a Small-Scale PHE Prototype under the Test Condition of a Small-Scale Gas Loop

A process heat exchanger (PHE) is a key component for transferring the high-temperature heat generated from a very high-temperature reactor (VHTR) to a chemical reaction for the massive production of hydrogen. The Korea Atomic Energy Research Institute has designed and assembled a small-scale nitrogen gas loop for a performance test on VHTR components and has manufactured a small-scale PHE prototype made of Hastelloy-X alloy. A performance test on the PHE prototype is underway in the gas loop, where different kinds of pipelines connecting to the PHE prototype are tested for reducing the thermal stress under the expansion of the PHE prototype. In this study, to evaluate the high-temperature structural integrity of the PHE prototype under the test condition of the gas loop, a realistic and effective boundary condition imposing the stiffness of the pipelines connected to the PHE prototype was suggested. An equivalent spring stiffness to reduce the thermal stress under the expansion of the PHE prototype was computed from the bending deformation and expansion of the pipelines connected to the PHE. A structural analysis on the PHE prototype was also carried out by imposing the suggested boundary condition. As a result of the analysis, the structural integrity of the PHE prototype seems to be maintained under the test condition of the gas loop.

High-Temperature Structural Analysis of a Small-Scale PHE Prototype - Analysis Considering Material Properties in Weld Zone -

A process heat exchanger (PHE) in a nuclear hydrogen system is a key component for transferring the considerable heat generated in a very high temperature reactor (VHTR) to a chemical reaction that yields a large quantity of hydrogen. A performance test on a small-scale PHE prototype made of Hastelloy-X is underway in a small- scale gas loop at the Korea Atomic Energy Research Institute. Previous research on the high-temperature structural analysis of the small-scale PHE prototype had been performed using base material properties. In this study, a high- temperature structural analysis considering the mechanical properties in the weld zone was performed, and the obtained results were compared with those of the previous research.

Temperature Measurement With Radiation Correction for Very High Temperature Gas

When a thermocouple is placed in a high temperature gas-flow stream, the measured temperature could be biased from the true gas temperature due to a large radiation heat transfer from a thermocouple surface to its surroundings. In this study, two thermocouples of unequal diameters of 1/8 inch and 1/16 inch were used to correct the radiation effect. This method is called the reduced radiation error (RRE). The test results show that the radiation on the thermocouple sheath tubes is the source of the error in the gas temperature measurement, and the RRE method is very effective for radiation correction under negligible conditions with the conductive dissipation through the sheath tubes.Copyright

High-Temperture Structural Analysis on a Small-Scale PHE Prototype Considering Mechanical Properties in the Heat-Affected Zone and in the Weld Zone

PHE (Process Heat Exchanger) is a key component in transferring the high temperature heat generated from a VHTR (Very High Temperature Reactor) to the chemical reaction for massive production of hydrogen. A performance test on a small-scale PHE prototype made of Hastelloy-X is currently undergoing in a small-scale gas loop at the Korea Atomic Energy Research Institute. Previous researches on the high-temperature structural analysis of the small-scale PHE prototype had been performed using parent material properties over the whole region. In this study, high-temperature elastic structural analysis considering mechanical properties in the weld zone was performed and the analysis result was compared with previous researches.Copyright