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Research Reactors

IAEA CRP 1309 (2003-2006)
Development of improved sources and imaging systems for neutron radiography

Background

Neutron radiography is a powerful tool for non-destructive testing of materials and finds numerous applications in industry and in material research as well. The basic principle is similar to that of X ray radiography. A beam of neutrons falls on the sample and after passing through the sample, leaves the sample image on a photographic plate or on a detector. The neutrons interact with the nuclei of the atoms that compose the sample and the absorption and scattering properties of the contained elements make it possible to produce images of components containing light elements, like hydrogen beneath a matrix of metallic elements, (lead or bismuth), which cannot be easily done with conventional X ray radiography. Exploiting this property, neutron radiography has been used in applications requiring the identification of (light) materials inside solid samples.Because state-of-the-art neutron detection methods are digital ones, both the performance and the diversity of neutron imaging methods have been improved. Strong neutron sources, like research reactors and accelerator-based spallation neutron sources, have been successfully used for neutron radiography during the last two decades and neutron radiography has found its greatest applications in the examination of nuclear fuels, explosives, electronic components and engine turbines blades. Recently, neutron imaging has been used in new branches: fuel cell research, the study of objects from cultural heritage, geoscience and soil physics. Progress in furthering applications has led to the development of three dimensional imaging methods (tomography) and real-time analysis of systems including fluid flow and/or moving components. With the advent of portable neutron sources, neutron radiography can also be employed away from reactors, opening up applications, like checking for drugs and explosives concealed in luggage and cargo containers. The outcome from the application of the neutron imaging depends strongly on the neutron source properties and the detection system used. Although neutron radiography is used to some extent in some research reactor centres in addition to the neutron scattering applications, there are only a few which are well developed and have advanced facilities (termed as type A) while the remainder employ standard technology requiring optimization and upgradation (termed as type B).

The aim of the present CRP was to bring these two facilities (and the involved operators) together to develop a good neutron imaging system, bring in young workers in this field who can maintain the facilities and are desirous of improving the existing set ups or building new facilities. Development of cost efficient, fast imaging systems for an optimized utilization of the available neutron beam conditions is another field of interest.

Objectives

The enhancement of utilization of research reactors is one of the major objectives of the IAEA's project on "Effective Utilization of Research Reactors". In particular, the improvement of existing installations for neutron imaging and the effective utilization of such facilities are intended. Therefore, one of the aims of the CRP was to look for adapted solutions for the individual reactor installation and beam line.

Others aims were :

  • To optimize the neutron beams for imaging purpose using modern simulation techniques.
  • To enhance the beam intensity using modern layout principles, neutron optics, like focusing and beam guides and filters.
  • To develop a standardized, low cost, neutron image grabber and analyzer for efficient data collection that can be used with low intensity sources.
  • To improve signal processing techniques used in neutron imaging applications.

Expected Research Outputs

  • Improvement inthe design of beam lines in terms of neutron collimation and intensity.
  • Improvements in resolution are normally achieved at a cost in intensity.
  • Help to expand the knowledge and understanding of various neutron radiography imaging techniques and their applications among the research reactor community in developing Member States and will be helpful in training qualified neutron radiography specialists who, in addition to operating existing facilities, will be able to take up developmental work in future.
  • Help in building long term relationships between scientists from developing and developed countries. This will help in encouraging further bilateral and/or multilateral collaborations among institutions/reactor facilities in various Member States.