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Title: Application of CdZnTe Gamma-Ray Detector for Imaging Corrosion under Insulation

Abstract

Corrosion under insulation (CUI) on the external wall of steel pipes is a common problem in many types of industrial plants. This is mainly due to the presence of moisture or water in the insulation materials. This type of corrosion can cause failures in areas that are not normally of a primary concern to an inspection program. The failures are often the result of localised corrosion and not general wasting over a large area. These failures can tee catastrophic in nature or at least have an adverse economic effect in terms of downtime and repairs. There are a number of techniques used today for CUI investigations. The main ones are profile radiography, pulse eddy current, ultrasonic spot readings and insulation removal. A new system now available is portable Pipe-CUI-Profiler. The nucleonic system is based on dual-beam gamma-ray absorption technique using Cadmium Zinc Telluride (CdZnTe) semiconductor detectors. The Pipe-CUI-Profiler is designed to inspect pipes of internal diameter 50, 65, 80, 90, 100, 125 and 150 mm. Pipeline of these sizes with aluminium or thin steel sheathing, containing fibreglass or calcium silicate insulation to thickness of 25, 40 and 50 mm can be inspected. The system has proven to be a safe,more » fast and effective method of inspecting pipe in industrial plant operations. This paper describes the application of gamma-ray techniques and CdZnTe semiconductor detectors in the development of Pipe-CUI-Profiler for non-destructive imaging of corrosion under insulation of steel pipes. Some results of actual pipe testing in large-scale industrial plant will be presented.« less

Authors:
;  [1]
  1. Plant Assessment Technology (PAT) Group, Industrial Technology Division, Malaysia Institute for Nuclear Technology Research (MINT), Bangi, 43000 Kajang (Malaysia)
Publication Date:
OSTI Identifier:
21061709
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 909; Journal Issue: 1; Conference: ICSSST 2006: 2. international conference on solid state science and technology 2006, Kuala Terengganu (Malaysia), 4-6 Sep 2006; Other Information: DOI: 10.1063/1.2739828; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ABSORPTION; CADMIUM TELLURIDES; CALCIUM SILICATES; CORROSION; EDDY CURRENTS; GAMMA RADIATION; INSPECTION; MOISTURE; PIPELINES; SEMICONDUCTOR DETECTORS; SEMICONDUCTOR DEVICES; STEELS; ZINC TELLURIDES

Citation Formats

Abdullah, J., and Yahya, R. Application of CdZnTe Gamma-Ray Detector for Imaging Corrosion under Insulation. United States: N. p., 2007. Web. doi:10.1063/1.2739828.
Abdullah, J., & Yahya, R. Application of CdZnTe Gamma-Ray Detector for Imaging Corrosion under Insulation. United States. doi:10.1063/1.2739828.
Abdullah, J., and Yahya, R. Wed . "Application of CdZnTe Gamma-Ray Detector for Imaging Corrosion under Insulation". United States. doi:10.1063/1.2739828.
@article{osti_21061709,
title = {Application of CdZnTe Gamma-Ray Detector for Imaging Corrosion under Insulation},
author = {Abdullah, J. and Yahya, R.},
abstractNote = {Corrosion under insulation (CUI) on the external wall of steel pipes is a common problem in many types of industrial plants. This is mainly due to the presence of moisture or water in the insulation materials. This type of corrosion can cause failures in areas that are not normally of a primary concern to an inspection program. The failures are often the result of localised corrosion and not general wasting over a large area. These failures can tee catastrophic in nature or at least have an adverse economic effect in terms of downtime and repairs. There are a number of techniques used today for CUI investigations. The main ones are profile radiography, pulse eddy current, ultrasonic spot readings and insulation removal. A new system now available is portable Pipe-CUI-Profiler. The nucleonic system is based on dual-beam gamma-ray absorption technique using Cadmium Zinc Telluride (CdZnTe) semiconductor detectors. The Pipe-CUI-Profiler is designed to inspect pipes of internal diameter 50, 65, 80, 90, 100, 125 and 150 mm. Pipeline of these sizes with aluminium or thin steel sheathing, containing fibreglass or calcium silicate insulation to thickness of 25, 40 and 50 mm can be inspected. The system has proven to be a safe, fast and effective method of inspecting pipe in industrial plant operations. This paper describes the application of gamma-ray techniques and CdZnTe semiconductor detectors in the development of Pipe-CUI-Profiler for non-destructive imaging of corrosion under insulation of steel pipes. Some results of actual pipe testing in large-scale industrial plant will be presented.},
doi = {10.1063/1.2739828},
journal = {AIP Conference Proceedings},
number = 1,
volume = 909,
place = {United States},
year = {Wed May 09 00:00:00 EDT 2007},
month = {Wed May 09 00:00:00 EDT 2007}
}
  • The recent development of CdZnTe detectors has made it possible to produce CdZnTe based clinical radionuclide imagers. The authors therefore investigate the pixellation geometry ideal for this application using numerical simulation. These studies indicate that, for a fixed pixel pitch, configuring the detector with wide pixel and small interpixel spacing will optimize energy resolution and photopeak efficiency. Other issues concerning the practicality of medical imagers using CdZnTe are also discussed.
  • The poor adhesion of common metals to CdZnTe (CZT)/CdTe surfaces has been a long-standing challenge for radiation detector applications. In this present work, we explored the use of an alternative electrode, viz., Al-doped ZnO (AZO) as a replacement to common metallic contacts. ZnO offers several advantages over the latter, such as having a higher hardness, a close match of the coefficients of thermal expansion for CZT and ZnO, and better adhesion to the surface of CZT due to the contact layer being an oxide. The AZO/CZT contact was investigated via high spatial-resolution X-ray response mapping for a planar detector atmore » the micron level. The durability of the device was investigated by acquiring I–V measurements over an 18-month period, and good long-term stability was observed. We have demonstrated that the AZO/CZT/AZO virtual-Frisch-grid device performs fairly well, with comparable or better characteristics than that for the same detector fabricated with gold contacts.« less
  • Cited by 1
  • CdZnTe is a relatively new semiconductor that is being developed for use as a nuclear radiation detector. Its highly atomic numbers provide good detection efficiency for gamma rays, while its wide bandgap allows operation at room temperature. The biggest drawback of this material is its poor charge transport characteristics, especially for the holes. The coplanar-grid charge-sensing technique has been developed over the past several years as a method to circumvent this problem so that detectors with good energy resolution can be realized. The technique is based on the use of two coplanar, interdigitated anodes (grids) to sense the collection ofmore » carriers in a detector. During detector operation, a voltage is applied between the two grids so that electrons are collected only to one of the grids. The signals induced on the collecting and noncollecting grids as a result of charge collection are subtracted to give a net output signal. By adjusting the relative gain of the two signals before subtraction, the output signal can be made insensitive to the effects of both hole trapping and electron trapping. The coplanar-grid technique has been successfully applied to CdZnTe detectors, and good energy resolution ({approximately}2% full-width at half-maximum for 662-keV gamma rays) combined with high efficiency has been obtained for detectors with volumes up to 2.2 cm{sup 3}. A single-electrode readout method has also been developed in which only the collecting anode signal is processed and signal subtraction is not used. In this case, the optimization of detector response is accomplished by adjusting the relative areas of the two anodes. An attractive feature of the coplanar-grid technique, whether employing signal subtraction or single-electrode readout, is that only simple readout electronics is needed. This enables the fabrication of small, low-power detector systems that are particularly well suited for field use. The authors are currently developing coplanar-grid CdZnTe gamma-ray detectors for use in environmental remediation and nuclear safe-guards applications.« less