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  • 301.
    Hans, Marcus
    et al.
    Rhein Westfal TH Aachen, Mat Chem, Aachen, Germany.
    Patterer, Lena
    Rhein Westfal TH Aachen, Mat Chem, Aachen, Germany.
    Music, Denis
    Rhein Westfal TH Aachen, Mat Chem, Aachen, Germany.
    Holzapfel, Damian M.
    Rhein Westfal TH Aachen, Mat Chem, Aachen, Germany.
    Evertz, Simon
    Rhein Westfal TH Aachen, Mat Chem, Aachen, Germany.
    Schnabel, Volker
    Rhein Westfal TH Aachen, Mat Chem, Aachen, Germany.
    Stelzer, Bastian
    Rhein Westfal TH Aachen, Mat Chem, Aachen, Germany.
    Primetzhofer, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Voelker, Bernhard
    Rhein Westfal TH Aachen, Mat Chem, Aachen, Germany; Max Planck Inst Eisenforsch GmbH, Dusseldorf, Germany.
    Widrig, Beno
    Oerlikon Surface Solut AG, Oerlikon Balzers, Balzers, Liechtenstein.
    Eriksson, Anders O.
    Oerlikon Surface Solut AG, Oerlikon Balzers, Balzers, Liechtenstein.
    Ramm, Juergen
    Oerlikon Surface Solut AG, Oerlikon Balzers, Balzers, Liechtenstein.
    Arndt, Mirjam
    Oerlikon Surface Solut AG, Oerlikon Balzers, Balzers, Liechtenstein.
    Rudigier, Helmut
    Oerlikon Surface Solut AG, Oerlikon Balzers, Pfaffikon, Switzerland.
    Schneider, Jochen M.
    Rhein Westfal TH Aachen, Mat Chem, Aachen, Germany.
    Stress-Dependent Elasticity of TiAlN Coatings2019In: Coatings, ISSN 2079-6412, Vol. 9, no 1, article id 24Article in journal (Refereed)
    Abstract [en]

    We investigate the effect of continuous vs. periodically interrupted plasma exposure during cathodic arc evaporation on the elastic modulus as well as the residual stress state of metastable cubic TiAlN coatings. Nanoindentation reveals that the elastic modulus of TiAlN grown at floating potential with continuous plasma exposure is 7%-11% larger than for coatings grown with periodically interrupted plasma exposure due to substrate rotation. In combination with X-ray stress analysis, it is evident that the elastic modulus is governed by the residual stress state. The experimental dependence of the elastic modulus on the stress state is in excellent agreement with ab initio predictions. The macroparticle surface coverage exhibits a strong angular dependence as both density and size of incorporated macroparticles are significantly lower during continuous plasma exposure. Scanning transmission electron microscopy in combination with energy dispersive X-ray spectroscopy reveals the formation of underdense boundary regions between the matrix and TiN-rich macroparticles. The estimated porosity is on the order of 1% and a porosity-induced elastic modulus reduction of 5%-9% may be expected based on effective medium theory. It appears reasonable to assume that these underdense boundary regions enable stress relaxation causing the experimentally determined reduction in elastic modulus as the population of macroparticles is increased.

  • 302.
    Hareland, Mathias
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    CONQUER CORROSION: Key issues of the lead-cooled fast reactor design2011Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The lead-cooled fast reactor (LFR) is one of the concepts of the Generation IV reactorsystems. There are some issues that have to be solved before a research orcommercial LFR can be built. The objective of this thesis was to identify these keyissues and analyse them by studying results from previous research: choice of fuel,corrosion on structural materials and corrosion/erosion on pumps.The major fuel candidates for the LFR are MOX fuel (Mixed OXide fuel), metallic fuel,nitride fuel and carbide fuel. Nitride fuel has desirable properties but its production ismore difficult than for MOX fuel.Most of today’s commercial steels are not corrosion resistant at higher temperaturesbut they could possibly be used for an LFR test demonstrator with an operatingtemperature lower than 450 ºC. A new type of steel called oxide dispersionstrengthened (ODS) steel and a new ceramic material MAXTHAL both showpromising corrosion resistance even at higher temperatures.By controlling the oxygen concentration a protective oxide film is produced. Flowingliquid coolant causes erosion and wears down the oxide film. Pumps are exposed tocoolant velocities of 10-15 m/s causing both erosion and corrosion. There is nosolution today, but MAXTHAL shows promising results in tests with liquid lead of lowvelocity. There are also other issues unsolved, such as irradiation damage onstructural materials, thus more research is needed.Economic and political aspects were not covered in this study. This thesis work wasperformed at Vattenfall Research and Development AB.

  • 303.
    Harrison, J. R.
    et al.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Akers, R. J.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Allan, S. Y.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Allcock, J. S.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England;Univ Durham, Ctr Adv Instrumentat, South Rd, Durham DH1 3LE, England.
    Allen, J. O.
    Univ York, York Plasma Inst, Dept Phys, York YO10 5DD, N Yorkshire, England.
    Appel, L.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Barnes, M.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England;Univ Oxford, Rudolf Peierls Ctr Theoret Phys, Oxford OX1 3PU, England;Plasma Sci & Fus Ctr, 167 Albany St, Cambridge, MA 02139 USA.
    Ben Ayedl, N.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Boeglin, W.
    Florida Int Univ, Dept Phys, 11200 SW, Miami, FL 33199 USA.
    Bowman, C.
    Univ York, York Plasma Inst, Dept Phys, York YO10 5DD, N Yorkshire, England.
    Bradley, J.
    Univ Liverpool, Dept Elect Engn & Elect, Brownlow Hill, Liverpool L69 3GJ, Merseyside, England.
    Browning, P.
    Univ Manchester, Sch Phys & Astron, Oxford Rd, Manchester M13 9PL, Lancs, England.
    Bryant, P.
    Univ Liverpool, Dept Elect Engn & Elect, Brownlow Hill, Liverpool L69 3GJ, Merseyside, England.
    Carr, M.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Cecconello, Marco
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Challis, C. D.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Chapman, S.
    Univ Warwick, Ctr Fus Space & Astrophys, Dept Phys, Coventry CV4 7AL, W Midlands, England.
    Chapman, I. T.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Colyer, G. J.
    Univ Oxford, Rudolf Peierls Ctr Theoret Phys, Oxford OX1 3PU, England;Univ Exeter, Engn Math & Phys Sci, Exeter EX4 4QF, Devon, England.
    Conroy, Sean
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Conway, N. J.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Cox, M.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Cunningham, G.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Dendy, R. O.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England;Univ Warwick, Ctr Fus Space & Astrophys, Dept Phys, Coventry CV4 7AL, W Midlands, England.
    Dorland, W.
    Univ Oxford, Rudolf Peierls Ctr Theoret Phys, Oxford OX1 3PU, England;Univ Maryland, Dept Phys, College Pk, MD 20742 USA.
    Dudson, B. D.
    Univ York, York Plasma Inst, Dept Phys, York YO10 5DD, N Yorkshire, England.
    Easy, L.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England;Univ York, York Plasma Inst, Dept Phys, York YO10 5DD, N Yorkshire, England.
    Elmore, S. D.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Farley, T.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England;Univ Liverpool, Dept Elect Engn & Elect, Brownlow Hill, Liverpool L69 3GJ, Merseyside, England.
    Feng, X.
    Univ Durham, Ctr Adv Instrumentat, South Rd, Durham DH1 3LE, England.
    Field, A. R.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Fil, A.
    Univ York, York Plasma Inst, Dept Phys, York YO10 5DD, N Yorkshire, England.
    Fishpool, G. M.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Fitzgerald, M.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Flesch, K.
    Univ Wisconsin, Madison, WI USA.
    Fox, M. F. J.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England;Univ Oxford, Rudolf Peierls Ctr Theoret Phys, Oxford OX1 3PU, England;Univ Oxford Merton Coll, Oxford OX1 4JD, England.
    Frerichs, H.
    Univ Wisconsin, Madison, WI USA.
    Gadgil, S.
    Univ Warwick, Ctr Fus Space & Astrophys, Dept Phys, Coventry CV4 7AL, W Midlands, England.
    Gahle, D.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England;Univ Strathclyde, Dept Phys SUPA, Glasgow G4 ONG, Lanark, Scotland.
    Garzotti, L.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Ghim, Y-C
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England;Univ Oxford, Rudolf Peierls Ctr Theoret Phys, Oxford OX1 3PU, England;Korea Adv Inst Sci & Technol, Dept Nucl & Quantum Engn, Daejeon 34141, South Korea.
    Gibson, S.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England;Univ Durham, Ctr Adv Instrumentat, South Rd, Durham DH1 3LE, England.
    Gibson, K. J.
    Univ York, York Plasma Inst, Dept Phys, York YO10 5DD, N Yorkshire, England.
    Hall, S.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Ham, C.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Heiberg, N.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Henderson, S. S.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Highcock, E.
    Univ Oxford, Rudolf Peierls Ctr Theoret Phys, Oxford OX1 3PU, England;Chalmers Univ Technol, Dept Phys, SE-41296 Gothenburg, Sweden.
    Hnat, B.
    Univ Warwick, Ctr Fus Space & Astrophys, Dept Phys, Coventry CV4 7AL, W Midlands, England.
    Howard, J.
    Australian Natl Univ, Plasma Res Lab, Canberra, ACT 0200, Australia.
    Huang, J.
    Chinese Acad Sci, Inst Plasma Phys, PO 1126, Hefei 230031, Anhui, Peoples R China.
    Irvine, S. W. A.
    Univ Warwick, Ctr Fus Space & Astrophys, Dept Phys, Coventry CV4 7AL, W Midlands, England.
    Jacobsen, A. S.
    Max Planck Inst Plasma Phys, Garching, Germany.
    Jones, O.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England;Univ Durham, Ctr Adv Instrumentat, South Rd, Durham DH1 3LE, England.
    Katramados, I
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Keeling, D.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Kirk, A.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Klimek, Iwona
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Kogan, L.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Leland, J.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England;Univ Liverpool, Dept Elect Engn & Elect, Brownlow Hill, Liverpool L69 3GJ, Merseyside, England.
    Lipschultz, B.
    Univ York, York Plasma Inst, Dept Phys, York YO10 5DD, N Yorkshire, England.
    Lloyd, B.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Lovell, J.
    Oak Ridge Natl Lab, Oak Ridge, TN 37831 USA.
    Madsen, B.
    Tech Univ Denmark, Dept Phys, Lyngby, Denmark.
    Marshall, O.
    Univ York, York Plasma Inst, Dept Phys, York YO10 5DD, N Yorkshire, England.
    Martin, R.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    McArdle, G.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    McClements, K.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    McMillan, B.
    Univ Warwick, Ctr Fus Space & Astrophys, Dept Phys, Coventry CV4 7AL, W Midlands, England.
    Meakins, A.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Meyer, H. F.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Militello, F.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Milnes, J.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Mordijck, S.
    Coll William & Mary, Dept Comp Sci, Williamsburg, VA 23185 USA.
    Morris, A. W.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Moulton, D.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Muir, D.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Mukhi, K.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England;Univ Manchester, Sch Phys & Astron, Oxford Rd, Manchester M13 9PL, Lancs, England.
    Murphy-Sugrue, S.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England;Univ Liverpool, Dept Elect Engn & Elect, Brownlow Hill, Liverpool L69 3GJ, Merseyside, England.
    Myatra, O.
    Univ York, York Plasma Inst, Dept Phys, York YO10 5DD, N Yorkshire, England.
    Naylor, G.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Naylor, P.
    Univ York, York Plasma Inst, Dept Phys, York YO10 5DD, N Yorkshire, England.
    Newton, S. L.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    O'Gorman, T.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Omotani, J.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    O'Mullane, M. G.
    Univ Strathclyde, Dept Phys SUPA, Glasgow G4 ONG, Lanark, Scotland.
    Orchard, S.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England;Univ York, York Plasma Inst, Dept Phys, York YO10 5DD, N Yorkshire, England.
    Pamela, S. J. P.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Pangione, L.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Parra, F.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England;Univ Oxford, Rudolf Peierls Ctr Theoret Phys, Oxford OX1 3PU, England.
    Perez, R. , V
    Piron, L.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Price, M.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Reinke, M. L.
    Oak Ridge Natl Lab, Oak Ridge, TN 37831 USA.
    Riva, F.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Roach, C. M.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Robb, D.
    Univ Glasgow, Dept Phys & Astron, Glasgow G12 8QQ, Lanark, Scotland.
    Ryan, D.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Saarelma, S.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Salewski, M.
    Tech Univ Denmark, Dept Phys, Lyngby, Denmark.
    Scannell, S.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Schekochihin, A. A.
    Univ Oxford, Rudolf Peierls Ctr Theoret Phys, Oxford OX1 3PU, England;Univ Oxford Merton Coll, Oxford OX1 4JD, England.
    Schmitz, O.
    Univ Wisconsin, Madison, WI USA.
    Sharapov, S.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Sharples, R.
    Univ Durham, Ctr Adv Instrumentat, South Rd, Durham DH1 3LE, England.
    Silburn, S. A.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Smith, S. F.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England;Univ York, York Plasma Inst, Dept Phys, York YO10 5DD, N Yorkshire, England.
    Sperduti, Andrea
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Stephen, R.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Thomas-Davies, N. T.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Thornton, A. J.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Turnyanskiy, M.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Valovic, M.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Van Wyk, F.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England;Univ Oxford, Rudolf Peierls Ctr Theoret Phys, Oxford OX1 3PU, England;STFC Daresbury Lab, Daresbury WA4 4AD, Cheshire, England.
    Vann, R. G. L.
    Univ York, York Plasma Inst, Dept Phys, York YO10 5DD, N Yorkshire, England.
    Walkden, N. R.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Waters, I
    Univ Wisconsin, Madison, WI USA.
    Wilson, H. R.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England;Univ York, York Plasma Inst, Dept Phys, York YO10 5DD, N Yorkshire, England.
    Overview of new MAST physics in anticipation of first results from MAST Upgrade2019In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 59, no 11, article id 112011Article in journal (Refereed)
    Abstract [en]

    The mega amp spherical tokamak (MAST) was a low aspect ratio device (R/a = 0.85/0.65 similar to 1.3) with similar poloidal cross-section to other medium-size tokamaks. The physics programme concentrates on addressing key physics issues for the operation of ITER, design of DEMO and future spherical tokamaks by utilising high resolution diagnostic measurements closely coupled with theory and modelling to significantly advance our understanding. An empirical scaling of the energy confinement time that favours higher power, lower collisionality devices is consistent with gyrokinetic modelling of electron scale turbulence. Measurements of ion scale turbulence with beam emission spectroscopy and gyrokinetic modelling in up-down symmetric plasmas find that the symmetry of the turbulence is broken by flow shear. Near the non-linear stability threshold, flow shear tilts the density fluctuation correlation function and skews the fluctuation amplitude distribution. Results from fast particle physics studies include the observation that sawteeth are found to redistribute passing and trapped fast particles injected from neutral beam injectors in equal measure, suggesting that resonances between the m = 1 perturbation and the fast ion orbits may be playing a dominant role in the fast ion transport. Measured D-D fusion products from a neutron camera and a charged fusion product detector are 40% lower than predictions from TRANSP/NUBEAM, highlighting possible deficiencies in the guiding centre approximation. Modelling of fast ion losses in the presence of resonant magnetic perturbations (RMPs) can reproduce trends observed in experiments when the plasma response and charge-exchange losses are accounted for. Measurements with a neutral particle analyser during merging-compression start-up indicate the acceleration of ions and electrons. Transport at the plasma edge has been improved through reciprocating probe measurements that have characterised a geodesic acoustic mode at the edge of an ohmic L-mode plasma and particle-in-cell modelling has improved the interpretation of plasma potential estimates from ball-pen probes. The application of RMPs leads to a reduction in particle confinement in L-mode and H-mode and an increase in the core ionization source. The ejection of secondary filaments following type-I ELMs correlates with interactions with surfaces near the X-point. Simulations of the interaction between pairs of filaments in the scrape-off layer suggest this results in modest changes to their velocity, and in most cases can be treated as moving independently. A stochastic model of scrape-off layer profile formation based on the superposition of non-interacting filaments is in good agreement with measured time-average profiles. Transport in the divertor has been improved through fast camera imaging, indicating the presence of a quiescent region devoid of filament near the X-point, extending from the separatrix to psi(n) similar to 1.02. Simulations of turbulent transport in the divertor show that the angle between the divertor leg on the curvature vector strongly influences transport into the private flux region via the interchange mechanism. Coherence imaging measurements show counter-streaming flows of impurities due to gas puffing increasing the pressure on field lines where the gas is ionised. MAST Upgrade is based on the original MAST device, with substantially improved capabilities to operate with a Super-X divertor to test extended divertor leg concepts. SOLPS-ITER modelling predicts the detachment threshold will be reduced by more than a factor of 2, in terms of upstream density, in the Super-X compared with a conventional configuration and that the radiation front movement is passively stabilised before it reaches the X-point. 1D fluid modelling reveals the key role of momentum and power loss mechanisms in governing detachment onset and evolution. Analytic modelling indicates that long legs placed at large major radius, or equivalently low B at the target compared with the X-point arc more amenable to external control. With MAST Upgrade experiments expected in 2019, a thorough characterisation of the sources of the intrinsic error field has been carried out and a mitigation strategy developed.

  • 304. Hatano, Y.
    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.
    Dzysiuk, Nataliia
    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.
    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
    Tritium distributions on W-coated divertor tiles used in the third JET ITER-like wall campaign2019In: Nuclear Materials and Energy, E-ISSN 2352-1791, Vol. 18, p. 258-261Article in journal (Refereed)
    Abstract [en]

    Tritium (T) distributions on tungsten (W)-coated plasma-facing tiles used in the third ITER-like wall campaign (2015-2016) of the Joint European Torus (JET) were examined by means of an imaging plate technique and beta-ray induced x-ray spectrometry, and they were compared with the distributions after the second (2013-2014) campaign. Strong enrichment of T in beryllium (Be) deposition layers was observed after the second campaign. In contrast, T distributions after the third campaign was more uniform though Be deposition layers were visually recognized. The one of the possible explanations is enhanced desorption of T from Be deposition layers due to higher tile temperatures caused by higher energy input in the third campaign.

  • 305.
    Hedkvist, Adam
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Ahrman, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Simulation of helium flow through ion guide with COMSOL multiphysics2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The program COMSOL Multiphysics was used to simulate a flow of helium gas transporting ionized fission products out of an ion guide. Two important parameters to study from the simulation was the evacuation time and velocity of the ions. The mean evacuation time was shown to be 0.1173s, and the velocity of a single particle peaked at 2500m/s, 1000-1500m/s being more common.

  • 306.
    Helgesson, Petter
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Approaching well-founded comprehensive nuclear data uncertainties: Fitting imperfect models to imperfect data2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Nuclear physics has a wide range of applications; e.g., low-carbon energy production, medical treatments, and non-proliferation of nuclear weapons. Nuclear data (ND) constitute necessary input to computations needed within all these applications.

    This thesis considers uncertainties in ND and their propagation to applications such as ma- terial damage in nuclear reactors. TENDL is today the most comprehensive library of evaluated ND (a combination of experimental ND and physical models), and it contains uncertainty estimates for all nuclides it contains; however, TENDL relies on an automatized process which, so far, includes a few practical remedies which are not statistically well-founded. A longterm goal of the thesis is to provide methods which make these comprehensive uncertainties well-founded. One of the main topics of the thesis is an automatic construction of experimental covariances; at first by attempting to complete the available uncertainty information using a set of simple rules. The thesis also investigates using the distribution of the data; this yields promising results, and the two approaches may be combined in future work.

    In one of the papers underlying the thesis, there are also manual analyses of experiments, for the thermal cross sections of Ni-59 (important for material damage). Based on this, uncertainty components in the experiments are sampled, resulting in a distribution of thermal cross sections. After being combined with other types of ND in a novel way, the distribution is propagated both to an application, and to an evaluated ND file, now part of the ND library JEFF 3.3.

    The thesis also compares a set of different techniques used to fit models in ND evaluation. For example, it is quantified how sensitive different techniques are to a model defect, i.e., the inability of the model to reproduce the truth underlying the data. All techniques are affected, but techniques fitting model parameters directly (such as the primary method used for TENDL) are more sensitive to model defects. There are also advantages with these methods, such as physical consistency and the possibility to build up a framework such as that of TENDL.

    The treatment of these model defects is another main topic of the thesis. To this end, two ways of using Gaussian processes (GPs) are studied, applied to quite different situations. First, the addition of a GP to the model is used to enable the fitting of arbitrarily shaped peaks in a histogram of data. This is shown to give a substantial improvement compared to if the peaks are assumed to be Gaussian (when they are not), both using synthetic and authentic data.

    The other approach uses GPs to fit smoothly energy-dependent model parameters in an ND evaluation context. Such an approach would be relatively easy to incorporate into the TENDL framework, and ensures a certain level of physical consistency. It is used on a TALYS-like model with synthetic data, and clearly outperforms fits without the energy-dependent model parameters, showing that the method can provide a viable route to improved ND evaluation. As a proof of concept, it is also used with authentic TALYS, and with authentic data.

    To conclude, the thesis takes significant steps towards well-founded comprehensive ND un- certainties.

  • 307.
    Helgesson, Petter
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Experimental data and Total Monte Carlo: Towards justified, transparent and complete nuclear data uncertainties2015Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The applications of nuclear physics are many with one important being nuclear power, which can help decelerating the climate change. In any of these applications, so-called nuclear data (ND, numerical representations of nuclear physics) is used in computations and simulations which are necessary for, e.g., design and maintenance. The ND is not perfectly known - there are uncertainties associated with it - and this thesis concerns the quantification and propagation of these uncertainties. In particular, methods are developed to include experimental data in the Total Monte Carlo methodology (TMC). The work goes in two directions. One is to include the experimental data by giving weights to the different "random files" used in TMC. This methodology is applied to practical cases using an automatic interpretation of an experimental database, including uncertainties and correlations. The weights are shown to give a consistent implementation of Bayes' theorem, such that the obtained uncertainty estimates in theory can be correct, given the experimental data. In the practical implementation, it is more complicated. This is much due to the interpretation of experimental data, but also because of model defects - the methodology assumes that there are parameter choices such that the model of the physics reproduces reality perfectly. This assumption is not valid, and in future work, model defects should be taken into account. Experimental data should also be used to give feedback to the distribution of the parameters, and not only to provide weights at a later stage.The other direction is based on the simulation of the experimental setup as a means to analyze the experiments in a structured way, and to obtain the full joint distribution of several different data points. In practice, this methodology has been applied to the thermal (n,α), (n,p), (n,γ) and (n,tot) cross sections of 59Ni. For example, the estimated expected value and standard deviation for the (n,α) cross section is (12.87 ± 0.72) b, which can be compared to the established value of (12.3 ± 0.6) b given in the work of Mughabghab. Note that also the correlations to the other thermal cross sections as well as other aspects of the distribution are obtained in this work - and this can be important when propagating the uncertainties. The careful evaluation of the thermal cross sections is complemented by a coarse analysis of the cross sections of 59Ni at other energies. The resulting nuclear data is used to study the propagation of the uncertainties through a model describing stainless steel in the spectrum of a thermal reactor. In particular, the helium production is studied. The distribution has a large uncertainty (a standard deviation of (17 ± 3) \%), and it shows a strong asymmetry. Much of the uncertainty and its shape can be attributed to the more coarse part of the uncertainty analysis, which, therefore, shall be refined in the future.

  • 308.
    Helgesson, Petter
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    TMC, adjustment to data, and model defects2018Other (Other (popular science, discussion, etc.))
  • 309.
    Helgesson, Petter
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    UO-2 vs MOX: Propagated nuclear data uncertainty with burnup using Fast Total Monte Carlo2013Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Precise assessment of propagated nuclear data uncertainties in integral reactor

    quantities is necessary for the development of new reactors as well as for modified

    use, e.g. when replacing UO-2 fuel by MOX fuel in conventional thermal reactors.

    The Fast Total Monte Carlo method (Fast TMC) is a further development of Total

    Monte Carlo - a reliable, general and flexible way to study how uncertainties

    propagate from differential nuclear data to integral results. The main idea is not new

    or unique for the field: integral quantities of interest are computed multiple times

    using differential data which is randomly sampled from distributions that quantify the

    uncertainty of the differential data; the spread in the results is then used in the

    quantification of the propagated uncertainties.

    This text compares UO-2 fuel to two types of MOX fuel with respect to propagated

    nuclear data uncertainty, primarily in the neutron multiplication factor k-eff, by

    applying Fast TMC to a typical PWR pin cell model in the Monte Carlo transport code

    SERPENT, including burnup. An extensive amount of nuclear data uncertainties is

    taken into account, including transport and activation data for 105 isotopes, fission

    yields for 13 actinides and thermal scattering data for hydrogen in water.

    There is indeed a significant difference in propagated nuclear data uncertainty in k-eff;

    at 0 burnup the uncertainty is 0.6 % for UO-2 and about 1 % for the MOX fuels. The

    difference decreases with burnup. Uncertainties in fissile fuel isotopes and thermal

    scattering are the most important for the difference and the reasons for this are

    understood and explained.

    This work thus suggests that there can be an important difference between UO-2 and

    MOX for the determination of uncertainty margins. However, the effects of the

    simplified model are difficult to overview; uncertainties should be propagated in more

    complicated models of any considered system. Fast TMC however allows for this.

  • 310.
    Helgesson, Petter
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Neudecker, Denise
    XCP Division, Los Alamos National Lab, NM, USA.
    Sjöstrand, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Grosskopf, Michael
    Department of Statistics and Actuarial Science, Simon Fraser University, Canada.
    Smith, Donald L.
    Argonne Associate of Seville, Argonne National Laboratory, CA, USA.
    Capote, Roberto
    NAPC-Nuclear Data Section, International Atomic Energy Agency, Austria.
    Assessment of Novel Techniques for Nuclear Data Evaluation2018In: Reactor Dosimetry: 16th International Symposium, ASTM International, 2018, p. 105-116Conference paper (Refereed)
    Abstract [en]

    The quality of evaluated nuclear data can be impacted by, e.g., the choice of the evaluation algorithm. The objective of this work is to compare the performance of the evaluation techniques GLS, GLS-P, UMC-G, and, UMC-B, by using synthetic data. In particular, the effects of model defects are investigated. For small model defects, UMC-B and GLS-P are found to perform best, while these techniques yield the worst results for a significantly defective model; in particular, they seriously underestimate the uncertainties. If UMC-B is augmented with Gaussian processes,it performs distinctly better for a defective model but is more susceptible to an inadequate experimental covariance estimate.

  • 311.
    Helgesson, Petter
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Rochman, Dimitri
    Nuclear Research and Consultancy Group NRG, Petten, The Netherlands.
    Sjöstrand, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Alhassan, Erwin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Koning, Arjan
    Nuclear Research and Consultancy Group NRG, Petten, The Netherlands.
    UO-2 Versus MOX: Propagated Nuclear Data Uncertainty for k-eff, with Burnup2014In: Nuclear science and engineering, ISSN 0029-5639, E-ISSN 1943-748X, Vol. 177, no 3, p. 321-336Article in journal (Refereed)
    Abstract [en]

    Precise assessment of propagated nuclear data uncertainties in integral reactor quantities is necessary for the development of new reactors as well as for modified use, e.g. when replacing UO-2 fuel by MOX fuel in conventional thermal reactors.

    This paper compares UO-2 fuel to two types of MOX fuel with respect to propagated nuclear data uncertainty, primarily in k-eff, by applying the Fast Total Monte Carlo method (Fast TMC) to a typical PWR pin cell model in Serpent, including burnup. An extensive amount of nuclear data is taken into account, including transport and activation data for 105 isotopes, fission yields for 13 actinides and thermal scattering data for H in H2O.

    There is indeed a significant difference in propagated nuclear data uncertainty in k-eff; at 0 burnup the uncertainty is 0.6 % for UO-2 and about 1 % for the MOX fuels. The difference decreases with burnup. Uncertainties in fissile fuel isotopes and thermal scattering are the most important for the difference and the reasons for this are understood and explained.

    This work thus suggests that there can be an important difference between UO-2 and MOX for the determination of uncertainty margins. However, the effects of the simplified model are difficult to overview; uncertainties should be propagated in more complicated models of any considered system. Fast TMC however allows for this without adding much computational time.

  • 312.
    Helgesson, Petter
    et al.
    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.
    Fitting a defect non-linear model with or without prior, distinguishing nuclear reaction products as an example2017In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 88, article id 115114Article in journal (Refereed)
    Abstract [en]

    Fitting parametrized functions to data is important for many researchers and scientists. If the model is non-linear and/or defect, it is not trivial to do correctly and to include an adequate uncertainty analysis. This work presents how the Levenberg-Marquardt algorithm for non-linear generalized least squares fitting can be used with a prior distribution for the parameters, and how it can be combined with Gaussian processes to treat model defects. An example, where three peaks in a histogram are to be distinguished, is carefully studied. In particular, the probability r1 for a nuclear reaction to end up in one out of two overlapping peaks is studied. Synthetic data is used to investigate effects of linearizations and other assumptions. For perfect Gaussian peaks, it is seen that the estimated parameters are distributed close to the truth with good covariance estimates. This assumes that the method is applied correctly; for example, prior knowledge should be implemented using a prior distribution, and not by assuming that some parameters are perfectly known (if they are not). It is also important to update the data covariance matrix using the fit if the uncertainties depend on the expected value of the data (e.g., for Poisson counting statistics or relative uncertainties). If a model defect is added to the peaks, such that their shape is unknown, a fit which assumes perfect Gaussian peaks becomes unable to reproduce the data, and the results for r1 become biased. It is, however, seen that it is possible to treat the model defect with a Gaussian process with a covariance function tailored for the situation, with hyper-parameters determined by leave-one-out cross validation. The resulting estimates for r1 are virtually unbiased, and the uncertainty estimates agree very well with the underlying uncertainty.

  • 313.
    Helgesson, Petter
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics. Nuclear Research and Consultancy Group NRG, Petten, The Netherlands.
    Sjöstrand, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Justified and complete gas-production cross sections with uncertainties for Ni-59 and consequences for stainless steel in LWR spectra2016Other (Other academic)
  • 314.
    Helgesson, Petter
    et al.
    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.
    Novel nuclear data evaluation combining sampling of experimental uncertainty components and TALYS parameters: Applied to helium production due to Ni-59 in stainless steel2016Other (Other academic)
  • 315.
    Helgesson, Petter
    et al.
    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.
    Treating defects in nuclear reaction models to improve material damage parameters and their uncertainties2017Conference paper (Other academic)
  • 316.
    Helgesson, Petter
    et al.
    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.
    Treating model defects by fitting smoothly varying model parameters: Energy dependence in nuclear data evaluation2018In: Annals of Nuclear Energy, ISSN 0306-4549, E-ISSN 1873-2100, Vol. 120, p. 35-47Article in journal (Refereed)
    Abstract [en]

    The fitting of models to data is essential in nuclear data evaluation, as in many other fields of science. The models maybe necessary for interpolation or extrapolation, but they are seldom perfect; there are model defects present which can result in severe biases and underestimated uncertainties. This work presents and investigates the idea to treat this problem by letting the model parameters vary smoothly with an input parameter. To be specific, the model parameters for neutron cross sections are allowed to vary with neutron energy. The parameter variation is limited by Gaussian processes, but the method should not be confused with adding a Gaussian process to the model. The performance of the method is studied using a large number of synthetic data sets, such that it is possible to quantitatively study the distribution of results compared to the underlying truth. There are imperfections in the results, but the method is seen to readily outperform fits without the energy dependent parameters. In particular, the estimates of uncertainty and correlations are much better. Hence, the method seems to offer a promising route for future treatment of model defects, both for nuclear data and elsewhere.

  • 317.
    Helgesson, Petter
    et al.
    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.
    Treating model defects with a Gaussian Process prior for the parameters2017Conference paper (Other academic)
    Abstract [en]

    The covariance information in TENDL is obtained by propagating uncertainties of, e.g., TALYSparameters to the observables, and by attempting to match the parameter uncertainties to the experimental data. This results in model-driven covariances with strong energy‐energy correlations, which can lead to erroneously estimated uncertainties for both differential and integral observables.Further, the model driven approach is sensitive to model defects, which can introduce biases and underestimated uncertainties.To resolve the issue of model defects in nuclear data (ND) evaluation, models the defect with a Gaussian process. This can reduce biases and give more correct covariances, including weakerenergy‐energy correlations. In the presented work, we continue the development of using Gaussian processes to treat model defects in ND evaluation, within a TENDL framework. The Gaussian processes are combined with the Levenberg‐Marquardt algorithm for non‐linear fitting, which reduces the need for a prior distribution. Further, it facilitates the transfer of knowledge to other nuclides by working in the parameter domain. First, synthetic data is used to validate the quality of both mean values and covariances provided by the method. After this, we fit TALYS parameters and a model defect correction to the 56Fe data in EXFOR.

  • 318.
    Helgesson, Petter
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics. Nucl Res & Consultancy Grp NRG, Petten, Netherlands.
    Sjöstrand, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Arjan, J. Koning
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics. Nucl Res & Consultancy Grp NRG, Petten, Netherlands.
    Rydén, Jesper
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Mathematics, Applied Mathematics and Statistics.
    Rochman, Dimitri
    PSI, Villigen, Switzerland.
    Alhassan, Erwin
    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.
    Combining Total Monte Carlo and Unified Monte Carlo: Bayesian nuclear data uncertainty quantification from auto-generated experimental covariances2017In: Progress in nuclear energy (New series), ISSN 0149-1970, E-ISSN 1878-4224, Vol. 96, p. 76-96Article in journal (Refereed)
    Abstract [en]

    The Total Monte Carlo methodology (TMC) for nuclear data (ND) uncertainty propagation has been subject to some critique because the nuclear reaction parameters are sampled from distributions which have not been rigorously determined from experimental data. In this study, it is thoroughly explained how TMC and Unified Monte Carlo-B (UMC-B) are combined to include experimental data in TMC. Random ND files are weighted with likelihood function values computed by comparing the ND files to experimental data, using experimental covariance matrices generated from information in the experimental database EXFOR and a set of simple rules. A proof that such weights give a consistent implementation of Bayes' theorem is provided. The impact of the weights is mainly studied for a set of integral systems/applications, e.g., a set of shielding fuel assemblies which shall prevent aging of the pressure vessels of the Swedish nuclear reactors Ringhals 3 and 4.

    In this implementation, the impact from the weighting is small for many of the applications. In some cases, this can be explained by the fact that the distributions used as priors are too narrow to be valid as such. Another possible explanation is that the integral systems are highly sensitive to resonance parameters, which effectively are not treated in this work. In other cases, only a very small number of files get significantly large weights, i.e., the region of interest is poorly resolved. This convergence issue can be due to the parameter distributions used as priors or model defects, for example.

    Further, some parameters used in the rules for the EXFOR interpretation have been varied. The observed impact from varying one parameter at a time is not very strong. This can partially be due to the general insensitivity to the weights seen for many applications, and there can be strong interaction effects. The automatic treatment of outliers has a quite large impact, however.

    To approach more justified ND uncertainties, the rules for the EXFOR interpretation shall be further discussed and developed, in particular the rules for rejecting outliers, and random ND files that are intended to describe prior distributions shall be generated. Further, model defects need to be treated.

  • 319.
    Helgesson, Petter
    et al.
    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.
    J. Koning, Arjan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics. IAEA.
    Rochman, Dimitri
    New 59Ni data including uncertainties and consequences for gas production in steel in LWR spectraNew 59Ni data including uncertainties and consequences for gas production in steel in LWR spectra2015Conference paper (Other academic)
    Abstract [en]

    Abstract: With ageing reactor fleets, the importance of estimating material damage parameters in structural materials is increasing. 59Ni is not naturally abundant, but as noted in, e.g., Ref. [1], the two-step reaction 58Ni(n,γ)59Ni(n,α)56Fe gives a very important contribution to the helium production and damage energy in stainless steel in thermal spectra, because of the extraordinarily large thermal (n,α) cross section for 59Ni (for most other nuclides, the (n,α) reaction has a threshold). None of the evaluated data libraries contain uncertainty information for (n,α) and (n,p) for 59Ni for thermal energies and the resonance region. Therefore, new such data is produced in this work, including random data to be used with the Total Monte Carlo methodology [2] for nuclear data uncertainty propagation.

                      The limited R-matrix format (“LRF = 7”) of ENDF-6 is used, with the Reich-Moore approximation (“LRF = 3” is just a subset of Reich-Moore). The neutron and gamma widths are obtained from TARES [2], with uncertainties, and are translated into LRF = 7. The α and proton widths are obtained from the little information available in EXFOR [3] (assuming large uncertainties because of lacking documentation) or from sampling from unresolved resonance parameters from TALYS [2], and they are split into different channels (different excited states of the recoiling nuclide, etc.). Finally, the cross sections are adjusted to match the experiments at thermal energies, with uncertainties.

                      The data is used to estimate the gas production rates for different systems, including the propagated nuclear data uncertainty. Preliminary results for SS304 in a typical thermal spectrum, show that including 59Ni at its peak concentration increases the helium production rate by a factor of 4.93 ± 0.28 including a 5.7 ± 0.2 % uncertainty due to the 59Ni data. It is however likely that the uncertainty will increase substantially from including the uncertainty of other nuclides and from re-evaluating the experimental thermal cross sections.

  • 320.
    Helgesson, Petter
    et al.
    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.
    J. Koning, Arjan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics. IAEA.
    Rochman, Dimitri
    Alhassan, Erwin
    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.
    Towards Transparent, Reproducible And Justified Nuclear Data Uncertainty Propagation For Lwr Applications2015Conference paper (Other academic)
    Abstract [en]

    Any calculated quantity is practically meaningless without estimates on the uncertainty of theobtained results, not the least when it comes to, e.g., safety parameters in a nuclear reactor. Oneof the sources of uncertainty in reactor physics computations or simulations are the uncertaintiesof the so called nuclear data, i.e., cross sections, angular distributions, fission yields, etc. Thecurrently dominating method for propagating nuclear data uncertainties (using covariance dataand sensitivity analysis) suffers from several limitations, not the least in how the the covariancedata is produced – the production relies to a large extent on personal judgment of nuclear dataevaluators, leading to results which are difficult to reproduce from fundamental principles.Further, such a method assumes linearity, it in practice limits both input and output to bemodeled as Gaussian distributions, and the covariance data in the established nuclear datalibraries is incomplete.“Total Monte Carlo” (TMC) is a nuclear data uncertainty propagation method based on randomsampling of nuclear reaction model parameters which aims to resolve these issues. The methodhas been applied to various applications, ranging from pin cells and criticality safety benchmarksto full core neutronics as well as models including thermo-hydraulics and transients. However,TMC has been subject to some critique since the distributions of the nuclear model parameters,and hence of the nuclear data, has not been deduced from really rigorous statistical theory. Thispresentation briefly discusses the ongoing work on how to use experimental data to approachjustified results from TMC, including the effects of correlations between experimental datapoints and the assessment of such correlations. In this study, the random nuclear data libraries areprovided with likelihood weights based on their agreement to the experimental data, as a meansto implement Bayes' theorem.Further, it is presented how TMC is applied to an MCNP-6 model of shielding fuel assemblies(SFA) at Ringhals 3 and 4. Since the damage from the fast neutron flux may limit the lifetimes ofthese reactors, parts of the fuel adjacent to the pressure vessel is replaced by steel (the SFA) toprotect the vessel, in particular the four points along the belt-line weld which have been exposedto the largest fluence over time. The 56Fe data uncertainties are considered, and the estimatedrelative uncertainty at a quarter of the pressure vessel is viewed in Figure 1 (right) as well as theflux pattern itself (left). The uncertainty in the flux reduction at a selected sensitive point is 2.5± 0.2 % (one standard deviation). Applying the likelihood weights does not have muchimpact for this case, which could indicate that the prior distribution for the 56Fe data is too“narrow” (the used libraries are not really intended to describe a prior distribution), and that thetrue uncertainty is substantially greater. Another explanation could be that the dominating sourceof uncertainty is the high-energy resonances which are treated inefficiently by such weights.In either case, the efforts to approach justified, transparent, reproducible and highly automatizednuclear data uncertainties shall continue. On top of using libraries that are intended to describeprior distributions and treating the resonance region appropriately, the experimental correlationsshould be better motivated and the treatment of outliers shall be improved. Finally, it is probablynecessary to use experimental data in a more direct sense where a lot of experimental data isavailable, since the nuclear models are imperfect.Figure 1. The high energy neutron flux at the reactor pressure vessel in the SFA model, and thecorresponding propagated 56Fe data uncertainty.

  • 321.
    Helgesson, Petter
    et al.
    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.
    J. Koning, Arjan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics. IAEA.
    Rydén, Jesper
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Mathematics, Applied Mathematics and Statistics.
    Rochman, Dimitri
    Paul Scherrer Institute PSI, Villigen, Switzerland.
    Alhassan, Erwin
    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.
    Sampling of systematic errors to estimate likelihood weights in nuclear data uncertainty propagation2016In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 807, p. 137-149Article in journal (Refereed)
    Abstract [en]

    In methodologies for nuclear data (ND) uncertainty assessment and propagation based on random sampling, likelihood weights can be used to infer experimental information into the distributions for the ND. As the included number of correlated experimental points grows large, the computational time for the matrix inversion involved in obtaining the likelihood can become a practical problem. There are also other problems related to the conventional computation of the likelihood, e.g., the assumption that all experimental uncertainties are Gaussian. In this study, a way to estimate the likelihood which avoids matrix inversion is investigated; instead, the experimental correlations are included by sampling of systematic errors. It is shown that the model underlying the sampling methodology (using univariate normal distributions for random and systematic errors) implies a multivariate Gaussian for the experimental points (i.e., the conventional model). It is also shown that the likelihood estimates obtained through sampling of systematic errors approach the likelihood obtained with matrix inversion as the sample size for the systematic errors grows large. In studied practical cases, it is seen that the estimates for the likelihood weights converge impractically slowly with the sample size, compared to matrix inversion. The computational time is estimated to be greater than for matrix inversion in cases with more experimental points, too. Hence, the sampling of systematic errors has little potential to compete with matrix inversion in cases where the latter is applicable. Nevertheless, the underlying model and the likelihood estimates can be easier to intuitively interpret than the conventional model and the likelihood function involving the inverted covariance matrix. Therefore, this work can both have pedagogical value and be used to help motivating the conventional assumption of a multivariate Gaussian for experimental data. The sampling of systematic errors could also be used in cases where the experimental uncertainties are not Gaussian, and for other purposes than to compute the likelihood, e.g., to produce random experimental data sets for a more direct use in ND evaluation.

  • 322.
    Helgesson, Petter
    et al.
    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.
    Koning, Arjan
    Nuclear Research and Consultancy Group NRG, Petten, The Netherlands.
    Rochman, Dimitri
    Nuclear Research and Consultancy Group NRG, Petten, The Netherlands.
    Alhassan, Erwin
    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.
    Incorporating Experimental Information in the Total Monte Carlo Methodology Using File Weights2015In: Nuclear Data Sheets, ISSN 0090-3752, E-ISSN 1095-9904, Vol. 123, no SI, p. 214-219Article in journal (Refereed)
    Abstract [en]

    Some criticism has been directed towards the Total Monte Carlo method because experimental information has not been taken into account in a statistically well-founded manner. In this work, a Bayesian calibration method is implemented by assigning weights to the random nuclear data files and the method is illustratively applied to a few applications. In some considered cases, the estimated nuclear data uncertainties are significantly reduced and the central values are significantly shifted. The study suggests that the method can be applied both to estimate uncertainties in a more justified way and in the search for better central values. Some improvements are however necessary; for example, the treatment of outliers and cross-experimental correlations should be more rigorous and random files that are intended to be prior files should be generated.

  • 323.
    Helgesson, Petter
    et al.
    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.
    Koning, Arjan
    Nuclear Research and Consultancy Group NRG, Petten, The Netherlands.
    Rydén, Jesper
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Mathematics.
    Rochman, Dimitri
    Paul Scherrer Institute PSI, Villigen, Switzerland.
    Alhassan, Erwin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Pomp, Stephan
    Including experimental information in TMC using file weights from automatically generated experimental covariance matricesManuscript (preprint) (Other academic)
    Abstract [en]

    The Total Monte Carlo methodology (TMC) for nuclear data (ND) uncertainty propagation has been subject to some critique because the nuclear reaction parameters are sampled from distributions which have not been rigorously determined from experimental data. In this study, it is thoroughly explained how random ND files are weighted with likelihood function values computed by comparing the ND files to experimental data, using experimental covariance matrices generated from information in the experimental database EXFOR and a set of simple rules. A proof that such weights give a consistent implementation of Bayes' theorem is provided. The impact of the weights is mainly studied for a set of integral systems/applications, e.g., a set of shielding fuel assemblies which shall prevent aging of the pressure vessels of the Swedish nuclear reactors Ringhals 3 and 4.For many applications, the weighting does not have much impact, something which can be explained by too narrow prior distributions. Another possible explanation is that the integral systems are highly sensitive to resonance parameters, which effectively are not treated in this work. In other cases, only a very small number of files get significantly large weights, which can be due to the prior parameter distributions or model defects.Further, some parameters used in the rules for the EXFOR interpretation have been varied. The observed impact from varying one parameter at a time is not very strong. This can partially be due to the general insensitivity to the weights seen for many applications, and there can be strong interaction effects. The automatic treatment of outliers has a quite large impact, however. To approach more justified ND uncertainties, the rules for the EXFOR interpretation shall be further discussed and developed, in particular the rules for rejecting outliers, and random ND files that are intended to describe prior distributions shall be generated. Further, model defects need to be treated.

  • 324.
    Helgesson, Petter
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics. Nuclear Research and Consultancy Group NRG, Petten, The Netherlands.
    Sjöstrand, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Rochman, Dimitri
    Paul Scherrer Institute PSI, Villigen, Switzerland.
    Uncertainty driven nuclear data evaluation including thermal (n,alpha) applied to Ni-592017In: Nuclear Data Sheets, ISSN 0090-3752, E-ISSN 1095-9904, Vol. 145, p. 1-24Article in journal (Refereed)
    Abstract [en]

    This paper presents a novel approach to the evaluation of nuclear data (ND), combining experimental data for thermalcross sections with resonance parameters and nuclear reaction modeling. The method involves sampling of variousuncertain parameters, in particular uncertain components in experimental setups, and provides extensive covarianceinformation, including consistent cross-channel correlations over the whole energy spectrum. The method is developed for, and applied to, Ni-59, but may be used as a whole, or in part, for other nuclides. Ni-59 is particularly interesting since a substantial amount of Ni-59 is produced in thermal nuclear reactors by neutron capture in Ni-58 and since it has a non-threshold (n,α) cross section. Therefore, Ni-59 gives a very important contribution to the helium production in stainless steel in a thermal reactor. However, current evaluated ND libraries contain old information for Ni-59, without any uncertainty information. The work includes a study of thermal cross section experiments and a novel combination of this experimental information, giving the full multivariate distribution of the thermal cross sections. In particular, the thermal (n,α) cross section is found to be (12.7 ± .7) b. This is consistent with, but yet different from, current established values. Further, the distribution of thermal cross sections is combined with reported resonance parameters, and with TENDL-2015 data, to provide full random ENDF files; all this is done in a novel way, keeping uncertainties and correlations in mind. The random files are also condensed into one single ENDF file with covariance information, which is now part ofa beta version of JEFF 3.3.Finally, the random ENDF files have been processed and used in an MCNP model to study the helium productionin stainless steel. The increase in the (n,α) rate due to Ni-59 compared to fresh stainless steel is found to be a factor of 5.2 at a certain time in the reactor vessel, with a relative uncertainty due to the Ni-59 data of 5.4 %.

  • 325.
    Helgesson, Petter
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics. Nuclear Research and Consultancy Group NRG, Petten, The Netherlands.
    Sjöstrand, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Rochman, Dimitri
    Paul Scherrer Institute PSI, Villigen, Switzerland.
    Koning, Arjan J.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics. IAEA Nuclear Data Section, Vienna, Austria.
    Evaluation of the Ni-59 cross sections including thermal (n,alpha), (n,p) and complete uncertainty information2016Other (Other academic)
  • 326.
    Helgesson, Petter
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics. Nuclear Research and Consultancy Group NRG, Petten, The Netherlands.
    Sjöstrand, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Rochman, Dimitri
    Paul Scherrer Institute PSI, Villigen, Switzerland.
    Koning, Arjan J.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics. IAEA Nuclear Data Section, Vienna, Austria.
    Ni-59 cross section evaluation: covariance focus2016Other (Other academic)
  • 327.
    Hellesen, C.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Qvist, S.
    Uppsala Univ, Uppsala, Sweden.;Univ Calif Berkeley, Dept Nucl Engn, Berkeley, CA 94720 USA..
    Benchmark and demonstration of the CHD code for transient analysis of fast reactor systems2017In: Annals of Nuclear Energy, ISSN 0306-4549, E-ISSN 1873-2100, Vol. 109, p. 712-719Article in journal (Refereed)
    Abstract [en]

    In this paper the dynamic thermal hydraulic fast reactor simulation code CHD is presented. The code is built around a scriptable object-oriented framework in the programming language Python to be able to flexibly describe different reactor geometries including thermal-hydraulics models of an arbitrary number of coolant channels as well as pumps, heat-exchangers and pools etc. In addition, custom objects such as the Autonomous Reactivity Control (ARC) system for enhanced passive safety are modeled in detail. In this paper we compare the performance of the CHD code with other similar fast reactor dynamics codes using a benchmark study of the European Sodium cooled Fast Reactor (ESFR). The results agree well, both qualitatively and quantitatively with the code benchmark. In addition, we demonstrate the code's ability to simulate the long-term asymptotic behavior of a neutronically shut down reactor in an unprotected loss of flow scenario using a model of the Advanced Burner Reactor (ABR). (C) 2017 Elsevier Ltd. All rights reserved.

  • 328.
    Hellesen, Carl
    et al.
    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.
    Conroy, Sean
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Dzysiuk, Nataliia
    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.
    Hjalmarsson, Anders
    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.
    Marcinkevicius, Benjaminas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Conceptual design of a BackTOF neutron spectrometer for fuel ion ratio measurements at ITER2017In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 57, no 6, article id 066021Article in journal (Refereed)
    Abstract [en]

    In this paper we present a conceptual design of a back scattering neutron time of flight spectrometer (BackTOF) for use at ITER. The proposed BackTOF design aims at fulfilling the requirements set on a neutron spectrometer system to be used for inferring the core fuel ion ratio in a DT plasma. Specifically we have investigated the requirements on the size, energy resolution, count rate capability, efficiency and signal to background ratio. These requirements are a compact size that fits in roughly 1 m3, an energy resolution of 4% or better, a count rate capability of at least 100 kHz, an efficiency of at least 10−5 and a signal to background ratio of 1000 or better.

    Using a Monte Carlo model of the BackTOF spectrometer we find that the proposed BackTOF design is compact enough to be installed at ITER while being capable of achieving a resolution of about 4% FWHM with a count rate capability of 300 kHz and an efficiency at 1.25 10−3. This is sufficient for achieving the requirements on the fuel ion ratio at ITER. We also demonstrate how data acquisition systems capable of providing both timing and energy information can be used to effectively discriminate random background at high count rates.

  • 329.
    Hellesen, Carl
    et al.
    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.
    Binda, Federico
    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.
    Hjalmarsson, Anders
    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.
    Fuel ion ratio determination in NBI heated deuterium tritium fusion plasmas at JET using neutron emission spectrometry2015In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 55, no 2, article id 023005Article in journal (Refereed)
    Abstract [en]

    The fuel ion ratio ( n t / n d ) is of central importance for the performance and control of a future burning fusion plasma, and reliable measurements of this quantity are essential for ITER. This paper demonstrates a method to derive the core fuel ion ratio by comparing the thermonuclear and beam-thermal neutron emission intensities, using a neutron spectrometer. The method is applied to NBI heated deuterium tritium (DT) plasmas at JET, using data from the magnetic proton recoil spectrometer. The trend in the results is consistent with Penning trap measurements of the fuel ion ratio at the edge of the plasma, but there is a discrepancy in the absolute values, possibly owing to the fact that the two measurements are weighted towards different parts of the plasma. It is suggested to further validate this method by comparing it to the traditionally proposed method to estimate n t / n d from the ratio of the thermal DD and DT neutron emission components. The spectrometer requirements for measuring n t / n d at ITER are also briefly discussed.

  • 330.
    Hellesen, Carl
    et al.
    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.
    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.
    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.
    Fuel ion ratio measurements in reactor relevant neutral beam heated fusion plasmas2012In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 83, no 10, p. 10D916-Article in journal (Refereed)
    Abstract [en]

    In this paper, we present a method to derive n tn d using the ratio of the thermonuclear neutron emission to the beam-target neutron emission. We apply it to neutron spectroscopy data from the magnetic proton recoil spectrometer taken during the deuterium tritium experiment at JET. n tn d-values obtained using neutron spectroscopy are in qualitative agreement with those from other diagnostics measuring the isotopic composition of the exhaust in the divertor.

  • 331.
    Hellesen, Carl
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Eriksson, Jakob
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Energetic particle instabilities in fusion plasmas2013In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 10, no 53, p. 104022-Article in journal (Refereed)
  • 332.
    Hellesen, Carl
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Gatu Johnson, Maria
    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.
    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.
    Gorini, Giuseppe
    Johnson, Thomas
    Kiptily, Vasily
    Pinches, Simon
    Sharapov, Sergei
    Sjöstrand, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Nocente, Massimo
    Tardocchi, Marco
    Weiszflog, Matthias
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Measurements of fast ions and their interactions with MHD activity using neutron emission spectroscopy2010In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 50, no 8, p. 084006-Article in journal (Refereed)
    Abstract [en]

    Ion cyclotron radio frequency (ICRF) heating can produce fast ion populations with energies reaching up to several megaelectronvolts. Here, we present unique measurements of fast ion distributions from an experiment with 3rd harmonic ICRF heating on deuterium beams using neutron emission spectroscopy (NES). From the experiment, very high DD neutron rates were observed, using only modest external heating powers. This was attributed to acceleration of deuterium beam ions to energies up to about 2-3 MeV, where the DD reactivity is on a par with that of the DT reaction. The high neutron rates allowed for observations of changes in the fast deuterium energy distribution on a time scale of 50 ms. Clear correlations were seen between fast deuterium ions in different energy ranges and magnetohydrodynamic activities, such as monster sawteeth and toroidal Alfven eigen modes (TAE). Specifically, NES data showed that the number of deuterons in the region between 1 and 1.5 MeV were decaying significantly during strong TAE activity, while ions with lower energies around 500 keV were not affected. This was attributed to resonances with the TAE modes.

  • 333.
    Hellesen, Carl
    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.
    Håkansson, Ane
    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.
    Jansson, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Improved proliferation resistance of fast reactor blankets manufactured from spent nuclear fuel2013Conference paper (Other academic)
    Abstract [en]

    In this paper we investigate how a blanket manufactured from recycled light water reactor (LWR)waste, instead of depleted uranium (DU), could potentially improve the non- proliferationcharacteristics. The blanket made from LWR waste would from the start of operation contain a fractionof plutonium isotopes unsuitable for weapons production. As 239Pu is bred in the blanket it istherefore always mixed with the plutonium already present.

    We use a Monte Carlo model of the advanced burner test reactor (ABTR) as reference design, andthe proliferation resistance of the blanket material is evaluated for two criteria, spontaneous neutronemission and decay heat. We show that it is possible to achieve a production of plutonium withproliferation resistance comparable to light water reactor waste with a burnup of 50MWd/kg.

  • 334.
    Hellesen, Carl
    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.
    Håkansson, Ane
    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.
    Jansson, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Improving the proliferation resistance of generation IV fast reactor fuel cycles using blankets manufactured from spent nuclear fuel.2013Conference paper (Other academic)
  • 335.
    Hellesen, Carl
    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.
    Jansson, Peter
    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.
    Åberg Lindell, Matilda
    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.
    Nuclear Spent Fuel Parameter Determination using Multivariate Analysis of Fission Product Gamma Spectra2017In: Annals of Nuclear Energy, ISSN 0306-4549, E-ISSN 1873-2100, Vol. 110, p. 886-895Article in journal (Refereed)
    Abstract [en]

    In this paper, we investigate the application of multivariate data analysis methods to the analysis of gamma spectroscopy measurements of spent nuclear fuel (SNF). Using a simulated irradiation and cooling of nuclear fuel over a wide range of cooling times (CT), total burnup at discharge (BU) and initial enrichments (IE) we investigate the possibilities of using a multivariate data analysis of the gamma ray emission signatures from the fuel to determine these fuel parameters. This is accomplished by training a multivariate analysis method on simulated data and then applying the method to simulated, but perturbed, data.

    We find that for SNF with CT less than about 20 years, a single gamma spectrum from a high resolution gamma spectrometer, such as a high-purity germanium spectrometer, allows for the determination of the above mentioned fuel parameters.

    Further, using measured gamma spectra from real SNF from Swedish pressurized light water reactors we were able to confirm the operator declared fuel parameters. In this case, a multivariate analysis trained on simulated data and applied to real data was used.

  • 336.
    Hellesen, Carl
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Johnson, M. Gatu
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Sundén, E. Andersson
    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.
    Sjöstrand, Henrik
    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.
    Johnson, T.
    Gorini, G.
    Nocente, M.
    Tardocchi, M.
    Kiptily, V. G.
    Pinches, S. D.
    Sharapov, S. E.
    Fast-ion distributions from third harmonic ICRF heating studied with neutron emission spectroscopy2013In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 53, no 11, p. 113009-Article in journal (Refereed)
    Abstract [en]

    The fast-ion distribution from third harmonic ion cyclotron resonance frequency (ICRF) heating on the Joint European Torus is studied using neutron emission spectroscopy with the time-of-flight spectrometer TOFOR. The energy dependence of the fast deuteron distribution function is inferred from the measured spectrum of neutrons born in DD fusion reactions, and the inferred distribution is compared with theoretical models for ICRF heating. Good agreements between modelling and measurements are seen with clear features in the fast-ion distribution function, that are due to the finite Larmor radius of the resonating ions, replicated. Strong synergetic effects between ICRF and neutral beam injection heating were also seen. The total energy content of the fast-ion population derived from TOFOR data was in good agreement with magnetic measurements for values below 350 kJ.

  • 337.
    Hellesen, Carl
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Mantsinen, Mervi
    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.
    Kiptily, Vasily
    Nabais, Fernando
    Analysis of resonant fast ion distributions during combined ICRF and NBI heating with transients using neutron emission spectroscopy2018In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 58, no 5, article id 056021Article in journal (Refereed)
    Abstract [en]

    ICRF heating at the fundamental cyclotron frequency of a hydrogen minority ion species also gives rise to a partial power absorption by deuterium ions at their second harmonic resonance. This paper studies the deuterium distributions resulting from such 2nd harmonic heating at JET using neutron emission spectroscopy data from the time of flight spectrometer TOFOR. The fast deuterium distributions are obtained over the energy range 100 keV to 2 MeV. Specifically, we study how the fast deuterium distributions vary as ICRF heating is used alone as well as in combination with NBI heating. When comparing the different heating scenarios, we observed both a difference in the shapes of the distributions as well as in their absolute level. The differences are most pronounced below 0.5 MeV. Comparisons are made with corresponding distributions calculated with the code PION. We find a good agreement between the measured distributions and those calculated with PION, both in terms of their shapes as well as their amplitudes. However, we also identified a period with signs of an inverted fast ion distribution, which showed large disagreements between the modeled and measured results. Resonant interactions with tornado modes, i.e. core localized toroidal alfven eigenmodes (TAEs), are put forward as a possible explanation for the inverted distribution.

  • 338.
    Hellesen, Carl
    et al.
    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.
    Dzysiuk, N.
    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.
    Hjalmarsson, Anders
    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.
    Conroy, Sean
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Sundén, Erik Andersson
    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.
    Binda, Federico
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Prospects for measuring the fuel ion ratio in burning ITER plasmas using a DT neutron emission spectrometer2014In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 85, no 11, p. 11D825-Article in journal (Refereed)
    Abstract [en]

    The fuel ion ratio n(t)/n(d) is an essential parameter for plasma control in fusion reactor relevant applications, since maximum fusion power is attained when equal amounts of tritium (T) and deuterium (D) are present in the plasma, i.e., n(t)/n(d) = 1.0. For neutral beam heated plasmas, this parameter can be measured using a single neutron spectrometer, as has been shown for tritium concentrations up to 90%, using data obtained with the MPR (Magnetic Proton Recoil) spectrometer during a DT experimental campaign at the Joint European Torus in 1997. In this paper, we evaluate the demands that a DT spectrometer has to fulfill to be able to determine n(t)/n(d) with a relative error below 20%, as is required for such measurements at ITER. The assessment shows that a back-scattering time-of-flight design is a promising concept for spectroscopy of 14 MeV DT emission neutrons.

  • 339.
    Hellesen, Carl
    et al.
    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.
    Ericsson, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Sundén, E. Andersson
    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.
    Conroy, Sean
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Eriksson, Jakob
    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.
    Impact of digitization for timing and pulse shape analysis of scintillator detector signals2013In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 720, p. 135-140Article in journal (Refereed)
    Abstract [en]

    In this paper we investigate the effects of full digitization of scintillator signals. The requirements on the analog to digital converter (ADC), in terms of sampling rate (f(s)) and bit resolution, are investigated. Two applications for scintillator detectors are studied, pulse timing and particle species identification. We find that signal reconstruction using sinc interpolation can be used e.g. for high-precision timing of a sampled electric pulse. Timing performances better than 6 ps (FWHM) were obtained if f(s) equals or exceeds twice the maximum frequency of the scintillator pulse. Failing to meet this criterion deteriorates both the performance of pulse timing and particle identification. We find that the bit resolution of the ADC is very important also for timing of pulses.

  • 340.
    Hellesen, Carl
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Wolniewicz, Peter
    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.
    Håkansson, Ane
    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.
    Österlund, Michael
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Transient Simulation of Gas Bubble in a Medium Sized Lead Cooled Fast Reactor2014In: Proceedings of the International Conference on Physics of Reactors (PHYSOR 2014) / [ed] Kenya Suyama, Takanori Sugawara, Kenichi Tada, Go Chiba and Akio Yamamoto, 2014Conference paper (Other academic)
    Abstract [en]

    A common problem for many liquid metal cooled fast reactor designs is the positive void worth of the coolant. In this context, an advantage of lead cooled fast reactors is the high temperature of coolant boiling. In contrast to sodium cooled fast reactors this, in practice, precludes coolant boiling. However, partial voiding of the core could result from e.g. gas bubbles entering the core from below. This would introduce a positive reactivity, if the bubble is large enough.

     

    In this paper we model this type of event using a point kinetics code coupled to a heat transport code. The reactivity parameters are obtained from a Monte Carlo code. The 300 MWth reactor design Alfred is used as a test case. We show that in general the reactor design studied is robust in such events, and we conclude that small bubbles a measureable Power oscillation would occur. For very large bubbles there exist a possibility of core damage. The cladding is the most sensitive part.

  • 341.
    Hellsten, T.
    et al.
    Culham Sci Ctr, JET, EUROfus Consortium, Abingdon OX14 3DB, Oxon, England.;KTH, Sch Elect Engn, Dept Fus Plasma Phys, Stockholm, Sweden..
    Johnson, T.
    Culham Sci Ctr, JET, EUROfus Consortium, Abingdon OX14 3DB, Oxon, England.;KTH, Sch Elect Engn, Dept Fus Plasma Phys, Stockholm, Sweden..
    Sharapov, S. E.
    Culham Sci Ctr, CCFE Fus Assoc, Abingdon OX14 3DB, Oxon, England..
    Kiptily, V.
    Culham Sci Ctr, CCFE Fus Assoc, Abingdon OX14 3DB, Oxon, England..
    Eriksson, J.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Mantsinen, M.
    Catalan Inst Res & Adv Studies, Barcelona, Spain..
    Schneider, M.
    IRFM CEA, St Paul Les Durance, France..
    Rimini, F.
    Culham Sci Ctr, CCFE Fus Assoc, Abingdon OX14 3DB, Oxon, England..
    Tsalas, M.
    DIFFER, FOM Inst, Nieuwegein, Netherlands..
    RF Heating for Fusion Product Studies2015Conference paper (Refereed)
    Abstract [en]

    Third harmonic cyclotron heating is an effective tool for accelerating deuterium (D) beams to the MeV energy range, suitable for studying ITER relevant fast particle physics in plasmas without significant tritium content. Such experiments were recently conducted in JET with an ITER like wall in D plasmas with He-3 concentrations up to 30% in order to boost the fusion reactivity by D-He-3 reactions. The harmonic cyclotron heating produces high-energy tails in the MeV range of D ions by on-axis heating and of He-3 ions by tangential off-axis heating. The discharges are characterized by long sawtooth free periods and a rich spectrum of MHD modes excited by the fast D and He-3 ions. The partitions of the power, which depend on the distribution function of D, vary strongly over several slowing down times. Self-consistent modelling of the distribution function with the SELFO-light code are presented and compared with experimental data from fast particle diagnostics.

  • 342.
    Hernandez Solis, Augusto
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Development of an in-house coupled neutronic and thermal-hydraulic code for the steady-state analysis of LWRs2015Conference paper (Refereed)
  • 343.
    Hernandez Solis, Augusto
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    On the importance of the spatial dependence of gap properties in the design of modern fast reactor cores2015Conference paper (Refereed)
  • 344.
    Hernandez Solis, Augusto
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Sjostrand, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Alhassan, Erwin
    Helgesson, Petter
    DRAG-MOC: A tool for the study of uncertainty analysis through OpenMOC2015Conference paper (Refereed)
  • 345.
    Hernandez Solis, Augusto
    et al.
    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.
    Alhassan, Erwin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Helgesson, Petter
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Development Of Drag-MOC: A tool for the study of uncertainty analysis through the deterministic OpenMOC transport code2016Conference paper (Refereed)
  • 346.
    Hernandez Solis, Augusto
    et al.
    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.
    Helgesson, Petter
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Propagation of neutron-reaction uncertainties through multi-physics models of novel LWR's2017In: 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 02035Conference paper (Refereed)
    Abstract [en]

    The novel design of the renewable boiling water reactor (RBWR) allows a breeding ratio greater than unity and thus, it aims at providing for a self-sustained fuel cycle. The neutron reactions that compose the different microscopic cross-sections and angular distributions are uncertain, so when they are employed in the determination of the spatial distribution of the neutron flux in a nuclear reactor, a methodology should be employed to account for these associated uncertainties. In this work, the Total Monte Carlo (TMC) method is used to propagate the different neutron-reactions (as well as angular distributions) covariances that are part of the TENDL-2014 nuclear data (ND) library. The main objective is to propagate them through coupled neutronic and thermal-hydraulic models in order to assess the uncertainty of important safety parameters related to multi-physics, such as peak cladding temperature along the axial direction of an RBWR fuel assembly. The objective of this study is to quantify the impact that ND covariances of important nuclides such as U-235, U-238, Pu-239 and the thermal scattering of hydrogen in H2O have in the deterministic safety analysis of novel nuclear reactors designs.

  • 347. Hirayama, S.
    et al.
    Watanabe, Y.
    Naitou, Y.
    Andersson, P
    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.
    Gustavsson, Cecilia
    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.
    Pomp, Stephan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Simutkin, Vasily
    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.
    Hjalmarsson, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics. Uppsala University, The Svedberg Laboratory.
    Prokofiev, Alexander V.
    Uppsala University, The Svedberg Laboratory.
    Tesinsky, M.
    Tippawan, U.
    Light-ion Production from a Thin Silicon Target Bombarded by 175 MeV Quasi Mono-energetic Neutrons2011In: Journal of the Korean Physical Society, ISSN 0374-4884, E-ISSN 1976-8524, Vol. 59, no 2, p. 1447-1450Article in journal (Refereed)
    Abstract [en]

    Double-differential production yields of light ions (p, d, t, (3)He, and alpha) from a thin silicon target induced by 175 MeV quasi mono-energetic neutrons were measured using the MEDLEY setup at the The Svedberg Laboratory (TSL) in Uppsala in order to benchmark evaluated nuclear data and nuclear reaction models. The MEDLEY is a conventional spectrometer system which consists of eight counter telescopes. Each telescope is composed of two silicon surface barrier detectors as the Delta E detectors and a CsI(Tl) scintillator as the E detector for particle identification. The telescopes are placed at angles from 20 degrees to 160 degrees in steps of 20 degrees. The measured double-differential yields of light ions are compared with PHITS calculations using the following nuclear reaction options: the high-energy nuclear data library (JENDL/HE-2007), the quantum molecular dynamics (QMD) model, and the intra-nuclear cascade (INC) model.

  • 348.
    Hirayama, Shusuke
    et al.
    Kyushu University.
    Watanabe, Yukinobu
    Hayashi, Masateru
    Naitou, Yuuki
    Watanabe, Takehito
    Bevilacqua, Riccardo
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Blomgren, Jan
    Nilsson, Leif
    Öhrn, Angelica
    Österlund, Michael
    Prokofiev, Alexander V.
    Uppsala University, The Svedberg Laboratory.
    Simutkin, Vasily
    Tippawan, Udomrat
    Production of protons, deuterons, and tritons from carbon bombarded by 175 MeV quasi mono-energetic neutrons2011In: Progress in Nuclear Science and Technology, Vol. 1, p. 69-72Article in journal (Refereed)
    Abstract [en]

    We have measured double-differential yields of protons, deuterons, and tritons produced from carbon induced by 175 MeV quasi mono-energetic neutrons using the MEDLEY setup at the TSL neutron beam facility. The measured data are used for benchmarking of a high-energy nuclear data file, JENDL/HE-2007, and both intra-nuclear cascade (INC) model and quantum molecular dynamics (QMD) calculations.

  • 349.
    Hirayama, Shusuke
    et al.
    Kyushu University.
    Watanabe, Yukinobu
    Naitou, Yuuki
    Andersson, Pernilla
    Bevilacqua, Riccardo
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Gustavsson, Cecilia
    Hjalmarsson, Anders
    Österlund, Michael
    Pomp, Stephan
    Prokofiev, Alexander
    Simutkin, Vasily
    Sjöstand, Herik
    Tesinsky, Milan
    Tippawan, Udomrat
    Light-ion production from a thin silicon target bombarded by 175 MeV quasi mono-energetic neutrons2011In: Nuclear Engineering and Technology: Proceedings of the International Conference on Nuclear Data for Science and Technology 2010 / [ed] Korean Nuclear Society, 2011Conference paper (Refereed)
  • 350. Hobirk, J.
    et al.
    Imbeaux, F.
    Crisanti, F.
    Buratti, P.
    Challis, C. D.
    Joffrin, E.
    Alper, B.
    Andrew, Y.
    Beaumont, P.
    Beurskens, M.
    Boboc, A.
    Botrugno, A.
    Brix, M.
    Calabro', G.
    Coffey, I.
    Conroy, Sean
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Ford, O.
    Frigione, D.
    Garcia, J.
    Giroud, C.
    Hawkes, N. C.
    Howell, D.
    Jenkins, I.
    Keeling, D.
    Kempenaars, M.
    Leggate, H.
    Lotte, P.
    de la Luna, E.
    Maddison, G. P.
    Mantica, P.
    Mazzotta, C.
    McDonald, D. C.
    Meigs, A.
    Nunes, I.
    Rachlew, E.
    Rimini, F.
    Schneider, M.
    Sips, A. C. C.
    Stober, J. K.
    Studholme, W.
    Tala, T.
    Tsalas, M.
    Voitsekhovitch, I.
    de Vries, P. C.
    Improved confinement in JET hybrid discharges2012In: Plasma Physics and Controlled Fusion, ISSN 0741-3335, E-ISSN 1361-6587, Vol. 54, no 9, p. 095001-Article in journal (Refereed)
    Abstract [en]

    A new technique has been developed to produce plasmas with improved confinement relative to the H-98,H-y2 scaling law (ITER Physics Expert Groups on Confinement and Transport and Confinement Modelling and Database ITER Physics Basics Editors and ITER EDA 1999 Nucl. Fusion 39 2175) on the JET tokamak. In the mid-size tokamaks ASDEX upgrade and DIII-D heating during the current formation is used to produce a flat q-profile with a minimum close to 1. On JET this technique leads to q-profiles with similar minimum q but opposite to the other tokamaks not to an improved confinement state. By changing the method utilizing a faster current ramp with temporary higher current than in the flattop (current overshoot) plasmas with improved confinement (H-98,H-y2 = 1.35) and good stability (beta(N) approximate to 3) have been produced and extended to many confinement times only limited by technical constraints. The increase in H-98,H-y2-factor is stronger with more heating power as can be seen in a power scan. The q-profile development during the high power phase in JET is reproduced by current diffusion calculated by TRANSP and CRONOS. Therefore the modifications produced by the current overshoot disappear quickly from the edge but the confinement improvement lasts longer, in some cases up to the end of the heating phase.

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