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  • 851.
    Wolniewicz, Peter
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Ane, Håkansson
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Jansson, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Detection of coolant bubbles in lead-cooled fast reactorsManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Previous work [1] has shown that using fission chambers coated with 242Pu and 235U, respectively, can provide the means of detecting changes in the neutron flux that are connected to coolant density changes in a small lead cooled fast reactor. Such density changes may be due to leakages of gas into the coolant, which, over time, may coalesce to large bubbles implying a high risk of causing severe damages of the core. By using the ratio of the information provided by the two types of detectors a quantity is obtained that is sensitive to these density changes and, to the first order approximation, independent of the power level of the reactor.

     

    In this work we continue the investigation of this proposed methodology by applying it to the Advanced LFR European Demonstrator (ALFRED) and using realistic modelling of the neutron detectors. The results show that the methodology may be used to detect density changes indicating the initial stages of a coalescence process that may result in a large bubble. Also, it is shown that under certain circumstances, large bubbles passing through the core could be detected with this methodology.

  • 852.
    Wolniewicz, Peter
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Hellesen, Carl
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Jacobsson Svärd, Staffan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Jansson, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Håkansson, Ane
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Österlund, Michael
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Detecting neutron spectrum perturbations due to coolant density changes in a small lead-cooled fast nuclear reactor2013Ingår i: Annals of Nuclear Energy, ISSN 0306-4549, E-ISSN 1873-2100, Vol. 58, s. 102-109Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The lead-cooled fast reactor (LFR) is one of the nuclear reactor technologies proposed by the Generation IV International Forum (GIF). The lead coolant allows for inherent safety properties attractive from a nuclear safety point of view, but issues related to corrosion of structural materials and the possible positive coolant reactivity coefficient must be addressed before LFRs can be commercially viable. As an example, a small crack in e.g. a heat exchanger can generate a more or less homogeneous distribution of bubbles in the coolant (void) which if unnoticed, has the potential to cause criticality issues. This fact motivated an investigation of a methodology to detect such voids.

    The suggested methodology is based on measurements of the “slow” and “fast” parts of the neutron spectrum because these parts respond in different ways to voiding. For detection, it is tentatively assumed that fission chambers loaded with U-235 and Pu-239, respectively, are deployed. To investigate the methodology according to sensitivity and precision, a number of scenarios have been simulated and analysed using the core simulator Serpent.

    The results show that the methodology yields a sensitivity of 3% for each per cent unit of void. Assuming typical detection limits of a few per cent this implies the possibility to detect voids down to the order of 1%. From these studies it was also concluded that the positioning of the detectors relative the reactor core is crucial, which may be useful input during the design phase of a reactor in order to achieve an efficient monitoring system.

  • 853.
    Wolniewicz, Peter
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Hellesen, Carl
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Jansson, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Ane, Håkansson
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Jacobsson Svärd, Staffan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Österlund, Michael
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Qvist, Staffan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Reactivity changes in lead-cooled fast reactors due to bubbles in the coolantManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    The formation of bubbles in the coolant of a Lead-Cooled Fast Reactor (LFR) may originate from a leaking heat-exchanger and is a potential safety hazard. Small bubbles can travel with the coolant without escaping to the cover gas, causing an increasing effective voiding of the coolant in a homogeneous manner. If the small bubbles coalesce into a larger bubble located at a stagnation zone, the reactor core may eventually be exposed to a transient bubble travelling axially through the core with a resulting change in the reactivity of the system. This study is focused on the reactivity changes caused by bubbles of various sizes and for different vertical positions as the bubble rises through the core. Three different sizes of LFR’s; 50 MWth, 300 MWth and 1200 MWth,respectively were user for the study. The 300 MWth reactor design is based on the Advanced LFR European Demonstrator (ALFRED) and the two other reactors are scaled up and scaled down versions of it and these were simulated in order study the sensitivity to void as a function of reactor size. We show that LFR’s may have a positive reactivity response to transient bubbles and that the sensitivity to changes in reactivity is larger the smaller the reactor. For sufficiently large bubbles all reactors may reach prompt criticality.

  • 854.
    Wolniewicz, Peter
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Håkansson, Ane
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Jacobsson Svärd, Staffan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Jansson, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Feasibility study of detection of coolant void in metal-cooled fast reactors using changes in the neutron spectrum2011Konferensbidrag (Övrigt vetenskapligt)
  • 855.
    Wolniewicz, Peter
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Håkansson, Ane
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Jansson, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Detection of coolant void in lead-cooled fast reactors2015Ingår i: Annals of Nuclear Energy, ISSN 0306-4549, E-ISSN 1873-2100, Vol. 85, s. 1096-1103Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Previous work (Wolniewicz et al., 2013) has indicated that using fission chambers coated with 242Pu and 235U, respectively, can provide the means of detecting changes in the neutron flux that are connected to coolant density changes in a small lead-cooled fast reactor. Such density changes may be due to leakages of gas into the coolant, which, over time, may coalesce to large bubbles implying a high risk of causing severe damage of the core. By using the ratio of the information provided by the two types of detectors a quantity is obtained that is sensitive to these density changes and, to the first order approximation, independent of the power level of the reactor.

    In this work we continue the investigation of this proposed methodology by applying it to the Advanced LFR European Demonstrator (ALFRED) and using realistic modelling of the neutron detectors. The results show that the methodology may be used to detect density changes indicating the initial stages of a coalescence process that may result in a large bubble. Also, it is shown that under certain circumstances, large bubbles passing through the core could be detected with this methodology.

  • 856.
    Wolniewicz, Peter
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Håkansson, Ane
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Jansson, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Jacobsson Svärd, Staffan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Feasibility study of detection of coolant void in liquid metal cooled fast reactors using changes in the neutron spectrum2013Ingår i: Nuclear Engineering and Design, ISSN 0029-5493, E-ISSN 1872-759X, Vol. 265, s. 1255-1265Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Formation of coolant void can lead to an increase in reactivity in metal-cooled fast reactors. Accordingly, the ability to detect formation of void and similar phenomena is highly relevant in order to counteract transient behaviour of such a reactor. As this work shows, the energy distribution of the neutron flux in a fast reactor is sensitive to formation of void. For monitoring purposes, this fact suggests the use of fission chambers with different isotopic content and thus different fission threshold energies. In such a way the monitoring system may be tailored in order to fit the purpose to obtain spectral information of the neutron flux.

    In this work, simulations have been performed using the Monte-Carlo-based code SERPENT on the ELECTRA reactor design, a 0.5 MWth lead-cooled fast reactor (LFR) planned for in Sweden. The simulations show significant changes in the neutron spectrum due to the formation of void located in specific in-core regions as well as due to a homogeneous core-wide distribution of small bubbles. In an attempt to quantify and to put a number on the spectroscopic changes, the number of neutrons in the high energy region (2–5 MeV) are compared to the number of neutrons in the low-energy region (50–500 keV) and the changes caused by the introduction of void are analyzed. The implications of the findings are discussed.

  • 857.
    Yadykin, Dimitry
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Frassinetti, L.
    Delabie, E.
    Chapman, I. T.
    Gerasimov, S.
    Kempenaars, M.
    Rimini, F. G.
    Studies of the non-axisymmetric plasma boundary displacement in JET in presence of externally applied magnetic field2015Ingår i: Plasma Physics and Controlled Fusion, ISSN 0741-3335, E-ISSN 1361-6587, Vol. 57, nr 10, artikel-id 104003Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Non-axisymmetric plasma boundary displacement is caused by the application of the external magnetic field with low toroidal mode number. Such displacement affects edge stability, power load on the first wall and could affect efficiency of the ICRH coupling in ITER. Studies of the displacement are presented for JET tokamak focusing on the interaction between error field correction coils (EFCCs) and shape control system. First results are shown on the direct measurement of the plasma boundary displacement at different toroidal locations. Both qualitative and quantitative studies of the plasma boundary displacement caused by interaction between EFCCs and shape control system are performed for different toroidal phases of the external field. Axisymmetric plasma boundary displacement caused by the EFCC/shape control system interaction is seen for certain phase values of the external field. The value of axisymmetric plasma boundary displacement caused by interaction can be comparable to the non-axisymmetric plasma boundary displacement value produced by EFCCs.

  • 858. Yamaguchi, T.
    et al.
    Fukuda, M.
    Fukuda, S.
    Fan, G. W.
    Hachiuma, I.
    Kanazawa, M.
    Kitagawa, A.
    Kuboki, T.
    Lantz, Mattias
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Mihara, M.
    Nagashima, M.
    Namihira, K.
    Nishimura, D.
    Okuma, Y.
    Ohtsubo, T.
    Sato, S.
    Suzuki, T.
    Takechi, M.
    Xu, W.
    Energy-dependent charge-changing cross sections and proton distribution of 28Si2010Ingår i: Phys. Rev. C, Vol. 82, s. 014609-1-014609-6Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The charge-changing cross sections (σcc) of 28Si on a carbon target were measured with high precision atintermediate energies from 100 to 600 MeV/nucleon. The measured σcc decreases rapidly from low energies upto 200 MeV/nucleon, whereas at higher energies it appears almost constant. The energy dependence of σcc iscompared with a Glauber-type model calculation where only the proton distribution of 28Si is taken into account.A phenomenological correction factor deduced from the present data satisfactorily reproduces the experimentalσcc for other stable nuclei, whose charge distributions were determined by electron scattering and muon captureexperiments.

  • 859.
    Yeung, Maggie S. Y.
    et al.
    Karolinska Inst, Dept Cell & Mol Biol, Stockholm, Sweden.
    Djelloul, Mehdi
    Karolinska Inst, Dept Cell & Mol Biol, Stockholm, Sweden.
    Steiner, Embla
    Karolinska Inst, Dept Cell & Mol Biol, Stockholm, Sweden.
    Bernard, Samuel
    Univ Lyon, CNRS, UMR 5208, Inst Camille Jordan, Villeurbanne, France.
    Salehpour, Mehran
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Possnert, Göran
    Brundin, Lou
    Karolinska Inst, Karolinska Univ Hosp, Div Neurol, Dept Clin Neurosci, Stockholm, Sweden.
    Frisen, Jonas
    Karolinska Inst, Dept Cell & Mol Biol, Stockholm, Sweden.
    Dynamics of oligodendrocyte generation in multiple sclerosis2019Ingår i: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 566, nr 7745, s. 538-+Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Oligodendrocytes wrap nerve fibres in the central nervous system with layers of specialized cell membrane to form myelin sheaths(1). Myelin is destroyed by the immune system in multiple sclerosis, but myelin is thought to regenerate and neurological function can be recovered. In animal models of demyelinating disease, myelin is regenerated by newly generated oligodendrocytes, and remaining mature oligodendrocytes do not seem to contribute to this process(2-4). Given the major differences in the dynamics of oligodendrocyte generation and adaptive myelination between rodents and humans(5-9), it is not clear how well experimental animal models reflect the situation in multiple sclerosis. Here, by measuring the integration of C-14 derived from nuclear testing in genomic DNA(10), we assess the dynamics of oligodendrocyte generation in patients with multiple sclerosis. The generation of new oligodendrocytes was increased several-fold in normal-appearing white matter in a subset of individuals with very aggressive multiple sclerosis, but not in most subjects with the disease, demonstrating an inherent potential to substantially increase oligodendrocyte generation that fails in most patients. Oligodendrocytes in shadow plaques-thinly myelinated lesions that are thought to represent remyelinated areas-were old in patients with multiple sclerosis. The absence of new oligodendrocytes in shadow plaques suggests that remyelination of lesions occurs transiently or not at all, or that myelin is regenerated by pre-existing, and not new, oligodendrocytes in multiple sclerosis. We report unexpected oligodendrocyte generation dynamics in multiple sclerosis, and this should guide the use of current, and the development of new, therapies.

  • 860.
    Yi, Peng
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära.
    Possnert, Göran
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandemlaboratoriet. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Aldahan, A.
    Hou, X. L.
    Bryhn, A. C.
    He, Peng
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära.
    I-129 in the Baltic Proper and Bothnian Sea: application for estimation of water exchange and environmental impact2013Ingår i: Journal of Environmental Radioactivity, ISSN 0265-931X, E-ISSN 1879-1700, Vol. 120, s. 64-72Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report here new data and a mass balance model for I-129 in the Baltic Proper and the Bothnian Sea covering the period from November-December 2009. The results showed that the general I-129 concentrations in the Bothnian Sea were two-four folds lower than in the Baltic Proper for both surface and deep water. Water exchange between the two basins based on the I-129 mass balance model suggests fluxes from the Baltic Proper to the Bothnian Sea and vice versa at 980 km(3)/y (600-1400 km(3)/y) and 1180 km(3)/y (780-1600 km(3)/y) respectively. Water retention time (residence time) in the Bothnian Sea was estimated at up to 4 years. Applying the I-129 exchange model, an estimate of total phosphorus and nitrogen inflow from the Baltic Proper to the Bothnian Sea indicates values of 20 +/- 7 x 10(3) tons/y and 300 +/- 50 x 10(3) tons/y respectively. The values for the outflow from the Bothnian Sea to the Baltic Proper hold 12 +/- 3 x 10(3) tons/y for total phosphorus and 283 +/- 55 x 10(3) tons/y for total nitrogen. These data and application of I-129 as a tracer of water masses provide information on small scale salinity changes which are vital for accurate understanding of the Baltic Sea ecosystems evolution through time.

  • 861.
    You, Chang Chuan
    et al.
    Inst Energy Technol, Dept Solar Energy, NO-2027 Kjeller, Norway..
    Moldarev, Dmitrii
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi. Moscow Engn Phys Inst, Dept Mat Sci, Moscow 115409, Russia..
    Mongstad, Trygve
    Inst Energy Technol, Dept Solar Energy, NO-2027 Kjeller, Norway..
    Primetzhofer, Daniel
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Wolff, Max
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialfysik.
    Stensrud Marstein, Erik
    Inst Energy Technol, Dept Solar Energy, NO-2027 Kjeller, Norway..
    Karazhanov, Smagul Zh.
    Inst Energy Technol, Dept Solar Energy, NO-2027 Kjeller, Norway..
    Enhanced photochromic response in oxygen-containing yttrium hydride thin films transformed by an oxidation process2017Ingår i: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 166, s. 185-189Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Photochromic oxygen-containing yttrium hydride (YHO) thin films with switchable optical properties have recently emerged as a promising material for the utilization in smart windows and sensor applications. In the present study, we have prepared YHO thin films with a lateral gradient of oxygen and hydrogen concentrations, which allows us to systematically investigate the effect of changes in chemical composition on their optical properties. We show that when the average lateral oxygen content exceeded a threshold level at a certain location in the as-deposited film, its appearance was abruptly changed from black opaque to yellow transparent, in which only yellow YHO exhibited photochromism. Moreover, we show that a small region (typically 510 mm lateral size) in the black opaque part of the as-deposited film, located adjacent to the yellow transparent part of the film, was observed to transform permanently to yellow transparent upon exposure to oxygen in air in the dark for several weeks. The black to yellow color transformation was caused by an increase in the oxygen concentration, originating from the oxidation process. Optical characterization revealed pronounced photo chromic response in the transformed region as compared to the rest of the yellow film. This finding demonstrates that the switchable optical properties can be tailored by changing the chemical composition of YHO films.

  • 862.
    Zackrisson, Magnus
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Zackrisson, Christian
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    System 348 - Rekombinator: Analys av reglerproblematik vid O22014Självständigt arbete på grundnivå (yrkesexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    In this project the focus has been on the system for recombination at Oskarshamn 2. The recombining systems have on several occasions switched paths due to low pressure before the last ejector that’s feeding the recombiner. Of the mentioned reason, events and several measuring points have been analyzed in this report since the installation of the recombining systems.

    In order to prove theories and demonstrate what may be the cause of this problem, we used heat balance calculations by the program Probera. Using the program, we can demonstrate that the catalytic process does not reach the desired temperature with the amount of combustible substance. We have used Oskarshamn 2's simulator to see what happens at increased concentration of hydrogen in the recombiner.

    The project demonstrates how the controlsystem can be changed for a greater margin to switching paths and thus should provide a more stable process. Analysis shows that setpoint have been reached extremely rarely. Even regulator gain and integration time proved to be incorrect when the system falls intoself-oscillation.

  • 863.
    Zhou, Y.
    et al.
    Royal Inst Technol, Sch Elect Engn, Dept Fus Plasma Phys, S-10405 Stockholm, Sweden..
    Bergsaker, H.
    Royal Inst Technol, Sch Elect Engn, Dept Fus Plasma Phys, S-10405 Stockholm, Sweden..
    Bykov, I.
    Royal Inst Technol, Sch Elect Engn, Dept Fus Plasma Phys, S-10405 Stockholm, Sweden..
    Petersson, P.
    Royal Inst Technol, Sch Elect Engn, Dept Fus Plasma Phys, S-10405 Stockholm, Sweden..
    Possnert, Göran
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandemlaboratoriet. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Likonen, J.
    VTT Tech Res Ctr Finland, POB 1000, FIN-02044 Espoo, Finland..
    Pettersson, Jean
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Analytisk kemi. Culham Sci Ctr, CCFE, Abingdon OX14 3DB, Oxon, England..
    Koivuranta, S.
    VTT Tech Res Ctr Finland, POB 1000, FIN-02044 Espoo, Finland..
    Widdowson, A. M.
    Proceedings 25th IAEA Fus Energy Conf 2014, St Petersburg, Russia..
    Microanalysis of deposited layers in the inner divertor of JET with ITER-like wall2017Ingår i: NUCLEAR MATERIALS AND ENERGY, ISSN 2352-1791, Vol. 12, nr SI, s. 412-417Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In JET with ITER-like wall, beryllium eroded in the main chamber is transported to the divertor and deposited mainly at the horizontal surfaces of tiles 1 and 0 (high field gap closure, HFGC). These surfaces are tungsten coated carbon fibre composite (CFC). Surface sampleswere collected following the plasma operations in 2011-2012 and 2013-2014 respectively. The surfaces, as well as polished cross sections of the deposited layers at the surfaces have been studied with micro ion beam analysis methods (mu-IBA). Deposition of Beand other impurities, and retention of D is microscopically inhomogeneous. Impurities and trapped deuterium accumulate preferentially in cracks, pits and depressed regions, and at the sides of large pits in the substrate (e.g. arc tracks where the W coating has been removed). With careful overlaying of mu-NRA elemental maps with optical microscopy images, it is possible to separate surface roughness effects from depth profiles at microscopically flat surface regions.

  • 864.
    Zhou, Y.
    et al.
    Royal Inst Technol, Sch Elect Engn, Dept Fus Plasma Phys, S-10405 Stockholm, Sweden.
    Bergsåker, H.
    Royal Inst Technol, Sch Elect Engn, Dept Fus Plasma Phys, S-10405 Stockholm, Sweden.
    Bykov, I.
    Univ Calif San Diego, Energy Res Ctr, La Jolla, CA 92093 USA.
    Petersson, P.
    Royal Inst Technol, Sch Elect Engn, Dept Fus Plasma Phys, S-10405 Stockholm, Sweden.
    Paneta, Valentina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Possnert, Göran
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Romanelli, F.
    Micro ion beam analysis for the erosion of beryllium marker tiles in a tokamak limiter2019Ingår i: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 450, s. 200-204Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Beryllium limiter marker tiles were exposed to plasma in the Joint European Torus to diagnose the erosion of main chamber wall materials. A limiter marker tile consists of a beryllium coating layer (7-9 mu m) on the top of bulk beryllium, with a nickel interlayer (2-3 mu m) between them. The thickness variation of the beryllium coating layer, after exposure to plasma, could indicate the erosion measured by ion beam analysis with backscattering spectrometry. However, interpretations from broad beam backscattering spectra were limited by the non-uniform surface structures. Therefore, micro-ion beam analysis (mu-IBA) with 3 MeV proton beam for Elastic back scattering spectrometry (EBS) and PIXE was used to scan samples. The spot size was in the range of 3-10 mu m. Scanned areas were analysed with scanning electron microscopy (SEM) as well. Combining results from mu-IBA and SEM, we obtained local spectra from carefully chosen areas on which the surface structures were relatively uniform. Local spectra suggested that the scanned area (approximate to 600 mu m x 1200 mu m) contained regions with serious erosion with only 2-3 mu m coating beryllium left, regions with intact marker tile, and droplets with 90% beryllium. The nonuniform erosion, droplets mainly formed by beryllium, and the possible mixture of beryllium and nickel were the major reasons that confused interpretation from broad beam EBS.

  • 865.
    Zoller, C. J.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Litta, E. Dentoni
    Primetzhofer, Daniel
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Characterization of high-k dielectrics using MeV elastic scattering of He ions2015Ingår i: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 347, s. 52-57Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present a systematic comparison of two distinct ion-beam based methods for composition analysis of nanometer oxide films: ion-beam channeling and elastic scattering using nuclear resonances, both at MeV energies. Thin films of the technologically highly relevant high-k dielectrics HfO2 and HfAIO are characterized in the present study, with the additional aim of obtaining a better quantification of the Al content for the latter system. We show that both employed ion scattering methods enable a quantitative determination of the oxygen concentrations with typical uncertainties of about 5-10% in the oxygen fraction. The influence of various kinds of systematic inaccuracies in the evaluation procedure are discussed. 

  • 866.
    Zsolt, Elter
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Mishra, Vaibhav
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Grape, Sophie
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Branger, Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Jansson, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Caldeira Balkeståhl, Li
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Investigating the gamma and neutron radiation around quivers for verification purposes2019Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Before encapsulation of spent nuclear fuel in a geological repository, the fuels need to be verified fors afeguards purposes. This requirement applies to all spent fuel assemblies, including those with properties or designs that are especially challenging to verify. One such example are quivers, a new type of containers used to hold damaged spent fuel rods. After placing damaged rods inside the quivers, they are sealed with a thick lid and the water is removed. The lid is thick enough to significantly reduce the amount of the gamma radiation penetrating through it, which can make safeguards verification from the top using gamma techniques difficult.

    In this paper we make a first feasibility study related to safeguards verification of quivers, aimed at investigating the gamma and neutron radiation field around a quiver using a simplified quiver geometry. The nuclide inventory of the rods placed in the quiver is calculated with Serpent and Origen-Arp, and the radiation transport is modeled with Serpent. The objective is to assess the capability of existing non-destructive assay instruments, measuring the gamma and/or neutron radiation from the object, to verify the content for nuclear safeguards purposes. The results show that the thick quiver lid attenuates the gamma radiation, thereby making gamma-radiation based verification from above the quiver difficult. Verification using neutron instruments above the quiver, or gamma and/or neutron instruments on the side may be possible. These results are in agreement with measurements of a BWR quiver using a DCVD, performed by the authors.

  • 867.
    Zuwak, Tariq Zuwak
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Calculation method based on CASMO/SIMULATE for isotopic concentrations of fuel samples irradiated in Ringhals PWR2012Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    This is a M. Eng. degree project at Uppsala University carried out at Vattenfall NuclearFuel AB. The goal of it is to present a best estimate method based on the code package CASMO/SIMULATE for the purpose of calculating the isotopic concentrations of a specified number of isotopes in a fuel sample. The calculations done with the method shall produce small deviations from reliable measured values, which characterize the accuracy of CASMO/SIMULATE, but also simplicity based onthe computing time and handling of the amount of data is an important factor in the development of the method.

    The development of the method has been based on a sensitivity calculation with CASMO/SIMULATE on a number of relevant parameters affecting the isotope concentrations. The proposed method has then been applied on three samples irradiated in Ringhals 4 and Ringhals 3. At last the calculated isotopic concentrations have been benchmarked against measured data from Studsvik Laboratory.

    The sensitivity analyzes has shown that the parameters affecting the neutron moderation are very important for calculating the isotopic concentrations. The core axial resolution is also an important factor for the samples taken from top of the rod,where the power gradient is large. The comparison of the calculated and measured values has shown that SIMULATE, in the analysed cases, simulates a lower finalburnup. This has created a need to correct the final burnup in order to get better results in terms of lower relative deviations between the measured and calculated data.

  • 868.
    Åberg Lindell, Matilda
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Nuclear safeguards evaluation and analysis techniques for application to nuclear fuel material in Generation IV nuclear energy systems2018Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    A new generation of nuclear energy systems called Generation IV is under development to ensure that nuclear power will be a safe, reliable and sustainable energy source for the future. This thesis addresses the challenge of making future nuclear energy systems increasingly resistant to nuclear material diversion attempts.

    Several tools have been developed for structured evaluation of a system's resistance to nuclear proliferation, in order to identify areas where nuclear energy systems are the most inherently vulnerable. In this thesis, the TOPS methodology has been applied to three different fuel cycles involving a fast reactor with fuel recycling and fuel fabrication capabilities. The recycling facility, where the fuel is dissolved and undergoes chemical separation, is identified as being particularly vulnerable. Nondestructive measurements for verification of fuel assemblies in the receipt area of the recycling facility are essential, since it is the last opportunity to verify intact fuel items. Moreover, iterative evaluation of proliferation resistance by using two different assessment methodologies – TOPS and PR&PP – as suggested in this thesis, may act as an aid in facility design and for proposing safeguards implementation.

    Based on the identified need to measure irradiated fuel assemblies prior to dissolution in the recycling facility, new methods used for analyzing gamma-ray spectroscopy data using multivariate analysis methods have been investigated. Fuel parameters of modeled nuclear fuel have been determined without any reliance on operator-declared data. Nonlinear classifiers, e.g. support vector machines (SVM), have successfully been used for discrimination between uranium oxide fuels and mixed oxide fuels. Cooling time, burnup and initial fissile content have been determined using decision tree and SVM regression. The results are promising and indicate that the nuclear safeguards regime may benefit from using multivariate techniques for data analysis. It must be emphasized, however, that experimental verification of the multivariate analysis techniques is necessary.

  • 869.
    Åberg Lindell, Matilda
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Proliferation resistances of Generation IV recycling facilities for nuclear fuel2013Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The effects of global warming raise demands for reduced CO2 emissions, whereas at the same time the world’s need for energy increases. With the aim to resolve some of the difficulties facing today’s nuclear power, striving for safety, sustainability and waste minimization, a new generation of nuclear energy systems is being pursued: Generation IV.

    New reactor concepts and new nuclear facilities should be at least as resistant to diversion of nuclear material for weapons production, as were the previous ones. However, the emerging generation of nuclear power will give rise to new challenges to the international safeguards community, due to new and increased flows of nuclear material in the nuclear fuel cycle. Before a wide implementation of Generation IV nuclear power facilities takes place, there lies still an opportunity to formulate safeguards requirements for the next generation of nuclear energy systems. In this context, this thesis constitutes one contribution to the global efforts to make future nuclear energy systems increasingly resistant to nuclear material diversion attempts.

    This thesis comprises three papers, all of which concern safeguards and proliferation resistance in Generation IV nuclear energy systems and especially recycling facilities:

    In Paper I, proliferation resistances of three fuel cycles, comprising different reprocessing techniques, are investigated. The results highlight the importance of making group actinide extraction techniques commercial, due to the inherently less vulnerable isotopic and radiological properties of the materials in such processes.

    Paper II covers the schematic design and safeguards instrumentation of a Generation IV recycling facility. The identification of the safeguards needs of planned facilities can act as a guide towards the development of new instrumentation suitable for Generation IV nuclear energy systems.

    Finally, Paper III describes a mode of procedure for assessing proliferation resistance of a recycling facility for fast reactor fuel. The assessments may be used, as in this case, as an aid to maintain or increase the inherent proliferation resistance when performing facility design changes and upgrades.

  • 870.
    Åberg Lindell, Matilda
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Andersson, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Grape, Sophie
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Hellesen, Carl
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Håkansson, Ane
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Eriksson, Måns
    Uppsala universitet, Humanistisk-samhällsvetenskapliga vetenskapsområdet, Samhällsvetenskapliga fakulteten, Statistiska institutionen.
    Discrimination of irradiated MOX fuel from UOX fuel by multivariate statistical analysis of simulated activities of gamma-emitting isotopes2018Ingår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 885, s. 67-78Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper investigates how concentrations of certain fission products and their related gamma-ray emissions can be used to discriminate between uranium oxide (UOX) and mixed oxide (MOX) type fuel. Discrimination of irradiated MOX fuel from irradiated UOX fuel is important in nuclear facilities and for transport of nuclear fuel, for purposes of both criticality safety and nuclear safeguards. Although facility operators keep records on the identity and properties of each fuel, tools for nuclear safeguards inspectors that enable independent verification of the fuel are critical in the recovery of continuity of knowledge, should it be lost. A discrimination methodology for classification of UOX and MOX fuel, based on passive gamma-ray spectroscopy data and multivariate analysis methods, is presented. Nuclear fuels and their gamma-ray emissions were simulated in the Monte Carlo code Serpent, and the resulting data was used as input to train seven different multivariate classification techniques. The trained classifiers were subsequently implemented and evaluated with respect to their capabilities to correctly predict the classes of unknown fuel items. The best results concerning successful discrimination of UOX and MOX-fuel were acquired when using non-linear classification techniques, such as the k nearest neighbors method and the Gaussian kernel support vector machine. For fuel with cooling times up to 20 years, when it is considered that gamma-rays from the isotope  134Cs can still be efficiently measured, success rates of 100% were obtained. A sensitivity analysis indicated that these methods were also robust.

  • 871.
    Åberg Lindell, Matilda
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Andersson, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Grape, Sophie
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Håkansson, Ane
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Eriksson, Måns
    Uppsala universitet, Humanistisk-samhällsvetenskapliga vetenskapsområdet, Samhällsvetenskapliga fakulteten, Statistiska institutionen.
    Estimating irradiated nuclear fuel characteristics by nonlinear multivariate regression of simulated gamma-ray emissions2018Ingår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 897, s. 85-91Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In addition to verifying operator declared parameters of spent nuclear fuel, the ability to experimentally infer such parameters with a minimum of intrusiveness is of great interest and has been long-sought after in the nuclear safeguards community. It can also be anticipated that such ability would be of interest for quality assurance in e.g. recycling facilities in future Generation IV nuclear fuel cycles. One way to obtain information regarding spent nuclear fuel is to measure various gamma-ray intensities using high-resolution gamma-ray spectroscopy. While intensities from a few isotopes obtained from such measurements have traditionally been used pairwise, the approach in this work is to simultaneously analyze correlations between all available isotopes, using multivariate analysis techniques. Based on this approach, a methodology for inferring burnup, cooling time, and initial fissile content of PWR fuels using passive gamma-ray spectroscopy data has been investigated. PWR nuclear fuels, of UOX and MOX type, and their gamma-ray emissions, were simulated using the Monte Carlo code Serpent. Data comprising relative isotope activities was analyzed with decision trees and support vector machines, for predicting fuel parameters and their associated uncertainties. From this work it may be concluded that up to a cooling time of twenty years, the 95% prediction intervals of burnup, cooling time and initial fissile content could be inferred to within approximately 7 MWd/kgHM, 8 months, and 1.4 percentage points, respectively. An attempt aiming to estimate the plutonium content in spent UOX fuel, using the developed multivariate analysis model, is also presented. The results for Pu mass estimation are promising and call for further studies.

  • 872.
    Åberg Lindell, Matilda
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Andersson, Peter
    Grape, Sophie
    Håkansson, Ane
    Thulin, Måns
    Determination of irradiated nuclear fuel characteristics by nonlinear multivariate regression of simulated gamma-ray emissions2017Ingår i: Artikel i tidskrift (Refereegranskat)
  • 873.
    Åberg Lindell, Matilda
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Grape, Sophie
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Håkansson, Ane
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Jacobsson Svärd, Staffan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Assessment of proliferation resistances of aqueous reprocessing techniques using the TOPS methodology2013Ingår i: Annals of Nuclear Energy, ISSN 0306-4549, E-ISSN 1873-2100, Vol. 62, s. 390-397Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The aim of this study is to assess and compare the proliferation resistances (PR) of three possible Generation IV lead-cooled fast reactor fuel cycles, involving the reprocessing techniques Purex, Ganex and a combination of Purex, Diamex and Sanex, respectively. The examined fuel cycle stages are reactor operation, reprocessing and fuel fabrication. The TOPS methodology has been chosen for the PR assessment, and the only threat studied is the case where a technically advanced state diverts nuclear material covertly.

    According to the TOPS methodology, the facilities have been divided into segments, here roughly representing the different forms of nuclear material occurring in each examined fuel cycle stage. For each segment, various proliferation barriers have been assessed.

    The results make it possible to pinpoint where the facilities can be improved. The results show that the proliferation resistance of a fuel cycle involving recycling of minor actinides is higher than for the traditional Purex reprocessing cycle. Furthermore, for the purpose of nuclear safeguards, group actinide extraction should be preferred over reprocessing options where pure plutonium streams occur. This is due to the fact that a solution containing minor actinides is less attractive to a proliferator than a pure Pu solution. Thus, the safeguards analysis speaks in favor of Ganex as opposed to the Purex process.

  • 874.
    Åberg Lindell, Matilda
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Grape, Sophie
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Håkansson, Ane
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Jacobsson Svärd, Staffan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Proliferation resistance assessments during the design phase of a fuel recycling facility as a means of reducing proliferation risks2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    The sustainability criterion for Gen IV nuclear energy systems inherently presumes the availability of efficient fuel recycling capabilities. One area for research on advanced fuel recycling concerns safeguards aspects of this type of facilities. Since a recycling facility may be considered as sensitive from a non-proliferation perspective, it is important to address these issues early in the design process, according to the principle of Safeguards By Design.

    Presented in this paper is a mode of procedure, where assessments of the proliferation resistance (PR) of a recycling facility for fast reactor fuel have been performed so as to identify the weakest barriers to proliferation of nuclear material. Two supplementing established methodologies have been applied; TOPS and PR&PP. The chosen fuel recycling facility belongs to a small Gen IV lead-cooled fast reactor system that is under study in Sweden. A schematic design of the recycling facility, where actinides are separated using solvent extraction, has been examined.

    The PR assessment methodologies make it possible to pinpoint areas in which the facility can be improved in order to reduce the risk of diversion. The initial facility design may then be slightly modified and/or safeguards measures may be introduced to reduce the total identified proliferation risk. After each modification of design and/or safeguards implementation, a new PR assessment of the revised system can been carried out. This way, each modification can be evaluated and new ways to further enhance the proliferation resistance can be identified.

    This type of iterative procedure may support Safeguards By Design in the planning of new recycling plants and other nuclear facilities.

  • 875.
    Åberg Lindell, Matilda
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Grape, Sophie
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Håkansson, Ane
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Jacobsson Svärd, Staffan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Safeguards Licensing Aspects of a Future Gen IV Test Facility: A Case Study2010Konferensbidrag (Övrigt vetenskapligt)
  • 876.
    Åberg Lindell, Matilda
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Grape, Sophie
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Håkansson, Ane
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Jacobsson Svärd, Staffan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Schematic design and safeguards instrumentation of a Gen IV fuel recycling facility.2013Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    The sustainability criterion for Gen IV systems, inherently presumes the availability of efficient fuel recycling capabilities. Research activities concerning advanced fuel recycling are currently pursued, and one area for such research concerns safeguards aspects of recycling facilities. Since a recycling facility may be considered as sensitive from a non-proliferation perspective, it is important to address these issues early in the design process, according to the principle of Safeguards By Design.

    Presented in this paper is a suggested safeguards approach for a fuel recycling facility belonging to a small Gen IV lead-cooled fast reactor system that is under study in Sweden. A schematic design of a small-scale recycling facility, where actinides are separated using group actinide solvent extraction, is put forward. Measurement points are suggested based on available information on the recycling process activities and calculated material flows.

    Based on the identified need for measurements in the facility, possible techniques and instrumentation for measurements have been identified with the purpose to provide both inspecting parties and facility operators with necessary information for their respective needs. More generally, this type of analysis may be used to support Safeguards By Design in the planning of new recycling facilities.

  • 877. Öhrn, A.
    et al.
    Gustavsson, Cecilia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Blann, M.
    Blideanu, V.
    Blomgren, Jan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Chiba, S.
    Duarte, H.
    Haddad, F.
    Kalbach, C.
    Klug, J.
    Koning, A.
    Le Brun, C.
    Lebrun, C.
    Lecolley, F. R.
    Ledoux, X.
    Marie-Noury, N.
    Mermod, P.
    Nilsson, L.
    Österlund, Michael
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Pomp, Stephan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Prokofiev, Alexander V.
    Uppsala universitet, The Svedberg-laboratoriet.
    Tippawan, U.
    Watanabe, Y.
    Measurements of Inelastic Neutron Scattering at 96 MeV from Carbon, Iron, Yttrium and Lead2011Ingår i: Journal of the Korean Physical Society, ISSN 0374-4884, E-ISSN 1976-8524, Vol. 59, nr 2, s. 1817-1820Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Inelastic neutron scattering for (12)C, (58)Fe, (89)Y and (208)Pb have been measured at 96 MeV at the The Svedberg Laboratory in Uppsala and double-differential cross sections are reported. Data cover an excitation energy range of 0-45 MeV and the angular intervals are 28 - 58 degrees for (12)C, 26 - 65 degrees for (58)Fe and 26 - 52 degrees for (89)Y and (208)Pb. In this experiment, neutron detection is based on conversion to protons in an active scintillator converter. An analysis technique in which the neutron spectra have been obtained through a folding procedure using the response of the detector system has been used. The results are compared to and are in reasonable agreement with several model predictions and with inelastic neutron scattering data at 65 MeV from University of California, Davis, USA.

  • 878.
    Östangård, Louise
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Reactivity Analysis of Nuclear Fuel Storages: The Effect of 238U Nuclear Data Uncertainties2013Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Nukleära databibliotek innehåller all nödvändig information för att till exempel kunna simulera en reaktor eller en bränslebassäng för kärnbränsle. Dessa bibliotek är centrala vid beräkningar av olika reaktorparametrar som krävs för en säker kärnkraftsproduktion. En viktig reaktorparameter är multiplikationskonstanten (keff) som anger reaktiviteten för ett system. Ett kritiskt system (keff = 1) innebär att en kedjereaktion av kärnklyvningar kan upprätthållas. Detta tillstånd erfordras i en reaktor för att möjliggöra elproduktion. I en bränslebassäng där använt kärnbränsle förvaras är det viktigt att systemet är underkritiskt (keff < 1). Olika reaktorkoder används för att utföra dessa beräkningar av keff, vars resultat används i processen för att designa säkra bränsleförråd för kärnbränsle.

    Dagens nukleära databibliotek innehåller osäkerheter som i sin tur beror på osäkerheter i de modellparametrar som används vid framställningen av biblioteken.  Ofta är dessa nukleära data osäkerheter okända, vilket ger upphov till okända osäkerheter vid beräkning av keff.

    Vattenfall Nuclear Fuel AB undersöker idag möjligheten att öka anrikningen på bränslet för att minska antalet behövda bränsleknippen för en viss energimängd.  Varje bränsleknippe blir då mer reaktiv och i och med det minskar marginalen till kriticitet i bränslebassängen. Därmed är osäkerheterna för nukleära data viktiga i processen för att kunna beräkna den maximalt tillåtna anrikningen för bränslet. För att undersöka hur stora dessa osäkerheter är, användes en relativ ny metod TMC (Total Monte Carlo) som propagerar osäkerheter i nukleära data till olika reaktorparametrar (t.ex. keff) i en enda simuleringsprocess. 

    TMC metoden användes för att undersöka hur osäkerheterna i nukleära data för 238U påverkar beräkningar av keff för en bränslebassäng med använt kärnbränsle. Beräkningar utfördes för en bränslebassäng under normala driftförhållanden samt för en olyckshändelse då optimal moderering förekommer. Resultaten visade på att standardavvikelsen för nukleära data för 238U var 209 pcm vid normala driftförhållanden och 672 pcm för fallet med optimal moderering.

    Den ursprungliga TMC metoden är en tidskrävande metod och nyligen har en snabbare variant av TMC utvecklats. Denna nya metod applicerades också på bränslebassängen under normala driftförhållanden och resultaten jämfördes. Resultaten visade att båda metoderna beräknade samma nukleära dataosäkerhet för 238U och genom att använda den snabba TMC metoden, minskade beräkningstiden betydligt jämfört med att använda den ursprungliga TMC metoden.

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