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Usnc graphite analysis framework

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USNC ASME Dive 5 HHA Graphite Analysis framework

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Usnc graphite analysis framework

  1. 1. Graphite Irradiated Lifetime Failure Analysis Framework 21/8/2017 D.N Wilke, S. Kok University of Pretoria M.P. Hindley USNC africa
  2. 2. 7/7/2017 / 2 © USNC 2017 • Introduction • Irradiated material model models • Fluence end Temperature requirements • Obtaining the software • Available data • Quick demo • Failure criteria • Concluding remarks Outline
  3. 3. 7/7/2017 / 3 © USNC 2017 Fluence and temperature gradients Criteria for selection of blocks: • Maximum temperature gradients • Maximum fluence
  4. 4. 7/7/2017 / 4 © USNC 2017 The total strain in the material is the sum of the following: • Elastic strain • Linear dimensional change strain due to irradiation • Primary and secondary irradiation induced creep • Thermal strain • This needs to be implemented in finite element analysis code since values are different at each location Constitutive equations for irradiated graphite Stress in the material
  5. 5. 7/7/2017 / 5 © USNC 2017 Material model dependant on avaiable data
  6. 6. 7/7/2017 / 6 © USNC 2017 Data currently used • Gerd Haag, “Properties of ATR-2E Graphite and Property Changes due to Fast Neutron Irradiation”, Institut für Sicherheitsforschung and Reaktortechnik, Forschungszentrum Jülich • Provided as a sample in Excel spreadsheet (headings of spreadsheet are important) • Use your own data! (contribute to open source by uploading data onto GitHub) Temperature(C) Fluence(dpa) LinearDimensionalChangesDl/l0(%)(unstressed) LinearDimensionalChangesDl/l0(%)(stressed) CreepStrainTensile & Compressive(%) TotalCreepStrain(%) 550 0,29 -0,07 -0,18 -0,11 0,11 550 0,41 -0,1 -0,21 -0,11 0,11 550 0,54 -0,15 -0,24 -0,09 0,09 550 1,66 -0,34 -0,56 -0,22 0,22 550 2,02 -0,42 -0,65 -0,23 0,23 550 2,21 -0,38 -0,61 -0,23 0,23 550 2,34 -0,49 -0,73 -0,24 0,24 550 2,38 -0,44 -0,77 -0,33 0,33 550 2,52 -0,56 -0,82 -0,26 0,26 550 2,67 -0,55 -0,77 -0,22 0,22 550 2,76 -0,56 -0,87 -0,31 0,31 550 3,92 -0,82 -1,26 -0,44 0,44 550 4,9 -1,06 -1,49 -0,43 0,43
  7. 7. 7/7/2017 / 7 © USNC 2017 Software packages Software is GNU v3 license and can be obtained from (GitHub repository) • https://github.com/makkemal/NGIMASEM • http://gitextensions.github.io/ (Tool for managing changes on GitHub) Requirements • Python anaconda with python 2.7 environment created (https://www.anaconda.com/download/ ) • FEM packages (Code written to be FEM solver independent, it can fit into any FEM solver ) –ANSYS (commercial verified and validated FEM code USNC will release a regulator qualified version ) –CalCuliX (open source http://www.dhondt.de/ for academic use ) FreeCad 0.17 (open source pre post processor for CalCulix https://freecadweb.org/)
  8. 8. 7/7/2017 / 8 © USNC 2017 Demo (Jupyter Notebook)
  9. 9. 7/7/2017 / 9 © USNC 2017 ASME Section III DIV 5 Section HH Graphite Simple Failure Methodology • Simple assessment uses standard two parameter Weibull equivalent stress • Allowable limits –10-2 –10-3 –10-3 1 exp( ) m n i sV i c P dv S            1 exp( ) m f V cV P dV S           dv, i Chain 1 1 exp m n j fV j i c P V S                 1 exp( ) m t f c P dv S          dv  dv ( , , ) 1 m t cS t cF S m e           
  10. 10. 7/7/2017 / 10 © USNC 2017 ASME Section III DIV 5 Section HH Graphite Full Failure Methodology Group volumes IL IIL v  Equivalent stress sorted 0 0 m v i c S X S S        part I II IIIL L L L    1 partL The Probability of Survival (PoS) of the part as a whole: The Probability of Failure (PoF) is then calculated as:1 1 , , I II I i i i i I IIi i n n n V V X X V V I IIL Le e                      PoS for each subgroup: . The modification to the Weakest Link Model essentially prescribes a minimum link size for each link. This is achieved by grouping volumes of material experiencing a similar stress state to form links (link volume).
  11. 11. 7/7/2017 / 11 © USNC 2017 Lifetime analysis Initial analysis show all components acceptable safe in expected operating conditions
  12. 12. 7/7/2017 / 12 © USNC 2017 Concluding remarks • This work presents a graphite simulation and analysis framework witch is open and free for anyone to use commercially or academically • This is a work in progress and by no means complete (no piece of software is ever complete) • The software is aimed at design using the ASME codes and standards as base requirements. • USNC will release a regulator qualified version in ANSYS
  13. 13. 7/7/2017 / 13 © USNC 2017 Michael P Hindley PhD PrEng Michael.Hindley@usnc.com Questions on this work only !

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