<?xml version='1.0' encoding='utf-8'?>
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  <cell id="1" material="1" region="-1" universe="1" />
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  <cell id="3" material="2" region="-2" universe="2" />
  <cell id="4" material="3" region="2" universe="2" />
  <cell id="5" material="3" universe="30" />
  <cell fill="4" id="6" region="-3" rotation="0.0 0.0 45.0" translation="-4.0 0.0 0.0" universe="5" />
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  <cell id="8" material="3" region="-5 3 4" universe="5" />
  <hex_lattice id="3" n_rings="3">
    <pitch>1.25</pitch>
    <outer>30</outer>
    <center>0.0 0.0</center>
    <universes>
  2
 1 1
1 2 1
 1 1
1 2 1
 1 1
1 1 1
 1 1
  1</universes>
  </hex_lattice>
  <lattice id="4">
    <pitch>1.25 1.25</pitch>
    <outer>30</outer>
    <dimension>4 4</dimension>
    <lower_left>-2.5 -2.5</lower_left>
    <universes>
2 2 2 2 
1 1 1 1 
1 1 1 1 
1 1 1 1 </universes>
  </lattice>
  <surface coeffs="0.0 0.0 0.25" id="1" type="z-cylinder" />
  <surface coeffs="0.0 0.0 0.5" id="2" type="z-cylinder" />
  <surface coeffs="-4.0 0.0 4.0" id="3" type="z-cylinder" />
  <surface coeffs="4.0 0.0 4.0" id="4" type="z-cylinder" />
  <surface boundary="vacuum" coeffs="0.0 0.0 8.0" id="5" type="z-cylinder" />
</geometry>
<?xml version='1.0' encoding='utf-8'?>
<materials>
  <material depletable="true" id="1">
    <density units="g/cm3" value="10.0" />
    <nuclide ao="1.0" name="U235" />
  </material>
  <material depletable="true" id="2">
    <density units="g/cm3" value="10.0" />
    <nuclide ao="1.0" name="U238" />
  </material>
  <material id="3">
    <density units="g/cm3" value="1.0" />
    <nuclide ao="2.0" name="H1" />
    <nuclide ao="1.0" name="O16" />
    <sab name="c_H_in_H2O" />
  </material>
</materials>
<?xml version='1.0' encoding='utf-8'?>
<settings>
  <run_mode>eigenvalue</run_mode>
  <particles>1000</particles>
  <batches>5</batches>
  <inactive>0</inactive>
  <source strength="1.0">
    <space type="point">
      <parameters>0.0 0.0 0.0</parameters>
    </space>
  </source>
</settings>
