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  • 401.
    Jacobsson, Staffan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Håkansson, Ane
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Andersson, Camilla
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Jansson, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Bäcklin, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    A Tomographic Method for Verification of the Integrity of Spent Nuclear Fuel1998Report (Other academic)
    Abstract [en]

    A tomographic method for experimental investigation of the integrity of usedLWR fuel has been developed. It is based on measurements of the gamma radiation fromthe fission products in the fuel rods. A reconstruction code of the algebraic type has beenwritten. The potential of the technique has been examined in extensive simulationsassuming a gamma-ray energy of either 0.66 MeV (137Cs) or 1.27 MeV (154Eu).The resultsof the simulations for BWR fuel indicate that single fuel rods or groups of rods replacedwith water or fresh fuel can be reliably detected independent of their position in the fuelassembly using 137Cs radiation. For PWR fuel the same result is obtained with the exceptionof the most central positions. Here the more penetrable radiation from 154Eu must be used inorder to allow a water channel to be distinguished from a fuel rod.

    The results of the simulations have been verified experimentally for a 8x8 BWRfuel assembly. Special equipment has been constructed and installed at the interim storageCLAB. The equipment allows the mapping of the radiation field around a fuel assemblywith the aid of a germanium detector fitted with a collimator with a vertical slit. Theintensities measured in 2 520 detector positions were used as input for the reconstructioncode used in the simulations. The results agreed very well with the simulations and revealedsignificantly a position containing a water channel in the central part of the assembly.

  • 402.
    Jacobsson, Staffan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Håkansson, Ane
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Andersson, Camilla
    Jansson, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Bäcklin, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    A Tomographic Method for Verification of the Integrity of Spent Nuclear Fuel1998Report (Other academic)
  • 403.
    Jacobsson, Staffan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Nuclear and Particle Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Håkansson, Ane
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Jansson, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Bäcklin, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    A Tomographic Method for Verification of the Integrity of Spent Nuclear Fuel Assemblies - II: Experimental Investigation2001In: Nuclear Technology, ISSN 0029-5450, E-ISSN 1943-7471, Vol. 135, no 2, p. 146-153Article in journal (Refereed)
    Abstract [en]

    A tomographic method for verification of the integrity of used light water reactor fuel has been experimentally investigated. The method utilizes emitted gamma rays from fission products in the fuel rods. The radiation field is recorded in a large number of positions relative to the assembly, whereby the source distribution is reconstructed using a special-purpose reconstruction code.

    An 8 × 8 boiling water reactor fuel assembly has been measured at the Swedish interim storage (CLAB), using installed gamma-scanning equipment modified for the purpose of tomography. The equipment allows the mapping of the radiation field around a fuel assembly with the aid of a germanium detector fitted with a collimator with a vertical slit. Two gamma-ray energies were recorded: 662 keV (137Cs) and 1274 keV (154Eu). The intensities measured in 2520 detector positions were used as input for the tomographic reconstruction code. The results agreed very well with simulations and significantly revealed a position containing a water channel in the central part of the assembly.

  • 404.
    Jacobsson, Staffan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Smith, Eric
    Pacific Northwest National Laboratory, USA.
    White, Timothy A.
    Pacific Northwest National Laboratory, USA.
    Mozin, Vladimir
    Lawrence Livermore National Laboratory, Livermore, CA, USA.
    Jansson, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Andersson, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Davour, Anna
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Grape, Sophie
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Trellue, Holly
    Los Alamos National Laboratory, Los Alamos, NM, USA.
    Deshmukh, Nikhil
    Pacific Northwest National Laboratory, USA.
    Miller, Erin
    Pacific Northwest National Laboratory, Richland, USA.
    Wittman, Richard
    Pacific Northwest National Laboratory, Richland, USA.
    Honkamaa, Tapani
    STUK – Radiation and Nuclear Safety Authority,Helsinki, Finland.
    Vaccaro, Stefano
    European Commission, DG Energy, Euratom Safeguards Luxemburg, Luxemburg.
    Ely, James
    International Atomic Energy Agency (IAEA), Vienna, Austria.
    Outcomes of the JNT 1955 Phase I Viability Study of Gamma Emission Tomography for Spent Fuel Verification2017In: ESARDA Bulletin, ISSN 1977-5296, no 55, p. 10-28Article in journal (Refereed)
    Abstract [en]

    The potential for gamma emission tomography (GET) to detect partial defects within a spent nuclear fuel assembly has been assessed within the IAEA Support Program project JNT 1955, phase I, which was completed and reported to the IAEA in October 2016. Two safeguards verification objectives were identified in the project; (1) independent determination of the number of active pins that are present in a measured assembly, in the absence of a priori information about the assembly; and (2) quantitative assessment of pin-by-pin properties, for example the activity of key isotopes or pin attributes such as cooling time and relative burnup, under the assumption that basic fuel parameters (e.g., assembly type and nominal fuel composition) are known. The efficacy of GET to meet these two verification objectives was evaluated across a range of fuel types, burnups and cooling times, while targeting a total interrogation time of less than 60 minutes.

    The evaluations were founded on a modelling and analysis framework applied to existing and emerging GET instrument designs. Monte Carlo models of different fuel types were used to produce simulated tomographer responses to large populations of "virtual" fuel assemblies. The simulated instrument response data were then processed using a variety of tomographic-reconstruction and image- processing methods, and scoring metrics were defined and used to evaluate the performance of the methods.

    This paper describes the analysis framework and metrics used to predict tomographer performance. It also presents the design of a "universal" GET (UGET) instrument intended to support the full range of verification scenarios envisioned by the IAEA. Finally, it gives examples of the expected partial-defect detection capabilities for some fuels and diversion scenarios, and it provides a comparison of predicted performance for the notional UGET design and an optimized variant of an existing IAEA instrument.

  • 405.
    Jacobsson Svärd, Staffan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Andersson, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Davour, Anna
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Grape, Sophie
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Holcombe, Scott
    OECD Halden Reactor Project.
    Jansson, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Tomographic determination of spent fuel assembly pin-wise burnup and cooling time for detection of anomalies2015Conference paper (Other academic)
    Abstract [en]

    The IAEA has initiated Member States’ Support Program project JNT A 1955 to assess the partial defect detection capabilities of gamma emission tomography (GET) for spent nuclear fuel assembly verification. The GET technique is based on measurements of the gamma-ray flux distribution around a spent fuel assembly using dedicated, tomographic equipment and subsequent reconstruction of the internal source distribution using tomographic algorithms applied on the recorded data. One of the verification objectives identified for the project is the quantitative measurement of pin-by-pin properties, e.g. burnup and/or cooling time, for the detection of anomalies and/or verification of operator-declared data. For this objective, reconstruction algorithms that return quantitative, isotopic pin-by-pin data are applied.

    Previously, GET measurements performed on commercial nuclear fuel assemblies in Sweden have proven capable of determining the relative pin-by-pin power distribution with high precision in BWR fuel with short cooling time, based on the measured distribution of the gamma-ray emitting fission product 140Ba/La in the fuel. In the current project, the capabilities of GET to determine additional pin-wise fuel parameters in additional fuel types are being assessed. The evaluations are based on Monte Carlo simulations of the emission of gamma-rays from the fuel and their detection in a tomographic measurement device.

    This paper describes the algorithms used for reconstructing quantitative pin-wise data and the results that are anticipated with this technique. It is argued that detailed modelling of the gamma-ray attenuation through the highly inhomogeneous mix of strongly-attenuating fuel rods and less-attenuating surrounding water (wet storage) or air (dry storage) is required to yield high precision in the reconstructed data. The burnup distribution assessment would be based on the recording of 662-keV gamma radiation from 137Cs, whereas the assessment of both burnup and cooling time simultaneously requires the GET measurement and pin-wise reconstruction of at least two isotopes, which puts constraints on the measurement equipment used.

  • 406.
    Jacobsson Svärd, Staffan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Grape, Sophie
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Hjalmarsson, Anders
    Uppsala University, The Svedberg Laboratory.
    Modeling of the Cherenkov Light Emission from Nuclear Fuel Assemblies with Partial Defects2010In: PHYSOR 2010: Advances in Reactor Physics to Power the Nuclear Renaissance, La Grange Park, Illinois, USA: American Nuclear Society , 2010Conference paper (Refereed)
    Abstract [en]

    The International Atomic Energy Agency poses requirements on the detection and verification of partial defects of nuclear fuel assemblies before being placed in difficult-to-access storage. One instrument being considered for such detection is the Digital Cherenkov Viewing Device, with which images of the Cherenkov light from fuel assemblies in storage pools can be recorded and analyzed.

    This paper accounts for a software toolkit for simulating the Cherenkov photon distribution in the fuel using GEANT4. The toolkit enables the user to access information on individual photon emission coordinates and their momentum vectors, as well as to take into account the expected rod-by-rod burnup distribution at different axial levels. An example of this modeling is demonstrated.

  • 407.
    Jacobsson Svärd, Staffan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Holcombe, Scott
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Grape, Sophie
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Applicability of a set of tomographic reconstruction algorithms for quantitative SPECT on irradiated nuclear fuel assemblies2015In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 783, p. 128-141Article in journal (Refereed)
    Abstract [en]

    A fuel assembly operated in a nuclear power plant typically contains 100–300 fuel rods, depending on fuel type, which become strongly radioactive during irradiation in the reactor core. For operational and security reasons, it is of interest to experimentally deduce rod-wise information from the fuel, preferably by means of non-destructive measurements. The tomographic SPECT technique offers such possibilities through its two-step application; (1) recording the gamma-ray flux distribution around the fuel assembly, and (2) reconstructing the assembly׳s internal source distribution, based on the recorded radiation field. In this paper, algorithms for performing the latter step and extracting quantitative relative rod-by-rod data are accounted for.

    As compared to application of SPECT in nuclear medicine, nuclear fuel assemblies present a much more heterogeneous distribution of internal attenuation to gamma radiation than the human body, typically with rods containing pellets of heavy uranium dioxide surrounded by cladding of a zirconium alloy placed in water or air. This inhomogeneity severely complicates the tomographic quantification of the rod-wise relative source content, and the deduction of conclusive data requires detailed modelling of the attenuation to be introduced in the reconstructions. However, as shown in this paper, simplified models may still produce valuable information about the fuel.

    Here, a set of reconstruction algorithms for SPECT on nuclear fuel assemblies are described and discussed in terms of their quantitative performance for two applications; verification of fuel assemblies׳ completeness in nuclear safeguards, and rod-wise fuel characterization. It is argued that a request not to base the former assessment on any a priori information brings constraints to which reconstruction methods that may be used in that case, whereas the use of a priori information on geometry and material content enables highly accurate quantitative assessment, which may be particularly useful in the latter application.

    Two main classes of algorithms are covered; (1) analytic filtered back-projection algorithms, and (2) a group of model-based or algebraic algorithms. For the former class, a basic algorithm has been implemented, which does not take attenuation in the materials of the fuel assemblies into account and which assumes an idealized imaging geometry. In addition, a novel methodology has been presented for introducing a first-order correction to the obtained images for these deficits; in particular, the effects of attenuation are taken into account by modelling the response for an object with a homogeneous mix of fuel materials in the image area. Neither the basic algorithm, nor the correction method requires prior knowledge of the fuel geometry, but they result in images of the assembly׳s internal activity distribution. Image analysis is then applied to deduce quantitative information.

    Two algebraic algorithms are also presented, which model attenuation in the fuel assemblies to different degrees; either assuming a homogenous mix of materials in the image area without a priori information or utilizing known information of the assembly geometry and of its position in the measuring setup for modelling the gamma-ray attenuation in detail. Both algorithms model the detection system in detail. The former algorithm returns an image of the cross-section of the object, from which quantitative information is extracted, whereas the latter returns conclusive relative rod-by-rod data.

    Here, all reconstruction methods are demonstrated on simulated data of a 96-rod fuel assembly in a tomographic measurement setup. The assembly was simulated with the same activity content in all rods for evaluation purposes. Based on the results, it is argued that the choice of algorithm to a large degree depends on application, and also that a combination of reconstruction methods may be useful. A discussion on alternative analysis methods is also included.

  • 408.
    Jacobsson Svärd, Staffan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Nuclear and Particle Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Håkansson, Ane
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Bäcklin, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Jansson, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Radiation Sciences.
    Osifo, Otasowie
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Radiation Sciences.
    Willman, Christofer
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Radiation Sciences.
    Tomography for partial-defect verification: experiences from measurements using different devices2006In: ESARDA Bulletin, ISSN 0392-3029, Vol. 33, p. 15-25Article in journal (Refereed)
    Abstract [en]

    Three devices of different types have been used in tomographic measurements for the purpose of partial-defect verification on the single-rod level. The devices range from a laboratory device used in measurements on a fuel model to an in-pool device used in measurements on irradiated fuel in a fuel-handling pool.

    The tomographic technique accounted for in this paper involves measurements of the gamma-ray flux distribution around a fuel assembly followed by computer-aided reconstruction of the internal source distribution. The results are rod-by-rod values of the relative concentrations of selected gamma-emitting isotopes. Also cross-sectional images are obtained.

    The tomographic technique presented here has proven to be robust and reliable. In laboratory experiments on a fuel model, reconstructions of relative rod-by-rod activities have been obtained with 1.5 % accuracy (1 σ). Using an in-pool device in measurements on fuel with a cooling time of about 4 weeks, data on fuel rods have been obtained in agreement with production-code calculations. Furthermore, tomographic images of good quality have been acquired.

    The applicability of the tomographic technique for partial-defect verification on the single-rod level has been investigated and demonstrated. The gamma-ray source concentration reconstructed in a position corresponding to a removed or replaced rod has been significantly lower than that of normal rods.

    Finally, requirements and properties of a device for tomographic measurements on nuclear fuel are discussed. It is argued that the use of a detector system with high energy resolution and high peak efficiency in connection to spectroscopic peak analysis is beneficial.

  • 409.
    Jacobsson Svärd, Staffan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Nuclear and Particle Physics, Nuclear Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Håkansson, Ane
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Nuclear and Particle Physics, Nuclear Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics. Kärnfysik.
    Bäcklin, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Nuclear and Particle Physics, Nuclear Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics. Kärnfysik.
    Osifo, Otasowie
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Nuclear and Particle Physics, Nuclear Physics. Kärnfysik.
    Willman, Christofer
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Nuclear and Particle Physics, Nuclear Physics. Kärnfysik.
    Jansson, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Nuclear and Particle Physics, Nuclear Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics. Kärnfysik.
    Nondestructive Experimental Determination of the Pin-Power Distribution in Nuclear Fuel Assemblies2005In: Nuclear Technology, ISSN 0029-5450, Vol. 151, no 1, p. 70-76Article in journal (Refereed)
    Abstract [en]

    A need for validation of modern production codes with respect to the calculated pin-power distribution has been recognized. A nondestructive experimental method for such validation has been developed based on a tomographic technique. The gamma-ray flux distribution is recorded in each axial node of the fuel assembly separately, whereby the relative rod-by-rod content of the fission product 140Ba is determined. Measurements indicate that 1 to 2% accuracy (1 sigma) is achievable.

    A device has been constructed for in-pool measurements at reactor sites. The applicability has been demonstrated in measurements at the Swedish boiling water reactor (BWR) Forsmark 2 on irradiated fuel with a cooling time of 4 to 5 weeks. Data from the production code POLCA-7 have been compared to measured rod-by-rod contents of 140Ba. An agreement of 3.1% (1 sigma) has been demonstrated.

    It is estimated that measurements can be performed on a complete BWR assembly in 25 axial nodes within an 8-h work shift. As compared to the conventional method, involving gamma scanning of individual fuel rods, this method does not require the fuel to be disassembled nor does the fuel channel have to be removed. The cost per measured fuel rod is estimated to be an order of magnitude lower than the conventional method.

  • 410.
    Jacobsson Svärd, Staffan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Lundqvist Saleh, Tobias
    Vattenfall Power Consultant AB.
    Håkansson, Ane
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Verification of completeness of spent nuclear fuel assemblies by means of tomography2008In: International Conference on the Physics of Reactors: Nuclear Power: A Sustainable Resource, Switzerland: Paul Scherrer Institute , 2008Conference paper (Other academic)
    Abstract [en]

    Within the safeguards regime, new technologies are desired to allow for detection of possible diversion of individual fuel rods from an irradiated nuclear fuel assembly.

    A measurement technique, based on Single-Photon Emission Computed Tomography, has been developed and demonstrated on a SVEA‑96 BWR assembly, which had been irradiated for one power cycle at the Forsmark 2 NPP. Images of the assembly’s internal distribution of the gamma-ray emitting isotope 140Ba/140La have been obtained tomographically, without requiring the assembly to be dismantled. Image analysis has been applied and the capability to detect the removal of a single rod from the assembly centre has been demonstrated.

    In addition, rod-activity reconstructions have been performed, involving detailed modelling of the gamma-ray transport through the fuel. An agreement of 3.1% (1 s) with data from the production code POLCA‑7 was demonstrated.

    An inspection procedure is suggested where tomographic data is collected, online image reconstruction is performed and image analysis is applied, resulting in a preliminary statement of the assembly’s completeness less than a minute after the measurement is completed. In cases where the completeness is questionable, an off-line rod-activity reconstruction can be performed, resulting in highly accurate data without the need for additional measurements.

  • 411.
    Jacobsson Svärd, Staffan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Smith, Eric
    Pacific Northwest National Laboratory, USA.
    White, Timothy A.
    Pacific Northwest National Laboratory, USA.
    Mozin, Vladimir
    Lawrence Livermore National Laboratory, Livermore, CA, USA.
    Jansson, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Andersson, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Grape, Sophie
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Davour, Anna
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Trellue, Holly
    Los Alamos National Laboratory, Los Alamos, NM, USA.
    Deshmukh, Nikhil
    Pacific Northwest National Laboratory, USA.
    Wittman, Richard
    Pacific Northwest National Laboratory, USA.
    Honkamaa, Tapani
    STUK – Radiation and Nuclear Safety Authority, Finland.
    Vaccaro, Stefano
    European Commission, DG Energy, Euratom Safeguards Luxemburg, Luxemburg.
    Ely, James
    International Atomic Energy Agency.
    Outcomes of the JNT 1955 Phase I Viability Study of Gamma EmissionTomography for Spent Fuel Verification2017Conference paper (Other academic)
    Abstract [en]

    The potential for gamma emission tomography (GET) to detect partial defectswithin a spent nuclear fuel assembly has been assessed within the IAEA SupportProgram project JNT 1955, phase I, which was completed and reported to theIAEA in October 2016. Two safeguards verification objectives were identified inthe project; (1) independent determination of the number of active pins that arepresent in a measured assembly, in the absence of a priori information about theassembly, and; (2) quantitative assessment of pin-by-pin properties, for examplethe activity of key isotopes or pin attributes such as cooling time and relativeburnup, under the assumption that basic fuel parameters (e.g., assembly typeand nominal fuel composition) are known. The efficacy of GET to meet these twoverification objectives was evaluated across a range of fuel types, burnups andcooling times, while targeting a total interrogation time of less than 60 minutes.The evaluations were founded on a modelling and analysis framework applied toexisting and emerging GET instrument designs. Monte Carlo models of differentfuel types were used to produce simulated tomographer responses to largepopulations of “virtual” fuel assemblies. The simulated instrument response datawere then processed using a variety of tomographic-reconstruction and image-processing methods, and scoring metrics were defined and used to evaluate theperformance of the methods.

    This paper describes the analysis framework and metrics used to predicttomographer performance. It also presents the design of a “universal” GET(UGET) instrument intended to support the full range of verification scenariosenvisioned by the IAEA. Finally, it gives examples of the expected partial-defectdetection capabilities for some fuels and diversion scenarios, and it provides acomparison of predicted performance for the notional UGET design and anoptimized variant of an existing IAEA instrument.

  • 412.
    Jacobsson Svärd, Staffan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    White, Timothy A.
    Pacific Northwest National Laboratory.
    Smith, Eric
    Pacific Northwest National Laboratory.
    Mozin, Vladimir
    Lawrence Livermore National Laboratory, USA.
    Jansson, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Davour, Anna
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Grape, Sophie
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Holcombe, Scott
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Trellue, Holly
    Los Alamos National Laboratory.
    Deshmukh, N.
    Pacific Northwest National Laboratory.
    Wittman, R. S.
    Pacific Northwest National Laboratory.
    Gamma-ray Emission Tomography: Modelling and evaluation of partial-defect testing capabilities2014Conference paper (Other academic)
    Abstract [en]

    Assessment of gamma emission tomography (GET) for spent nuclear fuel verification is the task in IAEA MSP project JNT1955. In line with IAEA Safeguards R&D plan 2012-2023, the aim of this effort is to “develop more sensitive and less intrusive alternatives to existing NDA instruments to perform partial defect tests on spent fuel assemblies prior to transfer to difficult to access storage". The current viability study constitutes the first phase of three, with evaluation and decision points between each phase. Two verification objectives have been identified; (1) counting of fuel pins in tomographic images without any a priori knowledge of the fuel assembly under study, and (2) quantitative measurements of pin-by-pin properties, e.g. burnup, for the detection of anomalies and/or verification of operator-declared data.

    Previous measurements performed in Sweden and Finland have proven GET highly promising for detecting removed or substituted fuel pins (i.e. partial defects) in BWR and VVER-440 fuel assemblies even down to the individual fuel pin level. The current project adds to previous experiences by pursuing a quantitative assessment of the capabilities of GET for partial defect detection, across a broad range of potential IAEA applications, fuel types, and fuel parameters. A modelling and performance-evaluation framework has been developed to provide quantitative GET performance predictions, incorporating burn-up and cooling-time calculations, Monte Carlo radiation-transport and detector-response modelling, GET instrument definitions (existing and notional) and tomographic reconstruction algorithms, which use recorded gamma-ray intensities to produce cross-sectional images of the source distribution in the fuel assembly or conclusive pin-by-pin data. The framework also comprises image-processing algorithms and performance metrics that recognize the inherent trade-off between the probability of detecting missing pins and the false-alarm rate. Here, the modelling and analysis framework is described and preliminary results are presented. 

  • 413.
    Jammes, Christian
    et al.
    CEA.
    Verma, Vasudha
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Hellesen, Carl
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Jacobsson Svärd, Staffan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Progress in the development of the neutron fluxmonitoring system of the French GEN-IV SFR:simulations and experimental validations2015Conference paper (Other academic)
    Abstract [en]

    The neutron flux monitoring system of the FrenchGEN-IV sodium-cooled fast reactor will rely on hightemperaturefission chambers installed in the reactor vessel andcapable of operating over a wide-range neutron flux. Thedefinition of such a system is presented and the technologicalsolutions are justified with the use of simulation andexperimental results.

  • 414.
    Janssens, Willem
    et al.
    European Commission - Joint Research Centre - DIR G - Dept G.II Nuclear Security and Safeguards, Ispra (VA), Italy.
    Niemeyer, Irmgard
    Forschungszentrum Jülich GmbH, Nuclear Safeguards and Security, Julich, Germany.
    Aregbe, Yetunde
    European Commission - Joint Research Centre, DIR G- G.2. Geel, Belgium.
    Bonino, Francois
    CTE- Comite Technique Euratom, Paris, France.
    Funk, Pierre
    IRSN - PDS - Nuclear Defense and Security Expertise Division, Fontenay-aux-Roses Cedex, France.
    Hildingsson, Lars
    Swedish Radiation Safety Authority, Stockholm, Sweden.
    Jansson, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Koutsoyannopoulos, Christos
    European Commission - DG ENERGY - EURATOM Safeguards, Luxembourg.
    Martikka, Elina
    STUK-Radiation and Nuclear Safety Authority, Helsinki, Finland.
    Medici, Fausto
    Federal Department of the Environment, Transport, Energy and Communications DETEC, Ittigen, Switzerland.
    Oddou, Julie
    CTE- Comite Technique Euratom, Paris, France.
    Okko, Olli
    TUK – Radiation and Nuclear Safety Authority, Helsinki, Finland.
    Rozle, Jakopic
    European Commission - Joint Research Centre, DIR G- G.2. Geel, Belgium.
    Sevini, Filippo
    European Commission - Joint Research Centre - DIR G - G.II.7, Ispra (VA), Italy.
    Tushingham, James
    UK National Nuclear Laboratory, Warrington, United Kingdom.
    Vince, Arpad
    Hungarian Atomic Energy Authority, Budapest, Hungary.
    Outcome and Actions of the 2019 Reflection Group of the European Safeguards Research and Development Association (ESARDA)2019Conference paper (Other academic)
    Abstract [en]

    The European Safeguards Research and Development Association (ESARDA), founded in 1969, is a voluntary association of European organizations formed to foster, advance and harmonize research and development (R&D) in the area of nuclear safeguards. It provides a forum for the exchange of information and ideas between nuclear facility operators, safeguards national authorities, regional and international inspectorates, and individuals engaged in safeguards-related research and development. Today ESARDA includes 33 Parties from within the European Union. In addition, a further eight laboratories, authorities, operators and academic institutions from outside the EU have joined ESARDA as Associate Members, while the Association signed Memoranda of Understanding with the Asia-Pacific Safeguards Network and the African Commission on Nuclear Energy, and a Letter of Intent with the Institute for Nuclear Materials Management.

    ESARDA seeks to maintain a dynamic approach to the developing priorities, while ensuring that its activities continue to anticipate future needs, which is why the Association periodically undertakes a formal Reflection Group exercise. In the last 2 years, the Reflection Group, RG2019, worked along the following objectives:

    1. develop a roadmap to improve and enhance the quality, effectiveness and efficiency of safeguards and non-proliferation in Europe and abroad; and
    2. ensure that the future activities of ESARDA are both consistent with the Association’s purpose, as stated in the ESARDA Agreement, and address the needs of the ESARDA members and/or stakeholders.

    In the report, finalized before the ESARDA Symposium in May 2019, three specific goals were identified:

    1. establish short term ESARDA priorities (2019 to 2024) and prepare a roadmap - i.e. WHAT;
    2. define ESARDA’s long-term future (2019-2050) activities based on the new landscape in Europe and internationally - to be reviewed before 2025 to establish the next 5 year plan; and
    3. review the ESARDA organization, and discuss HOW ESARDA can achieve the identified objectives and implement the identified roadmap.

    A World Café on these topics was organized and held during the 2019 Symposium. In this paper, the key outcomes and results of the ESARDA Reflection Group 2019 are presented, including their relevance for the international partners of ESARDA.

  • 415.
    Jansson, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    CFD simulation of pool dynamics in a nuclear reactor's condensation pool2014Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In a nuclear reactor the containment protects the environment from radioactive emissions. It is separated in two parts, a drywell and a wetwell. The drywell contains the reactor vessel and the steam pipes. If a steam leakage occurs in this part of the containment the pressure will increase. To reduce the pressure raising the reactor safety system uses the pressure suppression principle. By this principle the steam is condensed in a condensation pool filled with water. This pool is located in the wetwell part of the containment. To connect the drywell and wetwell there are pipes connected between them. These pipes are submerged under the water level in the condensation pool. This means that steam will be blown down into the condensation pool if the pressure in the drywell exceeds the hydrostatic pressure at the pipe outlet in the pool.

    In this thesis the blow down process has been studied with computational fluid dynamics (CFD). The aim was to study the pressure distribution in the condensation pool during a blow down sequence. It is useful to know the pressure distribution and the size of the pressure oscillations to calculate the forces acting on components in the pool and the pool structure. The CFD method has also been compared to the current used method for this type of calculations. The current method at Westinghouse uses a program called SPIEGEL.

    Simulations have been made on a model of a blow down pipe and a condensation pool. This model is called the PPOOLEX facility and is set up at Lappeenranta University of Technology in Finland. The facility has a simplified design compared to a real system. The blow down pipe in the PPOOLEX facility has only opening in the bottom of the pipe while a real blow down pipe has several small holes scattered along the pipe wrap.  One of the simulations made in this project was based on an experiment performed on the PPOOLEX facility. The results from the simulation were compared to the experimental results. In that experiment only air was blown in to the facility. Another simulation was made where steam was blown into the facility. Two different CFD solvers, CFX and STAR-CCM+, were used to perform the simulations. Because of the great need for computing power, however, mostly STAR-CCM+ was used.

    The result of the air simulation showed similar values ​​of the pressure distribution as in experiment. During the simulation also temperatures were measured and compared to the experiment temperature measurements. In these results there were larger differences between the simulation and the experiment, especially for points located in air. Graphic illustrations of volume fractions and pressures in the facility were produced during the simulation.

    When steam was used as a source fluid in the simulation some problems appeared in the solution. The CFD software had problems to get a converging solution, probably due to incomplete or incorrect settings for the solver.

    The conclusions of this thesis are that CFD can be used to simulate an air blow down process through the process and get reliable information about the pressure distribution in the pool. The method needs to be more developed in steam simulations to be able to calculate the blow down process in a real reactor. CFD is a good tool to produce graphics of the blow down process. Different types of physical properties, such as velocities, volume fractions, and pressure distributions can be illustrated.

  • 416.
    Jansson, Kaj
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Improving the Neutron Cross-section Standards 238U(n,f) and 6Li(n,a): Measurements and Simulations2015Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Improving or extending the range of cross-section standards, which in general are believed to be well known, require good control of the experimental conditions and the uncertainties involved. Two experiments that aspire to improve two different neutron cross-section standards, 238U(n,f) and 6Li(n,a, are presented in this thesis. Both standards have previously been extensively measured, but outside certain energy ranges discrepancies exist. In this thesis, a future precision measurement of the 238U(n,f) standard, relative to the elastic neutron scattering on hydrogen, is analysed through simulations. The status of the currently ongoing measurement of the second standard, 6Li(n,a), is also reported and some preliminary results are presented.Measurements of the uranium standard, with a total uncertainty better than 2%, are planned at the upcoming NFS facility. The new experimental situation requires our existing setup to be upgraded with new detectors. The simulation study has supplied limits on the target and detector designs but also provided estimates of the uncertainties that show the feasibility of a precision measurement. The design of the whole setup and the development of new detectors are guided by the simulation study presented in this thesis. When the upgrade is complete, the setup will consist of two parallel plate avalanche counters (PPACs), in addition to the eight detector telescopes already present in the existing setup.The 6Li(n,a) measurement is ongoing at the GELINA facility at IRMM in Geel, Belgium. A twin Frisch-grid ionisation chamber is employed measuring both 6Li(n,a) and 235U(n,f) in separate compartments. Although a problematic background was found, the preliminary cross section in the resonance region around 240 keV reproduces evaluated neutron library data fairly well. A recent move of the setup to a position closer to the neutron production shows promising improvements in the background situation.

  • 417.
    Jansson, Kaj
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Measurements of Neutron-induced Nuclear Reactions for More Precise Standard Cross Sections and Correlated Fission Properties2017Doctoral thesis, monograph (Other academic)
    Abstract [en]

    It is difficult to underestimate the importance of neutron cross section standards in the nuclear data field. Accurate and precise standards are prerequisites for measuring neutron cross sections. Two different projects are presented here with the aim of improving on neutron standards.

    A simulation study was performed for an experiment intended to measure the cross sections of H(n,n), 235U(n,f), and 238U(n,f) relative to each other. It gave the first estimates of the performance of the experimental setup. Its results have aided the development of the experimental setup by setting limits on the target and detector design.

    A second neutron-standard project resulted in three measurements of 6Li(n,α)t relative to 235U(n,f). Each subsequent measurement improved upon the previous one and changed the experimental setup accordingly. Although, preliminary cross sections were agreeing well with evaluated data files in some energy intervals, the main goal to measure the cross section up to 3 MeV was not reached.

    Mass yields and energy spectra are important outcomes of many fission experiments, but in low yield regions the uncertainties are still high even for recurrently studied nuclei. In order to understand the fission dynamics, one also needs correlated fission data. One particular important property is the distribution of excitation energy between the two nascent fission fragments. It is closely connected to the prompt emission of neutrons and γ’s and reveals information about how nucleons and energy are transferred within the fissioning nucleus.

    By measuring both the pre and post neutron-emission fragment masses, the cumbrance of detecting neutrons directly is overcome. This is done using the fission spectrometer VERDI and the 2E-2v method. In this work I describe how both the spectrometer, the analysis method, and the calibration procedures have been further developed. Preliminary experimental data show the great potential of VERDI, but also areas that call for more attention. A previously overlooked consequence of a central assumption was found and a correction method is proposed that can correct previously obtained data as well.

    The last part of this thesis concerns the efficiencies of the fission product extraction at the IGISOL facility. The methodology of the fission yield measurements at IGISOL are reliant on assumptions that have not been systematically investigated. The presented work is a first step of such an investigation that can also be used as a tool for optimising the setup for measurements of exotic nuclei. A simulation framework connecting three different simulation codes was developed to investigate the produced yield of fission products in a buffer gas. Several different variants of the setup were simulated and the findings were generally accordant with previous estimates. A reasonable agreement between experimental data and the simulation results is demonstrated.

  • 418.
    Jansson, Kaj
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Al-Adili, Ali
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Andersson Sundén, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Göök, Alf
    European Commission, Joint Research Centre, Directorate G, Geel, Belgium .
    Stephan, Oberstedt
    European Commission, Joint Research Centre, Directorate G, Geel, Belgium .
    Pomp, Stephan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    The impact of neutron emission on correlated fission data from the 2E-2v method2018In: European Physical Journal A, ISSN 1434-6001, E-ISSN 1434-601X, Vol. 54, article id 114Article in journal (Refereed)
    Abstract [en]

    The double-energy double-velocity (2E-2v) method allows assessing fission-fragment mass yields prior to and after prompt neutron emission with high resolution. It is, therefore, considered as a complementary technique to assess average prompt neutron multiplicity as a function of fragment properties. We have studied the intrinsic features of the 2E-2v method by means of event-wise generated fission-fragment data and found short-comings in the method itself as well as in some common practices of application. We find that the 2E-2v method leads to large deviations in the correlation between the prompt neutron multiplicity and pre-neutron mass, which deforms and exaggerates the so-called “sawtooth” shape of nubar(A). We have identified the treatment of prompt neutron emission from the fragments as the origin of the problem. The intrinsic nature of this deficiency risks to render 2E-2v experiments less interesting. We suggest a method to correct 2E-2v data that can even be applied on existing measurements.

  • 419.
    Jansson, Kaj
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Al-Adili, Ali
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Bevilacqua, Riccardo
    European Spallat Source, Box 176, S-22100 Lund, Sweden.
    Gustavsson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Hambsch, Franz-Josef
    European Commiss, Inst Reference Mat & Measurements, Joint Res Ctr, Retieseweg 111, B-2440 Geel, Belgium.
    Pomp, Stephan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Vidali, Marzio
    European Commiss, Inst Reference Mat & Measurements, Joint Res Ctr, Retieseweg 111, B-2440 Geel, Belgium.
    Measurement of the 6Li(n,α) neutron standard cross-section at the GELINA facility2016In: The European Physical Journal Conferences, ISSN 2101-6275, E-ISSN 2100-014X, Vol. 122Article in journal (Refereed)
    Abstract [en]

    The Li-6(n,alpha) reaction cross-section is commonly used as a reference cross section. However, it is only considered a neutron standard up to 1 MeV. For higher energies, there are discrepancies of several per cents between recent measurements and evaluated data files. In order to extend and establish Li-6 (n,alpha) as a neutron standard above 1 MeV these discrepancies must be resolved. Our measurement at the GELINA facility at JRC-IRMM in Geel, Belgium is ongoing. We are using a double twin Frisch-grid setup to detect both a-particles from two Li-6 targets and fission products from two U-235 reference targets. Our targets have thick backings but are employed in pairs, one forward facing and one backward facing. In this way we still cover, in principle, a solid angle of 4 pi. We present some preliminary results showing that the existing cross-section data is well reproduced around the resonance at 240 keV. The final data taking will start in the beginning of 2016, when the GELINA facility goes online again after a few months of shut down.

  • 420.
    Jansson, Kaj
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Al-Adili, Ali
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Bevilacqua, Riccardo
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics. European Spallation Source.
    Gustavsson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Hambsch, Franz-Josef
    EC-JRC-Dir. G-Unit G.2.
    Pomp, Stephan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Vidali, Marzio
    EC-JRC-Dir. G-Unit G.2.
    Measurement of the 6Li(n,α)t neutron standard cross-section at the GELINA facility2017In: ND 2016: INTERNATIONAL CONFERENCE ON NUCLEAR DATA FOR SCIENCE AND TECHNOLOGY / [ed] Plompen, A; Hambsch, FJ; Schillebeeckx, P; Mondelaers, W; Heyse, J; Kopecky, S; Siegler, P; Oberstedt, S, Les Ulis: EDP Sciences, 2017, Vol. 146, article id 11047Conference paper (Refereed)
    Abstract [en]

    The Li-6(n,alpha)t reaction cross-section is an established standard due to its relatively high crosssection as well as its high Q-value. However, it is only considered a neutron standard up to 1 MeV, because in the neutron energy region 1-3 MeV there exist discrepancies of several per cents between recent measurements [1,2] and evaluated data files [3]. It has been speculated [4] that neglecting of the particle leaking effect might be part of the explanation why there is a disagreement in this region. Based on R-matrix calculations, in the region around 2 MeV, one also expects three excitation levels of Li-7 to significantly influence the cross section [5]. In order to resolve these discrepancies, we perform measurements at the GELINA facility at JRC-Geel with two Frisch-gridded ionisation chambers. The Li-6(n,alpha)t cross section is measured relative to the U-235(n,f) standard. In order to solve previous encountered problems [6], the setup has been modified and moved to a new flight path station. In this proceeding we show that several problems have been eliminated and discuss possible solutions to newly arisen problems, due to the changed experimental conditions. Preliminary results from new data taken during 2016 with the updated setup are presented.

  • 421.
    Jansson, Kaj
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Al-Adili, Ali
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Nilsson, Niklas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Norlin, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Solders, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Simulated production rates of exotic nuclei from the ion guide for neutron-induced fission at IGISOL2017In: European Physical Journal A, ISSN 1434-6001, E-ISSN 1434-601X, Vol. 53, no 12, article id 243Article in journal (Refereed)
    Abstract [en]

    An investigation of the stopping efficiency of fission products, in the new ion guide designed for ion production through neutron-induced fission at IGISOL in Jyväskylä, Finland, has been conducted. Our simulations take into account the new neutron converter, enabling measurements of neutron-induced fission yields, and thereby provide estimates of the obtained yields as a function of primary proton beam current. Different geometries, targets, and pressures, as well as models for the effective charge of the stopped ions were tested, and optimisations to the setup for higher yields are suggested. The predicted number of ions stopped in the gas lets us estimate the survival probability of the ions reaching the downstream measurements stations.

  • 422.
    Jansson, Kaj
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Frégeau, Marc Olivier
    GANIL CEA/DRF-CNRS/IN2P3, France.
    Al-Adili, Ali
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Göök, Alf
    European Commission, Joint Research Centre, Directorate G, Geel, Belgium.
    Gustavsson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Hambsch, Franz-Josef
    European Commission, Joint Research Centre, Directorate G, Geel, Belgium.
    Oberstedt, Stephan
    European Commission, Joint Research Centre, Directorate G, Geel, Belgium.
    Pomp, Stephan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    The new double energy-velocity spectrometer VERDI2017In: ND 2016: INTERNATIONAL CONFERENCE ON NUCLEAR DATA FOR SCIENCE AND TECHNOLOGY / [ed] Plompen, A; Hambsch, FJ; Schillebeeckx, P; Mondelaers, W; Heyse, J; Kopecky, S; Siegler, P; Oberstedt, S, Les Ulis: EDP Sciences, 2017, Vol. 146, article id 04016Conference paper (Refereed)
    Abstract [en]

    VERDI (VElocity foR Direct particle Identification) is a fission-fragment spectrometer recently put into operation at JRC-Geel. It allows measuring the kinetic energy and velocity of both fission fragments simultaneously. The velocity provides information about the pre-neutron mass of each fission fragment when isotropic prompt-neutron emission from the fragments is assumed. The kinetic energy, in combination with the velocity, provides the post-neutron mass. From the difference between pre- and post-neutron masses, the number of neutrons emitted by each fragment can be determined. Multiplicity as a function of fragment mass and total kinetic energy is one important ingredient, essential for understanding the sharing of excitation energy between fission fragments at scission, and may be used to benchmark nuclear de-excitation models. The VERDI spectrometer design is a compromise between geometrical efficiency and mass resolution. The spectrometer consists of an electron detector located close to the target and two arrays of silicon detectors, each located 50 cm away from the target. In the present configuration pre-neutron and post-neutron mass distributions are in good agreement with reference data were obtained. Our latest measurements performed with spontaneously fissioning 252Cf is presented along with the developed calibration procedure to obtain pulse height defect and plasma delay time corrections.

  • 423.
    Jansson, Kaj
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Gustavsson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Al-Adili, Ali
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Hjalmarsson, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Andersson Sundén, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Prokofiev, Alexander V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics. Uppsala University, The Svedberg Laboratory.
    Tarrío, Diego
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Pomp, Stephan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Designing an upgrade of the Medley setup for light-ion production and fission cross-section measurements2015In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 794, p. 141-150Article in journal (Refereed)
    Abstract [en]

    Abstract Measurements of neutron-induced fission cross-sections and light-ion production are planned in the energy range 1-40 MeV at the upcoming Neutrons For Science (NFS) facility. In order to prepare our detector setup for the neutron beam with continuous energy spectrum, a simulation software was written using the Geant4 toolkit for both measurement situations. The neutron energy range around 20 MeV is troublesome when it comes to the cross-sections used by Geant4 since data-driven cross-sections are only available below 20 MeV but not above, where they are based on semi-empirical models. Several customisations were made to the standard classes in Geant4 in order to produce consistent results over the whole simulated energy range. Expected uncertainties are reported for both types of measurements. The simulations have shown that a simultaneous precision measurement of the three standard cross-sections H(n,n), 235U(n,f) and 238U(n,f) relative to each other is feasible using a triple layered target. As high resolution timing detectors for fission fragments we plan to use Parallel Plate Avalanche Counters (PPACs). The simulation results have put some restrictions on the design of these detectors as well as on the target design. This study suggests a fissile target no thicker than 2 µm (1.7 mg/cm2) and a PPAC foil thickness preferably less than 1 µm . We also comment on the usability of Geant4 for simulation studies of neutron reactions in this energy range.

  • 424.
    Jansson, Kaj
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Gustavsson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Pomp, Stephan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Prokofiev, Alexander V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics. Uppsala University, The Svedberg Laboratory.
    Scian, G.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Tarrio, Diego
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Measuring Light-ion Production and Fission Cross Sections Normalised to H(n,p) Scattering at the Upcoming NFS Facility2014In: Nuclear Data Sheets, ISSN 0090-3752, E-ISSN 1095-9904, Vol. 119, p. 395-397Article in journal (Refereed)
    Abstract [en]

    The Medley detector setup is planned to be moved to and used at the new neutron facility NFS where measurements of light-ion production and fission cross-sections are planned at 1-40 MeV. Medley has eight detector telescopes providing Delta E-Delta E-E data, each consisting of two silicon detectors and a CsI(Tl) detector at the back. The telescope setup can be rotated and arranged to cover any angle. Medley has previously been used in many measurements at The Svedberg Laboratory (TSL) in Uppsala mainly with a quasi-mono-energetic neutron beam at 96 and 175 MeV. To be able to do measurements at NFS, which will have a white neutron beam, Medley needs to detect the reaction products with a high timing resolution providing the ToF of the primary neutron. In this paper we discuss the design of the Medley upgrade along with simulations of the setup. We explore the use of Parallel Plate Avalanche Counters (PPACs) which work very well for detecting fission fragments but require more consideration for detecting deeply penetrating particles.

  • 425.
    Jansson, Kaj
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Gustavsson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Pomp, Stephan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Prokofiev, Alexander V.
    Uppsala University, The Svedberg Laboratory.
    Scian, Giovanni
    Tarrio, Diego
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Measuring light-ion production and fission cross sections versus elastic np-scattering at the upcoming NFS facility2014Conference paper (Refereed)
  • 426.
    Jansson, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Converged results from Geant4 calculations of pin-by-pin contributions to 137Cs gamma radiation flux at Clab2017Data set
    Abstract [en]

    A set of Geant4 calculations have been performed in reference [1] in which the gamma radiation flux through the opening of the collimator slit in the nuclear fuel gamma scanning equipment installed at the Swedish interim storage for used nuclear fuel (Clab) was calculated. This dataset contains data aggregated from the data in [1]. Specifically, the most converged gamma flux together with its calculated statistical uncertainty for each nuclear fuel rod is presented here.

    [1] Jansson P.; "Results from Geant4 calculations of pin-by-pin contributions to 137Cs gamma radiation flux at Clab"; URL: http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-316271; 2016

  • 427.
    Jansson, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Digital Pulse Processing in HPGe Gamma-ray Spectroscopy: Supplement to the spring 2013, 2016 & 2017 courses on Activity Measurements with Germanium Detectors2017Book (Other academic)
    Abstract [en]

    A summary of basic digital signal processing systems is provided. Methods currently used in gamma-ray spectroscopy based on digital techniques are summarized. A list of references regarding digital spectroscopy is provided to guide the reader to relevant work.

  • 428.
    Jansson, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Geant4 simulation results for the designed UGET-v1 tomographic measurement device.2016Data set
    Abstract [en]

    Results from simulations performed with Geant4 for the UGET v1 of a tomographic measurement device, designed in the UGET project.

  • 429.
    Jansson, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Nonproliferation and nuclear fuel cycle back-end research at Uppsala University, Sweden: Special Seminar at PNNL2018Other (Other academic)
    Abstract [en]

    A brief overview of Uppsala University and the Department of Physics and Astronomy will be followed by a presentation of current research activities within the Division of Applied Nuclear Physics. Special attention will be given to on-going research in two sub-groups; Research for Nuclear Nonproliferation and research for the needs of the Swedish Nuclear Fuel and Waste Management company that is responsible for managing all the used nuclear fuel in Sweden, including encapsulation and deep geological disposal.

    After the more organizational overview, the research performed within the research group regarding single photon gamma emission tomography (GET) of nuclear fuel assemblies will be presented both from a historical perspective and from the perspective of what is currently ongoing. Specifically, the work currently ongoing within the Swedish support program to IAEA Safeguards regarding GET will be presented.

  • 430.
    Jansson, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Results from Geant4 calculations of energy deposition from gamma- and neutron radiation emitted from selected cases of used boiling water reactor nuclear fuel assemblies in a KBS-3 type deep geological repository2017Data set
    Abstract [en]

    Monte Carlo calculations, using the Geant4 framework version 10.02, of energy deposition from gamma- and neutron radiation emitted from boiling water reator (BWR) fuel assemblies in a KBS-3 type deep geological repository for used nuclear fuel have been performed. This dataset contains the results of the calculations. Three fuel rods were arbitrarily selected as source rods for 662 keV and 2.75 MeV gamma- and neutron radiation, respectively. For each of the six cases, the energy deposited in a 3-dimensional (x,y,z) mesh with 1 cm resolution was calculated and tallied as function of the type of particle that deposited the energy.

  • 431.
    Jansson, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Results from Geant4 calculations of pin-by-pin contributions to 137Cs gamma radiation flux at Clab2016Data set
    Abstract [en]

    A set of Geant4 calculations have been performed in which the gamma radiation flux through the opening of the collimator slit in the nuclear fuel gamma scanning equipment installed at the Swedish interim storage for used nuclear fuel. Two types of boiling water reactor (BWR) and two types of pressurized water reactor (PWR) nuclear fuel assemblies were used in the calculations. For each fuel type and for each individual pin in each fuel assembly type, the contribution to the gamma flux was calculated for a 137Cs source with 662 keV gamma radiation. Some calculations were performed without a fuel assembly but instead using a point source with 137Cs  located at various positions in the collimator slit.

    This dataset contains the results of the calculations in the format of structured query language (SQL).

  • 432.
    Jansson, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Spent fuel characterization for geological repositories: Presented at the 2015 symposium of the Swedish Centre for Nuclear Technology (SKC) October 92015Conference paper (Other academic)
  • 433.
    Jansson, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    The proposed SPIRE project: Challenge, Scope and Impact2016Conference paper (Other academic)
    Abstract [en]

    Time is progressing towards 2025 when the vision of IGD-TP is to have an operating geological disposal facility in Europe, only nine years remains. As mature national programs are developing details on what is needed regarding characterisation of spent nuclear fuel, i.e. determining source terms to decay heat, criticality or dose rates, it becomes more evident that the uncertainties associated with such parameters and the underlying knowledge of source terms have large impacts on economy and safety of interim storage and deep geological facilities.

    With the Spent fuel characterization Program for the Implementation of (geological) Repositories (SPIRE), we try to address remaining issues for spent fuel characterization in relation to its storage, both short term and long term. We attack the operators' challenge both from a measurement and simulation point of view, including development of both old a new measurement techniques, enhancing the precision and reliability with which parameters of the fuel can be calculated and perform validation and verification efforts in this context.

    We believe that spent fuel characterization is an important contribution to enabling the vision of the IGD-TP.

  • 434.
    Jansson, Peter
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Andersson, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    White, Timothy A.
    Pacific Northwest National Laboratory.
    Mozin, Vladimir
    Lawrence Livermore National Laboratory.
    Monte Carlo simulations of a Universal Gamma-Ray Emission Tomography Device2015Conference paper (Other academic)
    Abstract [en]

    A design of a universal gamma-ray emission tomography (UGET) device has been definedwithin the IAEA MSSP project JNT1955 in order to evaluate partial defect detectioncapabilities when using tomography on used nuclear fuel assemblies. The design isintended to allow for fuel assembly verification using single photon emission tomographyon a broad range of fuel assembly types and fuel parameters.

    In this paper, results from a set of Monte Carlo radiation transport simulations for the UGETdesign are presented. In these simulations, two cases are studied, each of them with a PWR fuel, in one case the complete fuel assembly and in the other with 11 missing rods.The characteristic features of the design are presented including expected performancerequirements on the gamma-ray collimator and detector system, supported by thesimulation results. In addition, the agreement between the two simulation tools used, Geant4 and MCNP, indicate that any of the two can give satisfactory accuracy for this purpose.

  • 435.
    Jansson, Peter
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Grape, Sophie
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Jacobsson Svärd, Staffan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Håkansson, Ane
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    A laboratory device for developing analysis tools and methods for gamma emission tomography of nuclear fuel2013Conference paper (Other academic)
    Abstract [en]

    Tomography is a measurement technique that images the inner parts of objects using only external measurement. It is widely used within the field of medicine, and may become important also for nuclear fuel verification where inspectors can obtain information from fuel assemblies’ inner sections without dismantling them.

    At Uppsala University, Sweden, a laboratory device has been built for investigating the tomographic measurement techniques on nuclear fuel. The device is composed of machinery to position model fuelrods, activated with Cs-137, in a fuel assembly pattern according to the user's choice. The gamma radiation from the model fuel assembly is collimated to a set of detectors that record the radiation intensity in various positions around the fuel model. Reconstruction of the gamma activity distribution within the fuel model is performed off-line.

    The objective for constructing the laboratory device was to support the development of tomographic techniques for nuclear fuel diagnostics as well as for nuclear safeguards purposes. The device allows for evaluating the performance of different data-acquisition setups, measurement schemes and reconstruction algorithms, since the activity content of each fuel rod is well known.

    For safeguards purposes, the device is unique in its capability to model various fuel geometries and configurations of partial defects. The latter includes removed, empty and substituted fuel rods. It is well suited for developing tomographic techniques that are optimized for partial defect detection. It also allows for development of analysis tools necessary to quantify detection limits.

    Here, we describe the capabilities of the laboratory device and elaborate on how the device may be used to support the nuclear safeguards community with the development of unattended gamma emission tomography.

  • 436.
    Jansson, Peter
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Grape, Sophie
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Tobin, Steve
    Los Alamos National Laboratory.
    Liljenfeldt, Henrik
    Swedish Nuclear Fuel and Waste Management Company.
    Experimental Comparison between High Purity Germanium and Scintillator Detectors for Determining Burnup, Cooling Time and Decay Heat of Used Nuclear Fuel2014Conference paper (Other academic)
    Abstract [en]

    A experimental study of the gamma-ray energy spectra from used nuclear fuel has been performed. Four types of detectors were used to measure spectra from three PWR used fuel assemblies stored at the interim storage for used fuel in Sweden, CLAB: HPGe, LaBr3, NaI and BGO.

    The study was performed in the context of used fuel characterization for the back end of the fuel cycle in Sweden. Specifically, the purpose was to evaluate the behaviour of the different scintillator detectors (LaBr3, NaI and BGO) and their ability to be used instead of HPGe detectors when determining spent fuel parameters such as burnup, cooling time and decay heat of the used fuel.

    This paper presents results from the experimental study and an analysis of the capability of the detectors for used fuel characterization. The results shown are important when designing systems for used fuel characterization, e.g. for determining decay heat or fuel parameters concerning safeguards.

  • 437.
    Jansson, Peter
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Nuclear and Particle Physics, Nuclear Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Håkansson, Ane
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Nuclear and Particle Physics, Nuclear Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Bäcklin, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Nuclear and Particle Physics, Nuclear Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Jacobsson, Staffan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Nuclear and Particle Physics, Nuclear Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Gamma-Ray Spectroscopy Measurements of Decay Heat in Spent Nuclear Fuel2002In: Nuclear Science and Engineering, ISSN 0029-5639, Vol. 141, no 2, p. 129-139Article in journal (Refereed)
    Abstract [en]

    A method for determining the residual thermal power in spent nuclear fuel using gamma-ray spectroscopy is suggested. It is based on the correlation between the residual power and the 137Cs activity, which is nearly linear for fuel with cooling times between 10 and 50 yr. Using available data of calorimetrically measured values of the decay heat in 69 boiling water reactor and pressurized water reactor spent-fuel assemblies resulted in agreement with a standard deviation of 3%.

  • 438.
    Jansson, Peter
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Håkansson, Ane
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Jacobsson, Staffan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Bäcklin, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    A Method of Measuring Decay Heat in Spent Nuclear Fuel using Gamma-ray Spectroscopy2001In: Waste Management Symposium 2001 (WM'01), 2001Conference paper (Refereed)
    Abstract [en]

    In this paper, a method is presented for determining the decay heat in spent nuclear fuel by using gamma-ray spectroscopy. Using this method, the decay heat may be determined within ten minutes per assembly i.e. it is well suited for industrial applications in, for example, an encapsulation facility. The method has been tested and evaluated in the wet Swedish Central Storage for Spent Fuel, CLAB. Although only tested in a wet storage, the method should also be applicable for dry storage.

    The objective of developing the method was primarily to investigate possibilities to achieve a fast, robust and reasonable accurate determination of decay heat by gamma-ray measurements on fuel assemblies. Such a method could also be for verification of burnup and cooling time, for safeguard purposes prior to encapsulation, (1).

    So far, measurements and calculations on 35 BWR- and 34 PWR-assemblies, with various nuclear data, have been performed. The test measurements, using preliminary measuring equipment, have shown that the decay heat may be determined within an uncertainty of 3%.

  • 439.
    Jansson, Peter
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Jacobsson Svärd, Staffan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Grape, Sophie
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Gamma emission tomography of nuclear fuel: Objectives and status of the IAEA UGET project2013Conference paper (Other academic)
  • 440.
    Jansson, Peter
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Jacobsson Svärd, Staffan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Grape, Sophie
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Davour, Anna
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Mozin, Vladimir
    Lawrence Livermore National Laboratory, USA.
    Gamma Transport Calculations for Gamma Emission Tomography on Nuclear Fuel within the UGET Project2014Conference paper (Other academic)
    Abstract [en]

    The unattended gamma emission tomography (UGET) for spent nuclear fuel verification is an on-going project in the IAEA member states’ support program. In line with the long term R&D plan of the IAEA Department of Safeguards, it is anticipated that this effort will help develop “more sensitive and less intrusive alternatives to existing NDA instruments to perform partial defect test on spent fuel assembly prior to transfer to difficult to access storage”.

    In the first phase of the project, gamma transport calculations and modelling of exist- ing and proposed new designs of tomographic instruments is performed. In this paper, a set of Monte Carlo calculations regarding modelling of various tomographic devices are presented, including two existing tomographic instruments previously used for spent fuel measurements; one instrument based on scintillator detectors, developed by Uppsala University, and another based on CdTe detector arrays, developed by the JNT 1510 col- laborative effort (Hungary, Finland). Detailed models of the tomographic instruments, including structural materials, and the measured fuel assemblies are used in the simula- tions. The calculated results are compared to the experimentally measured data to provide a benchmark for the simulation procedure.

    The developed modelling capabilities are also used for evaluation of the partial-defect detection capabilities of the tomographic technique based on a proposed GET instrument design. 

  • 441.
    Jansson, Peter
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Nuclear and Particle Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Jacobsson Svärd, Staffan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Nuclear and Particle Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Håkansson, Ane
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Nuclear and Particle Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Bäcklin, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Nuclear and Particle Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    A Device for Nondestructive Experimental Determination of the Power Distribution in a Nuclear Fuel Assembly2006In: Nuclear science and engineering, ISSN 0029-5639, E-ISSN 1943-748X, Vol. 152, no 1, p. 76-86Article in journal (Refereed)
    Abstract [en]

    There is a general interest in experimentally determining the power distribution in nuclear fuel. The prevalent method is to measure the distribution of the fission product 140Ba, which represents the power distribution over the last few weeks. In order to obtain the rod-by-rod power distribution, the fuel assemblies have to be dismantled.

    In this paper, a device for experimental nondestructive determination of the thermal rod-by-rod power distribution in boiling water reactor and pressurized water reactor fuel assemblies is described. It is based on measurements of the 1.6-MeV gamma radiation from the decay of 140Ba/La and utilizes a tomographic method to reconstruct the rod-by-rod source distribution. No dismantling of the fuel assembly is required.

    The device is designed to measure an axial node in 20 min with a precision of >2% (1). It is primarily planned to be used for validation of production codes for core simulation but may also be used for safeguards purposes.

  • 442.
    Jansson, Peter
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Lantz, Mattias
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Räkneuppgifter till Säkerhetsanalyser inom energisektorn2018Book (Other academic)
  • 443.
    Jansson, Peter
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Schillebeeckx, Peter
    Joint Research Centre, European Commission.
    Zencker, Uwe
    Bundesanstalt für Materialforschung und-prüfung, Germany.
    Cobos, Joaquin
    Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas, Spain.
    EURAD: SFC WP: Spent Fuel Characterisation and Evolution Until Disposal2019Conference paper (Other academic)
  • 444.
    Jansson, Peter
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Tobin, Stephen
    Los Alamos National Laboratory, Los Alamos, NM, USA.
    Liljenfeldt, Henrik
    Oak Ridge National Laboratory, Oak Ridge, TN, USA.
    Fugate, Michael
    Los Alamos National Laboratory, Los Alamos, NM, USA.
    Favalli, Andrea
    Los Alamos National Laboratory, Los Alamos, NM, USA.
    Sjöland, Anders
    Swedish Nuclear Fuel and Waste Management Company.
    Axial and azimuthal gamma scanning of nuclear fuel - implications for spent fuel characterization2016In: Journal of Nuclear Materials Management, ISSN 0893-6188, Vol. 45, no 1, p. 34-47Article in journal (Refereed)
    Abstract [en]

    A project to research the application of non-destructive assay (NDA) to spent fuel assemblies is underway among a team comprised of the European Commission, DG Energy, Directorate Nuclear Safeguards; the Swedish Nuclear Fuel and Waste Management Company; Uppsala University, The University of Michigan, Los Alamos National Laboratory, Lawrence Livermore National Laboratory and Oak Ridge National Laboratory that collaboratively are advancing some of the goals of the Next Generation Safeguards Initiative’s Spent Fuel (NGSI-SF) Project. The NGSI–SF team is working to achieve the following technical goals more easily and efficiently using nondestructive assay measurements of spent fuel assemblies in order to improve both international safeguards and repository safety: (1) verify the initial enrichment, burnup, and cooling time of facility declaration; (2) detect the diversion or replacement of pins, (3) estimate the plutonium mass, (4) estimate the decay heat, and (5) determine the reactivity of spent fuel assemblies. The measured neutron, gamma-ray and heat signatures from spent fuel assemblies, as well as simulations, will be combined in advancement of the technical goals.

    This current study focuses primarily on the application of time stamped list mode data acquisition applied in the context of a fixed collimator that allowed a thin axial portion of the fuel to be observed as the fuel assembly moved vertically past the collimator. Measurements were performed at the Central Interim Storage Facility for Spent Nuclear Fuel (which is abbreviated using the Swedish acronym: Clab) in Sweden, in 2013 and 2014. In total, 50 spent nuclear fuel assemblies were measured in detail, 25 BWR and 25 PWR assemblies.

    In this context, time stamped list mode data acquisition have not previously been used for gamma-ray spectroscopy measurements of used nuclear fuel measurements. We compare it to the more typical fixed-axial location pulse height analysis approach. The flexibility of analyzing data from time stamped list mode measurements enables research into questions of how beneficial axially resolved information is for each of the varied research goals; in particular the current research is an initial step toward comparing the benefit of several fixed axial measurements vs. scanning an entire assembly.

  • 445.
    Jansson, Peter
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Österlund, Michael
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Jacobsson Svärd, Staffan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Grape, Sophie
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    A platform for feed-forward and follow-up of students' progression in oral presentation within a study programme2015Conference paper (Other academic)
    Abstract [en]

    Didactic research has shown that feedforward has a positive effect on students' experience of their progression in oral presentation. However, studies also show that students often experience a lack of feedback from teachers and audience attending their presentations and consequently they lack an experience of progression.

    In this work we present a platform for structured documentation and follow-up of students' progress of skills in oral presentation that has been been implemented within the bachelor programme in nuclear engineering at Uppsala University. The platform provides efficient communication of feedback and feedforward to the students over this one-year programme, involving several courses and teachers.

    The platform is implemented within the system for learning and study administration that is used by students and staff at Uppsala University ("Student Portal"). It consists of an interface where the students and teachers have an overview of progress made in all individual courses at the programme. For each course that includes an oral presentation, there is a folder where each student uploads a self assessment. In the same folder, the teachers upload their feedback as well as the feedback provided by fellow students for each oral presentation. Self assessments and feedback provide feedforward for future oral presentations. The platform was implemented in August 2014, and it has now been in use for one year within the nuclear engineering programme. Lessons learned from using the platform are presented in this work.

    In order to study the effects of implementing this platform, a questionnaire was distributed to the students for the purpose of collecting information regarding their experience of giving oral presentation, their perceived skill level and their experience of practising oral presentations. The same questionnaire was distributed to the students on three occasions: before, during and after the first year of using the platform. Results from analysis of data are presented, showing that the students have experienced progression during this year.

  • 446.
    Jason, Hou
    et al.
    Univ Calif Berkeley, Dept Nucl Engn, Berkeley, CA 94720 USA.
    Qvist, Staffan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Kellogg, Roger
    Argonne Natl Lab, Nucl Engn Div, 9700 S Cass Ave, Argonne, IL 60439 USA.
    Greenspan, Ehud
    Univ Calif Berkeley, Dept Nucl Engn, Berkeley, CA 94720 USA.
    3D in-core fuel management optimization for breed-and-burn reactors2016In: Progress in nuclear energy (New series), ISSN 0149-1970, E-ISSN 1878-4224, Vol. 88, p. 58-74Article in journal (Refereed)
    Abstract [en]

    Breed-and-burn (B&B) reactors are a special class of fast reactors that are designed to utilize low grade fuel such as depleted uranium without fuel reprocessing. One of the most challenging practical design feasibility issues faced by B&B reactors is the high level of radiation damage their fuel cladding has to withstand in order to sustain the B&B mode of operation more than twice the maximum radiation damage cladding materials were exposed to so far in fast reactors. This study explores the possibility of reducing the minimum required peak radiation damage by employment of 3-dimensional (3D) fuel shuffling that enables a significant reduction in the peak-to-average axial burnup, that is, more uniform fuel utilization. A new conceptual design of a B&B core made of axially segmented fuel assemblies was adopted to facilitate the 3D shuffling. Also developed is a Simulated Annealing (SA) algorithm to automate the search for the optimal 3D shuffling pattern (SP). The primary objective of the SA optimization is to minimize the peak radiation damage while its secondary objective is to minimize the burnup reactivity swing, radial power peaking factor and maximum change of fuel assembly power over the cycle. Also studied is the sensitivity of the 3D shuffled core performance to the number of axially stacked subassemblies, core height and power level.

    It was found that compared with the optimal 2-dimensional (2D) shuffled core, the optimal 3D shuffled B&B core made of four 70 cm long axially stacked sub-assemblies and 12 radial shuffling batches offers a 1/3 reduction of the peak radiation damage level from 534 down to 351 displacements per atom (dpa), along with a 45% increase in the average fuel discharge burnup, and hence, the depleted uranium utilization, while satisfying all major neutronics and thermal-hydraulics design constraints. For the same peak dpa level, the 3D shuffling offers more than double the uranium utilization and the cycle length relative to 2D shuffling. The minimum peak radiation damage is increased to 360 or to 403 dpa if the core is made of, respectively, three - 70 cm or two - 140 cm long axially stacked subassemblies. Reducing the length of the subassemblies of B&B cores made of three-segment assemblies from 70 cm to 60 or 50 cm results in an increase in the peak radiation damage from 360 dpa to, respectively, 368 and 397 dpa.

  • 447. Joffrin, E.
    et al.
    Andersson Sundén, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Binda, Federico
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Cecconello, Marco
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Conroy, Sean
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Ericsson, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Eriksson, Jacob
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Hellesen, Carl
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Hjalmarsson, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Primetzhofer, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Sahlberg, Arne
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Sjöstrand, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Skiba, Mateusz
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Weiszflog, Matthias
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Zychor, I
    Overview of the JET preparation for deuterium-tritium operation with the ITER like-wall2019In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 59, no 11, article id 112021Article in journal (Refereed)
    Abstract [en]

    For the past several years, the JET scientific programme (Pamela et al 2007 Fusion Eng. Des. 82 590) has been engaged in a multi-campaign effort, including experiments in D, H and T, leading up to 2020 and the first experiments with 50%/50% D-T mixtures since 1997 and the first ever D-T plasmas with the ITER mix of plasma-facing component materials. For this purpose, a concerted physics and technology programme was launched with a view to prepare the D-T campaign (DTE2). This paper addresses the key elements developed by the JET programme directly contributing to the D-T preparation. This intense preparation includes the review of the physics basis for the D-T operational scenarios, including the fusion power predictions through first principle and integrated modelling, and the impact of isotopes in the operation and physics of D-T plasmas (thermal and particle transport, high confinement mode (H-mode) access, Be and W erosion, fuel recovery, etc). This effort also requires improving several aspects of plasma operation for DTE2, such as real time control schemes, heat load control, disruption avoidance and a mitigation system (including the installation of a new shattered pellet injector), novel ion cyclotron resonance heating schemes (such as the three-ions scheme), new diagnostics (neutron camera and spectrometer, active Alfven eigenmode antennas, neutral gauges, radiation hard imaging systems...) and the calibration of the JET neutron diagnostics at 14 MeV for accurate fusion power measurement. The active preparation of JET for the 2020 D-T campaign provides an incomparable source of information and a basis for the future D-T operation of ITER, and it is also foreseen that a large number of key physics issues will be addressed in support of burning plasmas.

  • 448.
    Jonasson, Fredrik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Sparresäter, Björn
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Monte Carlo-simuleringar av germaniumdetektor för gammaspektroskopi2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Syftet med projektet är att undersöka en HPGe-detektors egenskaper med hjälp av Monte Carlo-simuleringar i simuleringskoden FLUKA. Resultaten från detta projekt ska sedan användas som underlag för en kartläggning där halten av den radioaktiva isotopen cesium-137 ska mätas på svampprover insamlade från hela landet. En rad simuleringar har gjorts med olika typer av strålningskällor och med variationer på detektorns geometri. Den detektor som ska användas för dessa mätningar är över 30 år gammal vilket kan medföra att vissa egenskaper kan ha förändrats med tiden. Resultaten från simuleringarna visar dock att eventuella förändringar är försumbara. En annan del av detektorns geometri, ett kylningshål i botten av germaniumkristallen, specificeras inte tydligt i produktspecifikationerna från tillverkaren. Även här visar dock simuleringarna att hålets storlek inte har någon större betydelse. Däremot visar simuleringarna, som förväntat, att detektorns effektivitet varierar beroende på strålningens energi och avståndet från strålningskällan.

  • 449.
    Jones, O. M.
    et al.
    Univ Durham, Dept Phys, South Rd, Durham DH1 3LE, England; Culham Sci Ctr, CCFE, Abingdon OX14 3DB, Oxon, England.
    Cecconello, Marco
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    McClements, K. G.
    Culham Sci Ctr, CCFE, Abingdon OX14 3DB, Oxon, England.
    Klimek, Iwona
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Akers, R. J.
    Culham Sci Ctr, CCFE, Abingdon OX14 3DB, Oxon, England.
    Boeglin, W. U.
    Florida Int Univ, Dept Phys, Miami, FL 33199 USA.
    Keeling, D. L.
    Culham Sci Ctr, CCFE, Abingdon OX14 3DB, Oxon, England.
    Meakins, A. J.
    Culham Sci Ctr, CCFE, Abingdon OX14 3DB, Oxon, England.
    Perez, R. V.
    Florida Int Univ, Dept Phys, Miami, FL 33199 USA.
    Sharapov, S. E.
    Culham Sci Ctr, CCFE, Abingdon OX14 3DB, Oxon, England.
    Turnyanskiy, M.
    EUROfus PMU Garching, ITER Phys Dept, D-85748 Garching, Germany.
    Measurements and modelling of fast-ion redistribution due to resonant MHD instabilities in MAST2015In: Plasma Physics and Controlled Fusion, ISSN 0741-3335, E-ISSN 1361-6587, Vol. 57, no 12, article id 125009Article in journal (Refereed)
    Abstract [en]

    The results of a comprehensive investigation into the effects of toroidicity-induced Alfven eigenmodes (TAE) and energetic particle modes on the NBI-generated fast-ion population in MAST plasmas are reported. Fast-ion redistribution due to frequency-chirping TAE in the range 50 kHz-100 kHz and frequency-chirping energetic particle modes known as fishbones in the range 20 kHz-50 kHz, is observed. TAE and fishbones are also observed to cause losses of fast ions from the plasma. The spatial and temporal evolution of the fast-ion distribution is determined using a fission chamber, a radially-scanning collimated neutron flux monitor, a fast-ion deuterium alpha spectrometer and a charged fusion product detector. Modelling using the global transport analysis code TRANSP, with ad hoc anomalous diffusion and fishbone loss models introduced, reproduces the coarsest features of the affected fast-ion distribution in the presence of energetic particle-driven modes. The spectrally and spatially resolved measurements show, however, that these models do not fully capture the effects of chirping modes on the fast-ion distribution.

  • 450.
    Jonsson, Niclas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Lindkvist, Tommie
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Pricing Models for Customers in Active Houses with Load Management2011Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In the new residential area, called Stockholm Royal Seaport (SRS), the customers will be living in Active Houses with Load Management. This implies that some balancing of the grid is shifted from the production to the consumption. To give the customer incentives to participate in the Load Management, new more dynamic pricing models needs to be implemented. At the same time, profits for the investors are needed to motivate an implementation of similar residential areas. To achieve this, an analysis of the electricity markets and an implementation of dynamic pricing models in a MATLAB simulation are done. A proposed trading profit for the investors and possible cost reductions for customers have been derived from the modelling. The results show that the difference in costs between utilized and unutilized Load Management are small, only considering the dynamic pricing models, therefore compliments to these are discussed. The conclusion is therefore that the energy for the manageable loads should be charged separately. Another important conclusion is that a change of the Spotmarket is needed in order to create a more beneficial market for retailers with flexible customers.

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