| 1. |
- Andersson, Peter, 1981-, et al.
(author)
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Coincidence spectroscopy for increased sensitivity in radionuclide monitoring
- 2022
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Conference paper (other academic/artistic)abstract
- The majority of the energy in a nuclear explosion is released in the immediate blast and the initial radiation accounts. The remaining fraction is released through radioactive decay of the explosion's fission products and neutron activation products over a longer time span. This allows for the detection of a nuclear explosion by detecting the presence of residual decay. Radionuclide monitoring stations for detection of radioactive emissions to the atmosphere is thereby an important tool in the verification of compliance with nuclear disarmament treaties. In particular, the globally spanning radionuclide station network of the International Monitoring System (IMS) has been implemented for verification of the Comprehensive Nuclear-Test-Ban Treaty.High Purity Germanium (HPGe) detectors are workhorses in radionuclide monitoring. The detection of characteristic gamma rays can be used to disclose the presence of signature nuclides produced innuclear weapon tests. A particular development that has potential to improve the sensitivity of radionuclide monitoring is the coincidence technique where decaying nuclides that emit several coincident gamma rays can be detected at much smaller activity concentrations than with conventional gamma spectroscopy.In this project, dedicated gamma-gamma coincidence detectors are being developed, utilizing electronically segmented HPGe detectors. These detectors are expected to be highly sensitive to low-activity samples of nuclides that present coincident emissions of gamma rays. In this paper we present the concept, define performance parameters, and explore the performance of such detectors to a subset of radionuclides of particular CTBT relevance. In addition, we discuss the path forward in developing a next generation gamma-gamma coincidence spectroscopy system of segmented HPGe.
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| 2. |
- Andersson, Peter, 1981-, et al.
(author)
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Neutron Tomography Using Mobile Neutron Generators for Assessment of Void Distributions in Thermal Hydraulic Test Loops
- 2015
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Conference paper (peer-reviewed)abstract
- Detailed knowledge of the lateral distribution of steam (void) and water in a nuclear fuel assembly is of great value for nuclear reactor operators and fuel manufacturers, with consequences for both reactor safety and economy of operation. Therefore, nuclear relevant two-phase flows are being studied at dedicated thermal-hydraulic test loop, using twophase flow systems ranging from simplified geometries such as heated circular pipes to full scale mock-ups of nuclear fuel assemblies. Neutron tomography (NT) has been suggested for assessment of the lateral distribution of steam and water in such test loops, motivated by a good ability of neutrons to penetrate the metallic structures of metal pipes and nuclear fuel rod mock-ups, as compared to e. g. conventional X-rays, while the liquid water simultaneously gives comparatively good contrast. However, these stationary test loops require the measurement setup to be mobile, which is often not the case for NT setups. Here, it is acknowledged that fast neutrons of 14 MeV from mobile neutron generators constitute a viable option for a mobile NT system. We present details of the development of neutron tomography for this purpose at the division of Applied Nuclear Physics at Uppsala University. Our concept contains a portable neutron generator, exploiting the fusion reaction of deuterium and tritium, and a detector with plastic scintillator elements designed to achieve adequate spatial and energy resolution, all mounted in a light-weight frame without collimators or bulky moderation to allow for a mobile instrument that can be moved about the stationary thermal hydraulic test sections. The detector system stores event-to-event pulse-height information to allow for discrimination based on the energy deposition in the scintillator elements. Experimental results from the tomographic assessment of axially symmetric test objects are shown, as well as simulation results from a scaled up version of the instrument for nonsymmetrical objects in quarter fuel-bundle size objects. In conclusion, the application of tomography on inch-wide vertical pipes has been experimentally demonstrated and simulation results indicate that tomography of the void distribution in nonsymmetrical vertical flows in quarter BWR fuel bundles is also feasible.
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| 3. |
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| 4. |
- Lantz, Mattias, 1971-, et al.
(author)
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Gamma spectroscopy methodology for large amounts of environmental samples in Sweden 30 years after the Chernobyl accident
- 2020
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In: ND 2019. - : EDP Sciences. - 9782759891061
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Conference paper (peer-reviewed)abstract
- In a Swedish citizen science project, more than 200 elementary school classes participated in collecting fungi, soil samples, and droppings from deer and wild boar, from all over Sweden. The samples have been sent to a laboratory at Uppsala University where they are being analyzed through gamma spectroscopy with a shielded HPGe detector. The main objective is to scan the samples for 137Cs from the Chernobyl accident and compare the data with measurements from 1986, but uptake of naturally occuring radionuclides like 40K and radon daughters will also be determined. Together with the soil samples, transfer factors will be derived, and correlations for these factors will be sought for different species of fungi and soil types. The potential for correlating the results with different biological processes will also be investigated, in part through the collected animal droppings. This is a work in progress where the present status of the experimental setup and methodology are presented. Issues with the initial approach for corrections are discussed and preliminary results are presented.
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| 5. |
- Eriksson, Jacob, et al.
(author)
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Finite Larmor radii effects in fast ion measurements as demonstrated using neutron emission spectrometry of JET plasmas heated with 3rd harmonic ICRF
- 2011
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In: 38th EPS Conference on Plasma Physics 2011 (EPS 2011): Europhysics Conference Abstracts. - 2914771681
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Conference paper (other academic/artistic)abstract
- This paper demonstrates how the finite Larmor radii (FLR) of fast ions can affect fast ion measurements by studying data from the neutron time-of-flight spectrometer TOFOR. Neutron spectra were calculated from a model of the fast ion velocity distribution for a JET experiment with 3rd harmonic ICRF heating of deuterium beams. It was found that FLR effects need to be considered to get a good description of the data, if the Larmor radius of the fast ions are comparable to the width of the field of view of the instrument. This applies not only to results from neutron spectrometry but also to other types of fast ion diagnostics.
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| 6. |
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| 7. |
- Grape, Sophie, 1982-, et al.
(author)
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Building a Strategy for ESARDA - Education, Training and Knowledge Management
- 2015
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Conference paper (other academic/artistic)abstract
- This document proposes a new strategy for how the ESARDA organization could work with education, training and knowledge management in nuclear safeguards. With this document we want to anchor these ideas within the organization and its management, in order to have a broad support for this initiative. We propose to activate all ESARDA working groups in the process of identifying, selecting and preparing material for module based education and training. ESARDA could then more effectively broaden its education and training activities and strengthen the connections with academia. In this way, we would also create a way to export knowledge on nuclear safeguards to nuclear education programs on the European level. We propose to create a task force that addresses a set of identified questions; examples are how to implement the new strategy, how to interact with academia and young professionals and how to develop, maintain, and structure the educational modules. By the end of 2015, the findings of the task force should be presented to the ESARDA management in order to be able to make a more informed decision on how to proceed with the new strategy.
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| 8. |
- Gustavsson, Cecilia, Dr, 1973-, et al.
(author)
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Citizen science in radiation research
- 2020
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In: ND 2019. - : EDP Sciences. - 9782759891061
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Conference paper (peer-reviewed)abstract
- A growing trend in science is that research institutions reach out to members of the public for participating in research. The reasons for outreach are many, spanning from the desire to collect and/or analyse large sets of data efficiently, to the idea of including the general public on a very fundamental level in science-making and ultimately decision-making. The presented project is curriculum-based and carried out in 240 lower secondary school classes (pupils of age 13-16). The task, as designed by the participating universities, is to collect mushrooms, soil and animal droppings from different parts of Sweden, do preliminary sample preparation and analyses and send the samples to the university institutions for radioactivity measurement. Behind the project is a desire to compare today’s levels of 137Cs with those deposited right after the Chernobyl accident in 1986, but also to study the exchange of caesium between organisms as well as the impacts of biological and geological processes on uptake and retention. The scientific outcome is a geodatabase with the 137Cs activity (Bq/m2) present in the Swedish environment, where radioactivity data can be linked to the species (fungi, competing species, animals foraging), forest type, land type, land use and other environmental factors. The science question is of interest to the general public as foraging for mushrooms, as well as spending recreational time in forests is widely popular in Sweden. In this article, we will discuss the current status of the project and the observations we have made about how well the public can participate in scientific research. Focus will be on organization of the project, such as logistics, preparation of supportive material, feedback and communication between researchers and schools. We will present observations about the impact the project has had on the participants, based on quantitative and qualitative evaluations.
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| 9. |
- Pawelec, E., et al.
(author)
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Molecular ND Band Spectroscopy in the Divertor Region of Nitrogen Seeded JET Discharges
- 2018
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In: International Conferences On Research And Applications Of Plasmas (Plasma-2017). - : IOP Publishing. ; , s. 012009-
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Conference paper (peer-reviewed)abstract
- In this contribution we present OES measurements in the JET tokamak of the deuterated NH (ND) radical and the correlation between results of those experiments and measurement of ammonia production. The observation region covers most of the divertor and its outer throat. Measurements are performed in different magnetic configurations. The results include temporal and spatial dependence of the molecular emission intensity and study of the emission band shape (vibrational and rotational temperatures) during different JET pulses, with or without nitrogen seeding. Results are a step towards the understanding of nitrogen-containing molecule creation and destruction in the divertor plasma.
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| 10. |
- Sjöstrand, Henrik, et al.
(author)
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Fusion Power Measurement Using a Combined Neutron Spectrometer - Camera System at ITER
- 2008
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In: BURNING PLASMA DIAGNOSTICS. - New York : American Institute of Physics (AIP). - 9780735405073 ; , s. 319-322
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Conference paper (peer-reviewed)abstract
- A central task for fusion plasma diagnostics is to measure the 2.5 and 14 MeV neutron emission rate in order to determine the fusion power. A new method for determining the neutron yield has been developed at JET. It makes use of the magnetic proton recoil neutron spectrometer and a neutron camera and provides the neutron yield with small systematic errors. At ITER a similar system could operate if a high-resolution, high-performance neutron spectrometer similar to the MPR was installed. In this paper, we present how such system could be implemented and how well it would perform under different assumption of plasma scenarios and diagnostic capabilities. It is found that the systematic uncertainty for using such a system as an absolute calibration reference is as low as 3 % and hence it would be an excellent candidate for the calibration of neutron monitors such as fission chambers. It is also shown that the system could provide a 1 ms time resolved estimation of the neutron rate with a total uncertainty of 5 %.
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