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Use and management of sulphated excavation material from the Montcenis Base Tunnel
Published in Daniele Peila, Giulia Viggiani, Tarcisio Celestino, Tunnels and Underground Cities: Engineering and Innovation meet Archaeology, Architecture and Art, 2020
E. Hugot, J. Burdin, L. Brino, P. Schriqui, M.E. Parisi
In order to comply with the EU environmental rules by maximizing the use of excavated material, TELT undertook a research and development programme in 2009 to check the sulphate content of this material and to find out a way of use. The first laboratory results and on-site studies are presented here. Furthermore, taking into account the forecasted excavation progress and the small available space at the Villarodin-Bourget/Modane site, the implementation of the chemical composition analysis of the excavated material is being critical, and especially their SO3 content, with the convenient accuracy and within a very short notice. One reliable on-site chemical characterisation process today identified is the one provided by the Prompt Gamma Neutron Activation Analyser (PGNAA). TELT therefore asked the CEA to carry out an expert appraisal of the equipment used and of the material submitted to radiation, in order to demonstrate that no residual radioactivity is remaining within the tested material. The details and results of the protocol, and the tests performed are presented here.
Implication of nuclear analytical techniques for the assessment of coal quality in terms of ash content
Published in International Journal of Coal Preparation and Utilization, 2023
S. K. Samanta, V. Sharma, A. Sengupta, R. Acharya
The calorific value of the coal is inversely related to coal ash content. Coal ash mainly consists of SiO2, Al2O3, MgO, Na2O, K2O, CaO, Fe2O3 and TiO2 (Singh et al. 2020). Higher ash content in coal may lead to several difficulties like abnormal combustion, increased accident rate, equipment damage, environmental pollution and other related problems (Zhang et al. 2020). Instruments for coal quality testing are used in wide applications such as coal exploration, production, transportation, storage, blending, etc (Zhang et al. 2020). However, laboratory testing methods for coal quality are most widely accepted worldwide. PGNAA (Prompt Gamma-ray Neutron Activation Analysis) is the most widely utilized technique for rapid determination of coal quality in coal-fired power plants (Borsaru and Jecny 2001; Lim and Abernethy 2005).
Partial Cross-Section Calculations for PGNAA Based on a Deterministic Neutron Transport Solver
Published in Nuclear Technology, 2022
Alexander Jesser, Kai Krycki, Martin Frank
With the measuring system QUANTOM (Ref. 4), for the first time, a technology is being developed that is able to determine in a nondestructive manner the material composition of 200-L drums filled with radioactive waste. It utilizes prompt gamma neutron activation analysis (PGNAA) to identify all chemical elements. Neutrons are generated by a deuterium-deuterium (D-D) neutron generator and moderated by surrounding graphite such that a (mostly) thermal neutron flux field is formed inside the waste drum. Atoms inside the measurement facility interact with free neutrons, resulting in the emission of element-specific (even isotope-specific) gamma radiation.5 Spatially resolved gamma spectra are acquired during the measurement process by two symmetrically mounted high-purity germanium detectors. By rotation and vertical translation of the waste drum inside the measurement chamber, the surface is completely and disjunctively scanned by the detectors at discrete positions. A joint evaluation of the spectra is used to reconstruct spatial element distributions within the waste drums. Therefore, the drum content is discretized into smaller subvolumes of the drums, called “sectors” in this paper. The gamma emission at a given characteristic energy emitted from each sector is given by the element mass in this volume, the partial (n,γ) cross section, and the incident neutron flux. By also including photon transport and summing over all disjunct sectors, one obtains a model for the measured signal. The reconstruction of spatially resolved element masses can then be interpreted as an inversion of this model.
An Overview of the Application of Pulsed Neutron Activation in Flow Measurements
Published in Nuclear Technology, 2020
Neutron activation analysis (NAA) is a nuclear technique that relies on the measurement of gamma rays emitted from a sample that is irradiated by a beam of neutrons.1 The energy of the emitted gamma rays from a sample exposes the element contents of the sample, and the intensity of the gamma rays are directly proportional to the concentration and abundance of the elements. NAA has a wide range of applications from chemistry to geology, archeology, soil science, environmental analysis, semiconductor industry, medicine, agriculture, and even forensic science. In this paper, we review applications of the neutron activation technique for flow velocity measurements based on tracing the activity in the medium flowing in a pipeline. As shown in Fig. 1, the NAA analysis process starts with bombarding the sample with a beam of neutrons. The neutron capture process by the elements of the sample produces unstable compound nuclei followed by gamma-ray emission (called prompt gamma with energies up to 11 MeV in a very short time of about 10−12 to 10−9 s) creating radioactive isotopes. Finally, the radionuclides decay to stable nuclei with the emission of beta particles along with gamma rays (called delayed gamma). Detection of the gamma rays provides the precise identification and quantification of elements in the sample. The rate at which gamma rays are emitted with particular energies can be measured by high-resolution semiconductor detectors. If the prompt gamma rays (measured during neutron irradiation) are used to determine the presence and amount of elements in the sample, then NAA is called prompt gamma neutron activation analysis (PGNAA). If the analysis is based on the delayed gamma rays (measured at some time after neutron irradiation), it is called delayed gamma neutron activation analysis (DGNAA). Both PGNAA and DGNAA are illustrated in Fig. 1. PGNAA applies to elements with extremely high neutron capture cross sections and short irradiation time, often on the order of seconds or minutes. While DGNAA is applicable for the vast majority of elements that produce radioactive nuclides, PGNAA concentrates on elements that produce stable isotopes or elements with weak decay gamma-ray intensities.2