The neutron field of various irradiation positions of the TRIGA Mark II reactor of the Jožef Stefan Institute (JSI) has been thoroughly characterized by neutron activation dosimetry and miniature ...fission chambers techniques. In order to have a fully validated calculation scheme to analyze and plan experiments, the gamma field also has to be experimentally validated. The 10-year long collaboration between CEA and JSI is a perfect framework to carry out such a study, and measurements of the gamma field started in late 2016. Several measurement techniques were investigated in in-core and ex-core positions. Online measurements were carried out using miniature ionization chambers (ICs) manufactured by the CEA and PTW Farmer. Positional dependence was studied, showing a decrease in the delayed gamma contribution to the total gamma flux with increasing distance from the reactor core center. To characterize the gamma dose in the core, as well as in the periphery, thermoluminescent and optically stimulated luminescent detectors (TLDs and OSLDs, respectively) were tested. These detectors are commonly used at CEA to measure the gamma dose in a given material, in order to study the nuclear heating in various core elements (control rod, baffle, structural material). Different filters were used in order to assess an integrated dose ranging from a few Gy up to several kGy. The comparisons of experimental results against calculations performed with the JSIR2S code package show a very good agreement. The feasibility of such measurements demonstrates the complementarity between measurements with dosimetry and ICs from low to very high gamma-dose environment, such as in material testing reactors.
In the frame of the effective Container inspection at BORDer control points (C-BORD) project H2020 program of the European Union (EU), a Rapidly Relocatable Tagged Neutron Inspection System (RRTNIS) ...has been developed for a nonintrusive inspection of cargo containers, aiming at explosives and other illicit goods detection. Twenty large-volume NaI detectors are used to determine the elements composing inspected materials from their specific gamma-ray spectra signatures induced by fast neutrons. The RRTNIS inspection is focused on a specific suspect area selected by X-ray radiography. An unfolding algorithm decomposes the energy spectrum of this suspect area on a database of pure element gamma signatures. A classification is then performed between inorganic materials, such as metals, ceramics, or chemicals, and organic materials like wood, fabrics, or plastic goods. Concerning organic materials, the obtained elemental proportions of carbon, nitrogen, and oxygen allow discriminating explosives from illicit drugs and benign substances. This article reports on the final laboratory tests performed at Commissariat à <inline-formula> <tex-math notation="LaTeX">\text{I}^\prime </tex-math></inline-formula>Énergie Atomique et aux Énergies Alternatives (CEA) Saclay, France, to assess the RRTNIS detection performances before further demonstration tests in a real seaport environment. Simulants of explosives and illicit drugs have been hidden at different depths inside iron or wood cargo materials, which are representative of the different neutron and gamma attenuation properties encountered in real cargo containers. Hundreds of experiments have been performed, showing that a few kilograms of explosives or narcotics can be detected by the RRTNIS in 10-min inspections.
The transfer function of a zero-power thermal reactor was successfully measured thanks to neutron noise techniques from 1 mHz to 160 Hz. During a month-long experimental campaign, the fluctuations of ...the neutron population in critical and subcritical configurations of the core were acquired using excore fission chambers and analysed through Cross-Power Spectral Density (CPSD) methodology. Firstly, the reactor’s kinetic parameters, i.e. prompt decay constant, effective delayed neutron fraction and generation time, were obtained at critical state. It required calibrating the reactor’s power, which was done by metal foil activation and measurement of the
235
U fission rate. Secondly, these parameters were used to estimate the groups’ abundances of delayed neutrons from the CPSD measured in a sub-critical state. Fitting data with a point kinetic model was done with Bayesian inference - CONRAD and Stan programs were used. A very good agreement was found between experimental abundances and the ones computed with TRIPOLI-4 Monte-Carlo transport code and JEFF3.1.1 nuclear data library. Uncertainties on prior abundances between 6 % to 101 %, held mainly by nuclear data, were lowered down to 4 % to 54 %, depending on the delayed group.
Abstract
The European H2020 project, entitled “effective Container inspection at BORDer control points” (C-BORD), aims to develop a framework of Non-Intrusive Inspection (NII) technologies,
for ...containers and large-volume freight at the EU borders. In this article the first results of the
field trials of the Rapidly Relocatable Tagged Neutron Inspection System (RRTNIS) are reported.
The tests were carried out at the customs administration of the Netherlands' (DCA) facility in the
seaport of Rotterdam, the Netherlands. For the tests mock-up cargo containers were prepared. The containers were analyzed using the whole set of NII subsystems of the C-BORD framework. Each container underwent a session of subsequent scans with all the subsystems, in order to realistically
reproduce the normal flow of inspections at the customs facility. The RRTNIS was tested under these realistic conditions, as well. The system was able to separate and identify the target materials, in mock-up containers, and improve the state-of-the-art in terms of the detected quantities.
In the frame of C-BORD project (H2020 program of the EU), a Rapidly relocatable Tagged Neutron Inspection System (RRTNIS) is being developed to non-intrusively detect explosives, chemical threats, ...and other illicit goods in cargo containers. Material identification is performed through gamma spectroscopy, using twenty NaI detectors and four LaBr3 detectors, to determine the different elements composing the inspected item from their specific gamma signatures induced by fast neutrons. This is performed using an unfolding algorithm to decompose the energy spectrum of a suspect item, selected by X-ray radiography and on which the RRTNIS inspection is focused, on a database of pure element gamma signatures. This paper reports on simulated signatures for the NaI and LaBr
3
detectors, constructed using the MCNP6 code. First experimental spectra of a few elements of interest are also presented.
The neutron field of various irradiation positions of the TRIGA Mark II reactor of the Jožef Stefan Institute has been thoroughly characterized by neutron activation dosimetry and miniature fission ...chambers techniques. In order to have a fully validated calculation scheme to analyze and plan experiments, the gamma field also has to be experimentally validated. The 10-year long collaboration between CEA and JSI is a perfect framework to carry out such a study, and measurements of the gamma field started in late 2016. Several measurement techniques were investigated in in-core and ex-core positions.
On-line measurements were carried out using miniature ionization chambers manufactured by the CEA and PTW Farmer ionization chambers. Positional dependence was studied, showing a decrease in the delayed gamma contribution to the total gamma flux with increasing distance from the reactor core center.
To characterize the gamma dose in the core, as well as in the periphery, thermo- and optically stimulated luminescent detectors were tested. These detectors are commonly used at CEA to measure the gamma dose in a given material in order to study the nuclear heating in various core elements (control rod, baffle, structural material). Different filters were used in order to assess an integrated dose ranging from a few Gy up to several kGy. The feasibility of such measurements demonstrates the complementarity between measurements with dosimetry and ionization chambers from low to very high gamma-dose environment, such as in material testing reactors.
In the frame of C-BORD project (H2020 program of the EU), a Rapidly Relocatable Tagged Neutron Inspection System (RRTNIS) has been developed for nonintrusive inspection in cargo containers aimed at ...explosives and other illicit goods detection. Twenty large volume NaI detectors are used to determine the elements composing inspected materials from their specific gamma spectra signatures induced by fast neutrons. The RRTNIS inspection is focused on a specific suspect area selected by X-ray radiography. An unfolding algorithm decomposes the energy spectrum of this suspect area on a database of pure element gamma signatures. A first classification is performed between inorganic materials like metals, ceramics or chemicals, and organic materials like wood, fabrics or plastic goods. Concerning organic materials, the obtained elemental proportions of carbon, nitrogen, and oxygen allow discriminating explosives from illicit drugs and benign substances. This paper reports on the final laboratory tests performed at CEA Saclay, France, to assess the RRTNIS detection performances before further demonstration tests in a real seaport environment. Simulants of explosives and illicit drugs have been hidden at different depths inside iron or wood cargo materials, which are representatives of the different neutron and gamma attenuation properties encountered in real cargo containers. Hundreds of experiments have been performed, showing that a few kg of explosives or narcotics can be detected by the RRTNIS in 10 min inspections.
Ataxia‐telangiectasia (AT) is a multi‐systemic disease caused by mutational inactivation of the ATM gene. We report a retrospective study of lung disease in 15 patients.
Patients and methods: A ...diagnosis of AT was made if the patient met the following criteria: neurological features and at least one the following: oculo‐cutaneous telangiectasia, elevated serum α‐feto‐protein level.
Results: Recurrent sino‐pulmonary infections were usually present in 11 of the cases and occurred during the first 2 years of life. Other lung injuries noted were bronchiectasis, obstruction and restriction of the airways, fibrosis, pneumothorax and haemoptysis. Eleven children had immunodeficiencies.
Discussion: Recurrent sino‐pulmonary manifestations precede neurological complications, but the severity of neuro‐degeneration and pulmonary disease were not correlated. Pulmonary status was a prognosis factor. Immunodeficiency was the main, but not the only, aetiology for lung disease in AT.
Conclusion: There is little dispute over the role of ATM in lung and respiratory epithelium. To reduce the morbidity associated with AT, there needs to be greater awareness of respiratory complications. Early management and monitoring lung function is necessary to minimize lung damage.
To inspect cargo containers, X-ray imaging can be complemented by fast neutron interrogation to provide indication concerning the chemical nature of the transported goods through the detection of ...neutron-induced gamma rays. Organic goods are of special interest since they constitute a significant part of the merchandises. In addition, in the context of NRBC-E threats search in cargo containers, a nondestructive inspection system should also be able to detect explosives. Until now, fast neutron interrogation systems identify organic materials in cargo containers using characteristic neutron-induced gamma-ray peaks of carbon, oxygen and nitrogen. However, identifying organics in this way can lead to ambiguities, since no hydrogen gamma ray can be measured with fast neutrons. Nevertheless, it is known that hydrogen strongly modifies the neutron energy spectrum, which in turn affects the amplitudes of gamma-ray peaks. The link between the hydrogen fraction and the amplitude of gamma ray peaks being complex, no attempt has been made to inverse this link until now. Simulations show, however, that a neural network that takes as inputs the heights of carbon, oxygen and nitrogen gamma ray peaks can indeed determine the hydrogen fraction. Simulations of realistic cases show that the use of a neural network indeed allows identifying compounds having similar fractions of carbon, oxygen and nitrogen but different hydrogen fraction, thus opening the way to more accurate materials identification.
•Hydrogen is measurable using gamma rays induced by fast neutrons on other nuclei.•A neural network can determine the hydrogen fraction in organic materials.•MCNP simulations validate the efficiency of the neural network approach.•Organic materials can be better discriminated.
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