• Journal of the Korean Society for Nondestructive Testing
• /
• v.8 no.1
• /
• pp.44-48
• /
• 1988

Quality and economy in radiography can be achieved by using the right techniques and the film material available on the market. Pre-packing with or without lead, under vacuum or not, play an important role provided the right kinds of procedures are applied. The author explains some of the ways used by different N.D.T.companies to achieve the best quality in an economical way.

• Journal of the Korean Society of Radiology
• /
• v.16 no.5
• /
• pp.585-594
• /
• 2022

The detector for digital radiography testing, which is currently mainly used, consists of a detector with a flat structure, making it impossible to fully adhere to the digital radiography testing of the test object with curvature. In this study, a curved panel detector capable of adhering to curvature was fabricated to improve the quality of the digital image during the digital radiography testing of piping welds at industrial sites, and digital radiography images using flat and curved panel detectors were obtained for 6in pipes with different nominal thickness. As a result of the experiment, it was confirmed that the flat panel detector does not fully adhere to the pipe, resulting in a gap between the outer part of the pipe and the detector, resulting in a difference in the unsharpness and diffusion of the digital image. On the other hand, it was confirmed that the curved panel detector minimizes the gap between the pipe outer part and the detector, so that digital image diffusion is less than that of the flat panel detector. The higher the confidence of the image, the lower the quality and error in reading, so it is believed that higher quality images can be obtained than conventional flat panel detectors when using detectors that can be closely attached to the inspection object.

• Journal of Radiation Protection and Research
• /
• v.35 no.1
• /
• pp.26-33
• /
• 2010

A computed Radiography (CR) system by use of reusable Image Plate (IP) offers a convenient and reliable way to replace a conventional film-screen system for NDT (non-destructive testing) field. The quality of a radiography to detect a defect of welded objects depends on the procedure embracing several factors such as measurement conditions, image plate type/class, radiation energy, radiation type, and source to image plate distance. Also, the ability of images to detect a flaw reduces with increasing object thickness. In the study, the properties of gamma ray source were summarized for NDT field and inspection images of CR image system manufactured by FUJI were acquired using $^{75}Se$ and $^{192}Ir$ with welded objects. We analyzed the gray scale of hole defect image by using XCAP image processing program and calculated the image contrast and SNR in definition. Also the sesitivities of image quality indicator(IQI) were calculated for hot and cooling tube image of $^{75}Se$ and $^{192}Ir$.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.33 no.1
• /
• pp.80-95
• /
• 2013

• Journal of the Korean Society for Nondestructive Testing
• /
• v.30 no.3
• /
• pp.271-281
• /
• 2010

Brazing fitting which is one of the aircraft hydraulic power system components is widely used for saving weight and achieving higher reliability. Any inherent defects or damage of fitting can cause system failure and/or physical damage of human body due to highly pressurized fluid. Radiographic testing(RT) technique and additional micro-structure investigation on cut-away surfaces have been accomplished to find out some defect-like-inhomogeneity in the fittings. The radiography results showed that some defect-like-inhomogeneity existed inside body. Additional micro-structure investigation on cut-away surface reveals that the inhomogeneity is due to internal voids. In this study, it can be is said that RT technique can be a useful tool for field acceptance test of hydraulic brazing fitting in short time.

• Journal of Power System Engineering
• /
• v.13 no.5
• /
• pp.95-102
• /
• 2009

A steam generator (boiler) in thermal power plants, consisting of more than 30,000 parts and components, can lead to the plant shutdown with damage to even the small part of the components; esp., like weld failures on boiler tubes. Consequently it is greatly demanded to improve the quality of the weld on the boiler tube for the stable operation of the power plants. Because of the feature of the welding, which is done past by melting the work pieces and adding a filler material that cools to become a strong coalescence, there is a great possibility that weld failures take place. As a result, it is regulated to make a non-destructive testing, like radiography test, to detect defects and flaws in the weld. The current film radiography test provides a lower image quality exceeding 2.0% of a basic quality level for a penetrameter, it is very likely to fail to detect micro defect. As a result, the prevention for the boiler tube failure has not been made effectively. In this study, computed radiography technology has been applied as a digital radiography test to the boiler tube weld, and Se-75 radiation source was used to improve the image quality, instead of Ir-192 source. As a result of this study, it is proven to save the time and cost for test and to enhance the quality level of penetrameter penetrating image, which enables to upgrade the quality of radiography test to the boiler tube weld.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.18 no.3
• /
• pp.205-210
• /
• 1998

이미 오래전부터 국내외에서 석유화학공장 등의 보온 배관에서 보온재를 벗기지 않고 배관의 부식 손상 및 잔존두께를 평가하는데 방사선투과시험법을 적용해 오고 있다. 그러나 배관 용접부의 결함 탐상에 관한 방사선투과법에 대한 국제 및 국내 코드는 이미 마련되어 있지만 배관의 두께와 내부에 존재하는 부착물(deposit) 등의 두께를 측정하는 것에 관련한 국제 및 국내 코드는 미비되어 시험 절차 및 시험 결과에 대한 시비가 근본적으로 존재할 수 밖에 없을 뿐만 아니라 표준화된 시험 기술의 미비로 현장에서 많은 시행착오를 동반하였다. 그러나 최근 이 시험법에 대한 관련 원안(protocol)을 확정하기 위해 각국에서 개별적으로 수행되었던 기존의 연구 결과들이 취합되고 있으며 부족한 부분들에 대한 연구가 국제 공동 연구 형식으로 이뤄지고 있다. 따라서 본 연구에서는 tangential radiography를 적용하여 보온된 배관의 잔존 두께를 평가할 수 있는 시험 방법을 제시하고자 하였다.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.3 no.2
• /
• pp.28-35
• /
• 1984

• Nuclear Engineering and Technology
• /
• v.48 no.1
• /
• pp.200-210
• /
• 2016

The neutron radiography reactor (NRAD) is a 250 kW Mark-II Training, Research, Isotopes, General Atomics (TRIGA) reactor at Idaho National Laboratory, Idaho Falls, ID, USA. The East Radiography Station (ERS) is one of two neutron beams at the NRAD used for neutron radiography, which sits beneath a large hot cell and is primarily used for neutron radiography of highly radioactive objects. Additional fuel elements were added to the NRAD core in 2013 to increase the excess reactivity of the reactor, and may have changed some characteristics of the neutron beamline. This report discusses characterization of the neutron beamline following the addition of fuel to the NRAD. This work includes determination of the facility category according to the American Society for Testing and Materials (ASTM) standards, and also uses an array of gold foils to determine the neutron beam flux and evaluate the neutron beam profile. The NRAD ERS neutron beam is a Category I neutron radiography facility, the highest possible quality level according to the ASTM. Gold foil activation experiments show that the average neutron flux with length-to-diameter ratio (L/D) = 125 is $5.96{\times}10^6n/cm^2/s$ with a $2{\sigma}$ standard error of $2.90{\times}10^5n/cm^2/s$. The neutron beam profile can be considered flat for qualitative neutron radiographic evaluation purposes. However, the neutron beam profile should be taken into account for quantitative evaluation.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.30 no.5
• /
• pp.479-483
• /
• 2010

9% nickel alloy steels used for LNG, cryogenic liquid, storage tank are welded with dissimilar Inconel or Hastelloy welding rod and the weldment shows similar characteristic with the dissimilar metal weld of low carbon steel and austenitic stainless steel. Band type indications are sometimes shown on the film during radiography test of the weldments. Thus this study identified whether the indications are non-relevant indications through material, radiographic test, ultrasonic test, liquid penetrant test and microstructure analysis and also proposed radiography film interpretation and cause of band type indications.