•  DOE-­‐EM  high  level  waste  exists  in  underground  tanks  in  Hanford,  WA,  and  Savannah  River,  SC.  • Most  will  be  converted  into  borosilicate  glass  and  cast  into  stainless  steel  containers.  •  Some  radionuclides  cannot  be  effecEvely  processed  through  glass  melter  and  must  be  stabilized  in  ceramic  or  metal  hosts.  Containers  are  metallic.  

Center  for  Performance  and  Design  of  Nuclear  Waste  Forms  and  Containers:    WastePD    

Gerald  S.  Frankel,  Director  The  Ohio  State  University  

An  Energy  FronEer  Research  Center  

Background:  DOE-­‐EM  Waste  

WastePD Mission

Mission  Understand  the  fundamental  mechanisms  of  waste  form  performance,  and  apply  that  understanding  to  develop  tools  for  design  of  waste  forms  with  improved  performance.  

https://efrc.osu.edu

Waste  Form  Performance  Primary  waste  form  performance  parameter  is  resistance  to  degradaEon  over  long  periods  of  Eme  (>  105  y)  when  exposed  to  aqueous  environment.  

Center  for  Performance  and  Design  of  Nuclear  Waste  Forms  and  Containers  

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•  Gerald Frankel, Ohio State University, Center Director and Metals Team Lead •  Jincheng Du, University of North Texas •  Stephane Gin, CEA France •  Seong Kim, Penn State University, Synergy Lead in Commonalities •  Jie Lian, Rensselaer Polytechnic Inst., Ceramics Team Lead •  Jenifer Locke, Ohio State University •  Greg Olson, QuesTek Innovations/Northwestern Univ., Synergy Lead in Design •  Joe Ryan, Pacific Northwest National Laboratory •  John Scully, University of Virginia •  Christopher Taylor, Ohio State University •  John Vienna, Pacific Northwest National Laboratory, Glass Team Lead •  Jianwei Wang, Louisiana State University •  Wolfgang Windl, Ohio State University, Synergy Lead in Modeling/Simulation

WastePD PIs

Glass  Corrosion:  Background Glass  Corrosion  Mechanisms  •  Primary  mechanisms  control  rate  under  different  condiEons:  

•  Glass/water  reacEon  •  Reactant  and  product  transport  •  Ion  exchange  •  PrecipitaEon  

Challenges  •  Corrosion  is  exceedingly  slow  in  normal  condiEons.  

•  PassivaEon  occurs  at  very  thin  buried  interface.  

•  Reactants/products  far  from  equilibrium  and  amorphous.  

•  TransiEon  of  water  from  solvent  to  solute  in  reacEon  zone.  

Develop  fundamental  understanding  of  structure  and  chemistry  of  reacEng  glass-­‐soluEon  interface  and  determine  dominant  mechanism  of  glass  corrosion  and  impact  of  environmental  and  chemical  parameters.    

ObjecEves  

Glass  PassivaEon  Layer •  PassivaEon  layer  theorized  to  control  long-­‐term  rate  (stage  II  rate).  

•  Combined  computaEonal  and  experimental  approach  to  understand  passivaEon  layer  properEes.  

SimulaEon  of  Waste  Glass  

•  MD  simulaEons  obtained  detailed  atomisEc  structures  of  glass  bulk  and  surfaces,  as  well  as  glass  surface  altered  by  water  (using  reacEve  FF).  

•  Key  structural  parameters  compare  well  to  experiments;  e.g.,  B[4]  =  0.56  vs  0.52.  

•  [ZrO6]2-­‐  units  in  glass  are  preferably  charge-­‐compensated  by  Ca2+  ions.  

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•  Currently  modeling  water  migraEon  through  simulated  constricted    1-­‐4  nm  pore  structure.  

Glass  PassivaEon  Layer

•  ReacEng  glass  sample  flash  frozen  to  observe  glass/soluEon  reacEon  interface,  in  parEcular  water  regions  in  gel.  

•  First-­‐ever  APT  characterizaEon  of  cryo-­‐prepared,  site-­‐specific  lif-­‐out  specimen.      

Cryo-­‐APT  of  Flash  Frozen  Gel  

400μm  

Altered    Glass:  Gel  Layer  

Start  of  hydrated  layer  

Adsorbed  Frost  

Scale  cube:  2×2×2  nm3  14%  Si  isoconcentraEon  surface  

•  First-­‐ever  3-­‐D  image  of  gel.  •  Tortuous  interpenetraEng  glass  and  water  channels,  1-­‐4  nm  sized.  

•  Possible  composiEon  fluctuaEons.  

Glass  PassivaEon  Layer

•  Measured  rate  of  H218O  migraEon  across  

passivaEng  alteraEon  layer.  •  Water  migraEon  found  to  be  ultra  slow  process:  nano-­‐confinement  effect.  

Impact  of  Results  

•  Water  migraEon  slower  than  forward  rate  for  boron  release  -­‐  H2O  flux  is  rate  limiEng.    

•  Significantly  challenges  current  understanding  of  residual  rate  controlling  mechanism.  

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Water  Transport  Measurement  

Ceramic  Waste  Form  DegradaEon  Developing  fundamental  understanding  of  radionuclide  incorporaEon,  confinement  and  

transport  behavior  in  bulk  crystalline  ceramics  and  across  solid-­‐solid  and  solid-­‐liquid  interfaces.  

Primary  mechanisms:  •  Ceramic/water  reacEon  (hydraEon  and  hydrolysis)  

•  Reactant  and  product  transport  •  Ion  exchange  •  DissoluEon-­‐  reprecipitaEon  •  Redox  reacEon  

ScienEfic  Issues:  •  Congruent  or  non-­‐congruent  dissoluEon  

•  PassivaEon  layer  formaEon  mechanisms  

•  Nano-­‐scale  water  interacEon  • Microstructure  and  environmental  impacts  

4 µm 1 µm 500  nm  

Hydrolysis   Re-­‐precipitaEon  

Science of Corrosion Resistant Alloy Design •  Corrosion  Resistant  Alloy  (CRA)  design  has  always  been  empirical  and  Edisonian  -­‐  need  scienEfic  basis  for  computaEonal  design  of  CRAs.    

•  High  Entropy  Alloys  (HEAs)  and  Bulk  Metallic  Glasses  (BMGs)  provide  unique  design  opportuniEes  and  serve  as  excellent  model  materials  to  address  scienEfic  gaps.  

•  Developing  fundamental  understanding  of  CRA  behavior  and  computaEonal  approaches  for  predicEon  of  long  term  behavior,  with  experimental  validaEon.  

New  HEA:    Ni38Cr21Fe20Ru13Mo6W2  

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21%  Cr

WastePD Presentations and Posters PresentaEons  (in  Nuclear  Energy  and  Waste  session):  •  Design  and  Performance  of  Ceramic  Waste  Forms  for  Iodine  and  Chlorine  SequestraEon  with  High  Waste  Loadings    (Mon  4:00)  

•  Understanding  the  FormaEon,  Structure,  and  Stability  of  the  PassivaEng  Layer  Formed  on  Nuclear  Waste  Glass  during  Aqueous  Corrosion    (Tues  9:30)  

•  Integrated  ComputaEonal  Materials  Design  of  a  Corrosion  Resistant  High  Entropy  Alloy  for  Harsh  Environments:  The  Science  Behind  It    (Tues  2:10)  

Posters:  •  Iodine  IncorporaEon  and  Confinement  in  ApaEte  Waste  Forms  -­‐  MechanisEc  Understanding  and  Long  Term  Performance    (Mon)  

•  TransformaEon  of  the  RAMPAGE  PotenEal  Finng  Program  into  a  QuanEfied  High-­‐Performance  Code:  a  WastePD  -­‐  SciDAC  CollaboraEon    (Mon)  

•  Structure  and  Diffusion  of  ISG  Nuclear  Waste  Glasses  and  Their  AlteraEon  Layers  During  DissoluEon:  an  Integrated  SimulaEon  and  Experimental  Study    (Mon)  

•  ICME  Design  of  Novel  Corrosion-­‐Resistant  High-­‐Entropy  Alloys    (Tues)  •  Atomic  Probe  Tomography  Analysis  and  DFT  Modeling  of  Cryogenically-­‐Prepared  Specimens  (Tues)