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Application of Large Sample Neutron Activation Analysis Techniques for Inhomogeneous Bulk Archaeological Samples and Large Objects
Closed for proposals
Project Type
Project Code
F23027CRP
1499Approved Date
Status
Start Date
Expected End Date
Completed Date
10 January 2014Description
Nuclear techniques based on X-ray and neutron probe principles play a very important role in both applied research and practical applications. Non-destructive X-ray fluorescence techniques are often applied for trace element characterisation but this technique provides information of the surface layers but not on the bulk composition of objects. Neutron activation analysis (NAA) is a well established nuclear technique, which is ideally suited to investigate the microstructural or elemental composition and can be applied to studies of a large variety of samples. However, there are limitations due to sample size for application in bulk analysis, in particular for archaeology and cultural art artefacts, findings, forensic materials as well as geological studies. This is due to the lack of verified and validated experimental procedures which are required for NAA implementation in bulk sample studies. The IAEA is initiating concerted efforts to support the planning, harmonisation and implementation of Large Sample Neutron Activation Analysis (LSNAA) techniques, which will enable new areas of applications. The LSNAA is still in the R&D phase; suggested collaborative efforts for further developments and the proposed IAEA Coordinated Research Project (CRP) aim to bring the technique developers and end-users together. The CRP will focus primarily on the application of LSNAA in area of archaeological and geological programmes, however the CRP will also be open for further utilisation in other subjects of industry and research. This work will contribute to the validation and harmonisation of methodology and in particular, provide support for the training of manpower for effective utilisation of the LSNAA.
Objectives
The objective of the project 2.5.2.4 under which the CRP is being proposed was: to demonstrate the role of nuclear techniques, including use of neutron based systems, as confirmatory method to conventional screening/inspection systems in detection of explosives and illicit materials, as well as analytical tools for compositional analysis
Specific objectives
To develop / standardize data acquisition / analysis systems
To harmonise / standardize data collection from facilities with similar kind of instrumentation for further analysis and benchmarking
To identify the needs for development or upgrade of the neutron irradiation facility for uniform irradiation of large samples
To validate and optimize the experimental procedures for LSNAA applications in archaeology and art objects
Impact
Compositional analysis is essential in many fields of science, ranging from environmental studies, geology, to advanced technology, food, nutrition and human health. Large Sample NAA (LSNAA) is the only available method to measure the bulk mass fractions of the elements present in a large sample (up to kilograms in mass) non-destructively. Examples amenable to LSNAA include irregularly shaped archaeological artefacts, excavated rock samples, large samples of assorted ore, finished products such as nuclear reactor components, etc.
Fifteen Member States joined the CRP from 2009 to 2012, ranging from laboratories with proven facilities to newcomers. During the CRP several new facilities have been built, innovative approaches have been developed and it has been demonstrated that trustworthy results can be obtained with LSNAA. The latter has been underpinned by a unique interlaboratory proficiency testing exercise. Replicas of an intact clay pottery art piece were distributed amongst the participants. Details on this exercise are given in this publication. The degree of agreement among the participants was good, reflecting the power of the LSNAA technique and the relative simplicity of implementation. LSNAA can be applied to many matrices that have relevance in archaeology, art pieces, food stuff, ores, and can be extended to many other materials.
The information on LSNAA generated during the CRP was made available to Member States and potential stakeholders of the technique in a TECDOC. LSNAA methodologies and approaches were described, and unique opportunities in developing infrastructure were highlighted with case studies developed during the CRP.
All taken together, the CRP was the essential step to definitely establishing LSNAA as a mature technique, available in research reactors to Member States. This impact was not limited to the duration of the CRP and to the participating laboratories, with continued use and developments after the CRP ended, as the technique took a momentum of its own. The role of the IAEA was essential in kickstarting this process.
Relevance
Several LSNAA facilities have been developed during the CRP and very strong methodological advancements were achieved. As the CRP was concluded in the year 2012, it is already possible to evaluate how its objectives and outputs remain appropriate and worthwhile to the Agency programme and to the stakeholders concerned.
The CRP brought about an increased awareness of the unique capability of the technique to measure chemical elements in large objects. This has resulted in both new applications in existing facilities and in new facilities being established after the CRP ended. Also, further developments of the technique, including utilization of non-research reactor based neutron sources, complementary use of imaging methods, and application to new fields, have occurred since 2012.
In addition, the use of neutron generators and isotopic neutron sources in belt-analysers and flow-analysers (e.g. for oil) for process control in industry continues. Although much less worldwide available, photon activation analysis shares many of the advantages of NAA and PGA for the analysis of large objects. A review of this technique has been published in 2017 referring to examples of the analysis of large samples by photon activation. Stamatelatos demonstrated in 2016 the use of photon activation analysis for multi-element measurements in intact large clumps (ca. 125 g) of metallurgical slag from a copper furnace; these measurements were done for an archaeological research project to gain more insight in the metallurgical techniques applied in the early bronze age.
The TECDOC published in 2018 includes all these new developments, and serves as a reference of interest not only to the NAA experts, research reactor personnel, and those considering implementing this technique, but also to various stakeholders such as industrialists, environmental and legal experts, and administrators. An international network has been established in the frame of this recent CRP that will contribute to future use of LSNAA and in many scientific publications and innovative methodologies.
In conclusion, the CRP remains and will continue to remain relevant to the Agency's programme and to the relevant stakeholders in the Member States, for the foreseeable future.